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زمین شناسی اقتصادی - سال هشتم شماره 2 (پیاپی 15، پاییز و زمستان 1395)
  • سال هشتم شماره 2 (پیاپی 15، پاییز و زمستان 1395)
  • تاریخ انتشار: 1395/12/18
  • تعداد عناوین: 17
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  • پژوهشی
  • سلیمه سادات کمیلی، محمود خلیلی، هوشنگ اسدی هارونی، هاشم باقری، فریماه آیتی صفحات 285-305
    کانسار مس پورفیری کهنگ در شمال شرق اصفهان و بر روی کمربند آتشفشانی ارومیه- دختر واقع شده است. این کانسار در ارتباط با استوک های گرانیتوئیدی میوسن است که به درون سنگهای آتشفشانی و آذرآواری های ائوسن تزریق شده است. رخ داد سه پهنه دگرسانی اصلی شامل دگرسانی فیلیک (سرسیت، کوارتز، پیریت)، آرژیلیک (کائولینیت، ایلیت، ژاروسیت، تورمالین) و پروپیلیتیک (کلسیت، کلریت و اپیدوت) در این منطقه به تاثیر سیالات گرمابی در منطقه اشاره دارد. زون ها و کانی های تشخیص داده شده در منطقه شامل سه زون اکسید (هماتیت، گوتیت، ژاروسیت، مالاکیت و آزوریت)، غنی شده سوپرژن (کالکوپیریت، کالکوسیت و کوولیت) و هیپوژن (کالکوپیریت، پیریت و مگنتیت) است. بررسی های سیالات درگیر نشان می دهد که تزریق توده مولد کانه زایی در منطقه کهنگ در چندین فاز مختلف انجام شده که هر کدام باعث ایجاد سیالات مولد کانه زایی خاص خود شده اند. یکی از این سیالات با دمای میانگین ̊C330 و شوری بیش از 26 تا 47 درصد وزنی NaCl باعث رخ داد دگرسانی فیلیک در منطقه کهنگ شده است. میزان مقادیر ایزوتوپی اکسیژن برای نمونه های کوارتز بررسی شده از 79/8 تا ‰ 1/10 در تغییر است. مقادیر O18δ محاسبه شده برای سیالاتی که در تعادل با این نمونه ها بوده اند، 9/2 تا ‰ 2/4 است. دامنه تغییرات ترکیب ایزوتوپی هیدروژن در نمونه های کوارتز گرمابی کانسار کهنگ از 5/115- تا ‰ 62- است؛ در حالی که این نسبت در نمونه اپیدوتی معادل ‰ 3/75- بوده و میزان δD محاسبه شده برای سیالاتی که باعث دگرسانی پروپیلیتیک شده اند، ‰ 43- است. به طور کلی بررسی ایزوتوپ های پایدار در سیستم مس پورفیری کهنگ مشابه با سایر سیستم های مس پورفیری جهان، اختلاط آبهای جوی و ماگمایی در بخشهای حاشیه ای کانسار کهنگ (منطبق بر پهنه پروپیلیتیک) را تایید می کند.
    کلیدواژگان: سیالات درگیر، ایزوتوپ های پایدار، مس پورفیری، کانسار کهنگ، کمربند آتشفشانی ارومیه- دختر
  • فاطمه سرجوقیان صفحات 307-323
    توده گرانیتوئیدی نصرند، واقع در 40 کیلومتری جنوب شرق اردستان، دارای ترکیب گرانیت و گرانودیوریت است و دایک های متعددی از جنس دیوریت و گابرو در آن تزریق شده است. پژوهشهای پتروگرافی نشان می دهد، سنگهای گرانیتی و گرانودیوریتی دارای مجموعه کانی های اصلی کوارتز، ارتوکلاز، پلاژیوکلاز، آمفیبول و بیوتیت هستند که در شرایط تقریبا تعادلی به سر می برند. دایک های دیوریتی و گابرویی به طور عمده شامل پلاژیوکلاز، آمفیبول و پیروکسن هستند. آمفیبول های این مجموعه کلسیک است و ترکیب آنها در سنگهای گرانیتوئیدی معمولا از هورنبلند تا اکتینولیت تغییر می کند؛ در حالی که در دایک های دیوریتی به سمت هاستینگزیت متمایل شده است. ترکیب پلاژیوکلازها در سنگهای گرانیتوئیدی از آلبیت تا الیگوکلاز و در دایک های دیوریتی و گابرویی از الیگوکلاز تا بیتونیت متغیر است. پیروکسن در دایک ها از نوع کلینوپیروکسن است و ترکیب اوژیت- دیوپسید دارد. میانگین فشار حاکم بر توده نفوذی، در هنگام جای گیری حدود 54/1 کیلوبار است که با عمق حدود 9/5 کیلومتری پوسته مطابقت دارد؛ در حالی که آمفیبول های موجود در دایک های دیوریتی، میانگین فشار تشکیل حدود 96/2 را نشان می دهند و بیانگر شکل گیری آن در اعماق حدود 4/11 کیلومتری است. میانگین دمای تبلور توده نفوذی حدود 700 درجه سانتی گراد و آمفیبول دایک های دیوریتی 940 درجه سانتی گراد محاسبه شده است. فوگاسیته اکسیژن در ماگمای سازنده سنگهای گرانیتوئیدی و دایک دیوریتی در بالای محدوده بافر Ni-NiO بوده و به ترتیب میزان 9/12- و 5/10- را نشان می دهد. میزان آب ماگمای سازنده سنگهای گرانیتوئیدی و دایک دیوریتی، به ترتیب حدود 6/3 و 6/4 محاسبه شده است.
    کلیدواژگان: فشارسنجی، دماسنجی، فوگاسیته اکسیژن، میزان آب، نصرند، اردستان
  • سید رضا مهرنیا صفحات 325-342
    کانسار تکیه در جنوب شرقی اراک متعلق به زون ساختاری سنندج- سیرجان در پهنه فلززایی ملایر- اصفهان است که در امتداد گسلهای وارونه و چین خوردگی های منسوب به تاقدیس ویشان- تکیه از توان کانه زایی خوبی برخوردار است. پیدایش سرب و روی این منطقه مرهون فعالیت پساآتشفشانی آلپ است که در نزدیکی سازندهای کربناتی کرتاسه، به دو شکل هم زاد و دیرزاد تشکیل شده است. در این پژوهش، از دو روش آمار کلاسیک و فرکتال، به ترتیب برای دست یابی به الگوی توزیع خطی و غیرخطی عناصر هدف استفاده شده است تا ارزیابی دقیقی از وضعیت بی هنجاری های منطقه به دست آید. در روش کلاسیک، از شاخصهای مرکزی و پراکندگی برای تعیین همبستگی داده ها استفاده شده است؛ اما در روش فرکتال، معیار توزیع بی هنجاری ها بر اساس تغییر بعد اجزای متناظر بوده و با افزایش همبستگی داده ها همراه است. هر دو روش، امکان ارزیابی رابطه مکانی سرب و روی را با تغییرات ژئوالکتریک کانسار تکیه فراهم کرده اند؛ ولی روش فرکتال با استناد بر ویژگی های خودتشابهی کمیتها، به شاخص همبستگی معتبری دست یافته است که با شواهد کانی شناختی این منطقه مطابقت دارد. بدین ترتیب احتمال غنی شدگی سرب در واحدهای دگرسانی غرب تکیه، بیشتر از شرق آن است؛ اما وضعیت ژئوشیمیایی روی در واحدهای دگرسانی شرقی تکیه امیدوار کننده تر از غرب آن است.
    کلیدواژگان: توزیع غیر خطی، روش های آماری، فرکتال، کانسار تکیه
  • آرزو مرادی، ناهید شبانیان بروجنی، علیرضا داودیان دهکردی صفحات 343-358
    نتایج آنالیز به روش LA-ICP-MS تورمالین های موجود در توده گرانیت- گنایس میلونیتی A-type شمال شرق معدن ژان در پهنه سنندج- سیرجان به سن انتهای پرکامبرین، بیان کننده تبلور کانی تورمالین از این مذاب گرانیتی با پیشرفت روند تفریق است. از طرفی، در نمودار عنکبوتی به هنجار شده نسبت به میانگین ترکیب گرانیت- گنایس میلونیتی شامل تورمالین های مورد بررسی هم ناهنجاری مثبت و هم ناهنجاری منفی در Eu را می بینیم که بیانگر آن است که دانه های تورمالین غالبا توسط دانه های کوارتز و فلدسپار احاطه شده اند. با توجه به شواهد پتروگرافی، هرجا تورمالین در خمیره غالب وجود دارد، بیوتیت و آلانیت به صورت محدود هستند و یا اصلا وجود ندارند. با استفاده از نمودارهای فاز ترکیبی (بیوتیت، تورمالین و مسکویت)، مشخص شد هم پوشانی بین تورمالین و بیوتیت های موجود در این گرانیت- گنایس میلونیتی وجود ندارد، که نشان دهنده واکنش ناسازگار بین بیوتیت و تورمالین در این سیستم گرانیت-گنایس میلونیتی است.
    کلیدواژگان: تورمالین، روند تفریق، نمودار فاز، معدن ژان، زون سنندج - سیرجان
  • میر علی اصغر مختاری، محمد ابراهیمی، محمدرضا قربانی صفحات 359-380
    اسکارن مس- آهن آوان در نتیجه نفوذ باتولیت گرانیتوئیدی قره داغ به داخل سنگهای کربناته ناخالص کرتاسه بالایی تشکیل شده است. اسکارن آوان متشکل از پهنه های مرمر، اگزواسکارن و اندواسکارن بوده و بخش اصلی آن پهنه اگزواسکارن، است. بررسی های کانی شناسی بیانگر آن است که پهنه اگزواسکارن شامل زیرپهنه های گارنت اسکارن، پیروکسن- گارنت اسکارن و کانه اسکارن است. مهمترین کانی کالک سیلیکاته بی آب در پهنه اگزواسکارن، گارنت و ترکیب آن اوگراندیتی (Ad53-89) است. برخی بلورهای گارنت، منطقه بندی دارد و ترکیب آنها به طرف حاشیه ها به آندرادیت خالص (Ad99) میل می کند. کلینوپیروکسن موجود در زیرپهنه پیروکسن- گارنت اسکارن از نوع دیوپسید (Di75-96) است. زیرپهنه کانه اسکارن از کانه های مگنتیت، هماتیت، پیریت، کالکوپیریت، بورنیت، مالاکیت و گوتیت تشکیل شده است. وجود میزان محدود ولاستونیت در مجموعه کانی شناسی اسکارن آوان، هم رشدی بلورهای گارنت و کلینوپیروکسن و نبود هاله واکنشی بین این دو کانی و نبود بافتهای جانشینی نشان دهنده آن است که این کانی ها به صورت هم زمان در محدوده دمایی C°600- 430 و فوگاسیته اکسیژن بیشتر از 10-26 تشکیل شده اند.
    کلیدواژگان: کانی شناسی، اسکارن مس - آهن، باتولیت قره داغ، آوان، خاروانا، آذربایجان خاوری
  • مروت فریدآزاد صفحات 381-398
    پریدوتیت های گوشت های بخش مهم کمپلکس دگرگونی شرقی افیولیت خوی هستند. این سنگها محدوده سنی از اوایل ژوراسیک تا اواخر کرتاسه دارند و کم و بیش سرپانتینی شده اند. بر اساس بررسی های شیمی کانی بر روی هارزبورگیت ها، ترکیب اولیوین ها بین Fo89.46 Fa10.37 تا Fo89.86 Fa10.0 در نوسان بوده و عدد منیزیم (Mg# = Mg/(Mg+Fe2+)) تمامی نقاط آنالیز شده، برابر 90/0 و ترکیب اولیوین ها از نوع فورستریت است. ترکیب اعضای نهایی ارتوپیروکسن ها بین En86.022 Wo2.491 Fs9.368 تا En87.314 Wo6.719 Fs10.474 در نوسان است. عدد منیزیم (Mg# = Mg/(Mg+Fe2+)) این کانی ها 90/0 و ترکیب آنها از نوع انستاتیت است. ترکیب اعضای نهایی کلینوپیروکسن ها بینEn44.159 Wo46.910 Fs4.323 Ac1.459 تا En46.803 Wo49.589 Fs4.786 Ac2.081 در نوسان است. عدد منیزیم (Mg# = Mg/(Mg+Fe2+)) این کانی ها 91/0 است. کلینوپیروکسن های مورد بررسی بسیار غنی از کروم (21/1-87/0Cr2O3=) و از نوع دیوپسید هستند. غنی بودن ارتوپیروکسن ها و کلینوپیروکسن ها از کروم، نشان دهنده ذوب بخشی محدود پریدوتیت هاست. بررسی های مینرال شیمی، ارتباط این هارزبورگیت ها را با محیط اقیانوسی نشان می دهند. همچنین اعداد منیزیم بالا در کانی های بالا و درصد فوستریت بالا در اولیوین ها نشان دهنده منشا زمین ساختی این سنگهاست. بررسی های دما و فشارسنجی برای تخمین شرایط فشار- دمای تشکیل هارزبورگیت های مورد بررسی انجام شد. برای دماسنجی از روش های ارتوپیروکسن (تک پیروکسن)، کلینوپیروکسن- اولیوین و ارتوپیروکسن- کلینوپیروکسن استفاده شد و دمای کلی حدود100 ±1100 درجه سانتی گراد به دست آمد. برای تخمین فشار از فشارسنج محتوای کروم درکلینوپیروکسن استفاده شد و فشار 4/2 ± 22 کیلو بار برآورد شد.
    کلیدواژگان: هارزبورگیت، شیمی کانی، ذوب بخشی، زمین - دما فشارسنجی، افیولیت خوی
  • مریم آهنکوب، یوشی هیرو آساهارا صفحات 399-413
    در رشته کوه های میشو، در شمال غرب ایران، مجموعه سنگهای گرانیتی توسط تعدادی دایک های بازیک با طول 2 تا 10 متر و پهنای 50 تا 150 سانتی متر قطع شده اند. این دایک ها دارای کانی شناسی اصلی الیوین، پلاژیوکلاز، پیروکسن هستند. داده های ژئوشیمیایی بیانگر ماهیت کالک آلکالن این دایک ها همراه با تهی شدگی در Nb، Ta و Ti و ویژگی بازالت های درون صفحه ای هستند که در موقعیت زمین ساختی مرتبط با زونهای کششی پس از برخورد تشکیل شده اند. نتایج آنالیزهای ایزوتوپی Rb-Sr و Sm-Nd به جای گزینی این دایک ها در 232 (میلیون سال) پیش، بیانگر منشا گوشته تهی شده با کمی اختلاط پوسته ای است. مقادیر منفی 4- تا 1 εNd(T) = - و نسبتهای Sr 86Sr/87، انحراف ترکیب شیمیایی ماگمای مادر نسبت به ترکیب آرایه گوشته ای را نشان می دهد که دچار آلایش پوسته ای شده است. بر اساس میزان εNd(T) ، نسبت ایزوتوپ 87Sr/86Sr اولیه و نسبت ایزوتوپ 144Nd Nd / 143 اولیه سنگ کل نمونه ها، به دنبال بسته شدن پالئوتتیس در شمال غرب ایران به واسطه تشکیل زونهای کششی در درون پوسته قاره ای، ماگمای دایک های میشو از یک منشا گوشته تهی شده با غنی شدگی نسبت به عناصر LILE تشکیل شده و به درون سنگهای گرانیتی تزریق شده اند.
    کلیدواژگان: داده های ایزوتوپی، Nd-Sr، تعیین سن، کالک آلکالن، زون های کششی دایک بازیک، کوه های میشو
  • فاطمه هرمزی نژاد، فاطمه راست منش، علیرضا زراسوندی صفحات 415-429
    هدف از پژوهش، ارزیابی میزان آلودگی خاک به عناصر جزئی (نیکل، آهن، روی، کروم، منگنز و سرب) مورد نظر در نمونه های خاک اطراف مجتمع صنایع فولاد خوزستان است. به این منظور تعداد 13 نمونه خاک سطحی از عمق ( 0- 10 سانتی متری) با در نظر گرفتن جهت وزش باد غالب منطقه برداشت شد. پس از آماده سازی، نمونه ها به روش طیف سنجی نشری پلاسمای جفت شده القایی تجزیه و تحلیل شد. برای ارزیابی آلودگی عناصر جزئی از شاخصهای گوناگون شامل عامل آلودگی، درجه آلودگی، درصد غنی شدگی انسان زاد و نیز درجه اشباع فلزات استفاده شد. همچنین از آنالیز آماری تحلیل مولفه اصلی برای تشخیص منشا فلزات استفاده شد. میانگین غلظت عناصر جزئی نمونه ها با غلظت این فلزات در خاکهای غیرآلوده مقایسه شد. ارزیابی شاخصهای مورد استفاده نشان داد، نمونه های خاک نزدیک به محل کارخانه و در جهت پایین دست باد، بیشترین میزان آلودگی را نشان می دهند که این نتایج با یافته های مربوط به شاخص درصد انسان زاد و درجه اشباع فلزات هم خوانی داشت. از بررسی تحلیل مولفه اصلی مشخص شد، فلزات نیکل و آهن تحت تاثیر عملکرد هر دو عامل زمین زاد و انسان زاد و فلزات روی، منگنز و سرب تحت تاثیر عامل انسان زاد هستند و نیز فلز کروم احتمالا دارای منشا زمین زاد است.
    کلیدواژگان: عناصر جزئی، صنایع فولاد خوزستان، درجه آلودگی، درصد غنی شدگی انسان زاد، شاخص درجه اشباع فلزات، اهواز
  • ابراهیم طالع فاضل، بهزاد مهرابی، حسن زمانیان، معصومه حیات الغیبی صفحات 431-455
    کانی سازی مس- مولیبدن سنج با ژئومتری استوک ورک و انتشاری در محل همبری توده نفوذی سنج و سنگ میزبان توف تا آندزیت پورفیری تشکیل شده است. کانه زایی کوارتز- سولفیدی استوک ورک همراه دگرسانی پتاسیک- فیلیک شامل رگه های کوارتز- بیوتیت-کالکوپیریت (QBC)، کوارتز- مولیبدنیت (QM) و کوارتز- پیریت (QP) است. طبق شواهد، میان بارهای اشباع از نمک اولیه در رگه های QBC با دمای بالا (C°450
    کلیدواژگان: کانی سازی مس - مولیبدن، میان بارهای سیال، تحول سیال کانه ساز، کانسار سنج، البرز مرکزی
  • امید یزدان پناه، علی اکبر حسن نژاد صفحات 457-472
    منطقه دهنو- عبید در فاصله 20 کیلومتری شمال شرق شهر عشق آباد در بلوک طبس و در قسمت شرقی زون ساختاری ایران مرکزی واقع شده است. لیتولوژی غالب در محدوده مورد بررسی شامل شیل های تیره رنگ و ماسه سنگهای ریزدانه و درشت دانه ی آرکوزی و لیتیک آرکوز است که تا اندازه ای دگرگونی درجه پایین را نشان می دهند. در این منطقه، کانی سازی سیلیس به صورت رگه ای، رگه چه ای و در قسمتهایی به صورت عدسی های بزرگ سیلیسی رخ داده است. بررسی ریز دماسنجی شاره های درگیر در کانی کوارتز نشان می دهد که دمای همگن شدگی بین 247 تا 336 درجه سانتی گراد و درجه شوری از 9/0 تا 8/15 درصد وزنی معادل نمک طعام و چگالی سیال کانی ساز بین 7/0 تا 9/0 گرم بر سانتی متر مکعب در تغییر است. با توجه به شواهد به دست آمده از بررسی های صحرایی و آزمایشگاهی، از جمله بررسی ریز دماسنجی و همچنین حضور فاز کربنیک در شاره های درگیر، احتمالا سیلیس های منطقه زیر شرایط دگرگونی تشکیل شده اند.
    کلیدواژگان: سیلیس، شاره های درگیر، فاز کربنیک، دگرگونی، دهنو - عبید
  • بهاره فاضلی، محمود خلیلی، روی بیورز، مهین منصوری اصفهانی، زهرا لقمانی دستجردی صفحات 473-491
    توده پلوتونیک منطقه قلعه یغمش در منتها الیه بخش غربی استان یزد و کمربند ماگمایی ارومیه- دختر قرار دارد و شامل دیوریت، کوارتز دیوریت، تونالیت، گرانودیوریت و گرانیت به سن الیگوسن می شود. عمده سنگ تشکیل دهنده منطقه، تونالیت است. ریولیت، ریوداسیت و نیز توف آندزیتی، ریوداسیتی و ریولیتی به سن ائوسن، گدازه ها و پیروکلاستیک های این منطقه را تشکیل می دهد. پلاژیوکلاز، ارتوکلاز، کوارتز، آمفیبول و بیوتیت، کانی های اصلی، پیروکسن، زیرکن، آپاتیت، اسفن، تورمالین و کانی های کدر از کانی های فرعی و نیز کلریت، اپیدوت و کلسیت در شمار کانی های ثانویه این توده نفوذی است. بر اساس داده های پتروگرافی، مینرال شیمی و ژئوشیمیایی، توده گرانیتوئیدی مورد بررسی از نوع I (گروه مگنتیت) با ترکیب کالک آلکالن و متاآلومین است. محتوای بالای LILE (Ba، Sr، K و Cs) و ناهنجاری منفی عناصر گروه HFSE (Ti،Nb ، Zr و Y) در این سنگها از جمله ویژگی های ماگماتیسم مرتبط با فرورانش است. بر این اساس، سنگهای گرانیتوئیدی قلعه یغمش دارای یک خاستگاه واحد بوده است و در پهنه فرورانش و در ارتباط با کمانهای آتشفشانی کالک آلکالن حاشیه فعال قاره ای به وجود آمده است. به احتمال زیاد، منشا ماگمای توده مورد بررسی از ذوب بخشی آمفیبولیت های پوسته زیرین (و احتمالا مواد رسوبی پوسته) است و تبلور تفریقی مذاب در سطوح بالاتر پوسته، تنوع سنگ شناسی این توده را سبب شده است. به نظر می رسد ماگمای بازیک حاصل از ذوب گوشته که در پوسته جای گزین شده، گرمای لازم برای ذوب پوسته را فراهم کرده است. شواهد صحرایی (وجود انکلاوهای میکروگرانولار مافیک با مرزهای مشخص) و یافته های پتروگرافی نظیر تشابه کانی شناسی انکلاو و سنگ میزبان، آپاتیت های سوزنی، حواشی تحلیل رفته کانی هایی همچون آمفیبول و پلاژیوکلاز و فراوانی بیشتر بیوتیت و هورنبلند در انکلاو نسبت به سنگ میزبان می تواند بیانگر وقوع پدیده اختلاط ماگماهای اسیدی و بازیک در تشکیل این توده باشد. توده پلوتونیکی قلعه یغمش با استفاده از نمودار SiO2 در برابر P2O5 در محدوده دمایی کمتر از °C800 تا کمی بیشتر از °C850 متبلور شده است.
    کلیدواژگان: گرانیتوئید نوع I، قوس آتشفشانی، ائوسن - الیگوسن، قلعه یغمش، ارومیه - دختر
  • رضوان مهوری، موسی نقره ئیان، مرتضی شریفی، محمد علی مکی زاده، سید حسن طباطبایی، قدرت ترابی صفحات 493-506
    سنگهای آتشفشانی و نیمه عمیق نابر در کمربند آتشفشانی- نفوذی ارومیه- دختر جای گزین شده اند. این مجموعه شامل آندزیت، تراکی آندزیت، داسیت، ریولیت، پیروکسن دیوریت پورفیری و سنگهای آذرآواری (توف) است .بررسی شیمی کانی های کلینوپیروکسن در سنگهای آندزیت و پیروکسن دیوریت پورفیری نشان می دهد که ترکیب کلینوپیروکسن ها از نوع اوژیت با ترکیب (42/43- 56/41Wo63/48- 78/39En36/16- 77/8Fs) است. توزیع آلومینیم در ساختار این کانی بیانگر تبلور کانی از یک ماگمای آب دار با فشار بخار آب بیشتر از 10 درصد است. همچنین کلینوپیروکسن ها در فشارهای کم تا متوسط تشکیل شده که بیانگر تبلور آنها طی صعود ماگما و در اعماق متفاوت است. میزان آهن فریک در کلینوپیروکسنها نشان دهنده فوگاسیته بالای اکسیژن ماگماست. زمین دما- فشار سنجی کلینوپیروکسن ها گستره دمایی 950 تا 1200 درجه سانتی گراد و فشار 2 تا 5 کیلوبار را نشان می دهد. شیمی کانی کلینوپیروکسن نشان می دهد که سنگهای آتشفشانی و نیمه عمیق نابر دارای ماهیت کالک آلکالن و در ارتباط با محیطهای کوه زایی هستند.
    کلیدواژگان: کلینوپیروکسن، دما - فشارسنجی، تکتونوماگمایی، نابر، ارومیه - دختر
  • مریم فیضی، محمد ابراهیمی، حسین کوهستانی، میر علی اصغر مختاری صفحات 507-524
    منطقه آق کند در فاصله 48 کیلومتری شمال زنجان واقع شده است و بخشی از زیرپهنه طارم- هشتجین در پهنه ساختاری البرز باختری- آذربایجان محسوب می شود. کانه زایی مس در این منطقه به صورت رگه کوارتز- فلوئورین مس دار در میزبان گدازه های بازالت آندزیتی ائوسن رخ داده است. بر اساس بررسی های میکروسکپی، کانه های فلزی در منطقه آق کند شامل کالکوپیریت و به مقدار کمتر اسپکیولاریت، کانی های مرحله سوپرژن و کانی های باطله کوارتز، فلوئورین و کلریت هستند. مهمترین بافتهای کانسنگ شامل دانه پراکنده، رگه-رگه چه ای، برشی، پرکننده فضای خالی، جانشینی، کوکاد، قشرگون، گل کلمی و پرمانند است. شش مرحله کانه زایی در رخ داد معدنی مس آق کند، قابل تشخیص است. این مراحل با رگه- رگه چه های فلوئورین (مرحله اول) آغاز و به ترتیب با ته نشست کوارتز و کالکوپیریت در رگه ها و سیمان گرمابی برش ها (مرحله دوم)، رگه- رگه چه های کوارتز- اسپکیولاریت (مرحله سوم)، رگه چه های منفرد و یا دسته رگه چه های نیمه موازی تا متقاطع کوارتز (مرحله چهارم)، بافت رگه- رگه چه ای و پرکننده فضاهای خالی کلریت (مرحله پنجم) و سرانجام تشکیل مالاکیت و هیدروکسیدهای آهن به صورت رگه- رگه چه ای و پرکننده فضاهای خالی (مرحله ششم) ادامه یافته است. دگرسانی گرمابی به بخشهای سیلیسی و کلریتی شده پهنه های کانه دار محدود می شود. دگرسانی پروپلیتی (سریسیت، اپیدوت، کلسیت و کلریت) در خارج از بخشهای کانه دار رخ داده است. مقایسه الگوی عناصر کمیاب در گدازه های بازالت آندزیتی سالم و بدون کانه زایی ائوسن، گدازه های ریولیتی- ریوداسیتی الیگوسن و بخشهای کانه دار، نشان دهنده ارتباط احتمالی سیالات کانی ساز با گدازه های ریولیتی- ریوداسیتی الیگوسن است. هرچند شسته شدن برخی عناصر از گدازه های بازالت آندزیتی میزبان نیز می تواند در تشکیل کانی سازی منطقه موثر بوده باشد، ویژگی های رخ داد معدنی مس آق کند با کانسارهای اپی ترمال فلزات پایه قابل مقایسه است.
    کلیدواژگان: زمین شناسی، کانه زایی، زمین شیمی، آق کند، زنجان، طارم - هشتجین
  • ریحانه احمدی روحانی، محمدحسن کریم پور، بهنام رحیمی، آزاده ملکزاده شفارودی، اورس کلوتزلی، ژوزه فرانسیسکو سانتوس صفحات 525-552
    توده های گرانیتوئیدی بجستان در شرق شهر بجستان، جنوب غرب استان خراسان رضوی واقع شده اند. توده های عمیق و نیمه عمیق اسیدی برون زد یافته در این منطقه دارای ترکیب سینوگرانیتی، مونزوگرانیتی و گرانیتی هستند. نتایج سن سنجی نشانگر حضور دو فاز ماگماتیسم در منطقه است. توده های بیوتیت مونزوگرانیت، گرانیت پورفیری و سینوگرانیت، دارای سن کرتاسه بالایی، کامپانین (76-79 میلیون سال) است و تنها توده پیروکسن هورنبلند بیوتیت مونزوگرانیت در جنوب غرب محدوده مورد بررسی، دارای سن الیگوسن (5/1±7/30 میلیون سال) است. در توده های با سن کرتاسه بالایی، میزان 87Sr/86Sr اولیه بین 710898/0 تا 717908/0 و 143Nd/144Nd اولیه بین 512058/0 تا 512211/0 و єNdI در دامنه 38/7- تا 65/10- متغیر است. نسبتهای 87Sr/86Sr و 143Nd/144Nd اولیه و єNdI برای توده پیروکسن هورنبلند بیوتیت مونزوگرانیت به ترتیب 713292/0، 512186/0 و 06/8- است. از نظر ویژگی های ژئوشیمیایی، توده های بالا، عمدتا ماهیت پرآلومین دارد و به گرانیتوئیدهای تیپ S دسته احیایی (ایلمینیت) تعلق دارند. با توجه به نتایج بررسی های انجام شده، منشا توده های نفوذی منطقه، پوسته ای و حاصل ذوب رسوبات دگرگون شده با ترکیب پسامیت و مرتبط با زون برخورد است. توده های گرانیتوئیدی با سن کرتاسه بالایی منطقه بجستان در مقایسه با سایر توده های متعلق به کرتاسه بالایی، مانند بزمان، گزو و کجه، دارای نسبت بالاتر 87Sr/86Sr هستند. توده پیروکسن هورنبلند بیوتیت مونزوگرانیت با سن الیگوسن با دارا بودن ویژگی های مشابه با توده های کرتاسه بالایی، نشان دهنده ادامه محیط زون برخوردی در این بخش از بلوک لوت است.
    کلیدواژگان: سن سنجی، ایزوتوپ های Rb-Sr و Sm-Nd، توده های گرانیتوئیدی احیایی، بجستان، بلوک لوت، ایران
  • مهشید ملکیان دستجردی، سید سعید محمدی، ملیحه نخعی، محمدحسین زرین کوب صفحات 553-568
    منطقه کنگان در شمال شرق سربیشه، خراسان جنوبی و حاشیه شرقی بلوک لوت قرار دارد. در این منطقه، گدازه های بازالتی بر روی سنگهای حدواسط و اسیدی شامل آندزیت، داسیت، ریولیت (گاهی پرلیتی) رخنمون دارد. کانی های اصلی بازالت شامل پلاژیوکلاز، اولیوین و پیروکسن، در آندزیت شامل پلاژیوکلاز، پیروکسن، بیوتیت، آمفیبول و در گدازه های اسیدی متشکل از پلاژیوکلاز، کوارتز، سانیدین، بیوتیت و آمفیبول هستند. سنگهای حدواسط و اسیدی ماهیت کالک آلکالن پتاسیم متوسط تا بالا و بازالت ماهیت آلکالن دارد. غنی شدگی LREE نسبت به HREE (7/28-14/21= Ce/Yb)، نسبت Zr/Y بالا (79/4 تا81/10)، غنی شدگی LILE و آنومالی منفی Eu، Nb، P،Ti ،Ba و Sr در گدازه های حدواسط و اسیدی بیانگر ماگماتیسم کالک آلکالن وابسته به فرورانش است. ویژگی های ژئوشیمیایی نظیر نسبت La/Yb بالا (18/8)، محتوای پایین Rb به همراه نمودارهای تمایز محیط زمین ساختی، بیانگر محیط درون صفحه ای قاره ای برای بازالت است. ماگمای سازنده سنگهای مورد بررسی، حاصل ذوب بخشی یک منبع گارنت لرزولیتی غنی شده در عمق 100 تا 110 کیلومتری است.
    کلیدواژگان: آندزیت، آلکالی بازالت، حاشیه قاره ای فعال، کنگان، بلوک لوت
  • علیرضا الماسی، محمدحسن کریم پور، کیکو هاتوری، ژوزه فرانسیسکو سانتوس، خسرو ابراهیمی نصرابادی، بهنام رحیمی صفحات 569-592
    منطقه اکتشافی در 30 کیلومتری شمال شرق کاشمر، در بخش مرکزی کمربند آتشفشانی و نفوذی خواف- کاشمر- بردسکن واقع شده است. زمین شناسی منطقه شامل سنگهای آتشفشانی و نفوذی نیمه عمیق و عمیق مافیک تا اسیدی کالک آلکالن با توانایی بالا و شوشونیتی به سن پالئوسن- ائوسن میانی است. توده های گرانیتوئیدی با پذیرفتاری مغناطیسی از 2 تا (SI)5-10 × 1654 جزو دسته مگنتیتی- ایلمنیتی هستند. دگرسانی و کانی سازی به دو صورت: 1) دگرسانی بیضوی- خطی شدید تا متوسط آرژیلیک- سیلیسی و سرسیتی شدن و دگرسانی متوسط پروپلیتیک همراه بارگه های کالکوپیریت- کوارتز ± پیریت در مناطق بهاریه، اوچ پلنگ و سرسفیدال، و 2) دگرسانی متوسط هماتیتی- کربناتی- کلریتی- سیلیسی همراه با رگه های غنی از اسپکیولاریت، کوارتز – گالن و باریت عقیم به همراه برش گرمابی در کمرمرد است. رگه ها بی هنجاری عناصر طلا، مس، سرب و روی دارند. بیشترین غنی شدگی طلا (تا 15 پی پی ام) به همراه مس، سرب و روی (هر کدام تا > 1 درصد) در برش گرمابی و رگه های غنی از اسپکیولاریت رخ داده است. بر اساس بررسی سیالات درگیر، سیستم به صورت H2O-NaCl-CaCl2، دماها متوسط تا نسبتا زیاد و بین 245 تا 530 درجه سانتی گراد و شوری ها نسبتا کم تا متوسط (بین 14 تا 6/17 (wt% NaCl)) است. دماها و شوری های بیشینه و کمینه به ترتیب مربوط به سیالات درگیر برش گرمابی و رگه های کوارتز - گالن است. هم زیستی بین سیالات درگیر دوفازی غنی از مایع و بخار و سیالات تک فاز گازی کم در رگه ها، برشی شدن سنگ و مشاهده سیالات درگیر نوع CO2 دار اندک در رگه های قله کمرمرد و نبود کوارتز حفره دار در کلاهکهای سیلیسی منطقه، نشان دهنده شرایط نزدیک به جوشش است. فراوانی کانی های اسپکیولاریت و باریت و مقدار کم کانی های سولفیدی نشان دهنده شرایط اکسیدان محلول و تاثیر کمپلکس های کلریدی CO2 دار در حمل، دخالت نداشتن آبهای متئوریک و ته نشست عناصر فلزی محلول گرمابی با کاهش تدریجی دما است. شواهد مختلف بیانگر سطحی ترین و بخشهای با عمق متوسط از یک سیستم کانی سازی مگنتیت طلا دار نوع IOCG دور از کمان در کاشمر است.
    کلیدواژگان: دگرسانی، کانی سازی رگه ای، سیالات درگیر، IOCG، کاشمر
  • سعید سعادت صفحات 593-607
    منطقه کلاته ناصر در شمال شرق بلوک لوت واقع شده است. توده های نفوذی با ترکیب هورنبلند کوارتز مونزونیت، بیوتیت گرانودیوریت و پیروکسن کوارتز دیوریت در محدوده رخنمون دارند. بخش اصلی محدوده توسط سنگهای کربناته پوشیده شده است که گاه به مرمر و به طور محدود به اسکارن تبدیل شده اند. کانه زایی آهن عمدتا در همین واحد کربناته دیده می شود. مقادیرF2O3 بین 31 تا 96 درصد، P2O5 حداکثر 45/0 درصد و TiO2 بین 02/0 تا 54/0 درصد در نمونه های کانسنگ متغیر است. بیشترین شدت میدان در منطقه حدود 70000 و کمترین آن حدود 40000 نانوتسلا اندازه گیری شده است. نقشه های شدت کل، برگردان به قطب، سیگنال تحلیلی، مشتق اول قائم و ادامه فراسو تهیه شد. نتایج به دست آمده از حفاری های انجام شده، انطباق بسیار خوبی با بررسی های مغناطیس سنجی دارد و گسترش کانی سازی آهن تا عمق 50 متر آشکار شده است. میزان پایین پذیرفتاری مغناطیسی توده های نفوذی و آلتراسیون ضعیف آنها نشان می دهد که این توده ها نقش اصلی در کانی سازی آهن ندارند و توده نفوذی مولد کانی سازی با فاصله و به احتمال زیاد در اعماق بیشتر قرار دارد.
    کلیدواژگان: کانی سازی مگنتیت، مغناطیس سنجی زمینی، کلاته ناصر، آهنگران، بلوک لوت
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  • Salimeh Sadat Komeili, Mahmoud Khalili, Hooshang Asadi Haroni, Hashem Bagheri, Farimah Ayati Pages 285-305
    Introduction
    The Kahang Cu- Mo deposit is situated approximately 73 Km northeast of Isfahan. Asadi (2007) identified a geological reserve of 40 Mt (proven reserve) grading at 0.53 Cu, 0.02 Mo and estimated reserve of 120 Mt. All the rock types in the region have been subjected to hydrothermal solutions which gave rise to three different alteration facies. The dacite and rhyodacite volcanic rocks and granitic- granodioritic stocks have experienced phyllic alteration. Disseminated and stockwork siliceous veins are the major styles of mineralization in this zone. Intermediate argillitic alteration developed on a part of dacitic and rhyodacitic rocks whereas andesite and basaltic-andesite plus related pyroclastic rocks have been subjected to propyllitic alteration. This paper presents the results of geological and mineralogical studies carried out in the Kahang area. This preliminary information is integrated with additional data on ore mineralogy, fluid inclusions and stable isotopes in view of understanding the genesis of the Cu- Mo deposit and the nature of the fluids involved in ore formation.
    Materials And Methods
    A total of 18 polished thin sections were prepared at the University of Isfahan for optical study. Fluid inclusions study was carried out on 8 double polished quartz thin sections (stockworks containing ore mineralization from phyllic zone). H – O stable isotope analysis was performed on 4 quartz samples from siliceous stockworks (from phyllic altered zone) and one vein epidote sample (from propyllitic zone). All isotopic analyses were performed at the University of Oregan, Oregan, USA.
    Discussion
    In the investigated mineralization area, the hypogene zone is characterized by the presence of pyrite, chalcopyrite, bornite and magnetite. Hematite, goethite, jarosite, malachite and azurite are the predominant minerals of supergene zone. The major textures of the primary sulfides are disseminated, vein and veinlet. Pyrite is the most common hypogene sulfide mineral and chalcopyrite is the predominant Cu- sulfide in the Kahang mineralized area. Primary magnetite grains having irregular boundaries formed in association with phyllic –potassic altered zones (Afshooni et al., 2014). Chalcocite and covellite as secondary copper minerals in the enriched supergene zone replaced the chalcopyrite.
    Thermometric studies on fluid inclusions conducted on quartz veins was related to the phyllic zone. Almost all studied fluid inclusions were homogenized to the liquid phase. Hydrothermal solutions with salinity over 26% wt equivalent NaCl, comparable with those of the other porphyry deposits (Morales Ruano et al., 2002; Hezarkhani, 2006; Hezarkhani, 2009) were responsible for the formation of the Kahang porphyry copper deposit. Homogenization temperatures of 200-450°C and 500-550°C were obtained from heating- cooling experiments on the two and multi phase fluid inclusions. The presence of gas riched fluid inclusions together with those of liquid riched and multiphase different salinities in the quartz veins as well as the occurrence of hydrothermal breccias are indicative of boiling fluids.
    Result
    In the Kahang porphyry Cu- deposit, the oxidation zone is characterized by hematite, goethite, jarosite, malachite, and azurite; the supergene zone is identified by chalcocite, chalcopyrite and coevllite; and chalcopyrite, pyrite and magnetite are the mineral assemblage of the hypogene zone. The volcanic as well as the plutonic rocks of the area have been hydrothermally altered which gave rise to the formation of propyllitic, intermediate argillic and mineralized phyllic zones. Fluid inclusion study on quartz veins revealed salinity over 26% wt equivalent NaCl and homogenization temperature of 200-450°C and 500-550°C. The presence of gas riched fluid inclusions together with those of liquid riched and multiphase different salinities in the quartz veins as well as the occurrence of hydrothermal breccias are indicative of boiling event, owing to the pressure reduction in the faulted zones and mineralized hydrothermal breccias and/or increase of hydrostatic pressure compared to the lithostatic pressure. This may be caused by the instability of the copper complex accompanied by precipitation of copper. The decrease of temperature and the diluted mineralized fluids could be the cause of precipitation of copper due to mixing with the meteoric water. Stable isotope study supports the mixing of magmatic and meteoric waters in the peripheral zones of ore deposit (phyllic and propyllitic zones).
    Keywords: Fluid Inclusions, Stable isotopes, Cu porphyry, Kahang deposit, Urumieh-Dokhtar magmatic belt
  • Fatemeh Sarjoughian Pages 307-323
    Introduction
    Mineral composition is sensitive to variations in the composition of the magma and can be used to characterize the physical conditions of crystallization such as temperature, pressure, oxygen fugacity and water content. The studies have demonstrated that geobarometery by amphibole provides a tool for determining the depth of crystallization and knowledge of the depth of crystallization of hornblende through to solidification of calc-alkaline plutons (Anderson and Smith, 1995). The composition of pyroxene can be used as crystallization pressure and temperature indicators of pyroxene too.
    Anlytical
    Methods
    The mineral compositions of the Nasrand intrusion were determined by electron microprobe, with special emphasis on the amphibole, feldspar, and pyroxene at the Naruto University, Japan, the EPMA (Jeol- JXA-8800R) was used at operating conditions of 15 kV, 20 nA acceleration voltage and 20s counting time.
    Results
    The Nasrand intrusion (33°13'–33°15' N, 52°33'–52°34'E) with an outcrop area of about 40 km2 is situated in the Urumieh–Dokhtar magmatic belt, SE of Ardestan. It is composed of granite and granodiorite and various dikes of diorite and gabbro which are intruded in it. It is intruded into Eocene volcanic rocks, including andesite, rhyolite, and dacite. The petrographical studies indicate that the granitic and granodioritic rocks contain major minerals such as quartz, K-feldspar, plagioclase, and amphibole, which are in an approximate equilibrium state. The gabbroic-dioritic dikes usually show microgranular porphyric texture. They mainly consist of plagioclase, amphibole, and pyroxene. The plagioclase shows variable composition from albite to oligoclase in the granitoid rocks and from oligoclase to bytownite in dioritic and gabbroic dikes (Deer et al., 1991). The amphiboles are calcic and their composition varies from hornblende to actinolite, whereas the composition of the basic dikes is inclined to hastingsite (Leake et al., 1997). Actinolitic probably crystallized as a subsolidus phase. Pyroxene in the dikes is clinopyroxene with augite- diopside composition (Morimoto, 1988).
    Discussion
    The total Al content of hornblende is a sensitive linear function of crystallization pressure and temperature (Schmidt 1992; Holland and Blundy, 1994). However, the computed pressure may reflect the level at which the hornblende crystallizes rather than the pressure at which the granite consolidates. Therefore, Al content in hornblende geobarometer is only applicable in the presence of quartz and plagioclase; alkali feldspars, biotite, hornblende, clearly limit compositional influences (Ague, 1997). Oxygen fugacity has a marked effect on the mineral system, so only hornblendes with Fe/(Fe)
    Keywords: Barometry, thermometry, oxygen fugacity, H2O, Nasrand, Ardestan
  • Seyed Reza Mehrnia Pages 325-342
    Introduction
    Tekieh Lead-Zinc ore deposit that is located in the Sanandaj-Sirjan structural zone has been recognized as one of the most important mineralized regions in Malayer-Isfahan metallogenic sub-state, south east of Arak (Momenzadeh and Ziseman, 1981). Carbonate host units have been developed along (or across) the Vishan-Tekieh anticline as the main structure extended in NW-SE trends (Annells et al, 1985). According to geochemical investigations (Salehi, 2004), the element content of the mineralized regions has originated from Alpine post-volcanisms and subsequently it has migrated toward early Cretaceous formations (dolomitic limestones) among several hypogenic stages (Torkashvand et al., 2009). Also echelon type structures consisting of folded systems and inversed faulting of structures are the most common features in western and eastern parts of ore deposit regions (Annells et al, 1985). Syngenetic enrichments beside limited (rarely developed) epigenetic mineralization have been known as two main phases which are closely relevant to ore forming processes in the massive lenses and vein type occurrences, respectively (Momenzadeh and Ziseman, 1981).
    Material and
    Methods
    In this research, two statistical techniques that consist of classical and fractal equations (Mandelbrot, 2005) were applied in geochemical (Torkashvand et al., 2009) and geophysical (Jafari, 2007) databases for obtaining the linear and nonlinear distributions of geochemical elements (Tekieh Pb-Zn content) in association with resistivity variations and induction polarization measurements (Calagari, 2010). According to linear statistical techniques (Torkashvand et al., 2009), the main central parameters such as mean, median and mode in addition to variances and standard deviations as distribution tendencies could be used for obtaining the regression coefficients of the databases. However, in fractal statistics, a reliable regression between geoelectrical - geochemical anomalies should be calculated based on measuring the fractal dimensional variations in the recursive patterns (Mehrnia, 2013). In practice, the Area-Concentration equations (Mandelbrot, 2005) were applied in resistivity, induction polarization, Pb and Zn datasets for achieving the nonlinear relationships in anomalous regions which were characterized by increasing in regression coefficients with more spatial correlation of the variable than linear statistics (Mehrnia, 2013).
    Results And Discussion
    This research showed that both linear and nonlinear statistics are able to estimate the spatial association of geochemical anomalies with geophysical variables. A meaningful increase in the regression coefficient was also revealed after measuring the self-similar peculiarities of concentration values on gridded plots (Salehi, 2004; Torkashvand et al., 2009). From the fractal point of view, Pb ore-minerals have been deposited in the western sub-region, while Zn mineralization seems to be extended in the depth of eastern alterations. Also a predictable geochemical zonation can be considered in the western target (meaningful Pb anomalies) that is more patterned than the eastern halos according to geological observations (Momenzadeh and Ziseman, 1981) and mineralogical evidences (Salehi, 2004). An increase in Supra ore/Sub ore proportional content was measured in the western sub-region which indicated more reliable potential of Pb mineralization (Galena as a particular indication of sulfide-rich minerals) than the same phases of ore forming processes in the eastern sub-region, although the content of Pb-ores rapidly decreases in the eastern target and is replaced by Zn minerals (Sphalerite as particular indication of sulfide-rich mineralization). Because power law relationships are significant in both geochemical and geophysical anomalies (Mehrnia, 2013) a detailed program including borehole geophysics and litho-geochemical land-surveys should be considered in the prospected regions. Therefore, upcoming phases should emphasize on self-organized distribution of Pb-Zn anomalies to introduce a new set of nonlinear distributions in order to find the confidence regression coefficients between the variables. As the final results, fractal analysis of available databases represented new target areas with better mineralization aggregations than linear analysis of the anomalous regions according to micrographs. It means that surficial mineralization processes could be extended in depth and enriched next to altered host units because of a nonlinear but self-organized distribution of geochemical- geophysical anomalies in Tekieh ore deposit region.
    Keywords: Fractal, Nonlinear Distribution, Statistical Techniques, Tekieh Ore Deposit
  • Arezoo Moradi, Nahid Shabanian Boroujeni, Ali Reza Davoudian Dehkordy Pages 343-358
    Introduction
    The study area is a part of the Sanandaj- Sirjan zone that is located in the NW of Azna city and NE of the dimension stone mine of Jan between 49° 11' 41"and 49° 16' 07" E longitude and 33° 36'35" and 33° 38'12" N latitude., A pluton of mylonitic granite-gneiss is exposed in the area which contains abundant tourmalines as black and patchy or subgrain association. Geochemically, the studied granite-gneiss is A-type, peraluminous to slightly metaluminous and calc – alkaline to slightly alkaline (Moradi et al., 2017). The electron microprobe analyses of the tourmalines display shorl-dravite in composition with more tendency to shorl (Moradi et al., 2015). In this paper we try to study the petrological sites of tourmaline formation with associated minerals, controller factors of crystallization using mineral chemistry of tourmaline, comprehensive behavior of trace elements in the tourmaline, synthetic phase diagrams and finally relationships between the associated minerals.
    Materials And Methods
    The results of trace-element and major-element analyses were obtained from one polished thin section including 2 tourmaline grains. Major-element analyses of tourmaline were obtained at Oklahama City University of America using the JEOL 8200 electron microprobe with a spot size of 5 μm and trace-element analyses were performed on just a sample by Laser Ablation-Inductively Coupled Plasma-Mass Spectroscopy (LA-ICP-MS) a 193nm ArF excimer laser ablation system (MicroLas GeoLas 200Q) in combination with a quadrupole ICP-MS (Micromass Platform ICP) at Utrecht University of Netherland. Representative EMP and LA-ICP-MS analyses of tourmaline samples are presented in Tables1 and 2.
    Results
    The results of LA-ICP-MS on tourmalines of Jan mine in the North east of mylonitic granite-gneiss body show that distribution and diffusion of trace elements during the growth of tourmaline trend is positive on the plots of binary Mn versus Fetot / (Fetot ) and it represents the formation of the tourmaline mineral from the melt is along with the progress of the differentiation (Jolliff et al., 1987; Kontak et al., 2002). Also the average composition of tourmaline – bearing mylonitic granite-gneiss pluton normalized spider diagram for the studied tourmaline shows positive anomaly and negative anomaly in Eu that indicates tourmaline minerals surrounded by quartz and feldspar grains (Copjakova et al., 2013). Secondary phases such as zircon and allanite very much effect on the REE patterns (Rollinson, 1993). Therefore, in the final stages of differentiation, allanite appeared earlier than it appeared in areas without tourmaline crystalliziation and LREE soon after tourmaline crystalized and they are deposited (Cuney and Friedrich, 1987). Using a combination of phase diagrams, the controlling factors of creation of tourmaline associated with biotite-tourmaline can be assessed, and the relationship between tourmaline and associated minerals, chemistry of tourmaline – bearing granitoid pluton, and location of petrological minerals tourmaline can be sought (Pesquera et al., 2005).
    Discussion
    The results of LA-ICP-MS on tourmalines of mylonitic granite-gneiss body in the north east of Jan mine in Sanandaj – Sirjan Zone represents tourmaline crystallization from the melt along with the progress of the differentiation. Also, the average composition of tourmaline – bearing mylonitic granite-gneiss pluton normalized spider diagram for the studied tourmaline shows positive anomaly and negative anomaly in Eu that indicates that tourmalines are surrounded by quartz and feldspar grains. According to petrographic evidence of tourmaline and biotite, it can be seen with muscovite. Therefore, where tourmaline is dominant, biotite and associated minerals are limited or do not exist. Using a combination of phase diagrams controlling factors of tourmaline crystallization associated with biotite-tourmaline can be assessed, and the relationship between tourmaline and associated minerals, chemistry of tourmaline – bearing granitoid pluton, and location of petrological of tourmaline minerals can be sought.
    Keywords: tourmaline, progress of the differentiation, phase diagram, Jan mine, Sanandaj-Sirjan Zone
  • Mir Ali Asghar Mokhtari, Mohammad Ebrahimi, Mohammad Reza Ghorbani Pages 359-380
    Introduction
    The Avan Cu-Fe skarn is located at the southern margin of Qaradagh batholith, about 60 km north of Tabriz. The Skarn-type metasomatic alteration is the result of Qaradagh batholith intrusion into the Upper Cretaceous impure carbonates. The studied area belongs to the Central Iranian structural zone. In regional scale, the studied area is a part of the Zangezour mineralization zone in the Lesser Caucasus. Several studies (Karimzadeh Somarin and Moayed, 2002; Calagari and Hosseinzadeh, 2005; Mokhtari, 2008; Baghban Asgharinezhad, 2012; Mokhtari, 2012) including master’s theses and research programs have been done on some skarns in the Azarbaijan area considering their petrologic and mineralization aspects. However, before this study, the Avan skarn aureole has not been studied in detail. In this paper, various geological aspects of the Avan skarn including mineralogy, bi-metasomatic alteration, metasomatism and mineralization during the progressive and retrograde stages of the skarnification processes have been studied in detail.
    Research
    Method
    This research consists of field and laboratory studies. Field studies include preparation of the geological map, identifying the relationship between the intrusion and the skarn aureole, identifying the relationship between different parts of the skarn zone and also collecting samples for laboratory studies. Laboratory studies include petrography, mineralography and microprobe studies. Cameca SX100 Microprobe belonging to Geological Survey of the Czech Republic was used in order to determine the chemical composition of the calc-silicate minerals such as pyroxene and garnet in garnet skarn and pyroxene- garnet skarn sub-zones.
    Discussion and
    Conclusion
    Qaradagh batholith is composed of discrete acid to mafic phases including gabbro, diorite, quartz diorite, quartz monzonite, quartz monzodiorite, tonalite, granodiorite, monzogranite and granite porphyry which is dominated by granodiorite-quartz monzonite. Granitoids of this batholith are metaluminus, high K calc-alkaline I-type granite (Mokhtari, 2008). The Avan Cu-Fe skarn is related to the intrusion of granodioritic-quartz monzonitic part of the Qaradagh batholith into the Upper Cretaceous flysch- type rocks consisting of biomicrite, clay limestone, marl, siltstone and mudstone.
    The Avan skarn consists of three zones of endoskarn, exoskarn and marble. The main Cu-Fe mineralized zone is related to the exoskarn zone, which has 600 meters of length and 50 meters of thickness, respectively. The Exoskarn zone consists of garnet skarn, pyroxene-garnet skarn and ore skarn sub-zones. Garnet, belonging to ugrandite series (Ad53-89) with more than 50 percentage in volume, is the most important anhydrous calc-silicate mineral in the garnet skarn and the pyroxene-garnet skarn sub-zones. Some of the garnet crystals are zoned and their chemical composition changes toward the rim to almost pure andradite (Ad99). Clinopyroxene which has diopsidic composition (Di75-96), is another anhydrous calc-silicate mineral in the exoskarn zone with an abundance that reaches up to 50 percent in volume in pyroxene-garnet skarn sub-zone.
    The ore skarn sub-zone is located toward the outer part of the exoskarn zone and close to the border of the marble zone. The abundance of ore minerals in this sub-zone reaches up to 50 percentage in volume and includes magnetite, hematite, pyrite, chalcopyrite, bornite, malachite and goethite among which pyrite is the most abundant. In this sub-zone, anhydrous calc-silicate minerals of garnet and clinopyroxene have undergone intensive alteration and are replaced with hydrous calc-silicate (epidote and tremolite- actinolite), oxide (magnetite and hematite) and sulfide (pyrite, chalcopyrite and bornite) minerals.
    Based on the textural and mineralogical studies, the skarnification processes in the studied area can be categorized into two main stages: 1) prograde and 2) retrograde. During the prograde stage, the heat flow of the granitoid has caused isochemical metamorphism and changing more pure limestones to marble and marlly limestones to skarnoid (metamorphism and bi-metasomatism). The high temperature magmatic fluids have caused prograde metamorphism during which anhydrous calc-silicate minerals including garnet and pyroxene have appeared. During the early retrograde stage, i.e. the mineralization sub-stage, lower temperature hydrothermal fluids have caused hydrolysis and carbonization because of which anhydrous calc-silicate minerals along with their fractures and microfractures are changed to hydrous calc-silicate (epidote and tremolite-actinolite), oxide (magnetite and hematite), sulfide (pyrite, chalcopyrite and bornite) and carbonate (calcite) minerals. During the late retrograde stage, relatively low temperature fluids have altered anhydrous and hydrous calc-silicate mineral assemblage formed during the previous stages into a very fine grained mineral assemblage including clay minerals, chlorite and iron hydroxides.
    Presence of replacement textures in ore minerals and anhydrous calc-silicate minerals accompanied with open filling textures in the anhydrous calc-silicate minerals, for example oxide and sulphide veinlets within the garnet crystals, indicate that the mentioned ore minerals have been simultaneously generated with hydrous calc-silicate minerals (epidote and tremolite-actinolite) during the early prograde stage. The presence of minor amounts of wollastonite among the mineral assemblage of the Avan skarn, intergrowth of garnet and pyroxene, absence of reaction rim between garnet and clinopyroxene and absence of replacement textures indicate that these minerals have been simultaneously generated within the temperature ranges of 430–600 ºC and ƒO2 > 10-26, respectively.
    Keywords: Mineralogy, Cu-Fe Skarn, Qaradagh batholith, Avan, Kharvana, Eastern Azarbaijan
  • Morovvat Faridazad Pages 381-398
    Introduction
    Khoy ophiolite at the global scale is in the middle part of the Alp-Himalaya orogenic belt and it is extended over 3900 Km2 which indicates remnant Neotethys oceanic lithosphere in the Mesozoic era (Kananian et al., 2010). In this paper, in addition to a review of previous investigations about Khoy ophiolite, we will try to determine the nature and kind of minerals, origin and partial melting rate as well as the equilibrium pressure and temperature of harzburgites from the Eastern Metamorphic Complex of Khoy ophiolite.
    Materials And Methods
    Thin sections microscopy studies were carried out following field investigations. EPMA analysis was carried out with using a Superprobe JEOL, JXA 8200 Microprobe unit at the state of WDS and under condition of 15kv accelerating voltage, 10nA current beam, 1µm beam diameter and collection of natural and synthetic standards for calibration.
    Results
    The study area is located at the NW of Iran and north of the Khoy city in the west Azarbaijan province. This area is part of the ophiolitic complex of NW Iran and belongs to its Eastern Metamorphic Complex. This metamorphic zone has large tectonically segments of the metamorphic ophiolites which mainly include serpentinized peridotites with associated metagabbros. There are three types of peridotitic rocks in this area which are: Lherzolites, harzburgites and dunites. Lherzolites are composed of olivine (60-70%), orthopyroxene (10-30%) and clinopyroxene (~10-20%) with minor amounts (~2%) of Cr-spinel mineral. Harzburgites are composed of olivine (70-80%), orthopyroxene (10-20%) and clinopyroxene (~5%) with minor amounts (~2%) of Cr-spinel mineral. Dunites are composed of olivine (90-95%), orthopyroxene (5-10%) with minor amounts (~1-2%) of Cr-spinel mineral. Composition range of olivines is between Fo89.46 Fa10.37 to Fo89.86 Fa10.0 as well as NiO content range is 018-046 (wt %). The calculated Mg# of olivines is 0.90 and the composition of olivines in Fo-Fa diagram is plotted in forsterite field. The end-members composition of clinopyroxenes is between En44.159 Wo46.910 Fs4.323 Ac1.459 to En46.803 Wo49.589 Fs4.786 Ac2.081. The calculated Mg# of clinopyroxenes is 0.91. The composition of clinopyroxenes in En-Wo-Fs (Morimoto et al., 1988) diagram is plotted on a diopside field. The plot of clinopyroxenes on Na versus Cr diagram (Kornprobst et al., 1981) indicates that the studied harzburgits are formed in the oceanic setting. Moreover, the Mg# versus Al2O3 in the clinopyroxenes is an indication of their relation to the Abyssal peridotites (Johnson et al., 1990). The end-members composition of orthopyroxenes is between En86.022 Wo2.491 Fs9.368 to En87.314 Wo6.719 Fs10.474. The calculated Mg# of orthopyroxenes is 0.90. The composition of orthopyroxenes in En-Wo-Fs diagram is plotted on an enstatite field. The plot of orthopyroxenes on Mg# versus Al2O3 diagram indicates their relation to Abyssal peridotites (Johnson et al., 1990). Compositions of spinels in the studied harzburgites indicates that they are high-Al type with Mg# and Cr# 0.67-0.72 and 0.19-0.26, respectively. Their TiO2 content are 0.01-0.11(Wt %) and Al2O3 content are 44.009-49.894 (Wt %). In Cr# versus Mg# diagram, spinels are plotted on the Abyssal peridotites field and indicate that the host peridotite has experienced 10-15% partial melting. In addition, using the equation F%=10Ln (Cr/Cr) spinel) (Hellebrand et al., 2001) 7.6-10.4 (average 9.7%), the partial melting degree was obtained that means a slow spreading rate for the study area. Using the Cr# versus Mg# diagram, alpine I-type, abyssal and back arc setting for the studied harzburgites are determined. PTMAFIC Software (Soto and Soto, 1995) is used for orthopyroxene (single pyroxene), clinopyroxene-olivine, and orthopyroxene-clinoproxene thermometry. Based on these thermometers, overall temperatures of 1100 ±100 °C are estimated for the equilibrium stage of the minerals. For pressure estimation, the Cr content in clinopyroxene (Nimis and Taylor, 2000) barometer is used. Using this calibration and temperatures from single pyroxene thermometer a pressure of ~22±2.4 Kbar for equilibrium clinopyroxene and associated minerals in the studied harzburgites was estimated.
    Discussion
    Mineral chemistry studies indicate that these harzburgites may be related to oceanic settings. Moreover, the high Mg# in orthopyroxenes and clinopyroxenes and the high Fo% in olivines are indications of their tectonite origin. Calculation of partial melting degree using spinels compositions indicate that they are experienced 7.6-10.4 partial melting. In this regard, they are consistent with the partial melting degree in the Atlantic and Indian oceans. The spreading rate studies indicate that harzburgites are produced in the region with slow spreading rate. Their tectonic setting is more consistent with MOR peridotites. Based on geothemobarometry studies an overall ~1100±100°C temperature and ~22±2.4Kbar pressure are estimated which are consistent with mantle spinel lherzolite facies.
    Keywords: Harzburgite, Mineral chemistry, Partial melting, Geothermobarometry, Khoy ophiolite
  • Maryam Ahankoub, Yoshihiro Asahara Pages 399-413
    Introduction
    There are some theories about the Paleotethys event during the Paleozoic that have been proposed by geologists (Metcalfe, 2006). Some scientist offered some pieces of evidence about the northern margin of Gondwana (Zhu et al., 2010). The Paleotethys Ocean and Hercynian orogenic report first in Iran, have been Offered from the Morrow and Misho Mountain (Eftekharnejad, 1981). Misho Mountains is located between the north and south Misho faults and cause the formation of a positive flower structure (Moayyed and Hossainzade, 2011). There is theory about Misho southern fault as the best candidate of the Paleotethys suture zone (Moayyed and Hossainzade, 2011). Geochemistry and Sr –Nd isotopic data of the A2 granitic and Synite rocks of the East Misho, indicate that the magmatism post collision has occurred in the active continental margin by extensional zones of the following the closure of the Paleotethys (Ahankoub, 2012). Granite and syenite rocks have been cut by mafic dikes. Mafic dikes are often formed in extensional tectonic settings related to mantle plume or continental break –up (Zhu et al., 2009). In this paper, we use the geochemistry and Nd-Sr isotope data to determined petrogenesis, tectono-magmatic setting and age of Misho mafic dikes.
    Materials And Methods
    After petrography study of 30 thin sections of mafic dike rocks, 8 samples were selected for whole-rock chemical analyses using ICP-MS and ICP-AES instruments by ACME Company in Vancouver, Canada. We prepared 6 sample For Sm-Nd and Rb-Sr analysis. Sr and Nd isotope ratios were measured with a thermal ionization mass spectrometer, VG Sector 54–30 at the Nagoya University. The isotope abundances of Rb, Sr, Nd, and Sm were measured by the ID method with a Finnigan MAT Thermoquad THQ thermal ionization quadrupole mass spectrometer at the Nagoya University. NBS987 and JNdi-1 were measured as natural Sr and Nd isotope ratio standards (Tanaka et al., 2000). Averages and 2σ errors for the repeated analyses of the standards during this study were as follows: NBS987 87Sr/86Sr=0.710264± 0.00001 (1 σ, n=9) and JNdi-1 143Nd/144Nd= 0.512097± 0.00001 (1σ, n=9).
    Results
    Results of the ICP-AES and ICP-MS analysis present that dikes chemical compounds contain SiO2 = 50.94 – 48.3%, TiO2 = 1.53 -1.43%, Al2O3= 16.37 -15. 64 and MgO = 6.61 -5. 54. Major and trace elements display the natural of the with in plate Calc-Alkalin basalts of the metaluminous. Amounts of the Mg # indicate the variety of the fractional crystallization processes (ol and Cpx) in these rocks. Also, the low Nb / La refers to crustal assimilation during fractional crystallization processes. Chondrite-normalized REE patterns of the samples (Sun and McDonough, 1989), indicate an enrichment LREE / HREE because of low partial melting of garnet in the source (Martin, 1999). The low degree of partial melting of the mantle caused LREE enriched to HREE (Wass and Rogers, 1980). There are Eu Positive anomalies that are due to the accumulation of plagioclase. REE normalized patterns to Chondrite point out the enrichment REE and Tb samples by separation amphibole, pyroxene, Hornblende, titanite and rutile (Thirlwall et al., 1994).
    Spider diagram (Sun and McDonough, 1989) displays enrichment Rb, Th and U elements and depletion in Nb, Ti and p because of source depletion or Nb minerals existence (such as rutile, ilmenite and spinel).
    Enrichment Cs, Th, U, Nb and Ti, p negative anomalies of the mafic dike are similar to geochemical characteristics of continental margin rocks. Nb, Ti negative anomalies and Pb positive anomalies demonstrate the interference of the crust in magmatic source (Martin, 1999).
    The TDM model ages of mafic dikes are 1.2 -1.8 milliard years that show time of the separation of the source of mafic rocks of the Proterozoic crust. Also Sr-Rb data indicate the formation of Misho mountain mafic dikes at 232 ma years age. The εNd (T) is -1 to -4 that indicates the array mantel component of the mafic dike.
    Discussion
    Geochemistry data indicate that Misho mafic dikes are similar to calc-alkaline basalts of the oceanic island basalts (OIB) whereas Nb and Ti negative anomalies of the trace elements patterns are similar to crustal contamination. Negative amount of the εNd(T) indicated depleted mantel source (array mantel) with some continental crust contamination during AFC processes .
    Base on the results of analysis, the upper crust is the best candidates for magma contamination of the mafic dikes in Misho.
    Isotopic data indicated to replace mafic dike 232ma years ago by closing of paleotethys and forming the extension zone (break up) in active continental margin.
    Keywords: Misho Mountain, Basic dyke, isotopic data, Nd-Sr, Calc-alkaline, extensional zone
  • Fatemeh Hormozi Nejad, Fatemeh Rastmanesh, Alireza Zarasvandi Pages 415-429
    Introduction
    Soil plays a vital role in human life as the very survival of mankind is tied to the preservation of soil productivity (Kabata- Pendies and Mukherjee, 2007).
    The purpose of this study is the assessment of heavy metal contamination (Zn, Mn, Pb, Fe, Ni, Cr) of the soil around the Khuzestan Steel Complex.
    Materials And Methods
    For this purpose, 13 surface soil samples (0-10 cm) were taken. Also a control sample was taken from an area away from the steel complex. The coordinates of each point were recorded by Global Positioning System (GPS). The samples were transferred to the laboratory and then were air dried at room temperature for 72 hours. Then they were sieved through a 2mm sieve for determining physical and chemical parameters (soil texture, pH, OC), and a 63-micron sieve for measurement of heavy metal concentration. pH was measured using a calibrated pH meter at a 2: 1 mixture (soil: water), and soil texture was determined using a hydrometer. The amount of organic matter was measured using the Valkey black method (Chopin and Alloway, 2007).
    After preparation of the samples in the laboratory, the samples were analyzed using the ICP-OES method to assess concentration of heavy metals.
    Measurement of heavy metals concentration was carried out at the Zar azma laboratory in Tehran. To ensure the accuracy of the analysis of soil samples, replicate samples were also sent to the laboratory.
    In order to assess the heavy metal pollution in the soil samples, different indices including contamination factor (CF), contamination degree (Cd), anthropogenic enrichment percent (An%), and saturation degree of metals (SDM) were calculated.
    Discussion
    In addition, the mean concentrations of heavy metals in soil samples were compared to the concentration of these metals in Control Sample and unpolluted soil standard.
    Measurement of soil pH showed that the soil has a tendency to alkalinity. Also, soil texture is sandy loam (Moyes, 2011).
    The results showed that the mean Organic Carbon in the soil sample is 1.03%, the higher amount of OC is related to soil sample numbers 7 and 11.
    The mean concentrations of Ni, Pb, Zn, Mn, Fe and Cr in soil samples were 61.42, 19.90, 156.63, 443.63, 38762.63 and 127.58 (mg/kg), respectively.
    The highest concentrations of manganese, chromium, zinc and lead were found in soil samples number 4 and 12. This is in agreement with the results of the saturation degree of metals so that, the highest values of saturation degree of metals were found for soil samples close to the factory, (i.e. 4 and 12). The SDM values decreased with distance to the factory. The highest contamination factor was obtained for soil samples which were taken near the steel factory (4 and 12).
    Also, the highest contamination degrees were found for soil samples 4 (23.7) and 12 (14.1) while, the lowest values were obtained for soil samples 6 (6.35) and 10 (6.07).
    The results of the contamination degree calculation, anthropogenic enrichment percent, as well as statistical analysis are consistent. It can be said that the origin of iron in study areas is related to anthropogenic and geogenic activites.
    The results of anthropogenic enrichment percent, indicated that Lead, Manganese, and Zinc in the soil samples which were taken around the steel factory have an anthropogenic source. Moreover, the source of Chromium and Nickel is mainly geogenic.
    The results showed that all variables are normally distributed. Three components originate with a cumulative variance of 79.55% for soil samples.
    PC1 which explains 41.47% of the total variance can be defined as an anthropogenic component since Mn, Pb and Zn soil samples have the highest loading on PC1. As previously indicated, the concentration of these elements in the study area is mainly influenced by the steel industrial complex.
    The PC2 represents 22.26% of the total variance, and is strongly associated with Ni, Fe can be defined as geogenic and anthropogenic component, as the variability of the elements seems to be controlled by parent rocks and human activities.
    Cr was individually included in the PC3 whith 15.82% of the total variance. The distribution of Cr in the studied soils confirmed that it was derived from the parent materials of soil.
    Results
    The highest concentrations were found at soil samples 4 and 12. Comparison of heavy metals concentration with unpolluted soil standard indicated that, concentrations of Cr, Zn, Fe, Ni and Pb is higher than that of unpolluted soil standard. In general, Manganese, Chromium, Zinc and Lead are the most important elements that are found in emissions of steel plants.
    The soil samples near the steel plant and downwind direction have much higher pollution level.
    The results showed that Mn, Pb and Zn is related to human activity and Cr have geogenic source and Fe and Ni have both geogenic and anthropogenic source in the study area in the city of Ahwaz.
    Keywords: heavy metals, Khouzestan Steel Company, contamination degree, Anthropogenic Enrichment Percent, saturation degree of metals, Ahwaz
  • Ebrahim Tale Fazel, Behzad Mehrabi, Hassan Zamanian, Masoumeh Hayatalgheybi Pages 431-455
    Introduction
    The Senj deposit has significant potential for different types of mineralization, particularly porphyry-like Cu deposits, associated with subduction-related Eocene–Oligocene calc-alkaline porphyritic volcano-plutonic rocks. The study of fluid inclusions in hydrothermal ore deposits aims to identify and characterize the pressure, temperature, volume and fluid composition, (PTX) conditions of fluids under which they were trapped (Heinrich et al., 1999; Ulrich and Heinrich, 2001; Redmond et al., 2004). Different characteristics of the deposit such as porphyrtic nature, alteration assemblage and the quartz-sulfide veins of the stockwork were poorly known. In this approach on the basis of alterations, vein cutting relationship and field distribution of fluid inclusions, the physical and chemical evolution of the hydrothermal system forming the porphyry Cu-Mo (±Au-Ag) deposit in Senj is reconstructed.
    Materials And Methods
    Over 1000 m of drill core was logged at a scale of 1:1000 by Pichab Kavosh Co. and samples containing various vein and alteration types from different depths were collected for laboratory analyses. A total of 14 samples collected from the altered and least altered igneous rocks in the Senj deposit were analyzed for their major oxide concentrations by X-ray fluorescence in the SGS Mineral Services (Toronto, Canada). The detection limit for major oxide analysis is 0.01%. Trace and rare earth elements (REE) were analyzed using inductively coupled plasma-mass spectrometery (ICP-MS), in the commercial laboratory of SGS Mineral Services. The analytical error for most elements is less than 2%. The detection limit for trace elements and REEs analysis is 0.01 to 0.1 ppm. Fluid inclusion microthermometry was conducted using a Linkam THMS600 heating–freezing stage (-190 °C to  °C) mounted on a ZEISS Axioplan2 microscope in the fluid inclusion laboratory of the Iranian Mineral Processing Research Center (Karaj, Iran).
    Results
    The Cu-Mo Senj deposit covering an area about 5 km2 is located in the central part of the Alborz Magmatic Arc (AMA). The Nb/Y versus Zr/TiO2 diagram (after Winchester and Floyd, 1977) illustrates a typical trend for the magmas in the Senj magmatic area–starting from basaltic and evolving to dacite/rhyodacitic compositions, with few data plotting in the alkali basalt field. Most of the igneous rocks plot within the medium- and high-K fields in the K2O versus SiO2 diagram. The igneous rocks from the Senj area define a typical high-K calc-alkaline on SiO2 versus K2O diagram (Le Maitre et al., 1989). All studied rocks show similar incompatible trace element patterns with an enrichment of large ion lithophile elements (LILE: K, Rb, Ba, Th) and depletion of high field strength elements (HFSE: Nb and Ti), which are typical features of magmas from convergent margin tectonic settings (Pearce and Can, 1973). At least three veining stages namely QBC, QM, and QP which are related to alteration and mineralization are distinguished at the Senj mineralized area. Three distinct alteration assemblages including K-feldspar-biotite-sericite-quartz, quartz-sericite-K-feldspar-pyrite, and K-feldspar-biotite-sericite-quartz, are distinguishable with these veins. About 80 % of the copper at Senj is associated with the early QBC-stage veins, with another 5 to 15 % in the QM-and QP-stage veins. About 70 % of the molybdenite occur in QM veins.
    Discussion
    Fluid inclusion distribution, fluid chemistry, and homogenization behavior document that S2-type fluids are samples of magma-derived aqueous-saline fluids characterized by high salinity and temperature, and high Cu content. Such parental fluids scavenged Cu and Mo from the melt below and transported them to the hydrothermal system above. The increased abundance of S- and LV-types inclusion coinciding with the highest grade Cu mineralization (early QBC-stage veins) at the Senj deposit suggests that brine-vapor unmixing and phase separation plays an important role in Cu-ore precipitation and alteration zonation. In addition to unmixing, cooling and water-rock interaction also played important roles in chalcopyrite precipitation at the Senj deposit.
    Compositions, deposit-scale distribution, and trapping conditions of fluid inclusions can be explained by the continued influx of a parental high salinity magmatic hydrothermal fluid, with no significant change in the bulk composition of the input fluid over the integrated lifetime of ore metal precipitation and vein formation. Fluid inclusion evidence and vein-cutting relationships indicate that molybdenum mineralization (QM vein) occurred at moderate temperatures coinciding with phyllic alteration, rather than from later, lower temperature fluids. Furthermore, early fluids decompressed rapidly relative to cooling, forming quartz-stockwork veins with K-silicate alteration at depth and QP veins at shallower levels in the Senj deposit. Later, as the hydrothermal system waned, the rate of decompression relative to fluid cooling slowed, causing the fluid to remain above its solvus, forming barren quartz-dominated veins with quartz-kaolinite±illite alteration which overprint much of the deposit.
    Keywords: Cu-Mo mineralization, fluid inclusions, ore-forming fluid evolution, Senj deposit, Central Alborz
  • Omid Yazdanpanah, Ali Akbar Hassannezhad Pages 457-472
    Introduction
    Dehnow-Abid area is a part of the geological map of Eshghabad with scale 1:100000 (Aghanabati, 1994) that is located about 20 kilometers northeast of Eshghabad and in the coordinates of 57° 6´ 0" to 57° 10´ 0" eastern longitude and 34° 28´ 0" to 34 21´ 0" northern latitude. The Dehnow-Abid area is located in Tabas block and east of central Iran structural zone. The small continent east central Iran (Takin, 1972) includes blocks: Loot, Tabas and Yazd that constitute Iran's eastern part (Davoudzadeh and Schmidt, 1982). In geology, we can acquire more information about temperature forming minerals and rocks, pressure, density of the fluid and the chemical composition of the ore bearing fluids by fluid inclusions studies. Properties as well as their role in our understanding of the sources and evolution of ore bearing hydrothermal fluids and genesis of mineral deposits are very important (Rodder, 1979). In this study, we tried to use both field and laboratory studies, including petrography and thermometry studies of fluid inclusions, environment formation of quartz in the specified Dehno-Abid.
    Materials And Methods
    At first, in order to identify the area, the 1:100000 map of Eshghabad was used. Then, for a complete cognition of mentioned area, after a few field visits and sampling of outcrops of quartz, we prepared 16 double polishing sections from some crystalline and milky quartz. Then, 10 thin sections of sandstones of that area were prepared for identification the host rock. Microscopic examinations on fluid inclusions were done by a LEICA DMLSP polarizing light microscope. Fluid inclusion micro-thermometry studies were done by using a Linkam THM S600 heating and freezing stage and with a TMS94 controller. Also, a cooling LNP which is mounted on an Olympus BX-41 microscope in Laboratory Fluid inclusion of Earth Sciences, Damghan University was used.
    Discussion and
    Results
    Lithology of the Dehnow-Abid area included dark shale, fine and coarse grains arkosic and lithic arkose sandstones (Tucker, 1994) that show low grade metamorphic texture which may be attributed to these sediments metamorphosed Jurassic age, but their equivalence is more with Shemshak forrnation (Aghanabati, 1994). Silica mineralization occurred as veins, veinlets and in some parts show silica mass of lense. In this area, there are two generations of faults with trends of northeast-southwest and north-south. Based on the geological section, the North – South faults is the second generation that cut system North-East to South-West faults (Kosari, 2004). In microscopic studies of fluid inclusions different characteristics such as their relationship with the host mineral, phase contents, size, shape, necking down and degree of filling were investigated. Microscopic investigates at room temperature, based on the criteria provided by Van den Kerkhof and Hein, 2001; Shepherd et al., 1985; Rodder, 1984 were performed. These studies indicated that as genetically point fluid inclusions in quartz area are able to divide into three groups (primary, secondary and pseudo secondary). The shapes of fluid inclusions are very different, but partly follow mineral crystallization system. Size of fluid inclusion varies between 5 to 120 microns, but most abundant fluid inclusions have size of 20 to 60 microns. According to a survey done on double polishing sections in laboratory conditions, the phase contents of fluid inclusions may be divided into six groups that include : monophase liquid (L), monophase vapor (V), two phases rich of liquid (L), two phases rich of vapor (V), three phases (L埤) and immiscible liquid (L1⽯). The presence of CO2 around gas bubbles can represent metamorphism environments (Yardley and Bodnar, 2014; Van den Kerkhof et al., 2014). Heating analysis was done on 113 samples of fluid inclusions studied in order to investigate the situation homogenization temperature, and cooling analysis was done on 99 selected samples. In addition, 38 samples were tested as heating in order to obtain a homogenization temperature of CO2 phase fluid inclusions (L1⽯). Micro-thermometric fluid inclusion investigates shows that the homogenization temperature of the CO2 is varied between 26.1 to 30.6. Fluid inclusion micro-thermometry studies on mineral quartz shows that the homogenization temperature is varied between 247 to 336 ° C, salinty is varied between 0.9 to 15.8 % NaCl eq and mineralizing fluid density range is between 0.7 to 0.9 gr/cm3. Based on evidences from field and laboratory studies, especially microthermometry studies and also the presence of carbonic phase in fluid inclusions, probably silica in the Dehnow-Abid region was formed under metamorphism conditions. On the basis of Wilkinson diagram (Wilkinson, 2001), regional data have been plotted in low temperature range and gold veins that shows metamorphic environments partly. Also plotting these data on a Kessler diagram (Kesler, 2005) suggests a metamorphic source for fluids which have made the veins, lenses and quartz mass of studied area.
    Keywords: Silica, Fluid inclusion, Carbonic phase, Metamorphism, Dehnow-Abid
  • Bahareh Fazeli, Mahmoud Khalili, Roy Beavers, Mahin Mansouri Esfahani, Zahra Loghmani Dastjerdi Pages 473-491
    Introduction
    The generation and evolution of granitic magmas has been a hot debated subject among petrologists. The diversity of their origin has led different authors to propose that these rocks are not simple in their origin and might be generated in more ways than one. In the past several decades, many petrologists used a variety characteristics to subdivide the granitoid rocks. Such proposals have of course been forward by Chappell and White (1974) for the granitoids of Eastern Australia. They divided these granitoids into two distinct types (I-and S-type granitic rocks), which they interpreted as being derived from igneous and sedimentary source rocks, respectively. The Ghaleh Yaghmesh plutonic massif is located in the most western part of Yazd and it forms a part of the Urumieh-Dokhtar magmatic belt. The belt is response to subduction of Neo-Tethyan oceanic crust beneath central Iran (Alavi, 1994). During Cretaceous-Late Tertiary, numerous granitoid bodies were exposed in this belt, many of which have been studied by a number of workers (e.g. Sepahi and Malvandi, 2008; Honarmand et al., 2013; Kananian et al., 2014).
    The massif composed of diorite, quartzdiorite, tonalite, granodiorite and granite (Oligocene) intruded into the Eocene volcanic and pyroclastic rocks including rhyolite, rhyodacite, andesitic, rhyodacitic and rhyolitic tuff. The main purpose of the present paper is to describe the petrography, and whole rock geochemistry of the Ghaleh Yaghmish granitoids as well as discussing their petrogenetic and tectonic significance in the light of the regional geological framework of the study area.
    Materials And Methods
    After field studies and sampling, fifty thin sections were prepared for petrographic study. Twenty-one fresh samples were selected for XRF chemical analysis performed at the Southern Methodist University (Dallas - USA). Thin polished sections of granodiorite rocks were prepared for composition determining and structure formula calculation of amphibole minerals by Cameca SX50 microprobe device at the Oklahomacity University (Norman - USA).
    Results
    The studied plutonic rocks are dominated by plagioclase, orthoclase, quartz, amphibole (magnesio hornblende and actinolite hornblende), biotite, and pyroxene. Zircon, apatite, sphene, tourmaline and opaque minerals as the common accessory and chlorite, epidote and calcite are the secondary minerals. On the base of petrographic observation as well as mineral-chemistry and geochemical data, the granitoid massif is classified as I-type (magnetite series), calc – alkaline and metaluminous composition. The rocks under discussion are characterized by the high level of LILE (Ba, Sr, K and Cs) and the negative anomaly of HFS elements (Ti, Nb, Zr and Y) indicating the subduction related magmatism. The Ghaleh Yaghmesh granitoids are cogenetic and possibly developed in subduction zone related to active continental margin calc – alkaline volcanic arcs. Mixing process of acidic and basic magmas is likely involved in generation of the rocks being studied.
    Discussion
    The parent magma probably formed by partial melting of amphibolites with some sedimentary materials. Fractional crystallization of melt in the higher levels of crust gave rise to various rock types. Mantle – derived basaltic magmas emplaced into the lower crust most likely provide heat for partial melting )Clemens et al., 2011(. Field evidences such as the presence of mafic microgranular enclaves having sharp boundaries with the host rocks (Zorpi et al., 1989; Didier, 1991), petrographic observations (similar mineralogy of MME and the host rock (Didier, 1991; Didier and Barbarin, 1991), the occurrence of accicular apatite (Zorpi et al., 1989; Didier, 1991), the corroded margin of amphibole and plagioclase (Zorpi et al., 1989; Shelley, 1993) and the abundance of biotite and hornblende in MME compared to the host rock (Ellis and Thompson, 1986)) and geochemical criteria (range of silica from 51.35 to 70.78) indicate that magma mixing process was likely responsible for the formation of the rocks being studied.
    Keywords: I-type granitoid, Volcanic arc, Eocene-Oligocene, Ghaleh Yaghmesh, Urumieh-Dokhtar
  • Rezvan Mehvari, Moussa Noghreyan, Mortaza Sharifi, Mohammad Ali Mackizadeh, Seyed Hassan Tabatabaei, Ghodrat Torabi Pages 493-506
    Introduction
    The Nabar area that is a part of the Urumieh- Dokhtar volcano- plutonic belt is located in the south of Kashan. Research works such as Emami (Emami, 1993) and Abbasi (Abbasi, 2012) have been done about the geology of this area.
    Rock units in the study area contain middle- upper Eocene intermediate to acidic lavas and pyroclastic rocks, green marl, shale and sandy marls of Oligo- Miocene, limestones of Qom formation, intrusive granitoids with Oligo- Miocene age and quaternary travertine and recent alluvium (Emami, 1993). The volcanic and sub volcanic rocks of this area are composed of andesite, trachyandesite, dacite, rhyolite and porphyric pyroxene diorite along with pyroclastic rocks.
    Materials And Methods
    In order to achieve the aims of this work, at first field surveying and sampling were done. Then, thin and polished thin sections were prepared. Some of the samples were selected for microprobe analysis and clinopyroxene minerals were analyzed by using JEOL- JXA-8800 analyzer with a voltage of 20 Kv and a current of 12 nA in the Kanazava University of Japan and Cameca-Sx100 analyzer with a voltage of 15 Kv and a current of 15 nA in the Iranian mineral processing research center, Karaj.
    Discussion
    On the basis of petrographic investigations, porphyritic, porphyroid, fluidal, amygdaloidal and porphyry with microlitic groundmass are common textures of these rocks. Also plagioclase, clinopyroxene, amphibole, biotite, sanidine and quartz are essential minerals, opaque, zircon and apatite as accessory minerals are observed in the studied rocks. Clinopyroxenes are observed with corona texture that resulted during the uralitization process. On the basis of minerals’ chemistry, pyroxenes are Fe- Mg- Ca type in composition (Morimoto et al., 1988). These clinopyroxenes are augite. Investigations indicate that mineral composition of clinopyroxene can be effectively used to evaluation the P-T conditions during crystallization. Previous research works have proposed several methods such as Soesoo (Soesoo, 1997) and Putrika (Putrika, 2008). Thermobarometric studies of clinopyroxenes reveal that Nabar rocks were formed at temperatures of 900 -1200 ˚C and the pressure of 2-5 kbar. According to the Aoki and Shiba (Aoki and Shiba, 1973) and Helz (Helz, 1973) approaches, the pyroxenes of the studied rocks are in a range of low to medium pressure that shows crystallization of clinopyroxenes during ascending of magma in different depths. Also according to Helz (Helz, 1973), the water vapor content in the crystallization of clinopyroxenes is more than 10 percent. Using AlIV versus AlIV 2Ti Cr diagram which depends on the amount of ferric iron in pyroxenes, we can get oxygen fugacity. Based on this diagram, the pyroxenes which crystalized at high oxygen fugacity, has been situated above the line of Fe3. Furthermore, Cameron and Papike (Cameron and Papike, 1981) have mentioned to the distances of the samples from the Fe3 line and noted that further distances of the samples from this line are indicating more oxygen fugacities in their geological setting. On the basis of this diagram samples were located above the line of Fe3橷 these rocks are formed in high oxygen fugacities. Pyroxene composition depends on the chemical composition and tectonic setting of the host lava which can be used widely to determine tectonic setting of the rocks. On the basis of approaches of Le Bas (Le Bas, 1962) and Sun and Bertrand (Sun and Bertrand, 1991), the chemical composition of clinopyroxenes shows that the studied rocks are related to calc-alkaline series and orogenic settings.
    Results
    On the basis of mineral chemistry, pyroxenes are Fe-Mg-Ca type in composition. These clinopyroxenes are augite. Thermometric studies of clinopyroxenes reveal that Nabar rocks are formed at temperatures of 900-1200 ˚C. According to the distribution of aluminum in clinopyroxenes, these minerals were formed at 2-5 k bar pressure and water vapor content of more than 10 percent. Therefore, pyroxenes of the Nabar rocks are in a range of low to medium pressure that shows crystallization of clinopyroxenes during ascending of magma in different depths. Moreover, the volcanic rocks in Nabar were formed in high oxygen fugacity. The chemical composition of clinopyroxenes reveals that these rocks are related to calc-alkaline series and orogenic settings.
    Keywords: Clinopyroxene_Thermobarometry_Tectonomagmatic_Nabar_Urumieh - Dokhtar
  • Maryam Feyzi, Mohammad Ebrahimi, Hossein Kouhestani, Mir Ali Asghar Mokhtari Pages 507-524
    Introduction
    The Aqkand Cu occurrence, 48 km north of Zanjan, is located in the Tarom subzone of the Western Alborz-Azerbaijan structural zone. Apart from small scale geological maps of the area, i.e., 1:250,000 geological maps of Bandar-e-Anzali (Davies, 1977) and 1:100,000 geological maps of Hashtjin (Faridi and Anvari, 2000) and a number of unpublished perlite exploration reports, prior to this research no work has been done on Cu mineralization at Aqkand. The present paper provides an overview of the geological framework, the mineralization characteristics, and the results of geochemistry study of the Aqkand Cu occurrence with an application to the ore genesis. Identification of these characteristics can be used as a model for exploration of this type of copper mineralization in the Tarom area and elsewhere.
    Materials And Methods
    Detailed field work has been carried out at different scales in the Aqkand area. About 35 polished thin and thin sections from host rocks and mineralized and altered zones were studied by conventional petrographic and mineralogic methods at the University of Zanjan. In addition, a total of 6 samples from ore zones at the Aqkand occurrence were analyzed by ICP-MS for trace elements and REE compositions at Kimia Pazhuh Alborz Co., Isfahan, Iran.
    Results And Discussion
    The oldest units exposed in the Aqkand area are Eocene volcanic rocks which are overlain unconformably by Oligocene acidic rocks. The Eocene units consist of lithic and vitric tuff with intercalations of andesitic basalt lavas (equal to Karaj Formation, Hirayama et al., 1966). The andesitic basalt lavas show porphyritic texture consisting of plagioclase and altered ferromagnesian minerals set in a fine-grained groundmass. The Oligocene acidic rocks consist of rhyolite-rhyodacite, perlite, pitchstone and ignimbrite. These rocks are exposed as domes and lava flows. The rhyolite-rhyodacite lavas usually show onion-skin weathering and locally display flow bands. Rapid cooling of rhyolitic-rhyodacitic lavas has resulted in the formation of volcanic glasses (obsidian). Hydration of these volcanic glasses by hydrothermal fluids caused perlite formation which is located in the lower parts of the rhyolitic-rhyodacitic domes.
    Copper mineralization at Aqkand occurs as Cu-bearing quartz-fluorite veins in Eocene andesitic basalt lavas. The main ore vein reaches up to 50 m in length and average of 2 m in width. It has NW-trend and mostly dips NE. Six stages of mineralization can be distinguished at the Aqkand Cu occurrence. Stage-1 is characterized by
    Keywords: Geology, mineralization, geochemistry, Aqkand, Zanjan, Tarom-Hashtjin
  • Reyhaneh Ahmadirouhani, Mohammad Hassan Karimpour, Behnam Rahimi, Azadeh Malekzadeh Shafaroudi, Urs Klotzli, Jose Francisco Santos Pages 525-552
    Introduction
    The investigated area is situated in the south west of the Khorasan Razavi Province along the North West of the Lut Block. Different types of metal ore bodies along with non-metal deposits have already been documented in the Lut Block (Karimpour et al., 2008). Most of the study area is covered with granitoid rocks. Metamorphic rocks with unknown age are present in the north of the area. Skarns are observed in contact with fault zones and intrusive bodies. Eocene volcanic rocks with andesite and andesibasalt composition are located in the east and north east of the area (Ahmadirouhani et al., 2015). The study area that is a part of the Lut Block has a high potentials for Cu, Fe, Au, and Barite mineralization along the observed alteration zones. In the present study, the petrography, petrogenesis, Sr–Nd isotopes, and U–Pb zircon age of acidic granitoids in the east of Bajestan were investigated.
    Materials And Methods
    In the current study, 400 rock samples were collected from the field and 170 thin sections were prepared for petrography studies. Thirty samples of volcanic rocks, intrusions, and dykes were analyzed using XRF at the Geological Survey of Iran. Twenty-five samples were selected for the elemental analysis using ICP-MS by the Acme Lab Company (Canada), 16 samples of them were related to acidic intrusive bodies and dykes. In addition, zircon crystals from four samples of the granitoids bodies were collected for U–Pb dating. Approximately 50 zircon grains (i.e. euhedral, clear, uncracked crystals with no visible heritage cores and no inclusions) were hand-picked from each sample. Through cathodoluminescence imaging, the internal structure and the origin of zircon grains were examined at the Geological Survey of Vienna, Austria. Moreover, zircons were dated using the (LA)-ICP-MS method at the Laboratory of Geochronology, the University of Vienna, Austria using the methodology outlined in Klötzli et al., (2009). Sr and Nd isotopic compositions were also determined for the same samples (i.e. U-Pb samples) using the whole-rock method. The samples were analyzed in the Laboratório de Geologia Isotópica da Universidade de Aveiro, Portugal.
    Results
    Granitoids in the study area have mostly monzogranite (biotite monzogranite, hornblende biotite monzogranite and pyroxene hornblende biotite monzogranite), granite, and syenogranite composition. Granular, micro-granular, and porphyritic textures are common textures in these rocks. Common mafic minerals in these rocks include biotite, hornblende and pyroxene. Based on mineralogy, low values of magnetic susceptibility, high aluminum saturation index, and high initial 87Sr/86Sr ratios (> 0.710) of the study of granitoid rocks belong to the ilmenite-series of the reduced S-type granitoids. These magmas originated from the upper continental crust at a syncollosion zone. Furthermore, the rocks normalizing spider diagrams showed characteristics of a crustal environment. The age of the granitoids based on zircon U–Pb age dating was determined, including granite porphyry (79±1 Ma), syenogranite (76±1 Ma), biotite monzogranite (76±1 Ma), all of which belong to the Upper Cretaceous (Campanian), except pyroxene hornblende biotite monzogranite with 30.7±1 Ma, Oligocene age (Rupelian) has a different age. The ranges of their initial 87Sr/86Sr and 143Nd/144Nd ratios for Upper Cretaceous granitoids are 0.710897–0.717908 and 0.511995–0.512186, respectively while they are 0.713292 and 0.512186 for Oligocene intrusion. The initial єNd isotope values for the syenogranite, biotite monzogranite, and granite porphyry are -10.65, -7.38 and -9.51, respectively. The initial єNd isotope value for pyroxene hornblende biotite monzogranite is -8.06. The values of the igneous rocks could be considered as representative of continental crust derived from magma, and melt derived from psammite rocks is considered to have been the source of the granitoids.
    Discussion
    Based on the U-Pb dating results, there are two magmatism phases (Upper Cretaceous and Oligocene) in the area which have not reported in the north of Lut Block yet. During the Upper Cretaceous, three localities of granitoids are reported, excluding Bajestan: Bazman (initial 87Sr/86Sr =0.7056) is located in the southern part of the Lut Block, Gazu (initial 87Sr/86Sr =0.7045) is located near the Nayband fault in the Tabas Block and Kaje is located in Ferdows (initial 87Sr/86Sr =0.7061-0.7080). All of these granitoids were formed due to the subduction zone and their magma (I type) originated from mantle. However, granitoids in Bajestan with the initial 87Sr/86Sr =0.711-0.718 were formed during the continental collision while their magma was originated from the continental crust. In addition, the Middle Jurassic granitoids in the Lut Block (Shah Kuh, KlatehAhani and SurkhKuh) with the origin of continental crustal magma have an initial 87Sr/86Sr = 0.7068-0.7081. That is, the continental crust from which Bajestan granitoid magma is originated, is different from the other parts of the Lut Block due to very high (87Sr/86Sr). This indicates that Bajestan perhaps joined the Lut Block after the Upper Cretaceous collision.
    In addition to Bajestan, the Oligocene granitoids in the Lut block are reported in the Chah-Shaljami, Dehsalm, Mahoor and Khunik areas. Except Bajestan, all of these granitoids were formed in the subduction zone and their magma is I type. Mineralization in Chah-shaljami, Dehsalm, and Mahoor is related to the porphyric system, whereas no mineralization in Khunik and Bajestan Granitoids has been reported yet.
    Keywords: U-Pb dating, Rb-Sr, Sm-Nd isotopes, Bajestan, the Lut Block, Iran
  • Mahshid Malekian Dastjerdi, Seyyed Saeid Mohammadi, Malihe Nakhaei, Mohammad Hossein Zarrinkoub Pages 553-568
    Introduction
    The study area is located 12km away from the north east of Sarbisheh at the eastern border of the Lut block (Karimpour et al., 2011; Richards et al., 2012). The magmatic activity in the Lut blockhas begun in the middle Jurassic (165-162 Ma) and reached its peak in the Tertiary age (Jung et al., 1983; Karimpour et al., 2011). Volcanic and subvolcanic rocks in the Tertiary age cover over half of the Lut block with up to 2000 m thickness and they were formed due to subduction prior to the collision of the Arabian and Asian plates (Jung et al., 1983; Karimpour et al., 2011).
    In the Kangan area, the basaltic lavas cropped out beyond the above intermediate to acid volcanic rocks. In this area, bentonite and perlite deposits have an economic importance. The main purpose of this paper is to present a better understanding of the tectono-magmatic settings of volcanic rocks in the northeast of Sarbisheh, east of Iran based on their geochemical characteristics.
    Materials And Methods
    Fifteen samples were analyzed for major elements by inductively coupled plasma (ICP) technologies and trace elements by using inductively coupled plasma mass spectrometry (ICP-MS), following a lithium metaborate/tetraborate fusion and nitric acid total digestion, at the Acme laboratories, Vancouver, Canada.
    Results
    The Kangan area is located at the northeast of Sarbishe, Southern Khorasan and the eastern border of the Lut block. In this area, basaltic lavas have cropped out above intermediate to acid lavas such as andesite, dacite, rhyolite (sometimes perlitic) .The main minerals in the basalt are plagioclase, olivine and pyroxene, in andesite contain plagioclase, pyroxene, biotite and amphibole and in acid rocks include plagioclase, quartz, sanidine, biotite and amphibole. Intermediate to acid rocks have medium to high-K calc-alkaline nature and basalt is alkaline. Enrichment in LREE relative to HREE (Ce/Yb= 21.14-28.7), high ratio of Zr/Y(4.79- 10.81), enrichment in LILE and negative anomaly of Eu, Nb, P, Ti, Ba and Sr in intermediate to acid lavas are characteristics of subduction related calc-alkaline magmatism. Geochemical characteristics such as high ratio of La/Yb (8.18), low content of Rb with tectonic setting discriminant diagrams show within plate environment for basalt. The constituent magma of the studied rocks originated from an enriched garnet lherzolite source in 100 to 110km depth.
    Discussion
    Enrichment in LREE relative to HREE (Ce/Yb= 21.14-28.7), high ratio of Zr/Y (4.79- 10.81), enrichment in LILE and negative anomaly of Eu, Nb, P, Ti, Ba and Sr in intermediate to acid lavas are characteristics of subduction related calc-alkaline magmatism. Tectonic setting discrimination diagrams show that andesite to dacitic rocks are located in active continental margin (Schandle and Gorton, 2002) and basalt is placed within the volcanic plate zone and continental rift type (Verma et al., 2006). Intermediate to acid rocks of Kangan area originated from lithospheric mantle (Moharami et al., 2014) that is enriched by sediment melt related metasomatism (Ersoy et al., 2010) whereas Kangan basaltic lava origin is Nb enriched (Wang et al., 2008; Sajona et al., 1996) mixed lithospheric - asthenospheric mantle (Moharamiet al., 2014). According to the trace elements diagrams (Ellam, 1992), partial melting depth for generation of Kangan area lavas was determined to be about 100 to 110Km. Because of absent crustal contamination instances in the basalt, it can be argued that ascending of magma has been rapid and probably similar to other alkali basalts in east of Iran, it may be related to deep fault systems.
    Keywords: Andesite, Alkali basalt, Active continental margin, Kangan, Lut block
  • Alireza Almasi, Mohammad Hassan Karimpour, Keiko Hattori, Jose Francisco Santos, Khosrow Ebrahimi Nasrabadi, Behnam Rahimi Pages 569-592
    Introduction
    The study area is located in the central part of the Khaf- Kashmar- Bardaskan volcano-plotunic belt (briefly KKBB). Several IOCG deposits such as Tanourjeh Au-bearing magnetite deposit and Kuh-e-Zar Specularite-rich Au deposit have been explored in KKBB. Geology, alteration, mineralization, geochemistry and fluid inclusion results in Kashmar suggest the IOCG type Au-bearing magnetite mineralization. These IOCG deposits at KKBB form at an active continental arc related to SSZ-type Sabzevar oceanic subduction.
    Materials And Methods
    Use of Landsat 7, IRS and Aster satellites.
    Petrography and alteration Studies in 150 thin sections of volcanic and intrusive rocks.
    Sampling of ore-bearing quartz vein and mineralography.
    Preparation of 28 geochemistry samples by the chip composite method of ore-bearing quartz vein and analyzing them in the ACME laboratory by Aqua Regia 1DX1.
    Fluid inclusions studies of 14 samples of quartz and barite related to the ore minerals of ore-bearing quartz vein by THM600 stage of Linkam company.
    Results
    Magmatic events in Kashmar occur at Paleocene-Eocene and include: (1) old mafic - intermediate volcano-plutonic series; (2) felsic volcanic and granitoids; and (3) parallel swarm dykes which are youngest (Almasi et al., 2016). Geochemically, Kashmar rocks are metaluminous to highly peraluminous and Tholeitic to calc-alkaline and shoshonitic in composition (Almasi et al., 2016). The field characteristics, together with isotope and geochemical analyses show that all rock types are essentially co-magmatic and post-collisional I-type (Almasi et al., 2016). Alteration of Kashmar is described in two ways: (1) intense ellipsoidal-linear Argillic-Sillicification and low sericitic with Silica caps and with medium widespread and propylitic alterations in triple regions, next to Dorouneh fault; and (2) Medium Hematite-Carbonate-Chlorite-Silicification alterations in Kamarmard heights. In parts of near the Doruneh fault, sometimes fractures of rocks are filled with tourmaline (Dumortierite type) and iron oxides.
    Kashmar surface mineralization is described in the ore-bearing quartz veins. Principal mineralization textures are layered, comb and Brecciation. The most important types of veins are those containing Chalcopyrite - Quartz veins, Specularite-rich veins – Quartz-Galena veins accompany with hydrothermal Breccias. Barren barite veins also exist in the region. The Chalcopyrite - Quartz veins occur on the main fracture zone and next to the Argillic alterations and silica cap in three regions (Bahariyeh, Uch Palang and Sarsefidal). Hydrothermal Breccias, Spicularite- rich veins, Quartz - Galena and barite veins occurred within Hematite- Carbonate-Chlorite-Silicification alterations in the Kamarmard area. Geochemistry of veins indicates anomalies of gold, copper, lead and zinc in them. Most enrichments of gold are accompanied with copper, lead and zinc and they occurs in hydrothermal Breccias and then specularite- rich veins. Gold values up to about 15 ppm and Cu, Pb and Zn each to > 1%.
    Temperature – salinity studies of fluid inclusions of ore-bearing Quartz veins in Kashmar show the fluid temperature and salinity values in all veins are close together. Temperatures are moderate to relatively high and between 245° C and 530 ° C and salinities are relatively low to moderate and between 14 to 18 (wt% NaCl). Maximum and minimum of temperatures and salinities are related to fluid inclusions of hydrothermal Breccias and Quartz-Galena vein. Co-existence between two-phase liquid-vapor rich fluids and single-phase gas fluids in the veins indicate that conditions were close to boiling, and maybe a little boiling occurred, which strengthened with brecciaing of rock and view rare CO2-bearing fluid inclusion in veins on the Kamarmard peak. Non-existence of vuggy Quartz in silica caps in the region shows this issue. The frequency of oxide minerals (Specularite, Barite), H2O-NaCl-CaCl2 system, and the low amounts of sulfide minerals in Kashmar, all represent the oxidized conditions of hydrothermal fluid and the impact of CO2-bearing chloride complex in transport, non-interference of meteoric waters and precipitation of metallic elements with reducing of temperature.
    Discussion
    Most important IOCG deposits of south America (Candelaria, Mantoverde and Raul Condstable) have Au-bearing massive magnetite bodies accompanied with Potassium (actinolite, biotite and K-feldspar) alterations with high temperatures (500-700 O C) and salinities (>40%wt NaCl) at deepest parts (Sillitoe, 2003). At the upper levels, there are magnetite changes to hematite (Specular) and the possibility of coarse calcite (± silver mineralisation). Hematite zone may display hydrothermal/tectonic brecciation. The hematite-rich veins tend to contain sericite and/or chlorite, with or without K-feldspar or albite, and to possess alteration haloes characterized by these same minerals. Both the magnetite- and specular hematite-rich IOCG veins contain chalcopyrite and generally subordinate Pyrite (Fuller et al., 1965).
    Keywords: Alteration, Vein mineralization, Fluid inclusions, IOCG, Kashmar
  • Saeed Saadat Pages 593-607
    Introduction
    Ground magnetometer surveys is one of the oldest geophysical exploration methods used in identifying iron reserves. The correct interpretation of ground magnetic surveys, along with geological and geochemical data will not only reduce costs but also to indicate the location, depth and dimensions of the hidden reserves of iron (Robinson and Coruh, 2005; Calagari, 1992). Kalateh Naser prospecting area is located at 33° 19ó to 33° 19óó 42" latitude and 60° 0' to 60° 9ó 35" longitude in the western side of the central Ahangaran mountain range, eastern Iran (Fig.1). Based on primary field evidences, limited outcrops of magnetite mineralization were observed and upon conducting ground magnetic survey, evidence for large Iron ore deposits were detected (Saadat, 2014). This paper presents the geological and geochemical studies and the results of magnetic measurements in the area of interest and its applicability in exploration of other potential Iron deposits in the neighboring areas.
    Materials And Methods
    To better understand the geological units of the area, samples were taken and thin sections were studied. Geochemical studies were conducted through XRF and ICP-Ms and wet chemistry analysis. The ground magnetic survey was designed to take measurements from grids of 20 meter apart lines and 10 meter apart points along the north-south trend. 2000 points were measured during a 6-day field work by expert geophysicists. Records were made by Canadian manufactured product Magnetometer Proton GSM19T (Fig. 2). Properties of Proton Magnetometer using in magnetic survey in Kalateh Naser prospecting area is shown in Table 1. Total magnetic intensity map, reduced to pole magnetic map, analytic single map, first vertical derivative map and upward continuation map have been prepared for this area.
    Results
    The most significant rock units in the area are cretaceous carbonate rocks (Fig. 3). The unit turns to shale and thin bedded limestone in the central part and into red and white crystalline limestone towards the west, which sometimes can be referred as marble and skarn (Figs. 4, 5 and 6; Saadat, 2014). Iron mineralization is mostly observed in these units. Acidic to intermediate intrusive bodies consisting hornblende quartz monzonite, biotite granodiorite, pyroxene quartz diorite have outcrops in the north and northwestern part of the area (Fig. 3). Outcrops from andesite to dacite volcanic rocks in combination with ultra-mafic rocks can be seen in the southern part of the region.
    The geochemical results indicated F2O3 value range of %31 to %96. P2O5 of maximum %0.45 was observed and TiO2 varied from %0.02 to %0.54 (Tables 2 and 3 and Figs 7, 8 and 9). The highest values of iron and copper are found in the northern part, titanium and phosphorus are located in the southern part and manganese and vanadium are placed in the central sector. According to the obtained results, the highest magnetic susceptibility was associated with the skarn units and was measured at 34000*10-5 SI which is related to the mineralization of Iron in the area. Magnetic susceptibility of limestone crystalline units were close to 50*10-5 SI and marble was less than 10* 10-5 SI which highlights the influence of iron mineralization in the carbonates rocks. This value was around 80*10-5 SI for intrusive rocks such as hornblende quartz monzonite in the area (Table 4). Ground magnetic studies suggest minimum of 40000 nT and maximum of 70000 nT total magnetic intensity in the area (Fig. 10-A; Ryahei, 2013). Utilizing the Reduced to Pole Magnetic Filter is to locate the anomalies in the study area (Fig. 11-A). Since magnetic declination causes a degree of deviation between the source and magnetic anomalies, the said filter is applied to magnetic data and ultimately, analysis is done based on the magnetic data transferred to the pole (Nakatsuka and Okuma, 2006; Clark, 1997). The results of reduce to pole magnetic map for this area yielded three large and two small magnetic anomalies (Figs 12-A and 12-B). The upward continuation maps were taken with 5m, 10m, 20m, 30m, 40m, and 50m. Smaller anomalies tend to disappear more comparing the 5m to 20m continuation maps respectively, and a homogenous large anomaly starts to form in the 50m map (Fig. 13). Large and clear anomalies continue to be present in the 50m continuation map and only two smaller anomalies are disappeared from the west of the area (Ryahei, 2013).
    Discussion
    The results of geological, geochemical and magnetic susceptibility measurements indicate that magnetic anomalies in the Kalate-Naser area is related to the iron mineralization in this area. Lower amount of magnetic susceptibility in intrusive mass outcrops also indicate that these intrusive rocks did not play the main role in iron mineralization and were in fact have been weakly altered. It can only be concluded that the intrusive mass that led to mineralization sits beneath, at a higher depth.
    The initial geophysical survey results are closely comparable to the powder drilling trials that confirm magnetite mineralization to the named depth (Saadat, 2014). Thus far, 1.5 Million ton of Iron ore deposits have been confirmed in the area and exploration continues during production. The obtained results once again highlight the importance of ground magnetic surveys that combined with other exploration methods can reduce costs, increase efficiency and simplify the exploration process. Methodology and results of the magnetic measurements conducted in Kalateh Naser can help to better understand the magnetite bodies in the neighboring areas.
    Keywords: Magnetite mineralization, Ground Magnetometery, Kalateh Naser, Ahangaran, Lut block