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زمین شناسی اقتصادی - سال نهم شماره 1 (پیاپی 16، بهار و تابستان 1396)
  • سال نهم شماره 1 (پیاپی 16، بهار و تابستان 1396)
  • تاریخ انتشار: 1396/04/26
  • تعداد عناوین: 13
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  • حیدر اصغرزاده اصل، بهزاد مهرابی، ابراهیم طالع فاضل صفحات 1-23
    منطقه فلززایی اهر- ارسباران (زون قره داغ) از دیدگاه کانی سازی های طلا، مس و مولیبدن دارای اهمیت بالایی است که این کانی سازی ها اغلب هم زمان با رخ داد ماگماتیسم در محدوده زمانی ائوسن- الیگوسن شکل گرفته است. منطقه آق درق در بخش شرقی توده نفوذی شیورداغ (باتولیت اهر)، متشکل از سنگ های رسوبی مزوزوئیک و آذرین نیمه عمیق کالک آلکالن به سن الیگوسن است. روند اغلب گسل ها در این منطقه شمال شرق- جنوب غرب است. کانی سازی های آق درق در سه بخش چوپانلار، آیران گلی و گودال با حضور عناصر مس (±طلا-تنگستن) و کانی های کالکوپیریت، مگنتیت، روتیل، اسفالریت، شیلیت و طلای آزاد رخ داده است. بافت و ساخت کانی سازی شامل رگه- رگه چه ای، استوک ورک، انتشاری، جانشینی و پرکننده فضای خالی است که آن را دگرسانی های پتاسیک، فیلیک و آرژیلیک همراهی می کنند. طبق شواهد پتروگرافی میان بارها، سه نوع میان بار شامل میان بارهای آبگین دارای فاز هالیت (H2O-NaCl±KCl)، دو فازی آبگین (H2O-NaCl±CaCl2)، و تک فاز مایع و گاز در رگه های کوارتز- سولفیدی تشخیص داده شد. طبق شواهد، به نظر می رسد سیالات نخستین با شوری 4/31 تا 5/44 درصد معادل نمک طعام و دمای 201 تا C°474 از نفوذی های اسیدی تا حدواسط که حاوی کانه زایی قلع- تنگستن هستند، از عمق تقریبی 4 کیلومتر سرچشمه گرفته اند. پس از آن، با صعود سیالات به عمق کم و اختلاط با آب های سطحی، کانه زایی چندفلزی غنی از طلا در منطقه رخ داده است.
    کلیدواژگان: میان بارهای سیال، مراحل کانی سازی، منطقه فلززایی اهر، ارسباران، آق درق
  • ملیحه گلستانی، محمدحسن کریم پور، آزاده ملکزاده شفارودی، محمدرضا حیدریان شهری صفحات 25-55
    کانسار ایجو در پهنه فلززایی مس پورفیری کرمان، در کمان ماگمایی ارومیه- دختر و 60 کیلومتری شمال غرب شهر بابک قرار گرفته است. کانی سازی مس مرتبط با توده های اسیدی تا حدواسط میوسن بالایی با ترکیب تونالیت تا کوارتز دیوریت است. دگرسانی گرمابی شامل کوارتز- سرسیت- پیریت و پروپلیتیک است که از این میان، دگرسانی کوارتز- سرسیت- پیریت بیشترین گسترش را داراست. کانی سازی به شکل پراکنده، استوک ورک و برش هیدروترمالی دیده می شود. مشاهدات صحرایی و پتروگرافی انجام شده، نشان می دهد که 3 گروه اصلی رگه-رگه چه در منطقه وجود دارد که رگه چه های کوارتز+پیریت از بقیه فراوانتر است و برای بررسی های سیال درگیر و ایزوتوپ گوگرد انتخاب شدند. همچنین پتروگرافی سیالات درگیر نشان می دهد که در کانسار ایجو هشت گروه سیال درگیر شامل سیالات درگیر تک فازی غنی از مایع، سیالات درگیر دو فازی غنی از مایع، سیالات درگیر دو فازی غنی از بخار، سیالات درگیر سه فازی غنی از بخار (بخار- مایع- فلز)، سیالات درگیر سه فازی غنی از مایع (مایع- بخار- فلز)، سیالات درگیر 3 فازی هالیت دار (مایع-بخار- هالیت)، سیال درگیر چهار فازی (مایع- بخار- فلز± کالکوپیریت) که به صورت ثانویه است و فقط یکی از آن دیده شد و سیالات درگیر چند فازی شامل: (مایع-بخار-هالیت-فلز)، (مایع-بخار-هالیت-فلز±انیدریت) و (مایع-بخار-هالیت-فلز±کالکوپیریت) وجود دارد که در دو گروه بدون فاز هالیت و حاوی فاز هالیت قرار می گیرند. بررسی های دماسنجی نشان می دهد که محدوده دمای همگن شدگی نهایی و شوری برای سیالات درگیر بدون فاز هالیت °C380 تا 140 و Wt.%NaCl 24 تا 18/0 و برای سیالات درگیر حاوی فاز هالیت °C480 تا 230 و Wt.%NaCl 52 تا 30 است که با کانسارهای مس پورفیری ایران مشابهت دارد. بیشترین دمای همگن شدگی نهایی مربوط به سیالات سه فازی (L+V+H) است. همچنین فشار و عمق برای سیالات درگیر حاوی فاز هالیت به طور میانگین bar750 و m3500 است. سیالات درگیر مایع+بخار+هالیت+فلز+کالکوپیریت با شوری بالای 27/49 تا 55/51 و دمای 7/420 تا 442 درجه سانتی گراد مسوول حمل مس و به دنبال آن رسوب کالکوپیریت است. محدوده وسیع در بین داده های سیالات درگیر می تواند به وسیله تغییرات فیزیکوشیمیایی در سیال مانند جوشش، سرد شدن و اختلاط با سیالات سطحی توجیه شود. مقدار 34Sδ کانی پیریت از 86/0- تا 27/1+ در هزار (میانگین 228/0+ درهزار) در حال نوسان است که مقدار 34SH2Sδ سیال همزاد با کانی پیریت محدوده 23/0- تا 36/2- در هزار (میانگین 17/1- در هزار) بوده که خاستگاه ماگمایی را برای گوگرد نشان می دهد. به نظر می رسد، به دلیل عمق زیاد جایگذاری، پایین بودن آب در ماگمای مولد و به تبع آن فقیر بودن سیال کانه ساز اولیه از مس و نبود شرایط مناسب (نبود گسل های منطقه ای و شکستگی های فراوان) برای خروج و تثبیت مس در سنگ میزبان، کانسار مس پورفیری ایجو نیمه اقتصادی تا غیراقتصادی باشد.
    کلیدواژگان: سیال درگیر، ایزوتوپ گوگرد، مس پورفیری، ایجو، کرمان
  • نرگس شیردشت زاده، قدرت ترابی، رامین صمدی صفحات 57-72
    پریدوتیت های گوشته ای از واحدهای سنگی تشکیل دهنده افیولیت نایین هستند که در بیشتر رخنمون ها دگرسان و سرپانتینی شده اند. پریدوتیت های گوشته ای دره ده به صورت توده منفرد در خاور افیولیت نایین رخنمون دارند. پریدوتیت های این منطقه عبارتند از: لرزولیت (شامل کانی های الیوین (فورستریت)، کلینوپیروکسن (اوژیت)، ارتوپیروکسن (انستاتیت)، کروم اسپینل ، سرپانتین (کریزوتیل، لیزاردیت و آنتی گوریت)، تالک ، کلریت، ترمولیت و الیوین دگرگونی)، هارزبورگیت (شامل کانی های الیوین جانشینی، ارتوپیروکسن، کروم اسپینل ، اندکی کلینوپیروکسن، سرپانتین، تالک ، کلریت و ترمولیت) و دونیت (شامل کانی های الیوین جانشینی، کروم اسپینل ، اندکی ارتوپیروکسن، سرپانتین، تالک ، کلریت و ترمولیت). شواهد سنگ نگاری بیانگر رویداد یک دگرگونی در حد رخساره آمفیبولیت پس از سرپانتینی شدن و کلریتی شدن مجموعه پریدوتیت های منطقه دره ده است. وجود آثار دگرگونی در هارزبورگیت و دونیت نشان دهنده رخ داد این دگرگونی پس از فرآیندهای مذاب- سنگ در محیط سوپراسابداکشن دیرینه است.
    کلیدواژگان: کانی شناسی، دگرگونی، پریدوتیت گوشته ای، افیولیت نایین، ایران مرکزی
  • هوشنگ پورکاسب، علیرضا زراسوندی، مدینه ساعد، علیرضا داودیان دهکردی صفحات 73-92
    کانسار مس- طلای پورفیری دالی در غرب روستای راوه، شهرستان دلیجان و در بخش مرکزی کمربند ماگمایی ارومیه- دختر قرار دارد و ناشی از نفوذ توده هایی با ترکیب دیوریت و کوارتز دیوریت به سن میوسن در سنگ های آتشفشانی با ترکیب آندزیت تا آندزیت بازالت پورفیری الیگو- میوسن است. دگرسانی های پتاسیک، آرژیلیک، پروپلیتیک و به طور محلی فیلیک باعث افزایش شدت کانه زایی در بعضی مناطق شده اند. هدف از این پژوهش، بررسی ترکیب شیمیایی کانی های موثر بر کانه زایی و تکامل سیال کانه دار در ماگمای مولد و تاثیر آن در توان کانه زایی کانسار مورد نظر است. برای این منظور کانی های آمفیبول و پلاژیوکلاز در سنگ های کانه دار با استفاده از روش ریز پردازش الکترونی مورد بررسی قرار گرفتند و داده های به دست آمده با بررسی میان بارهای سیال در رگه های دخیل در کانه زایی تلفیق شدند. نتایج حاصل از بررسی های ریز پردازش الکترونی1 نشان داد که آمفیبول های ماگمایی، از نوع کلسیک و در گستره منیزیو هورنبلند، ادنیت، منیزیو هستینگزیت و چرماکیت است. همچنین پلاژیوکلازها در گستره آندزین و لابرادوریت هستند. با توجه به دما– فشار سنجی، آمفیبول ها در فشار 5/3 تا 3/5 کیلوبار و دمای 818 تا 899 درجه سانتی گراد در محیطی با گریزندگی اکسیژن بالا و در شرایط اکسیدان شکل گرفته، این شرایط زمینه را برای حمل و انتقال مس و طلا فراهم می کند و بیانگر شرایط ماگمایی، ماگمای مادر پورفیری دالی است. نتایج به دست آمده از داده های ریز دماسنجی سیال درگیر مربوط به رگه های نابارور اولیه همراه با دگرسانی پتاسیک میزان دمای340-620 درجه سانتی گراد، شوری 35-75% درصد وزنی را نشان می دهد که با توجه به دمای آمفیبول ها این افت دما بیانگر تغییر از شرایط ماگمایی به گرمابی و آغاز فرآیندهای کانه زایی در این کانسار است.
    کلیدواژگان: پلاژیوکلاز، آمفیبول، گریزندگی اکسیژن، ریز پردازش الکترونی، دالی، کمربند ماگمایی ارومیه - دختر
  • حبیب بیابانگرد، محمد بومری، خسرو تیموری، فاطمه محمدپور صفحات 93-115
    کانی زایی آهن رشتخوار در جنوب شرقی استان خراسان رضوی و 48 کیلومتری شرق شهر رشتخوار قرار دارد. از نظر زمین شناسی این محدوده در شمال شرقی بلوک لوت واقع شده و متعلق به نوار ولکانو پلوتونیک خواف-بردسکن است. سنگ های آذرین حدواسط به صورت استوک، دایک، گدازه و نهشته های آذرآواری سنگ میزبان کانی زایی آهن هستند. این سنگ ها شامل دیوریت پورفیری، مونزوسینیت پورفیری، آندزیت، بازالت و لیتیک توف و دارای بافت های گرانولار، پورفیری، میکرولیتیک پورفیری و هیالومیکرولیتیک هستند و از کانی های پلاژیوکلاز، فلدسپات های پتاسیم، آمفیبول و پیروکسن تشکیل شده اند. واحدهای رسوبی اغلب کنگلومرا، شیل و ماسه سنگ هستند. دگرسانی های پروپیلیتیک، سریستیک- پروپیلیتیک، سیلیسی و آرژیلیک پیشرفته مهمترین دگرسانی ها هستند که طی آنها برخی از کانی ها مثل پلاژیوکلاز ها، فلدسپات های پتاسیم و آمفیبول ها به سریسیت، کلریت و کانی های رسی دگرسان شده اند. مگنتیت و اسپیکولاریت مهمترین کانه های محدوده معدنی آهن رشتخوار هستند. عامل اصلی کانی سازی در این محدوده معدنی تغییرات فوگاسیته اکسیژن و گوگرد محیط است؛ به طوری که آب های سطحی اکسیژن دار پس از نفوذ به اعماق و ترکیب با آب های ماگمایی دما بالا، در شرایط فوگاسیته بالای اکسیژن و fS2 پایین به تشکیل کانی اسپیکولاریت و مگنتیت در مرحله اولیه کانی سازی منجر شده است. نمودار های ژئوشیمیایی مختلف نشان می دهد که محدوده معدنی مورد بررسی در محدوده ذخایر گرمابی قرار می گیرد.
    کلیدواژگان: ایران، آهن رشتخوار، کانی زایی آهن، دگرسانی، بلوک لوت
  • سمانه نادرمزرجی، محمدحسن کریم پور، آزاده ملکزاده شفارودی صفحات 117-139
    منطقه اکتشافی شاه سلطان علی در شرق بلوک لوت و جنوب غربی بیرجند قرار دارد. در این منطقه طیف گسترده ای از واحدهای نیمه عمیق با ترکیب مونزونیت پورفیری، مونزودیوریت- پورفیری و دیوریت پورفیری درون واحدهای آتشفشانی با ترکیب آندزیت – بازالت نفوذ کرده، و به تشکیل انواع دگرسانی های پروپلیتیک، کوارتز – سرسیت – پیریت، آرژیلیک، سیلیسی، سرسیتی و کربناته منجر شده است. طبق بررسی های ژئوشیمیایی، توده های درونی منطقه همه از نوع متا آلومینوس با ماهیت کالک آلکالن پتاسیم بالا تا شوشونیتی است و این توده ها در دسته مگنتیت نوع I طبقه بندی می شوند. غنی شدگی عناصر LREE نسبت به HREE همراه با آنومالی منفی Nb نشان دهنده تشکیل ماگما در زون فرورانش است. از نظر تکتنوماگمایی توده های بالا در محیط گرانیتوئیدهای کمان های آتشفشانی قرار می گیرند. کانی سازی اصلی منطقه در واحد های مونزونیت پورفیری و مونزودیوریت پورفیری با دگرسانی کوارتز – سرسیت – پیریت رخ داده است. این توده ها بالاترین تراکم رگه چه، بالاترین درصد اکسید آهن و بیشترین ناهنجاری ژئوشیمیایی عناصر را نشان می دهند. همچنین چهار نوع کانی سازی استوک ورک، رگه ای، افشان و برش گرمابی همراه این توده ها دیده می شود. در بررسی های ژئوشیمیایی خرده سنگی، دامنه تغییرات عناصری مثل مس از 30 تا 454 گرم در تن، روی 27 تا 279 گرم در تن، آنتیموان 9/0 تا 152 گرم در تن، طلا 5 تا 128 میلی گرم در تن متغیر است که این آنومالی ها بر دگرسانی کوارتز – سرسیت – پیریت با کانی سازی استوک ورک منطبق است. با توجه به تنوع واحد های نیمه عمیق نوع I با ماهیت کالک آلکالن پتاسیم بالا تا شوشونیتی، گسترش و نوع آلتراسیون ها، کانی سازی استوک ورک و آنومالی عناصر، احتمالا این منطقه مرتبط با سیستم های مس پورفیری است.
    کلیدواژگان: دگرسانی، کانی سازی، گرانیتوئید I، مس پورفیری، شاه سلطان علی، بیرجند، بلوک لوت
  • آرزو مرادی، ناهید شبانیان بروجنی، علیرضا داودیان دهکردی صفحات 141-158
    توده گرانیت- گنایس میلونیتی شمال شرق معدن ژان، جزئی از مجموعه ماگمایی- دگرگونی شمال غرب شهرستان ازنا در استان لرستان و در پهنه ساختاری سنندج- سیرجان واقع شده است. این مجموعه ماگمایی- دگرگونی شامل گرانیت- گنایس ، آمفیبولیت ، مرمر و شیست است. گرانیت - گنایس مورد بررسی، دارای بافت اصلی لپیدوگرانوبلاستیک و کانی های اصلی کوارتز، آلکالی فلدسپار (میکروکلین پرتیتی)، پلاژیوکلاز، کانی های فرعی مسکویت فنژیتی، اپیدوت (ماگمایی)، آلانیت، تورمالین، زیرکن، اسفن و کانی متداول بیوتیت است. این توده گرانیتوئیدی از نظر ژئوشیمیایی پرآلومین تا کمی متاآلومین، کالک آلکالن تا حدودی آلکالن بوده و در موقعیت زمین ساختی پس از برخورد در حاشیه فعال قاره واقع شده است. در نمودار SNX در برابر SNY در دو محدوده هم زمان با دگرشکلی و مراحل پایانی دگرشکلی هم پوشانی دارند و از نوع آلکالن- کلسیک هستند. این توده گرانیتوئیدی دارای ماهیت A-type است و در زیرگروه A2 قرار می گیرد.
    کلیدواژگان: ژئوشیمی، گرانیت A2، پس از برخورد، شمال شرق معدن ژان، پهنه سنندج - سیرجان
  • هوشنگ پورکاسب، علیرضا زراسوندی، زهرا فریدونی، بابک مختاری، ندا میرزایی صفحات 159-174
    کانسار فسفات کوه سفید در کمربند زاگرس چین خورده ساده در شمال شرق استان خوزستان، شهرستان رامهرمز واقع است. سازند پابده با سه بخش بالایی (کانه زایی فسفات)، میانی (کانی های اکسیدی) و شیل های زیرین (مواد آلی همراه کانه زایی) میزبان کانه زایی است. هدف این پژوهش، بررسی انواع ترکیبات آلی همراه کانه زایی فسفات است. بنابراین 12 نمونه از واحد های فسفاته و شیلی برای بررسی های کانی شناسی، XRD، FTIR و راک ایول برداشت شد. بررسی مقاطع میکروسکپی نشان داد که اجزای فسفاته شامل پلت، اائید، اینتراکلاست، خرده استخوان و میکروفسیل هاست. بررسی های XRD و FTIRباند های معدنی– آلی مانند OH، OH کربوکسیلیک، C=O اسید های کربوکسیلیک، C≡Cآلکین، گروه CH2، C=Cآروماتیک، CHآروماتیک و آلیفاتیک همراه کانه زایی را مشخص کردند. کربن های آلی و قاره ای نیز توسط پیرولیز راک ایول تعیین شدند که نشان داد، کانه زایی اغلب منشا قاره ای دارد و بخشی نیز حاصل تخریب مواد آلی توسط میکروارگانیسم هاست.
    کلیدواژگان: ماده آلی، آپاتیت، فسفات، کوه سفید، سازند پابده
  • جمال رسولی، منصور قربانی، وحید احدنژاد صفحات 175-195
    کمپلکس گرانیتوئیدی جبال بارز در جنوب شرق استان کرمان، بین طول های شرقی ′45 ◦57 تا ′00 ◦58 و عرض های شمالی ′30 ◦28 تا ′00 ◦29 واقع شده است. در این کمپلکس، پیکره اصلی سنگ شناسی شامل گرانودیوریت بوده؛ ولی سنگ هایی با ترکیب کوارتزدیوریت، گرانیت و آلکالی گرانیت و به مقدار بسیار کم تونالیت نیز دیده شده است که به وفور دارای انکلاوهای ماگمایی فلسیک و مافیک هستند. احتمالا انکلاوهای فلسیک حاصل گسیختگی های حاشیه ای در اثر ضربان های تزریق متوالی در فازهای اولیه و سقف توده نفوذی گرانیتوئیدی بوده و انکلاوهای مافیک نیز با استناد به تفاوت های آشکار با سنگ میزبان گرانیتوئیدی، نشانه ای از اختلاط ماگمای فلسیک و مافیک در منطقه است. بررسی های میکروسکپی ریزساختارها نشان دهنده سه نوع ریزساختار ماگمایی، ساب ماگمایی و میلونیتی است که ریزساختارهای ماگمایی و ساب ماگمایی، هم زمان با جایگیری توده اتفاق افتاده است؛ ولی ریزساختارهای میلونیتی، حاصل فعالیت های پس از جایگیری توده هستند. بر اساس بررسی های ژئوشیمیایی، ماگمای مجموعه مورد بررسی، سرشت پرآلومین تا متاآلومین داشته و گروه ماگمایی آن از نوع کالک آلکالن پتاسیم متوسط تا بالاست. همچنین بررسی نمودارهای تغییرات اکسیدهای اصلی و عناصر فرعی، طیف پیوسته ای بین ترکیبات سنگ های مورد بررسی نشان داده که بیانگر انجام تفریق ماگمایی گسترده در طی تبلور است. بررسی های صحرایی، مطالعات پتروگرافی و ژئوشیمیایی نشان می دهد که سنگ های مورد بررسی از نوع گرانیتوئیدهای نوع I است و در زیر مجموعه گرانیت های CAG قرار می گیرند. از نظر جایگاه زمین ساختی، این سنگ ها جزو گرانیتوئیدهای کمان قاره ای بوده اند و از گرانیت های قبل از برخورد تا هم زمان با برخورد به شمار می آیند. به نظر می رسد کمپلکس گرانیتوئیدی جبال بارز در داخل یک پهنه برشی قرار گرفته و ماگما از محل کالداری میجان در دفعات مختلف در طول پهنه برشی، به شکل سیل تزریق و جایگزین شده و خاستگاه ساختاری کمپلکس گرانیتوئیدی جبال بارز، فضاهای کششی است که محصول رژیم زمین ساختی ترافشارشی هستند.
    کلیدواژگان: مجموعه گرانیتوئیدی جبال بارز، فرورانش، ریزساختارها، زمین ساخت ترافشارشی
  • بهروز کریمی شهرکی، بهزاد مهرابی صفحات 197-211
    روش میکروآنالیز LA-ICP-MS برای آنالیز ترکیب سیال های درگیر واقع در کانسار آهن جلال آباد استفاده شد. نمونه های مورد بررسی از گمانه های حفاری شده و پیت معدن که با کانی سازی ارتباط داشتند، برداشت شده است. سیالات درگیر چند فازی (L+V+S) در کوارتز فراوان است و دمای همگن شدن آنها 260 تا 440 درجه سانتی گراد است. شوری سیالات بین 30 تا 52 درصد معادل وزنی نمک طعام است. نتایج LA-ICP-MS روی سیالات درگیر نشان داد که مقدار Fe و Cu به ترتیب تا 16076 و 3204 گرم بر تن و میانگین 6914 و 792 گرم بر تن هستند. مقدار Na در سیالات درگیر بین 26906 تا 140716 گرم بر تن و K در محدوده 2372 تا 70484 گرم بر تن اندازه گیری شد. نسبت Ca/K بین 53/0 تا 68/8 و با میانگین 75/1 است که نشان دهنده اختلاط سیالات ماگمایی و غیر ماگمایی است. نسبت Mn/Fe در سیالات درگیر در محدوده 21/0 تا 87/1 است که نشان دهنده حضور دو نوع سیال اکسیدی و احیایی است. نتایج به دست آمده از بررسی های کانی شناسی، میکروترمومتری و شیمی سیالات درگیر نشان می دهد سیالات ماگمایی- گرمابی حاوی فلزات، سیالات گرمابی- غیر ماگمایی و اختلاط آنها با یکدیگر علت کانی سازی اکسید آهن- مس- طلا در کانسار جلال آباد بوده است.
    کلیدواژگان: مگنتیت، سیالات درگیر، کانسار IOCG، LA-ICP-MS، جلال آباد، زرند
  • مجید طاشی، فردین موسیوند، حبیب الله قاسمی صفحات 213-233
    کانسار مس- نقره گرماب پایین در توالی آتشفشانی- رسوبی کرتاسه پسین زیر پهنه سبزوار واقع شده است. کانه زایی به شکل هندسی چینه سان و چینه کران در افق چینه ای خاص به همراه نهشته های برون دمی رخ داده است. سنگ میزبان کانه زایی را سنگ های آتشفشانی آندزیتی- داسیتی و آذرآواری های وابسته تشکیل می دهند. کانه زایی از کمرپایین به سمت کمربالا در چهار رخساره رگه- رگه چه ای، توده ای- نیمه توده ای، لایه ای و رسوبات برون دمی رخ داده است. کانی شناسی ماده معدنی شامل کانی های اولیه نظیر پیریت، مگنتیت و کالکوپیریت و کانی های ثانویه نظیر مس طبیعی، مالاکیت، کوپریت، کولیت و اکسیدهای آهن- منگنز است. دگرسانی سنگ دیواره، به طور عمده از نوع کلریتی و به مقدار کمتر شامل سیلیسی، آرژیلیتی و زئولیتی است. حداکثر عیار طلا و نقره در کانسار به ترتیب 1 و 19 گرم در تن است. به نظر می رسد که بروز فعالیت آتشفشانی زیردریایی در یک حوضه پشت کمانی در کرتاسه پسین، به تشکیل این کانسار سولفید توده ای نوع بشی منجر شده است.
    کلیدواژگان: سولفید توده ای، نوع بشی، کانسار گرماب پایین، کرتاسه پسین، زیر پهنه سبزوار
  • مهرداد براتی، ابراهیم طالع فاضل، افشین اکبرپور، بابک طلایی، مسعود مصلحی صفحات 235-248
    کانسار فلوریت قهرآباد در 57 کیلومتری جنوب شرق شهرستان سقز، در استان کردستان واقع شده است. این نهشته به صورت عدسی های پراکنده، رگه ای، رگه چه ای و شکافه پرکن در سنگ میزبان های کربناتی- دولومیتی معادل سازند الیکا به سن تریاس رخ داده است. در این منطقه، روند گسل ها تقریبا عمود بر روند اصلی گسل های زاگرس و شیب آن ها تقریبا عمودی است و کانی سازی در زون برشی این گسل ها روی داده است. کانی های اصلی ذخیره شامل فلوریت (با رنگ های بنفش، سبز و بی رنگ) و گانگ ها، کوارتز، کلسیت، باریت و دولومیت هستند. انواع سیالات درگیر دو فازی L+V، سیالات سه فازیH2O+ (CO2)L + (CO2)V و L+V+S و حتی چهار فازی L+V+S1+S2 در نمونه ها دیده شده است. پدیده هایی مثل بلور منفی، سوزنی شدن و دم بریدگی نیز در سیالات درگیر دیده شده است. دماهای همگن شدن سیالات درگیر اولیه و ثانویه کاذب در فلوریت ها از °C155 تا °C245 با میانگین °C187 به دست آمد. در اغلب سیالات درگیر، فاز گاز به مایع در طی همگن شدن تبدیل شد. درجه پرشدگی اغلب سیالات درگیر بیش از 90 درصد بوده است. با استفاده از روش سرمایش، کمترین و بیشترین دمای یوتکتیک در نمونه ها، به ترتیب 1/23- و 18- با میانگین °C7/20- است که میزان شوری معادل درصد وزنی معادل نمک طعام حداکثر 8/30 درصد در سیستم H2O-CO2-NaCl محاسبه شده است. اثر برنولی در این ذخیره به وقوع پیوسته است و چهار فرآیند اختلاط با دمای ثابت، جوشش، رقیق شدن با آب های سطحی و کاهش فشار در کانی سازی دخالت داشته اند. در نهایت می توان نتیجه گرفت که ذخیره فلوریت قهرآباد محصول فعالیت هیدروترمال از نوع اپی ترمال است و سیالات کانی ساز دارای منشا حوضه ای هستند که به هنگام مخلوط شدن با آب سطحی کانسار ته نشین شده است.
    کلیدواژگان: قهرآباد، ذخیره فلوریت، سیالات درگیر، سقز، هیدروترمال
  • امین حسین مرشدی، امیر حسین کوهساری، محمدرضا شاکری ورزنه صفحات 249-263
    امروزه، اکتشاف ذخایر عناصر نادر خاکی به عنوان منابع و اولویت های راهبردی مورد تاکید قرار گرفته است که از جایگاهی ویژه در صنایع پیشرفته و هوشمند برخوردار است. پژوهش های اخیر، به شناسایی توانایی های امیدبخش این عناصر در ایران منجر شده است که از جمله می توان به بی هنجاری های پلاسر مونازیت مروست یزد در محدوده خاوری و باختری اشاره کرد. در این پژوهش، از داده ها و نمونه های تجزیه شده از 53 چاهک در محدوده خاوری این بی هنجاری در جنوب شهرستان یزد به منظور مدل سازی و پتانسیل یابی عناصر نادرخاکی استفاده شد. در منطقه مروست، سنگ منشا مونازیت شیل های سیاه است که به صورت متناوب با ماسه سنگ های آهکی، آهک و کنگلومرا و به شکل گرهک های پراکنده در شیل ها دیده می شود. بررسی الگوی توزیع عناصر نادر خاکی استاندارد شده به مقادیر کندریت، بیانگر مطابقت بالا با الگوی استاندارد مونازیت است. برای بررسی توزیع و تمرکز ژئوشیمیایی در منطقه، نقشه درون یابی توزیع این عناصر ترسیم شد که بیشترین تمرکز به ترتیب مرتبط با عناصر سبک، حد واسط و سنگین بود و بی هنجاری در قسمت جنوب و جنوب باختری محدوده واقع شده است. محدوده بی هنجاری ژئوشیمیایی از طریق ضریب شدت بخشی از جمله نسبت غلظت عناصر نادر خاکی سبک به سنگین نیز به اثبات رسید. در مرحله بعد، خوشه بندی داده ها در دو سطح عناصر و نمونه ها انجام شد که نشانگر چهار گروه بندی عناصر بر اساس سبک و سنگینی (ساختار اتمی و شیمیایی) و چهار پهنه فضایی بر اساس مناطق امیدبخش تعیین شد که مناطق دارای برچسب خوشه چهارم، منطبق بر منطقه بی هنجاری است. در نهایت، از روش آماری چند متغیره تحلیل مولفه های اصلی در راستای مدل سازی بی هنجاری استفاده شد که نقشه توزیع بار فاکتوری مولفه اول، منطبق بر منطقه بی هنجاری جنوبی محدوده است.
    کلیدواژگان: عناصر نادر خاکی، خوشه بندی سلسله مراتبی، پهنه بندی، تحلیل مولفه اصلی، مونازیت، پلاسر مروست، یزد
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  • Heydar Asgharzadeh Asl, Behzad Mehrabi, Ebrahim Tale Fazel Pages 1-23
    IntroductionThe Ahar-Arasbaran metallogenic area (Qara Dagh zone) is located in the northwest of Iran and the western part of the Mazandaran Sea. At the base of the structural classification from Nabavi (1976), this area is situated in the Alborz-Azerbijan magmatic belt. Sheviar Dagh (Ahar batholite) intrusive suite, subvolcanic and volcanic accompanied rocks with east-west trending and 30 km long serves as the main Eocene-Oligocene magmatic event in the north of the Ahar province. Considering geochemistry, this assemblage includes two shoshonitic and calc-alkaline to high-K calc-alkaline series which are the shoshonitic series in the central part and the calc-alkaline series outcrop in the western and eastern part (Aghazadeh, 2009). Textural characteristic, mineral chemistry and fluid inclusion studies were carried out at the tree part of the Agh-Daragh prospecting area.
    Material and methodsA total of 50 samples were collected from the host rocks (including 4 trench and 250 m), ore deposit and altered rocks. Ten altered samples were analyzed for their mineral recognition by X-ray diffraction in the Iran Mineral Process and Research Center (IMPRC). Electron microprobe analyses (EMPA) and backscattered electron (BSE) images of minerals were obtained using a Cameca SX100 electron microprobe in the Iran Mineral Process and Research Center (IMPRC). An accelerating voltage of 15 to 25 kV and beam current of 20 mA was used for all analyses. Typical spot sizes ranged from 2 to 5 μm. A total of 5 double-polish thin sections representative of quartz samples were selected from mineralized veins after petrographic and field studies. 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 school of Earth Sciences of the Kharazmi University. The heating rate was 5–10 °C/min at higher temperatures (>100°C), with a reproducibility of ±1°C. However, it was reduced to 0.1–0.5°C/min near phase transformation, with a reproducibility of ±0.1°C.
    ResultsMineralization that occurs in the area is mainly related to the Sheiviar Dagh intrusive rocks and it includes a variety of types of skarn, porphyry- and vein-type, epithermal and intrusion related deposits. Agh Daragh mineralization occurs at least in three states including: 1) stockwork-disseminated, 2) vein-type and 3) replacement (skarn). In order to determine the nature and characteristics of granodiorites hosted Ayran Goli mineralization, the biotites points were analyzed. The Ayran Goli granodiorite with calc-alkaline nature is related to orogenic zones that is associated with subduction zones. To determine the chemical properties of the minerals in Gowdal skarn mineralization, garnet and chlorite have been used for analysis which are often located at repidolite and picnochlorite positions. Electron micro probe analysis (EMPA) of magnetite from the Chupanlar area showed that it belongs to porphyry and Kiruna type deposits. Based on the observations made, three types of aqueous fluid inclusions were distinguished in the quartz-sulfide veins, including halite-saturated aqueous (H2O–NaCl±KCl), aqueous two-phase (H2O–NaCl±CaCl2), and monophase liquid and vapor fluid inclusions.
    DiscussionBecause of the lack of CO2-bearing fluid inclusions phase in the samples, we used a temperature-pressure relationship intersection in order to obtain the depth of mineralization. However, but at this study salt-rich inclusions (type 1) the dissolution of halite homogeneous solid phase (Bodnar, 1994) were used in order to estimate the standing deposit. Considering the temperature of the liquid-vapor homogenization (Thl-v), temperatures between 201 to 474°C, homogenization halite (TmNaCl) between 196 to 434°C (48 wt% NaCl eq.) in the solid phase inclusions with halite, minimum and the maximum pressure between 4.0 and 7.2, respectively that occur at 0.4 to 2.7 kb (average of 5.1 kb and 4 km depth) under lithostatic pressure. These conditions are consistent with the occurrence of gold porphyry copper deposits introduced by Hedenquist et al., (1998). The presence of gas-phase inclusions (type 3), gas-rich (type 2) and a solid-bearing phase, halite (type 1) in a mixture of fluid inclusions indicates the occurrence of fluid immiscibility (Bodnar, 1995; Fournier, 1999). In such circumstances, homogenization temperature inclusions are trapped as their temperature is taken. Petrographic evidence on the simultaneous presence of these two categories is stored as the initial fluid temperature up 400 to 500°C with boiling and fluid immiscibility.
    Keywords: fluid inclusions, ore forming fluid evolution, porphyry-skarn, Ahar-Arasbaran metallogenic area
  • Malihe Golestani, Mohammad Hassan Karimpour, Azadeh Malekzadeh Shafaroudi, Mohammad Reza Haidarian Shahri Pages 25-55
    IntroductionThe Iju porphyry copper deposit is located in the southern part of the Urumieh-Dokhtar magmatic arc (Dehaj-Sarduieh belt) within the Kerman copper belt (Dimitrijevic, 1973). The Porphyry Copper mineralization in the Iranian plate occurs dominantly along the Urumieh-Dokhtar arc, which has resulted from the subduction of the Arabian plate beneath the central Iran and the closure of the Neo-Tethys Ocean during the Alpine orogeny (Hassanzadeh, 1993). The Iju porphyry copper deposit with 25 million tons of ore reserves is one of the main copper deposits within the Kerman copper belt. The mining area is composed of upper Miocene volcanic and subvolcanic rocks (mineralized and barren subvolcanic rocks) and quaternary deposits. Two hydrothermal alteration zones of quartz-sericite-pyrite and propylitic zones can be identified in the Iju area. The copper mineralization in the Iju deposit occurs as disseminated, stockwork and hydrothermal breccia. In the hypogene zone, the mineral paragenesis include chalcopyrite, pyrite, with minor occurrences of bornite and magnetite. This paper reports geological, mineralogical, fluid inclusion and S isotope data from the Iju deposit in order to investigate ore-bearing fluids’ characteristics and the mechanisms of ore deposition.
    Materials and methodsFifteen samples of syngenetic quartzꜪ bearing veinlets within the quartz-sericite-pyrite zone were selected from different depths across the seven boreholes. Quartz was used for double-polished thin sections and pyrite was used for sulfur isotope analysis. Fluid inclusion studies were performed using the Linkam cooling and heating stage, the THMSG 600 model. The syngenetic pyrite with thermometry quartz sample was used for the sulfur isotope experiments. Stable isotope analysis was performed at the Hatch Stable Isotope Laboratory in the University of Ottawa, Canada.
    ResultsThe fluid inclusions of the Iju deposit represent a wide range in the homogenization temperatures between 140 to 480°C and salinity between 0.18 to >52.99 wt.% NaCl equiv., which are most similar to the results of the other Iranian porphyry copper deposits. Being located in the quartz-sericite-pyrite alteration zone, the results of thermometry indicates that ore deposition in the Iju deposit has occurred via mixing of magmatic and surface fluids. Variations in salinity and paragenesis of the saline multiphase fluid inclusions and two-phase gas-rich fluid inclusions indicate the occurrence of boiling phenomenon in some samples of the Iju deposit. The amount of δ34S for pyrite has a limited range close to zero (average, 0.229‰) that shows a magmatic origin for sulfur. Considering the presence of subvolcanic rocks, the type and extension of alteration zones, the structure and texture of ore bodies, thermometry results of fluid inclusions and sulfur isotope values, the Iju deposit is similar to porphyry copper deposits.
    DiscussionIn the quartz-sericite-pyrite zone, three main groups of veinlets have been identified. The quartzꜪ veinlets are more abundant than the other types and they were selected for fluid inclusions and stable isotope studies. Petrographic studies of fluid inclusions identifies two groups of fluids including: 1- fluid inclusions without the halite phase, including the types L, L埤 and (L埤뗹, that is secondary), 2- fluid inclusions with halite phase, including the types L埡, L埡﹋, L埡﹋徒 and L埡﹋往. Homogenization temperature and salinity for the fluid inclusions without halite phase are as follows: 140 to 380°C and 0.18 to 24 wt.% NaCl (Fig. 8A and C) and for the fluid inclusions with halite phase they range from 230 to 480°C and 30 to 52 wt.% NaCl (Fig. 9A, B and D), In addition, the pressure and depth for the fluid inclusions containing halite phase are 750 bar and 3500 m on the average. Fluid inclusions available at the quartz veinlets of porphyry copper deposits can be formed in a wide range of chemical composition and under different temperature and pressure conditions (Rusk and Reed, 2008). The wide range in fluid inclusions data of the Iju deposit can be justified by physicochemical changes in the fluid as it is boiling and mixing with the surface fluids. Cooling, fluids mixing, boiling and fluid-rock reaction play important roles in the settling of chalcopyrite from the hydrothermal fluid and the dilution of saline ore-bearing fluids can cause the formation of copper ores from the ore-bearing fluid (Ulrich et al., 2002). Pyrite δ34S value ranges from -0.86 to .27‰ (average, .22‰) and the δ34SH2S value of the syngenetic fluid with pyrite ranges from -0.23 to -2.36‰ (average, -1.17‰). The limited and near zero range that is observed about δ34S value of the sulfur minerals indicates the controlling role of magmatic processes in the mineralization events (Chen et al., 2009).
    Keywords: Fluid inclusion, Sulfur isotope, Porphyry copper, Iju, Kerman
  • Nargess Shirdashtzadeh, Ghodrat Torabi, Ramin Samadi Pages 57-72
    IntroductionStudy of the petrology of the ophiolites as the relics of ancient oceanic lithosphere, is a powerful tool to reconstruct Earth’s history. Mantle peridotites have mostly undergone alteration and serpentinization to some extent. Thus, the relics of metamorphic signatures from the upper mantle and crustal processes from most of the peridotites have been ruined. Several recent papers deal with the mantle peridotites of Nain Ophiolite (e.g. Ghazi et al., 2010). However, no scientific work has been carried out on the metamorphosed mantle peridotites. The study area of the Darreh Deh that is located in the east of the Nain Ophiolite, is composed of huge massifs of metamorphosed mantle peridotites (i.e. lherzolite, clinopyroxene-bearing harzburgite, and harzburgite, and small volumes of dunite), characterized by darker color, higher topographic relief, smaller number of basic intrusives, lower serpentinization degree, and amphibolite-facies metamorphism. In this study, the petrography and mineralogy of metamorphosed peridotites in the Darreh Deh has been considered based on geochemical data.
    Geological SettingThe Mesozoic ophiolitic mélange of Nain is located in the west of CEIM, along the Nain-Baft fault. As a part of a metamorphosed oceanic crust, it is mainly composed of harzburgite, lherzolite, dunite and their serpentinized varieties, chromitite, pyroxenite, gabbro, diabasic dike, spilitized pillow lava, plagiogranite, amphibolite, metaperidotites, schist, skarn, marble, rodingite, metachert and listwaenite (Shirdashtzadeh et al., 2010, 2014a, 2014b). Geochemical investigations indicate a suprasubduction zone in the eastern branch of the Neo-Tethys Ocean (Ghasemi and Talbot, 2006; Shirdashtzadeh et al., 2010, 2014a, 2014b).
    Materials and MethodsChemical analyses of mineral compositions were carried out using a JEOL JXA8800R wavelength-dispersive electron probe micro-analyzer (accelerating voltage of 15 kV and a beam current of 15 nA) at the Centre for Cooperative Research of the Kanazawa University (Kanazawa, Japan). The Micro-Raman spectroscopy (a HORIBA Jobin Yvon, LabRAM HR800 system equipped with a 532 nm Nd:YAG laser of Showa Optronics co., Ltd, J100GS-16, and an optical microscope of Olympus, BX41, Kanazawa University) were used in determination of serpentine minerals.
    ResultsThe lherzolite is primarily composed olivine, orthopyroxene, clinopyroxene and Cr-spinel, but secondary hydrous and non-hydrous Mg-silicate minerals have been formed during the further serpentinization and metamorphism. Lherzolite is including of olivine (~70 Vol%, forsterite-rich), orthopyroxene (~15-20 Vol%, enstatite – bronzite), clinopyroxene (5-7 Vol%, diopside - augite), and vermicular brown Cr-spinel (60-70 Vol%, chrysolite), orthopyroxene (~30 Vol%, bronzite), a small amount of clinopyroxene, and subhedral dark brown Cr-spinel, talc, tremolite, magnetite, and chlorite. Dunites are composed exclusively of olivine, minor amounts of subhedral, dark brown Cr-spinel, serpentine, metamorphic tremolite, talc and chlorite. The rocks show secondary textures of mesh, poikiloblastic, nematoblastic and jack-straw textures, but original granublastic and porphyroclastic textures are well preserved. Pyroxenes show kink bands, warped cleavages, and undulatory extinction related to metamorphic condition of upper mantle. Petrographical features indicate that a metamorphism at amphibolite facies occurred after serpentinization and chloritization of the Darreh Deh peridotites. Chrysotile cut the primary phases of olivine and pyroxene, but not the metamorphic phases of olivine neoblasts, tremolite, talc and chlorite. Some chlorite crosscut the serpentine veins, and some are in the rim of Cr-spinel and clinopyroxenes. They are mostly replaced by tremolite. Metamorphic olivines have recrystallized as fine-grained neoblasts with lower CaO content (in comparison with the primary and replacive olivines), because they have been formed at the expense of Ca-free mineral of serpentine. Tremolite were produced after chrysotile, talc, and chlorite, wherever enough Ca2 ions were released from the associated olivine and/or orthopyroxene by serpentinization.
    DiscussionPetrographical and geochemical studies indicate a greenschist-facies stage (serpentinization and chloritization) followed and overprinted by amphibolite-facies metamorphism. The regional metamorphism is verified by the formation of antigorite after lizardite and chrysotile, metamorphic olivine neoblasts after serpentines, chlorite after Cr-spinel, talc after olivine and orthopyroxene, and tremolite after pyroxene, talc, serpentine, and chlorite. The metamorphism imprints on harzburgite and dunite indicate that metamorphism has occurred after melt-rock reactions.
    Keywords: Mineralogy, Metamorphism, Mantle peridotite, ophiolite, Central Iran
  • Houshang Pourkaseb, Alireza Zarasvandi, Madineh Saed, Ali Reza Davoudian Dehkordy Pages 73-92
    IntroductionThe formation of porphyry copper deposits is attributed to the shallow emplacement, and subsequent cooling of the hydrothermal system of porphyritic intrusive rocks (Titley and Bean, 1981). These deposits have usually been developed along the chain of subduction-related volcanic and calc-alkalin batholiths (Sillitoe, 2010). Nevertheless, it is now confirmed that porphyry copper systems can also form in collisional and post collisional settings (Zarasvandi et al., 2015b). Detailed studies on the geochemical features of ore-hosting porphyry Cu-Mo-Au intrusions indicate that they are generally adakitic, water and sulfur- riched, and oxidized (Wang et al., 2014). For example, high oxygen fugacity of magma has decisive role in transmission of copper and gold to the porphyry systems as revealed in (Wang et al., 2014). In this regard, the present work deals with the mineral chemistry of amphibole and plagioclase in the Dalli porphyry Cu-Au deposit. The data is used to achieve the physical and chemical conditions of magma and its impact on mineralization. Moreover, the results of previous studies on the hydrothermal system of the Dalli deposit such as Raman laser spectroscopy and fluid inclusion studies are included for determination of the evolution from magmatic to hydrothermal conditions.
    Materials and methodsIn order to correctly characterize the physical and chemical conditions affecting the trend of mineralization, 20 least altered and fractured samples of diorite and quartz-diorite intrusions were chosen from boreholes. Subsequently, 20 thin-polished sections were prepared in the Shahid Chamran University of Ahvaz. Finally, mineral chemistry of amphibole and plagioclase were determined using electron micro probe analyses (EMPA) in the central lab of the Leoben University.
    ResultsAmphibole that is one of the the main rock-forming minerals can form in a wide variety of igneous and metamorphic rocks. Accordingly, amphibole chemistry can be used as an indicator for characterizing the conditions involved during the evaluation of magma crystallization i.e., pressure, temperature, liquid water content and oxygen fugacity. Most recent studies on the porphyry copper intrusions in the Urumieh- Dokhtar magmatic arc by (Zarasvandi et al., 2015a), indicate that all of the mineralized porphyry systems (Dalli porphyry is included) consistently show high levels of La/Sm and Sm/Yb, with concave upward patterns in the rare earth elements’ spider diagrams. Importantly, such features indicate high crustal assimilation in a relatively thickened crust and provide insight into the contribution of hornblende during the development of mineralized porphyry systems in the Urumieh- Dokhtar belt. The results of this study indicate that amphiboles of Dalli intrusions belong to the calsic group and range in composition from magnesio- hornblende, to edenite, magnesiohastingsite, and tschermakite. (Ridolfi et al., 2010), indicating that the alumina content of amphibole could be used for geobarometry. The calculations of geobarometry for quartz diorite intrusions of Dalli indicate that they formed in the pressure range of 136 to 287 (MPa). Also, calculation of magmatic water content using amphibole geochemistry indicates that the water content of quartz diorite intrusions in the Dalli were between 4.6- 5.7 (wt. %). The results of plagioclase chemistry indicate that there is a little zoning in this mineral. Also, the plagioclase composition varies from Or0.01 to Ab 0.48, An 0.50, Or 0.018, Ab 0.62 and An 0.35. They mostly have Andesine and Labradorite compositions.
    DiscussionAmphibole minerals of the Dalli intrusions are calcic type and exhibit geochemical signatures of subduction zones. Also, characterizing the source of ore-hosting intrusions with amphibole chemistry indicate that parental magma of Dalli intrusion were generated from mixing of mantle melts with crustal materials. It seems that in an ongoing process of closure of Neo-Tethys, during compression and crustal shortening favourable conditions were provided for mixing of mantle melts with crustal materials. The geothermobaromerty calculations using amphibole and plagioclase minerals indicate conditions of 777 - 850 oC and 1-4 Kbar, representing magmatic stage of Dalli intrusions. Also, amphibole minerals are characterized by Fetot/Fetot Mg > 0.3 and AlIV > 0.7 which reveal the presence of primary oxidative magma in the Dalli porphyry Cu-Au deposit. Oxidative conditions seem to have prevailed during the onset of the hydrothermal stage of the Dalli porphyry deposit. This is because it has been confirmed by laser Raman spectroscopy analyses that the most primitive quartz veins in the potassic alteration of the Dalli deposit are characterized by the presence of anhydrite and hematite minerals (see Zarasvandi et al., 2015b). Also, microthermometry results on the most primitive barren quartz veins in potassic alteration represent temperatures as high as 620oC which indicate the beginning temperature of hydrothermal conditions.
    Keywords: Plagioclas, Amphibole, Oxygen fugacity, EMPA, Dalli, Urumieh- Dokhtar Magmatic Arc
  • Habib Biabangard, Mohammad Boomeri, Khosro Taimouri, Fatemeh Mohammadpour Pages 93-115
    IntroductionIron mineralization in Roshtkhar is located in 48 Km east of the city of Roshtkhar and south of the Khorasan Razavi province. It is geologically located in the north east of the Lut block and the Khaf-Bardeskan volcano-plutonic belt. The Khaf-Bardeskan belt is an important metallogenic province since it is a host of valuable ore deposits such as the Kuh-e-Zar Au-Spicularite, the Tanourcheh and the Khaf Iron ore deposits (Karimpour and Malekzadeh Shafaroudi, 2007). Iron and Copper mineralization in this belt are known as the hydrothermal, skarn and IOCG types (Karimpour and Malekzadeh Shafaroudi, 2007). IOCG deposits are a new type of magmatic to hydrothermal mineralization in the continental crust (Hitzman et al., 1992). Precambrian marble, Lower Paleozoic schist and metavolcanics are the oldest rocks of the area. The younger units are Oligocene conglomerate, shale and sandstone, Miocene marl and Quaternary deposits. Iron oxides and Cu sulfides are associated with igneous rocks. Fe and Cu mineralization in Roshtkhar has been subject of a few studies such as Yousefi Surani (2006). This study describes the petrography of the host rocks, ore paragenesis, alteration types, geochemistry, genesis and other features of the Fe and Cu mineralization in the Roshtkhar iron.
    MethodsAfter detailed field studies and sampling, 30 thin sections and 20 polished sections that were prepared from host rocks and ores were studied by conventional petrographic and mineraloghraphic methods in the geology department of the University of Sistan and Baluchestan. 5 samples from the alteration zones were examined by XRD in the Yamagata University in Japan, and 8 samples from the less altered ones were analyzed by XRF and ICP-OES in the Kharazmi University and the Iranian mineral processing research center (IMPRC) in Karaj, respectively. The XRF and ICP-OES data are presented in Table 1.
    Result and discussionThe host rocks of the Roshtkhar Iron deposit are diorite, diorite porphyry, monzosyenitie porphyry, andesite, basalt and lithic tuff in composition and granular, porphyry, microlitic porphyry and hyalomicrolitic in texture and they consist of plagioclase, K-feldspar, amphibole and pyroxene as main primary minerals. These minerals in altered rocks were replaced by phylosilicates, epidote, carbonates and opaque minerals. There are the following alteration zones in the study area: propylitic, sericitic-propylitic, argillic and silicic. The propylitic alteration is characterized by chlorite and calcite as the dominant hydrothermal minerals and little quartz, sericite, kaolinite, and biotite. Hematie and magnetite occur as the main opaque mineral in this alteration zone. Since the proportion of sericite is relatively high in some parts of this zone, it can be named the propylitic-sericitic alteration zone. The argillic alteration zone occurs intensively in the syenite and it is characterized by clay minerals. The silicic alteration occurs as veinlets, silicic breccias, and other open space fillings and it is characterized by dominant quartz. In this study, we use a simple variation of the Gresens method. This method was redescribed by Grant (2005). The samples that were analyzed are dioritic rocks as less altered rocks, altered rocks and mineralized rocks. Samples from the propylitic-sericitic alteration zone relative to less-altered diorite show enrichment in Cl, Ho, Cr, Nd, Ta, Tb, Er, La, Cs, Cu, Zn, Dy, and Fe and depletion in Na2O, K2O, P2O5, Ba, S, Sr, Ce, Sn, Co, Sm, Mo, Ga, Zr, Th, Ni, Nb, Rb, Yb.
    Hypogene mineralization in Rhoshtkhar is of two types, i.e. oxide and sulfide mineralization. Oxide mineralization occurs as massive veins mainly in the intrusive rocks and it has been controlled by a fault between the dioritic unit and the diorite porphyry and monzosyenite, and it is characterized by spicularitic hematite and magnetite. The sulfide mineralization mainly occurs as silicic veins and veinlets and it is characterized by pyrite and chalcopyrite. Both of these two types were affected by supergene processes and iron hydroxides (goethite and limonite) and Cu carbonates (malachite and azurite) were formed as a result. The gangue minerals are mainly calcite, quartz and clay minerals. The common textures of the hypogene mineralization are mainly open space filling that are characterized by crustification, layered, geode and vug infill, cockade and comb structures. The supergene mineralization is characterized by both open space filling and replacement textures. Based on ore microscopic studies, the iron oxide minerals of hematite and magnetite were mainly formed earlier than the sulfide minerals of chalcopyrite and pyrite. The hypogene vein deposits such as those of the city of Roshtkhar are mainly formed by hydrothermal fluids. The ore minerals in the veins and breccias are deposited as a result of simple cooling, depressurization, fluid mixing, boiling and chemical barriers. The Fe and Cu mineralization in Roshtkhar is genetically related to the hydrothermal fluids that were derived from the magma during emplacement of the intrusive rocks. It seems that the spicularitic hematite is a hypogene early phase indicating the oxygen fugacity of formation environment was high. In the lower fO2, magnetite was replaced by hematite and chalcopyrite and pyrite were probably deposited from hydrothermal fluids as a result of a decrease in fO2, temperature or pH and increase of fS2. The Cu carbonates, secondary sulfides and iron hydroxides were formed by oxidation of the primary sulfides and iron oxides in supergene stage.
    Keywords: Iran, Roshtekhar Iron, Fe mineralization, Alteration, Lut block
  • Samaneh Nadermezerji, Mohammad Hassan Karimpour, Azadeh Malekzadeh Shafaroudi Pages 117-139
    IntroductionThe Shah Soltan Ali area is located 85 km southwest of Birjand in the South Khorasan province. This area is part of the Tertiary volcanic-plutonic rocks in the east of the Lut block. The Lut block is bounded to the east by the Nehbandan and associated faults, to the north by the Doruneh and related faults (Sabzevar zone), to the south by the Makran arc and Bazman volcanic complex and to the west by the Nayband Fault. The Lut block is the main metallogenic province in the east of Iran (Karimpour et al., 2012), that comprises of numerous porphyry Cu and Cu–Au deposits, low and high sulfidation epithermal Au deposits, iron oxide deposits, base-metal deposits and Cu–Pb–Zn vein-type deposits. The geology of Shah Soltan Ali area is dominated by volcanic rocks, comprised of andesite and basalt, which are intruded by subvolanic units such as monzonite porphyry, monzodiorite porphyry and diorite porphyry.
    Materials And Methods
    1. 170 thin sections of the rock samples as well as 25 polished and thin polished sections were prepared for petrography, alteration and mineralization.
    2. Twenty five samples were analyzed for Cu, Pb, Zn, Sb, Mo and As elements by the Aqua regia method in the Zarazama laboratory in Tehran, Iran.
    3. Nine samples were analyzed for trace elements [including rare earth elements (REEs)]. As a result of these analyses, trace elements and REE were determined by inductively coupled plasma mass spectrometry (ICP-MS) in the ACME Analytical Laboratories (Vancouver) Ltd., Canada.
    4. Ten samples were analyzed for major elements by wavelength dispersive X-ray fluorescence spectrometry in the East Amethyst laboratory in Mashhad, Iran.
    5. Five samples were analyzed for Firre Assay analysis in the Zarazma Laboratory in Tehran, Iran.
    6. The results of XRD analysis were used for 4 samples.
    Discussion and resultsPetrographic studies indicate that subvolcanic rocks consist of diorite porphyry, monzonite porphyry and monzodiorite porphyry. Based on field and lab work several alteration zones such as: quartz–sericite–pyrite (QSP), propylitic, argillic, silicified, sericitic and carbonate were identified. Geochemical studies show that intrusive units are metaluminous, high calcalkalic to shoshonitic. These rocks belong to the I-type granitoid (Chappell and White, 2001), and they have formed in a volcanic arc granitoids (VAG) tectonic setting (Pearce et al., 1984). Mantle-normalized, trace-element spider diagrams display enrichment in large ion lithophile elements, such as Rb, Sr, K, and Cs, and depletion in high field strength elements, e.g., Nb, Ti, Zr. Enrichment of LREE versus HREE and enrichment of LILE and depletion in HFSE indicate magma formed in the subduction zone. Negative Nb and Ti anomalies are recognized as a fingerprint of a subduction process (Nagudi et al., 2003). All of the intrusive rocks have a weak negative Eu anomaly (Eu/Eu*=0.82–0.94) (Tepper et al., 1993), and a low ratio of (La/Yb)N. The magmatic source of intrusive rocks had been generated from 1% to 5% of partial melting of garnet-spinel lherzolite (Aldanmaz et al., 2000). In the south area, four types of mineralization such as: veinlet to vein, disseminated, hydrothermal breccia and stockwork occur from which stockwork is the most important type of mineralization. The veinlets that were found within the stockwork zone are:1) pyrite chalcopyrite, 2) quartz pyrite ± chalcopyrite, 3) quartz ± pyrite. Compositional variations of elements within the Shah Soltan Ali area are as follows: Cu = 30-454 (ppm), Zn = 27-279 (ppm), Pb = 11- 70 (ppm), Sb = 0.9-152 (ppm), Au= 5-128 (ppb), As = 7-203 (ppm). There is a high concentration of Cu – Zn – Au and Sb that is associated with the high density of veinlets in the quartz-sericite-pyrite zone in the southeast of Shah Soltan Ali area. Based on the obtained data, the Shah Soltan Ali area is a part of the porphyry Cu-Au deposit.
    Keywords: Alteration, Mineralization, I-type granitoid, Cu porphyry, Shah Soltan Ali, Birjand, Lut Block
  • Arezoo Moradi, Nahid Shabanian Boroujeni, Ali Reza Davoudian Dehkordy Pages 141-158
    IntroductionStudied mylonitic granite-gneiss body is located in the Northwest of the Azna region in the Lorestan province close to the June dimension stone mine. It is a part of the metamorphic- magmatic complex including granite-gneiss, amphibolite, marble and schist. The crystalline basement is attributed to late-Neoproterozoic and it indicates a Panafrican basement, which yields a laser-ablation ICP–MS U–Pb zircon ages of 608 ± 18 Ma and 588 ± 41 Ma (Shakerardakani et al., 2015). There are two granite-gneiss plutons in the complex that are Galeh– Dezh (Shabanian et al., 2009), and June plutons. The Galeh-Doz pluton are previously proposed as syn-deformation pluton with a major S-shaped bend which has been imparted during dextral shearing with a Late Cretaceous (Mohajjel and Fergusson, 2000). However, new age dating on the pluton using U–Pb in the magmatic zircon produced the late-Neoproterozoic dates (Nutman et al., 2014; Shakerardakani et al., 2015). The granite-gneiss plutons show mylonitic fabrics and microstructures (Shabanian et al., 2010). The geochemical characteristics of mylonitic granite-gneiss body near June mine in NW Azna, is in the focus of our research.
    Materials and methodsPetrographic investigations of 30 thin sections were made. Then eight samples were selected and analyzed for whole rock major, trace and REE compositions by ICP-emission spectrometry and ICP-mass spectrometry using natural rock standards as reference samples for calibration at the ACME Analytical Laboratories in Vancouver, British Columbia, Canada.
    ResultsThe studied gneiss- granitic body has lepido-granoblastic texture as its major texture. It variably shows evidence of dynamic deformation from ultramylonite to protomylonite. The gneiss- granite consists of quartz, alkali feldspar (mostly as perthite), plagioclase, biotite, white mica (muscovite and phengitic muscovite). Accessory phases in the granitoid include, tourmaline, zircon, magmatic epidote, allanite, apatite, and magnetite. The mylonitic gneiss-granite has a mantled porphyroclast texture that may be characterized by large asymmetrical porphyroclasts of K-feldspar and plagioclase with a mantle which includes white-mica, biotite, quartz and feldspar aggregates. Some of the petrographic evidence show dynamic deformation during the crystallization such as grain boundary migration (GBM) or sub-grain rotation (SGR), patchy perthite. Evidence of strain, such as deformation twins, bent or curved twins, undulatory extinction occur characteristically in plagioclase and display dynamic deformation in solid state. The rocks exhibit identical compositional ranges with 71.24–78.35 wt.% SiO2; high levels of alkalies (Na2O ranges from 3.07 to 4.02 %, K2O varies from 4.18 to 5.53 %); low levels of Fe2O3tot (0.80 to 2.60 %). Also, the trace element compositions display significant variations, such as Zr (157.7-330.5 ppm), Eu (0.07-0.28 ppm), Nb (40.9-77.3 ppm), Ga (19.7-25.97 ppm). The studied rocks are strongly enriched in LREE and HFSE and show a strong depletion in Ba, Sr, Eu and Ti and enrichment in Rb and Zr. The element contents are also similar to typical A-type granite (Whalen et al., 1987). The rocks are alkali to alkali-calcic, metaluminous to mildly peraluminous granite and ferroan in new geochemical classification scheme for granitoids (proposed by Frost et al., 2001).
    DiscussionThe chondrite-normalized rare-earth element patterns of the mylonitic gneiss- granitic rocks indicate the LREE over HREE fractionation with significant negative Eu anomalies. Primitive-mantle-normalized spidergrams (Sun and McDonough, 1989) normalized trace element patterns with negative Ba and Nb anomalies, and positive Rb, Th and Ce anomalies, simulate the collisional and post-collisional granitoids of Pearce et al (Pearce et al., 1984). All of the samples fall in the A2 group in Eby classification (Eby, 1992). On the tectonic discrimination plots, the granites show a within-plate granite (WPG) character (Pearce et al., 1984).
    Keywords: Geochemistry, A2-granite, Post-collision, northeastern of mine Jan, Sanandaj- Sirjan Zone
  • Houshang Pourkaseb, Alireza Zarasvandi, Zahra Fereydouni, Babak Mokhtari, Neda Mirzaei Pages 159-174
    IntroductionIt has been recently stated that phosphorite deposits are in fact marine biogenic materials, due to bacterial activity producing bio-apatite. In addition, Phosphorites contain 15–20 wt.% P2O5 (Tzifas et al., 2014). In this deposit, phosphate mineralization has occurred as phosphorite lenses with Eocene age within the Pabdeh Formation, with thickness up to 1.5 meters and width of 15 meters and its hosted rock is black shale. According to the presence of indices of fossils such as Globorotalia, Hantkenina, its age can be attributed to the middle Eocene. The Pabdeh formation is a very rich organic matter in addition to the presence of phosphate (Damiri, 2011). The formation due to planktonic foraminifera rich in organic matter is like the hydrocarbon source rock (Daneshian et al., 2012). In marine basins where upwelling and productivity are limited, phosphates may develop outside of microbial cells and also within bacterial cellular structures, formed by slow bacterial assimilation of phosphorus from assaying organic matter in areas of restricted sedimentation (O’Brine et al., 1981). It is therefore suggested that the upwelling currents did that in the recycling of phosphorus from dead organisms such as fishes and other marine vertebrates. The aim of this study is investigation of organic matter’s species and their roles in deposition and phosphate mineralization in the Kuh-e-Sefid phosphate deposit using XRD, FTIR and Rock-Eval pyrolysis.
    Materials and methodsIn field observations, 12 samples were selected and they were taken from units of phosphate and shale host rock in the Kuh-e-Sefid phosphate ore deposit. Ten cross sections were studied by conventional microscopic methods. Rock-Eval analysis was used in order to determine the organic carbon in the geology Department of the Shahid Chamran University of Ahvaz. The Phosphorite samples were determined by XRD at the Kansaran Binaloud Company in the Science and Technology campus in Tehran. FTIR analyses were carried out on the phosphorite samples in the chemistry department of the Shahid Chamran University of Ahvaz.
    ResultsOrganic matter appears to be essential for phosphogenesis in two ways: 1) as an energy supply for redox change and 2) as a source of phosphate. Similarly, bacteria are important on two levels: 1) they provide a mechanism for the release of phosphorus from phospholipids and other high-energy phosphorus compounds by organic phosphate cracking and organic carbon oxidation, 2) they are capable of concentrating and precipitating phosphate (Jarvis, 1992).The sedimentary organic matter is first decomposed exclusively by aerobic bacteria. When O2 is completely utilized, further decomposition occurs via sulfate reduction until the oxidants are exhausted, then phosphorus and carbon are released from organic matter during decomposition (Ingall and Cappellen, 1990). Field observation and microscopic studies indicate that phosphate-bearing layers mainly consist of shale, marl, limestone with textures varying from wackestone to packestone forms. Also, phosphate components such as plettal, ooid, intraclast, fish skeletal fragments and microfossils are present. In additions to phosphate and biogenic component, nonphosphate minerals such as glauconite, calcite, pyrite, iron oxide and quartz, are present in different forms and sizes. The results of XRD analysis show the mineral phosphate (fluorapatite) besides calcite as one of the nonphosphate components in the Kuh-e-Sefid ore deposit as the main constituents, while the minerals montmorillonite and quartz are minor constituents. FTIR studies reveal qualitative information about the bonding pattern and nature of the components of the organic matters. Thus, phosphogenesis in marine phosphate deposits resulting in the destruction of areas around the continents that contain different components of phosphate and non-phosphate, and the resulting destruction of organic materials as well. Therefore, according to data from the Rock Evil, samples of the deposit represent more continental carbon. In general, it can be shown that, most of the phosphate mineralization in this deposit is mainly of a continental origin, and it is partly as a result of decomposition and oxidation of organic matter by bacteria and microorganisms that occurs.
    Discussion- Since shales rich in organic matter are capable of transferring sedimentary phosphorus as organic materials, it can be concluded that the deposits shale as the phosphate deposits host were the main factors of phosphorus transmission and the most mineralization occurs in parts that are rich in organic matter.
    - Rock-Eval results showed that more samples contain continental carbon and this suggests that phosphate mineralization is of continental origin in this deposit and it is partly achieved by biodegradation of organic matter by microorganisms.
    - FTIR, XRD studies have proved the frequency of fluorapatite minerals with calcite and organic materials that are most probably associated with phosphate mineralization in the deposit.
    - FTIR studies reveal mineral-organic bounds such as OH, Carboxylic OH, Carboxylic acid C=O, C≡C Alkaline, group CH2, C=C aromatic, CH Aliphatic and aromatic stretching associated with identified mineralization.
    Keywords: Organic Matters, Apatite, Phosphate, Kuh-e-Sefid, Pabde formation
  • Jamal Rasouli, Mansour Ghorbani, Vahid Ahadnejad Pages 175-195
    IntroductionThe Jebale-Barez Plutonic Complex (JBPC) is composed of many intrusive bodies and is located in the southeastern province of Kerman on the longitude of the 57◦ 45 ' east to 58◦ 00' and Northern latitudes 28◦ 30' to 29◦ 00'. The petrologic composition is composed of granodiorite, quartzdiorite, granite, alkali-granite, and trace amounts of tonalite with dominant granodiorite composition. Previously, the JBPC was separated into three plutonic phases by Ghorbani (2014). The first plutonic phase is the main body of the complex with composition of quartz-diorite to granodiorite. After differentiation of magma in the magmatic chamber, the porphyritic and not fully consolidated magmas have intruded into the main body. Their compositions were dominantly granodiorite and granite that are defined as the second plutonic phase. Finally, the last phase was started by an intrusion of the holo- leucogranite into the previous bodies. This plutonic activity was pursued by the minor Quaternary basaltic volcanism that shows metamorphic haloes in the contacts. They are dominantly porphyric leucogranites. However, some bodies show dendritic texture that may imply the existence of silicic fluids in the latest crystallization stages.
    Materials and methodsIn this article different analysis methods were used. For example, we used a total of two hundred samples of the various granitoids that were selected for common thin section study. Forty four representative samples from the different granitic rocks were selected for whole rock chemical analyses. The analyses of both major and trace elements were performed at the Department of Earth Sciences, the University of Perugia, Italy. The analysis for all major elements was carried out by an X-ray fluorescence spectrometry (XRF) using a tube completed with a Rn and W anode under conditions with acceleration voltage of 40-45 kV and electric current ranging from I=30-35 mA. After calcination of powdered samples and full matrix correction, the sum of all major oxides was equal to about 100 wt.%. The concentration of trace elements in the selected samples has been performed by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The uncertainty is
    Keywords: Jebale-Barez Plutonic Complex, subduction, microstructures, transpression tectonic
  • Behrouz Karimi Shahraki, Behzad Mehrabi Pages 197-211
    IntroductionThe Poshtebadam Bafq Zarand district in central Iran is a world class iron oxide province. This region contains over two billion tons of iron ore reserves within more than 34 major magnetic anomalies and deposits in an area of 7,500 km2 (Stosch et al., 2011). The Jalal-Abad iron ore deposit (200Mt at 45% Fe, 1.18% S and 0.08% P) is located 38 km northwest of Zarand, 16 km southeast of the Rizu town in the Kerman province, Iran. Iron ore deposits are hosted by the Early Cambrian Rizu Series, composed mainly of sedimentary, volcanic and volcaniclastic rocks which are dominated by dolomite, sandstone, shale, siltstone, tuff, ignimbrite and rhyodacite. The origin of the iron oxide deposits is controversial and various genetic models have been suggested. Some researchers believe in magmatic origins or Kiruna type, while others suggest metasomatic replacement from pre-existing rocks (Stosch et al., 2011). LA-ICP-MS has been used to characterize the multi element chemistry of the diverse fluid inclusions found in the Jalal–Abad iron oxide deposit. The aim of this investigation was to understand the genesis of the ore body and identify possible hydrothermal fluid sources in the Jalal-Abad district.
    Sampling and method of studyAbout 100 samples from different types of ore were collected from surface outcrops and a drill core whose association with mineralization are well established. Thin sections, polished thin sections and polished sections were prepared. SEM studies (FEI 5900LV) and LA-ICP-MS analyses of fluid inclusions were carried out in the School of Earth and Environment, the University of Leeds, UK. Fluid inclusions were studied using a Linkam THM-600 heating-freezing stage mounted on Zeiss petrography microscope at the Iranian Mineral Processing Research Center.
    Result and discussionJalal Abad deposit is hosted by the early Cambrian volcano-sedimentary rocks of the Rizu series. Stratabound mineralization occurs in a variety of forms being massive, disseminated, replacement, open space filling, veins and breccias. Immediate host rocks include sandy siltstone, acidic volcanic rocks and dolomite. The Jalal Abad deposit mainly consists of iron oxides (magnetite, hematite and goethite), pyrite, chalcopyrite, and malachite that occur in massive, brecciated, open space filling, disseminated and vein forms. Hematite mostly occurs close to the surface and along fractured zones, formed as a secondary mineral due to magnetite oxidation and it is rare at depth. Pyrite is the most important sulphide mineral and is associated with magnetite, calcite, quartz, talc, dolomite, actinolite and chlorite. Copper mineralization at shallow levels is mainly in oxides formed from sulphide oxidation and at deeper levels primary chalcopyrite is also associated with magnetite. Cu mineralization is formed as disseminated or in veins form. Native gold was detected as inclusions smaller than 50 µm in chalcopyrite. Common alteration minerals are goethite, pyrite, talc, actinolite, chlorite, tremolite, dolomite, quartz, calcite, albite and sericite. The earliest hydrothermal alteration includes Na-Ca alteration which is associated with actinolite, magnetite and pyrite. Multiphase fluid inclusions (L埤) in quartz are abundant and homogenization temperatures are in the range of 260 to 440◦C. Salinities vary between 30 to 52 wt% NaCl equivalents.
    The concentrations of Na and K are in the range 26906 to 140716 ppm and 2372 to 70484 ppm, respectively. Fe content varies from 576 to16076 ppm with an average of 6914 ppm and Cu contents vary from 51 to 3204 ppm with a mean of 792 ppm. The Na/Ca values for fluid inclusions vary from 0.38 to 37.51 with a mean of 3.79. The average content of Na is 61511 ppm which is in agreement with salinity of fluid inclusions measured by microthermometry techniques. Magmatic fluids normally yield K > Ca, with Ca/K ratios between 0.01 to 1, whereas non magmatic fluids are often richer in Ca with Ca/K between 1 to 100 (Yardley, 2005). The amounts of Fe and Cu in magmatic fluids are commonly above 10000 and 1000 ppm, respectively. However, it depends on chlorinity (Fisher and Kendrick, 2008; Gillen, 2010; Appold and Wenz, 2011). Mn concentrations are 424 to 3645 ppm, with an average concentration of 7581 ppm. Mn/Fe ratio is varied from 0.21 to 1.87 with an average of 0.60.The wide range of homogenization temperature (170 -450 °C) and salinity (31- 52 wt % NaCl equiv) of the fluid inclusions and ratios of K/Ca in fluid inclusions indicate different fluid sources with magmatic and basinal type fluids (Yardley, 2005). Mn/Fe ratios in fluid inclusions are in wide ranges (0.21 -1.87) which indicate the presence of both reduced type and oxidized type fluids (Fisher and Kendrick, 2008).
    ResultsIn addition to iron oxide, economical Cu mineralization occurs in the Jalal Abad deposit with Au, Bi and As mineralzation with insignificant apatite. The K, Fe, Ca, Na and Cu concentrations in fluid inclusions are most probably related to the mixing of magmatic and basinal fluids. The mineralogical, microthermometry and chemistry of fluid inclusions data show that magmatic-hydrothermal metal bearing fluids, nonmagmatic hydrothermal fluids and mixing of them are responsible for iron-Cu-Au mineralization (IOCG) in the Jalal- Abad deposit.
    Keywords: Magnetite, Fluid inclusion, IOCG deposit, LA-ICP-MS, Jalal-Abad
  • Majid Tashi, Fardin Mousivand, Habibollah Ghasemi Pages 213-233
    IntroductionIran hosts numerous types of Volcanogenic massive sulfide (VMS) deposits that occur within different tectonic assemblages and have formed at discrete time periods (Mousivand et al. 2008). The Sabzevar zone hosts several VMS deposits including the Nudeh Cu-Ag deposit (Maghfouri, 2012) and some deposits in the Kharturan area (Tashi et al. , 2014), and the Kharturan area locates in the Sabzevar subzone of the Central East Iranian Microcontinent. The Sabzevar subzone mainly involves Mesozoic and Cenozoic rock unites. The Late Cretaceous ophiolite mellanges and volcano-sedimentary sequences have high extension in the Subzone. Based on Rossetti (Rossetti et al. 2010), the Cretaceous rock units were formed in a back-arc setting due to subduction of the Neo-Tethyan oceanic crust beneath the Iranian plate. The exposed rock units of the Kharturan area from bottom to top are dominated by Early Cretaceous, orbitolina-bearing massive limestone, dacitic-andesitic volcanics and related volcaniclastic rocks٫ chert and radiolarite and Late Cretaceous globotrunkana- bearing limestone, paleocene polygenic conglomerate consisting of the Cretaceous volcanics and limestone pebbles (equal to the Kerman conglomerate), and Pliocene weakly-cemented polygenic conglomerate horizon. The Garmabe Paein copper-silver deposit and the Asbkeshan deposit and a few occurrences, are located at 290 km southeast of Shahrood and they have occurred within the Upper Cretaceous volcano-sedimentary sequence in the Sabzevar subzone. The aim of this study is to discuss the genesis of the Garmabe Paein deposit based on geological, textural and structural, mineralogical and geochemical evidence.
    Materials and methodsA field study and sampling was performed during the year 2013. During the field observations, 94 rock samples were collected from the study area, and 45 thin sections were prepared and studied using a polarizing microscope. Also, 5 samples for the XRD method, 21 samples for the XRF and ICP-OES methods were analyzed in the Iranian Mines and Mining Industries Development and Renovation (IMIDRO) Company labs.
    ResultsThe Garmabe Paein copper-silver deposit is located in the Sabzevar subzone of the Late Cretaceous Volcanio-sedimentary sequence. This mineralization occurred as stratiform and stratabound in a specific stratigraphic horizon. The host rocks of mineralization are andesitic-dacitic volcanic rocks and their related volcaniclastics. The mineralization occurred as four ore facies, from footwall to hanging wall: vein-veinlet-s (stringer), massive, bedded and exhalites. Ore textures and structures involve massive, semi-massive, laminated, banded, vein-veinlets, replacement and open space fillings. Minerlogically, the deposit contains primary minerals such as pyrite, chalcopyrite and magnetite, and secondary minerals such as native copper, cuprite, covellite, malachite and Fe-Mn oxides. Wallrock alterations are dominated by chloritic and minor siliceous and argillic. The highest grades of gold and silver in the deposit are 1 and 19 grams per ton, respectively. The amounts of Zn, Pb, Au, As, Ag and Mn increase from the stringer to the upper part of the deposit. It seems that the occurrence of submarine volcanic activity in the Late Cretaceous back- arc basin have resulted in the deposition of this Besshi type massive sulfide deposit.
    DiscussionMost of characteristics of the Garmabe Paein Cu-Ag deposit including tectonic setting, geological environment, host rocks, geometry, textural and structural, mineralogical and geochemical features, are very similar to those of the Besshi- or pelitic mafic-type (Franklin et al. , 2005) volcanogenic massive sulfide (VMS) deposits.
    Keywords: Volcanogenic massive sulfide, Besshi type, Garmabe Paein, Late Cretaceous, Sabzevar subzone
  • Mehrdad Barati, Ebrahim Tale Fazel, Afshin Akbarpour, Babak Talaei, Masoud Moslehi Pages 235-248
    IntroductionThe Qahr-abad fluorite deposit is located in the area of 36°10′ 3′′ N and 46°34′ 21′′E within the Sanandaj-Sirjan district east of the Kurdistan province , Iran and it is located ~57 km southeast of the city of Saqqez (Kholghi Khasraghi, 1999). This deposit is developed as scatter lenses, veins, and veinlets (stockwork structure) within carbonate rocks of Elika formation and controlled by the regional NW–SE trending Zagross thrust nappe system. Fault trends in this area are perpendicular to fault trends in the Zagros zone. The fault dips are nearly vertical and mineralization has occurred in the brecciation fault zone (Talaii, 2010). The rough geological instruction of the deposit has indicated that it is similar to worldwide Epithermal deposits.
    The mineralization occurs as replacement (type I)/ open-space (type II) vein fillings and bodies within Mesozoic lime stones (mostly Upper Triassic and Lower Jurassic members of the Elika Formation), where they crop out to form horst structures. The mineralization is typically associated with post Pliocene disjunctive faults, which in part appear to have served as channel ways for the fluorite forming fluids that are representative of the geological setting of the mineralized area.
    Fluorite occurs in several color variations such as green, violet, blue, white or colorless, and is accompanied by quartz, barite and calcite (Moslehi, 2013).
    Materials and methodsThe minerals sampled for the fluid inclusion study include fluorite from mineralization stages. Samples covered all ore types. Micro thermometry analyses for 23 samples were performed after careful microscopic observation of 35 sections and 30 doubly polished sections. Micro thermometry was undertaken using a Linkam THS600 heating-freezing stage, with a measurable temperature range of between −196 and  °C (precision of freezing data and homogenization temperature of ±0.2 °C). Micro thermometry was undertaken in the Department of geology of the Karazmy University.
    ResultsPetrography and classification of inclusions:The samples used for the inclusion study were doubly polished sections of fluorite from mineralization stages 1 to 2. A number of inclusion types were identified. These include negative crystals and elongate round, polygonal or irregular shapes with a size range from
    Keywords: Qahr-Abad, fluorite deposit, fluid inclusions, Saqqez City, Hydrothermal
  • Amin Hossein Morshedy, Amir Hossein Kouhsari, Mohammad Reza Shakery Varzaneh Pages 249-263
    IntroductionNowadays, exploration of rare earth element (REE) resources is considered as one of the strategic priorities, which has a special position in the advanced and intelligent industries (Castor and Hedrick, 2006). Significant resources of REEs are found in a wide range of geological settings, including primary deposits associated with igneous and hydrothermal processes (e.g. carbonatite, (per) alkaline-igneous rocks, iron-oxide breccia complexes, scarns, fluorapatite veins and pegmatites), and secondary deposits concentrated by sedimentary processes and weathering (e.g. heavy-mineral sand deposits, fluviatile sandstones, unconformity-related uranium deposits, and lignites) (Jaireth et al., 2014). Recent studies on various parts of Iran led to the identification of promising potential of these elements, including Central Iran, alkaline rocks in the Eslami Peninsula, iron and apatite in the Hormuz Island, Kahnouj titanium deposit, granitoid bodies in Yazd, Azerbaijan, and Mashhad and associated dikes, and finally placers related to the Shemshak formation in Marvast, Kharanagh, and Ardekan indicate high concentration of REE in magmatogenic iron–apatite deposits in Central Iran and placers in Marvast area in Yazd (Ghorbani, 2013).
    Materials and methodsIn the present study, the geochemical behavior of rare earth elements is modeled by using multivariate statistical methods in the eastern part of the Marvast placer. Marvast is located 185 km south of the city of Yazd in central Iran between Yazd and Mehriz. This area lies within the southeastern part of the Sanandaj-Sirjan Zone (Alipour-Asll et al., 2012). The samples of 53 wells were analyzed for Whole-rock trace-element concentrations (including REE) by inductively coupled plasma-mass spectrometry (ICP-MS) (GSI, 2004).
    The clustering techniques such as multivariate statistical analysis technique can be employed to find appropriate groups in data sets. One of the main objectives of data clustering is to maximize both the similarity within each cluster and the difference between clusters, and finally find the structure in the data. Nowadays, cluster analysis is applied in many disciplines: biology, botany, medicine, psychology, geography, marketing, image processing, psychiatry, archaeology, etc. (Everitt et al., 2011). To execute a partitioning algorithm, the principal components analysis (PCA) algorithm is applied for feature selection, feature extraction and dimension reduction. Hierarchical clustering can be utilized to provide a nested sequence of partitions with bottom-up or top-down methods based on similarity. The single linkage and complete linkage are the most popular hierarchical algorithms (Jain et al., 1999; Ji et al., 2007).
    Results and discussionThe REE chondrite-normalized pattern for the eastern area in the Marvast placer represents a high match to the standard pattern of monazite. This pattern shows the positive anomaly of Ce and the negative anomaly of Eu. To determine the distribution of REEs concentration, 2D interpolation maps were plotted in three groups of light, middle, and heavy REEs (LREE, MREE, and HREE), which were indicated in the geochemical anomaly at the south and south-west of the area. The relative ratios of (LREE/HREE) and (Ce/Eu) exposed the high proportion of LREEs to HREEs. In the next section, the hierarchical clustering algorithm was employed to partition the data in the feature and sample levels. The elements portioning demonstrated four separated groups, which can be related to atomic and chemical structures. The studied region was divided into four zones by the clustering approach. The fourth zone confine coincided with the REE anomaly area. Finally, PCA was applied as the multivariate statistical tool to this dataset. Hence three principal components modeled over 90% of the variance. For the first component, the distribution map of load factor has a good agreement with anomaly area.
    Keywords: Rare earth elements, Hierarchical clustering, Zonation, Principal component analysis, Monazite, Marvast placer, Yaz