فهرست مطالب

  • پیاپی 17 (بهار 1398)
  • تاریخ انتشار: 1398/01/14
  • تعداد عناوین: 7
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  • قاسم عزیزی، محمود داوودی* صفحات 1-25

    مطالعه آب وهوای دیرینه می تواند به ابهامات فراوان درباره تغییرات اقلیمی گذشته پاسخ دهد و راهنمای تغییر اقلیم آینده باشد؛ موضوعی که هرچند در ایران کمتر بدان توجه شده، در دنیا محققان فراوانی را مشغول کرده است. هدف این پژوهش واکاوی تغییرات اقلیمی هولوسن در ایران بود. ازین رو، ابتدا منابع مختلف داخلی و خارجی مرتبط با آب وهوای کواترنری پیشین بررسی و تغییرات اقلیمی عمده این دوره در دنیا شناسایی شد. سپس، با تغییرات اقلیمی همین دوره در ایران مورد مقایسه قرار گرفت. برای راستی آزمایی نتایج مطالعات مروری از یک نمونه موردی کمک گرفته شد.نتایج نشان داد بین دوره های سرد/ گرم بازسازی شده در مطالعات مرتبط با آب وهوای دیرینه کره زمین در دیگر کشورها، به ویژه منطقه اروپا و آب وهوای دیرینه ایران ارتباط خوبی وجود دارد. فاصله زمانی بازسازی شده این دوره ها در ایران با شمال اروپا و امریکا تفاوت زمانی تقریبا 200 تا 300 ساله را نشان می دهد. این دوره ها با تاخیر در ایران آغاز شده اند. همچنین وجود دوره های سرد/ خشک و گرم/ مرطوب در اقلیم گذشته ایران قابل مشاهده است. در همه دوره های گرم مقدار شاخص رطوبتی تعداد گرده های درختی به غیردرختی نسبت به دوره های سرد بیشتر بوده است. به نظر می رسد ایران در دوره های گرم نسبت به دوره های سرد مرطوب تر بوده است.

    کلیدواژگان: تغییرات اقلیمی، پذیرفتاری مغناطیس، شاخص AP، NAP، هولوسن
  • سحر بابایی، منوچهر قرشی*، محسن پورکرمانی، حسن حاجی حسینلو، سهیلا بوذری صفحات 27-45

    مورفوتکتونیک یکی از شاخه های اصلی زمین شناسی که با ارزیابی لند فرم های موجود در سطح زمین، به نیروها و عوامل توسعه آنها  می پردازد و در بسیاری از انواع تحقیقات مورد بحث قرار گرفته است. از آنجائیکه لندفرم ها به طور کلی با آخرین حرکات پوسته زمین در ارتباط  می باشند، مطالعه آنها می تواند در مورد موضوعات مربوط به زمین شناسی جنبا کمک شایانی کند. از طرف دیگر، اشکال و شکل های سطح زمین فقط محصول عوامل و نیرو های داخلی نیستند در عوض، عوامل خارجی نیز باعث ایجاد تغییر شکل در اشکال و اشکال ناشی از نیروهای داخلی زمین می شوند و در زمینه های ژئومورفولوژی مورد بررسی قرار می گیرند و تاثیر آنها نیز باید در مطالعات مورفوتکتونیک مورد توجه قرار گیرد. با توجه به رابطه نزدیک تکتونیک و ژئومورفولوژی، موضوعی به نام ژئومورفولوژی تکتونیکی تهیه شده است که به تاثیر متقابل این عوامل  می پردازد. تمام اشکال و ناهمواری های سطح زمین را می توان با توجه به اندازه، ارتفاع و شیب آنها توصیف کرد و سپس با پارامترهای کمی مقایسه گردد. در حالی که اندازه گیری کمی از این فرم ها امکان محاسبه خصوصیات ویژه یک منطقه مانند سطح فعالیت تکتونیکی آنها را علاوه بر مقایسه دقیق تر شاخص ها و پارامترهای ژئومورفولوژیکی، مهم ترین هدف استفاده از شاخص های مورفوتکتونیک و اندازه گیری های مورفومتریک در ژئومورفولوژی که کسب و بررسی فرم ها و ناهمواری های سطح زمین از یک کیفیت و توصیفی به عددی می باشد را در بر می گیرد. مورفومتری یعنی اندازه گیری کمی شکل مناظر یا چشم اندازها که در این مقاله به عنوان روش اساسی تعیین زمین ساخت نسبی جنبای ناحیه مورد استفاده قرار گرفته است. بنابراین مورفومتری یکی از راه های مهم برای تعیین نرخ فعالیت تکتونیکی منطقه در نظر گرفته می شود، در سطح ساده تر شکل های زمین ساختی می توانند در اندازه و ارتفاع (حداقل، متوسط و حداکثر) مشخص شوند. اندازه گیری های کمی توسط ژئومورفولوژیست ها برای شکل های مختلف زمین ساختی انجام شده است و کمتر به صورت پارامترهای مستقیم تعیین گردیده اند. این موضوع ممکن است جهت تشخیص ویژگی های مشخص کننده سطح فعالیت های تکتونیکی به کار گرفته شوند. بعضی شاخص های ژئومورفولوژیکی به عنوان یک ابزار اکتشافی توسعه یافته اند، تا در مناطق مختلف به طور تجربی سرعت تغییر شکل تکتونیکی را مشخص نمایند. این اطلاعات برای طراحی های تحقیقاتی به کار می روند، تا اطلاعاتی برای فعالیت های تکتونیکی به دست آورند،  شاخص های دیگر به صورت توصیف کیفی توسعه پیدا کرده اند. اما شاخص های کمی ژئومورفیکی به ویژه در مطالعات تکتونیکی مفید هستند، چون از آن ها می توان برای ارزیابی سریع مناطق بزرگ استفاده کرد و اطلاعات مورد نیاز اغلب به طور ساده از نقشه های توپوگرافی و عکس های هوایی به دست می آیند. در بررسی های مورفومتری یا ریخت سنجی دو دسته شاخص های کیفی و کمی قابل بررسی هستند. بررسی این شاخص ها به ما کمک می کند، در خصوص وضعیت تکتونیکی منطقه از لحاظ فعالیت یا عدم فعالیت اطلاعات دقیقی را به دست آوریم. به عبارتی مورف یا ریخت ها در منطقه انعکاسی از نرخ فعالیت های تکتونیکی در آن منطقه هستند. اهمیت مطالعه ی مورفوتکتونیکی به منظور دستیابی به نتایج اساسی و مهمی است که معمولا از طریق مطلعات آزمایشگاهی و صحرایی حاصل می گردد. اندازه گیری کمی به ژئومورفولوژیست ها اجازه می دهد که اشکال مختلف سطح زمین را به طور عینی با یکدیگر مقایسه کنند. یکی از مهم ترین شواهد ژئومورفولوژیکی، میزان و نحوه ی عملکرد خطوط گسلی، ویژگی های ژئومورفیک عوارض پیرامون آنها و به ویژه مورفولوژی حوضه آبخیز و مخروط افکنه ها می باشد. همچنین نیروهای درونی زمین در قالب فرآیندهای تکتونیک موجب تشکیل ناهمواری های زمین و تشکیل فرم های اصلی را فراهم می آورد، اما تاثیر آنها در تغییر چشم اندازهای ساختمانی و ژئومورفولوژیک زمین در همه جا یکنواخت و یکسان نیست بلکه همواره در تغییروتحول و ایجاد شکل های جدید نقش اساسی دارد. شاخص های ژئومورفولوژیک در ارزیابی فعالیت تکتونیکی یکی از مهم ترین راه های شناخت این تغییرات می باشد. علم مورفوتکتونیک در بررسی نوع ارتباط بین گسل ها و لندفرم های حاصل، از نقشه های خمیدگی برای تشخیص و توصیف خطوط گسل استفاده می گردد.  در این مقاله زمین ساخت فعال حوضه‏های ناحیه مراغه، که در شمال باختر واقع شده، بر پایه شاخص‏های زمین ریختی بررسی شده است. شاخص طول شیب رودخانه (Sl)، انتگرال فرازسنجی (Hi)، شکل حوضه زهکشی (Bs)، نبود تقارن حوضه زهکشی (Af)، شاخص تقارن توپوگرافی عرضی حوضه (T)، شاخص نسبت پهنای کف دره به ارتفاع آن (Vf)، شاخص سینوسیته پیشانی کوهستانی (Smf) محاسبه شدند. در پایان شاخص زمین ساخت  فعال نسبی (Iat) محاسبه شد که ترکیبی از شاخص‏های بالاست. با میانگین‏گیری از کلاس‏های به دست آمده (S/n)، منطقه مطالعه شده به سه پهنه زمین‏ساختی تقسیم شد. هدف تعیین سطح فعالیت تکتونیکی بود که به منظور تحلیل درست از ناحیه مطالعاتی مدل تحلیل سلسله مراتبی (AHP) با وزن‏های حاصله از ضرایب همبستگی بین شاخص ها و در نهایت لایه نهایی زمین ساخت فعال ناحیه تهیه شد. با استفاده از شاخص های ریخت زمین ساختی و مدل تحلیل سلسله مراتبی (AHP)، فعالیت نسبی زمین ساختی از ناحیه مورد مطالعه به دست آمد.

    کلیدواژگان: تحلیل سلسله مراتبی، حوضه های ناحیه مراغه، زمین ساخت فعال، شاخص های ژئومورفیک
  • زانیار امیری، فرهاد خرمالی*، چوقی بایرام کمکی صفحات 47-58

    بسیاری از نقشه های خاک ایران به به روزرسانی نیاز دارند. اما روش های رایج در نقشه برداری خاک پرهزینه و زمان بر است. به همین دلیل امروزه استفاده از داده های سنجش ازدور مطرح است. مناطق مختلفی از استان گلستان با رسوبات لسی پوشیده شده اند. مطالعات اخیر در فلات لسی استان گلستان نشان می دهند این لس ها حاوی اطلاعاتی مفید برای تغییر اقلیم و تکامل زمین نما در دوره کواترنرند. در این تحقیق با استفاده از داده های ماهواره لندست 8 و سنتینل 2 نقشه پراکنش واحدهای مختلف مواد مادری به روش های طبقه بندی ماشین بردار پشتیبان و حداکثر احتمال در 4000 هکتار از اراضی لسی منطقه آق بند تهیه شد. پس از تهیه نقشه پراکنش واحدهای مختلف مواد مادری، دقت آن ها با استفاده از 607 نقطه در ماتریس خطا بررسی شد، که نتایج برای طبقه بندی تصویر سنتینل 2 به روش های ماشین بردار پشتیبان  و حداکثر احتمال به ترتیب دقت 45/89 درصد و 8/87 درصد و همچنین با طبقه بندی تصویر لندست به روش های مذکور دقت 17/85 درصد و 87/81 درصد حاصل شد. با توجه به دقت های به دست آمده، این نتیجه حاصل می شود که روش ماشین بردار پشتیبان  نسبت به روش حداکثر احتمال از دقت بالاتری برخوردار است.

    کلیدواژگان: حداکثر احتمال، سیستم اطلاعات جغرافیایی، فلات لسی، ماتریس خطا، ماشین بردار پشتیبان
  • شهره عرفان، خلیل رضایی*، راضیه لک، سید محسن آل علی صفحات 59-78

    مطالعات بین رشته ای نقش مهمی در پاسخگویی به سوالات پروژه های مهندسی بازی می کنند. مطالعات تلفیقی رسوب شناسی و ژئوالکتریک برای بررسی پراکنش انواع رسوبات دو سوی غربی و شرقی بخش جنوبی دریاچه ارومیه، نقش آن ها در تبادل آب های زیرزمینی و وجود گسل در بستر دریاچه انجام شد. بدین منظور 18 گمانه 10 متری در سه پروفیل در دو سوی دریاچه حفاری و رسوبات ستون چینه شناسی آن ها تحت آزمایش دانه بندی و کانی شناسی و تطابق قرار گرفت. تعداد 391 سونداژ ژئوالکتریکی قائم با آرایه شلومبرژه در دشت های حاشیه برداشت شدند. ستون دانه بندی گمانه ها با سونداژ مجاور متناظر شد و با تصحیحات نرمال سازی، به روش دیفیوژن، درون یابی و نقشه های هم مقاومت ترسیم و تفسیر شد. در 5 مقطع عرضی، برش هایی از غرب تا شرق دریاچه تهیه و تغییرات دانه بندی و مقاومت الکتریکی در آن ها بررسی شد. نتایج نشان داد در دو ناحیه، به دلیل وجود رسوبات درشت دانه و دارای مقاومت الکتریکی بالا، امکان تبادل آب های زیرزمینی وجود دارد. این نقاط می توانند مسیل های قدیمی رودخانه شهرچای و باراندازچای و انشعابات آن ها بوده باشند. به دلیل تمایز بالا و اختلاف مقادیر دو پارامتر مقاومت الکتریکی و مغناطیسی در دو سوی دریاچه، یک گسستگی ژئوفیزیکی در دو روش ژئوالکتریک و مغناطیس سنجی هوایی در محل دریاچه قابل اثبات است.

    کلیدواژگان: دریاچه ارومیه، رسوب شناسی، زمین آمار، ژئوالکتریک، کواترنر
  • مژگان جایز* صفحات 79-104

    زرزی نام صنعتی شاخص مربوط به واپسین دوران پارینه سنگی در منطقه زاگرس است. مطالعات محوطه های منتسب به دوران فراپارینه سنگی در زاگرس مرکزی با چالش های فراوانی روبه رو است که مهم ترین آنها مسئله ویژگی های صنایعی است که می بایست به صنعت زرزی منتسب نمود. در این مقاله ضمن ارائه خلاصه ای از پیشینه مطالعات صورت گرفته درباره زرزی، تلاش شده است تا با نگاهی انتقادی ماهیت زرزی در مطالعات پارینه سنگی ایران بر اساس یافته های مادی حاصل از محوطه های منتسب به آن، که مهم ترین آنها غار زرزی و پناهگاه صخره ای ورواسی هستند، مورد بررسی قرار گیرد. مهم ترین ویژگی های زرزی در صنایع سنگی آن منعکس شده است که صنایعی با تولید میکرولیت های هندسی و غیرهندسی و ابزارهای کنگره دار/دندانه دار همراه با فراوانی خراشنده ها به ویژه خراشنده های ناخنی و حضور سایر ابزارها همچون اسکنه ها در مقادیر بسیار کمتر از دوران پارینه سنگی جدید و سوراخ کننده ها و سرتیرهای شانه ای است. به لحاظ فن آوری تولید، زنجیره تولید و مصرف دست ساخته های سنگی و ترکیب بندی فن آوری در انواع مختلف محوطه ها ابهامات فراوانی درباره صنایع زرزی وجود دارد. بر اساس یافته های موجود می توان زرزی را نه «فرهنگ دوران فراپارینه سنگی زاگرس»، بلکه صنعتی مربوط به دوران فراپارینه سنگی در ناحیه زاگرس با سنت های خاص خود دانست که بخشی از فرهنگ گسترده تری محسوب می شود که یافته های موجود برای تبیین آن بسیار ناکارآمد و ناکافی است.

    کلیدواژگان: فراپارینه سنگی، صنایع زرزی، زاگرس مرکزی، صنعت دست ساخته های سنگی
  • صلاح اشترابه، رضا علی پور*، حسن محسنی صفحات 105-124

    هدف از این مطالعه بررسی شواهد تکتونیک فعال مرتبط با گسل‏ جوان ‏اصلی ‏زاگرس (MRF) در منطقه سروآباد در شمال باختری ایران بود؛ که مطالعه ای در مورد ریخت زمین ساخت و ساختار این منطقه تا قبل از این پژوهش صورت نگرفته است. این گسل با حرکت امتدادلغز راست بر یکی از ساختارهای مهم لرزه‏خیز در باختر ایران است که مسبب زلزله‏های بزرگی بوده است. در این مطالعه، با استفاده از شاخص‏های ریخت‏زمین ساختی، فعالیت تکتونیکی نسبی در راستای این گسل بررسی شد. نتایج به دست آمده از شاخص‏های ریخت‏زمین ساختی بر اساس تحلیل‏های سلسله مراتبی وزن‏دهی شده و وزن هر شاخص در نقشه مربوطه آمده است. برای یکسان‏سازی فاکتورها با استفاده از منطق فازی هر نقشه به بازه بین 0 تا 1 تبدیل و با همپوشانی همه نقشه‏های فازی نقشه نهایی فعالیت نسبی تکتونیکی تهیه شد. با توجه به نقشه نهایی بخش‏های جنوبی و جنوب خاوری منطقه مورد مطالعه با راستای شمال‏باختری جنوب‏خاوری و منطبق با MRF فعالیت نسبی بالایی دارد. شواهد صحرایی نشان می‏دهد حرکت امتدادلغز راست بر این گسل در منطقه سروآباد همراه مولفه فشارشی مثل گسل‏های معکوس و ساختارهای گل‏مثبت (جنوب‏باختری گسل) و کششی مثل گسل‏های نرمال (شمال‏باختری گسل) است و به صورت دره‏های خطی گسلی قابل مشاهده است.

    کلیدواژگان: تکتونیک فعال، زلزله، سروآباد، گسل جوان اصلی
  • شهریار محمودی*، علی محمد خواجه ای صفحات 125-142

    مجموعه آتشفشانی حسن‌آباد دره زرشک در غرب ایران مرکزی، کمربند آتشفشانی ارومیه‌ دختر و جنوب‌غربی شهرستان یزد، واقع است. این مجموعه از سنگ‌های آذرین خروجی با ترکیب حد واسط تا اسیدی است. بر اساس خصوصیات چینه‌شناسی، طی یک دوره فعالیت‌های آتشفشانی در پلیو کواترنری فوران یافته است. همچمین دایک‌های ، تراکی آندزیت، آندزیت، و دولریت در سنگ‌ها نفوذ کرده. بافت اصلی پورفیری است. اما بافت‌های دیگری نیز دیده می‌شود. برخی از ویژگی‌های بافتی و حاکی از عدم‌ تعادل بلور با مذاب است. روند تغییرات عناصر اصلی و کمیاب و شیمی‌بلورها پدیده آلایش ماگمایی را در  منطقه تایید می‌کند. الگوی عناصر ناسازگار شاخص‌های ماگماهای کالک آلکالن را در مناطق فرورانش نشان می‌دهد. علاوه بر این ویژگی‌ها، وجود برخی خصوصیات نظیر SiO2 ≥ 56 wt%، Al2O3 ≥ 15 wt%، K2O/Na2O < 0.5 wt%، Sr > 400 ppm، Y ≤ 18 ppm، و Nb < 10 ppm در مجموعه آذرین منطقه بیانگر ماگماهای مناطق فرورانش، با عنوان ماگماهای آداکیتی، تعلق دارند. بر اساس طبقه‌بندی، آداکیت‌های منطقه مطالعاتی در زمره آداکیت‌های پرسیلیس (HSA) هستند. زینولیت‌هایی موجود که منشا عمق‌تر دارند. شواهد ترموبارمتری به‌دست‌آمده از بررسی شیمی‌کانی‌ها نیز عمق و دمای تشکیل این سنگ‌ها در مناطق مشابه تشکیل ماگمای آداکیتی را تایید می‌کند.

    کلیدواژگان: آداکیت، آلایش ماگمایی، ایران مرکزی، بلوک یزد، جایگاه تکتونیکی، داسیت
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  • Ghasem Azizi, Mahmoud Davoodi* Pages 1-25
    Introduction

    Paleoclimatics studies can respond the many uncertainties about past climate change; an issue that is being studied seriously in the world but less attention has been paid in Iran. The Late Quaternary can be considered as Holocene. Holocene, which spans over 11,000 years ago; In general, it is considered as a period with relatively warm and stable climatic conditions. However, recent studies have shown that the Holocene climate is relatively unstable and characterized by several short-term climate fluctuations. The present study attempts to investigate the events of the late quaternary climate change in Iran. Hence, by studying various internal and external sources, first major climatic changes were identified at the late quaternary, and then these changes were detected in Iran. Then, based on the results of a case study, the results of the studies were tested.This research seeks to answer the following questions:- Is it possible to detect the major events of the Holocene climate change in Iran?- Is there a difference between the time of occurrence of major Holocene climate changes in Iran and other parts of the world?
    - How has moisture changes been in cold and hot periods?

    Method and Materials

    This research consists of two sections. In the first, a review has been conducted. In this section, first, using studies in relation to the late Quaternary climate change in the world, major climatic changes were identified in the Late Quaternary. Then, by studying and reviewing existing theories and resources, including books and articles, it has been attempted to determine the overall framework for climate change in Iran at the Late Quaternary. In the second part, the results of a case study were used to confirm the review studies. This case study includes a core length of 8.5 m, taken from the Parishan lake floor. In this section, two proxies were used to carry out analyzes and identify climate changes of late Quaternary, which include the use of palynology and magnetism susceptibility methods. The magnetism susceptibility technique was used to determine the warm-cold periods and the reconstruction of paleo-vegetation was used to determine wet-dry periods. To calculate the AP/NAP index, samples were taken in 10 cm interval from the sedimentary cores and pollens extracted and identified by the method of Moore et al., 1991 (with slightly change). Samples were also used to measure the magnetism susceptibility by use the Bartington Susceptibility Meter with a 1 cm interval.

    Results

     The studies on climate change in this period show a number of significant fluctuations, including four cold events: The Younger Dryas, The 8.2 ka cooling event, The Cold period of Migration time and The Little Ica Age (LIA), and 4 warm events: The climatic optimum, The Roman warm period, The Medieval Warm Period (MWP) and The Modern warming period. In the Parishan Lake, 6 major cold and warm periods in Holocene can be identified, for the four of them, it can be found that there is an approximate correspondence with the temperature changes occurring on the planet, but these courses have been delayed.

    Discussion

    The results indicate a reverse relationship between the moisture index and the magnetism susceptibility; in fact, during warm periods humidity has increased, and humidity has decreased during cold periods. The rate of moisture index has also decreased with increasing cold intensity; in the Younger Dryas and The 8.2 ka cooling events have lowest temperatures in the region and the lowest moisture index has been recorded in these two periods. The highest moisture content was recorded in The Climatic Optimum.

     Conclusion

    The results of this study showed that there is a good correlation between cold and warm periods in other parts of the world with Iran, although between these periods in Iran and North Europe and the United States there is a time lag of approximately 200 to 300 years. Also, the existence of cold-dry and warm-wet periods was confirmed in the past of Iran. In the studied region, at the Younger Dryas and The 8.2 ka cooling events, with the lowest temperatures in the area, the amount of tree species has reached almost zero, which indicates the dryness of the area during cold periods. In all warm periods, the moisture index of AP/NAP was higher than the cold periods. It can be concluded that warm periods were generally more humid than cold periods.

    Keywords: Climate change, Holocene, Magnetism susceptibility, AP, NAP index
  • Sahar Babie, Manouchehr Ghorashi*, Mohsen Pourkermani, Hassan Haji Hosseinloo, Soheila Bouzari Pages 27-45
    Introduction

    Paleoclimatics studies can respond the many uncertainties about past climate change; an issue that is being studied seriously in the world but less attention has been paid in Iran. The Late Quaternary can be considered as Holocene. Holocene, which spans over 11,000 years ago; In general, it is considered as a period with relatively warm and stable climatic conditions. However, recent studies have shown that the Holocene climate is relatively unstable and characterized by several short-term climate fluctuations. The present study attempts to investigate the events of the late quaternary climate change in Iran. Hence, by studying various internal and external sources, first major climatic changes were identified at the late quaternary, and then these changes were detected in Iran. Then, based on the results of a case study, the results of the studies were tested.This research seeks to answer the following questions:- Is it possible to detect the major events of the Holocene climate change in Iran?
    - Is there a difference between the time of occurrence of major Holocene climate changes in Iranand other parts of the world? - How has moisture changes been in cold and hot periods?

    Method and Materials

    This research consists of two sections. In the first, a review has been conducted. In this section, first, using studies in relation to the late Quaternary climate change in the world, major climatic changes were identified in the Late Quaternary. Then, by studying and reviewing existing theories and resources, including books and articles, it has been attempted to determine the overall framework for climate change in Iran at the Late Quaternary. In the second part, the results of a case study were used to confirm the review studies. This case study includes a core length of 8.5 m, taken from the Parishan lake floor. In this section, two proxies were used to carry out analyzes and identify climate changes of late Quaternary, which include the use of palynology and magnetism susceptibility methods. The magnetism susceptibility technique was used to determine the warm-cold periods and the reconstruction of paleo-vegetation was used to determine wet-dry periods. To calculate the AP/NAP index, samples were taken in 10 cm interval from the sedimentary cores and pollens extracted and identified by the method of Moore et al., 1991 (with slightly change). Samples were also used to measure the magnetism susceptibility by use the Bartington Susceptibility Meter with a 1 cm interval.

    Results

    The studies on climate change in this period show a number of significant fluctuations, including four cold events: The Younger Dryas, The 8.2 ka cooling event, The Cold period of Migration time and The Little Ica Age (LIA), and 4 warm events: The climatic optimum, The Roman warm period, The Medieval Warm Period (MWP) and The Modern warming period. In the Parishan Lake, 6 major cold and warm periods in Holocene can be identified, for the four of them, it can be found that there is an approximate correspondence with the temperature changes occurring on the planet, but these courses have been delayed.

    Discussion

    The results indicate a reverse relationship between the moisture index and the magnetism susceptibility; in fact, during warm periods humidity has increased, and humidity has decreased during cold periods. The rate of moisture index has also decreased with increasing cold intensity; in the Younger Dryas and The 8.2 ka cooling events have lowest temperatures in the region and the lowest moisture index has been recorded in these two periods. The highest moisture content was recorded in The Climatic Optimum.

     Conclusion

    The results of this study showed that there is a good correlation between cold and warm periods in other parts of the world with Iran, although between these periods in Iran and North Europe and the United States there is a time lag of approximately 200 to 300 years. Also, the existence of cold-dry and warm-wet periods was confirmed in the past of Iran. In the studied region, at the Younger Dryas and The 8.2 ka cooling events, with the lowest temperatures in the area, the amount of tree species has reached almost zero, which indicates the dryness of the area during cold periods. In all warm periods, the moisture index of AP/NAP was higher than the cold periods. It can be concluded that warm periods were generally more humid than cold periods.

    Keywords: Climate change, Holocene, Magnetism susceptibility, AP, NAP index
  • Zaniar Amiri, Farhad Khormali* Pages 47-58
    Introduction

    Along with the climate, Soil is an essential natural resource. Although soil studies in Iran have been started more than 50 years ago, the soil map of the country has not been fully prepared yet, and only 20-25% of the lands have been mapped already. Many soil maps of Iran need to be updated, but the common methods in soil mapping are costly and time-consuming. Hence, using data obtained from remote sensing is trending nowadays. These data possess a great importance as a proper approach for preparation of various maps due to timely presentation of information, variety in type, being digitized and possibility of digital processing. Classification is one of the useful methods of obtaining data from remote sensing images which allows the user to generate various types of information such as different maps. Different regions of Golestan province are covered with loessial sediments. Recent studies in loess plateau of Golestan province show that these loesses possess useful information about climate change and landscape evolution in quaternary period. The aims of the present study was mapping different lithologic units in loess plateau of eastern Golestan using remote sensing technique and evaluating the efficiency of using remote sensing images to identify and prepare the distribution map of different lithology units in the study area.

    Material and methods

    Loess plateau of Golestan province which is located at the north of Alborz Mountains and western region of Qopeh-dagh Mountains possesses an area equal to 250000 hectares; the height of the mentioned loess plateau is in the range of 45 m to 700 m from sea level. In this study, about 40 km2 of western part of Golestan loess plateau is selected as the study area located near Aghband village, 60 km from Gonbad city. In the following study, distribution map of different lithology units using the data from Landsat 8 and Sentinel 2 satellites was performed via classification of support vector machine, maximum likelihood and photomorphic image analysis methods in GIS software interface by Sentinel-2A (RGB band  No. 2,3, 4) and Landsat8-OLI (band  No. 2,3, 4). After preparing distribution map of different lithology units, their accuracy was evaluated via confusion matrix, The produced maps were evaluated by 607 ground truth points obtained by field survey and Google Earth and their overall accuracies and kappa coefficients were calculated.

    Result and discussion

    Field observations revealed four types of lithology units including loess, loess-paleosol of early Pleistocene, marl and limestone. Each of these lithology types had specific colors and could be identified by color difference in true color composite bands of satellite data and Google Earth images. After the lithology units were digitally classified via the maximum likelihood and support vector machine methods, their distribution maps were prepared and evaluated. Classification of Sentinel 2 images via support vector machine and maximum likelihood methods led to a accuracy of 89.45% and 87.7%, respectively, whereas these values for Landsat were 85.17% and 81.87%.

     Conclusion

    Each lithology of Golestan loess plateau had a specific color of its own; color of loesses are yellow and yellowish, marls have different colors including blue and green and colors between them, color of lime-stone are white and milky and color of loess-paleosols are red.The results associated with the comparison of overall accuracy and Kappa coefficient of the classified images indicate that although both algorithms of support vector machine and maximum likelihood which are utilized for digital classification had high overall accuracy and Kappa coefficient, superiority of support vector machine compared to maximum likelihood method is obvious in both images utilized in the present study. However, on the other hand, a higher accuracy may be observed in the images taken by Sentinel 2 due to smaller pixel size. Thus, it may be concluded that support vector machine method not only has performed more capably in detection of different lithologies, but also changing the source of the satellite images has no impact on the efficiency of this method. Noting that one of the objectives of the study was evaluating the efficiency of using remote sensing technique to identify and prepare the distribution map of different lithology units in the study area, it was concluded that utilizing remote sensing techniques in the studied region may be feasible along with the other mapping methods.

    Keywords: Confusing matrix, Geographic Information System, Loess Plateau, Maximum likelihood, Support Vector Machine
  • Shohreh Erfan, Khalil Rezaie*, Razyeh Lak, Seyed Mohsen Ale Ali Pages 59-78
    Introduction

    Interdisciplinary studies play an important role in answering engineering questions. Identifying the characteristics of alluviums, underground water exploration and minerals, along with geotechnical studies in the construction of heavy structures are just some of these applications. Following the increasing drying of Lake Urmia, various research has been conducted to answer multiple questions posed by the agenda of various organizations. The two most important questions in the set of questions were that: 1. Is the water of Urmia Lake connected to the subterranean sediments of the two sides with the wells of the region and where is the location of this exchange and passage of the subterranean saline and fresh waters in which regions?2. Is there a fault under the lake? To answer these two questions, geological and geophysical surveys were planned and designed with financial constraints. In this research, sedimentology and Geoelectric studies with the aim of investigating the distribution of various sediments in the western and eastern margins of the southern part of Lake Urmia, their role in the exchange of groundwater between the lake and the wells of the marginal plains, as well as the presence or absence of faults in the lake bed was done.

    Material and method

    Lake Urmia is located in north west of Iran and in Azerbaijan province. This lake is one of the most saturated lakes in the world and the largest and warmest permanent lake in Iran. This is a lake with fresh water that gradually salted to an overestimation of salt. In this study, 18 boreholes of 10 meters were drilled in three profiles along the lake, and the stratigraphic column of sediments within them were subjected to granulation and mineralogy experiments and adapted to each other. A total of 391 Schlumberger Geoelectric vertical soundings was taken and interpreted in marginal plains. The grain size column of the boreholes was fitted with adjacent soundings. The data were analyzed using standardized variables and statistical maps. Then, after analyzing the statistical ground by two GS + and ARCGIS software and calculating the statistical parameters and normalizing the data. The data were interpolated using diffusion method and the iso-resistivity maps were interpreted. In five cross sections, from west to east of the lake were prepared and the gradient and electrical resistance changes were investigated. Finally, these maps were compared with the map of the report of aerial geophysical studies (magnetism) and final conclusion was made.

    Result and discussion

    By examining boreholes, it was found that in terms of grain size, in almost no specimens, very coarse gravel particles were found and fine grains and clay minerals had the highest frequency. At some depths, due to the increased energy of the sedimentary environment, the sands suddenly increased and may indicate an increase in rainfall and the flow of rivers and streams. An increase in evapotranspiration minerals is also found in some depths that are consistent with the dryness of the environment and the reduction of precipitation. In the boreholes corresponding to Geoelectric assays, the effect of water table can be clearly observed in the change of electrical resistivity. The presence of clay causes relative decrease and the presence of sand increases electrical resistivity. While, the presence of salt water and evaporation will greatly reduce electrical resistivity. From a statistical viewpoint, the data range is very large and represents less than one to more than 2000 ohm meters. But the abundance of points and depths with low electrical resistance (containing clay and saline water) is much higher than the high resistivity values ​​ (containing dry sand or floor rock). Several geo-electrical horizons can be identified in these sections and maps: 1. Horizons with electrical resistivity less than 10 ohms (saline water and fine-grained sediments); 2- Horizons with electrical resistivity of 10 to 20 ohms (clay with or without fresh water); 3. Horizon with electrical resistivity between 20 and 60 ohms (sand and coarse grained or freshwater sediments); 4. Horizon with electrical resistivity of more than 100 ohms (limestone, sandstone, volcanism). Based on the magnitude map of the entire magnetic field, the highest field strength for the investigated range is 50170 Nano-Tesla, the lowest intensity is 47118 Nano-Tesla field, and the average field intensity is 48213 Nano-Tesla, and the region is separable in two parts in terms of magnetization. Areas with relatively high to high field intensity and often include parts of the northwest, center of south and southwest of the study area. Also, in two areas due to coarse-grained sediments and high electrical resistivity, there is the possibility of underground water exchange with adjacent sedimentary environments.

    Conclusion

    The results showed that in two areas due to coarse-grained sediments and high electrical resistivity, there is the possibility of underground water transfer and exchange pathway. A geophysical disruption is proven by two methods of Geoelectric and magneto metric analysis in the lake.

    Keywords: Quaternary, Sedimentology, Geoelectric, Geo-statistic, Urmia Lake
  • Mozhgan Jayez* Pages 79-104
    Introduction

    The final phase of Late Paleolithic of Zagros Mountains has been introduced as the Zarzian of the Epipaleolithic (EP), which was defined based on the assemblage from type site of Zarzi Cave in Iraqi Kurdistan. This techno-complex has been much less investigated and introduced in comparison to the earlier groups of Upper Paleolithic. The Zarzian is a microlithic industry with small (thumbnail) scrapers, backed bladelets and geometric forms. Although the type site of the Zarzian, i.e. Zarzi Cave in Iraqi Kurdistan, was excavated 90 years ago, few other Zarzian sites have been excavated in Zagros and there are only two absolute dating available, both of which from sites outside political borders of Iran excavated in 1960s. In 2012 Deborah I. Olszewski provided a comprehensive review on the background of research on the Zarzian, although she did not have full access to information on newly found sites, probably because most of them have been published in Persian language or because there have been many Paleolithic surveys conducted in the last decade by local archaeologists making them difficult to follow comprehensively. In this article, a critical review of Zarzian research is presented with regard to the finds from the most important sites, with the goal of defining Zarzian nature and limiting it in a framework of its unique characteristics.

    Method & material

    Although the research on Zagros EP started in early 20th century, there is not enough information regarding even absolute chronology and few sites have been excavated with Zarzian cultural deposits. Nevertheless, the terminology is used extensively across Zagros Mountains for Late Paleolithic assemblages despite their heterogeneity. In many recent surveys, especially in Central Zagros, caves and rock shelters as well as open sites have been attributed to EP and/or Zarzian based on surface lithics (references in this regard are provided in Persian extended text), but the increase in the number of EP/Zarzian sites has not contributed much in clarifying the debates regarding technological aspects of the period (e.g. the explanation for the presence/absence of geometric/non-geometric elements as a chronological criterion or a functional pattern), let alone the more complicated notions such as transition from UP to EP in the region, or identifying cultural groups and their interrelations. It is clear that there are variations in lithic industries attributed to Zarzian, and even EP, in central and Southern Zagros. Either some of attributions should be re-evaluated, or there exist variations in the techno-complexes of the period.

    Result

    When the Zarzian was first introduced by Dorothy Garrod, it was described as an “industry of the final stage of Upper Paleolithic”. In fact, the detailed configuration of Zarzian Industry was established in 1990s based on chipped stone assemblage from Warwasi rock shelter by Deborah Olszewski. The lithic industry is characterized as having non-geometric microliths, mainly Dufour bladelets, and thumbnail scrapers in the earliest phases and introduction and increase in geometric microliths (i.e. scalene triangles and lunates) in the course of later phases. Despite limited number of excavated sites and lack of reliable chronological framework and ambiguities in sequential phases based on lithic industry, the terminology has been even applied in Southern Zagros sites.

    Discussion

    Interpretive approach to Zarzian lithic industry has been developed only in a handful of sites, including Zarzi, Shanidar, Warwasi and a small assemblage form Ghar-e Khar and few of these sites have been radiocarbon dated and all of them were excavated more than 50 years ago (Zarzi in 1928; Shanidar in 1950s; Warwasi in 1960; Ghar-e Khar in 1965) with methods that were not only inaccurate in comparison to methods applied today, but also different from site to site; Statistical information is not available in publications on assemblages such as Pa Sangar in Khorramabad Valley and even Shanidar. As a result, when Warwasi assemblage was introduced in detail in 1990s, almost immediately it turned into the only reliable source of Zarzian research in the region, regardless of the fact that the function of the site has been introduced as a “game overlook/butchering station” and even if such a recognition would be accepted, its characteristics could not be exclusively generalized to other types of hunter-gatherers spatial locations. It should be also noticed that most lithic analysis of Zarzian assemblages are focused on tools typology and composition and few research take technological aspects into account (e.g. core morphology and technology are introduced in Zarzian assemblages from Pa Sangar and Warwasi).Another point is that the UP-EP transition has only been briefly mentioned in few sites with cultural materials of both periods, the most important of which being still Warwasi rock shelter in Central Zagros. As mentioned previously lack of excavations in stratified EP sites and scarce absolute dating of these site, as well as lack of interest in the cultural period among Paleolithic archaeologists make any attempt to understand the long-term changes of the Zarzian group extremely difficult, if not inconclusive.

    Conclusion

    The main goal of this review is to emphasise the difference of the nature of what we consider “Epipalaeolithic” and what is defined as “Zarzian” as an identity within the limits of Epipalaeolithic culture; hence, it is important to restrict the attribution of Epipalaeolithic finds to “Zarzian”and set up a limit for what we can consider as Zarzian. Considering various aspects of Zarzian other than lithic technology, makes it clear that Zarzi could not be defined as an Epipalaeolithi culture, first because we do not have enough finding regarding its chronology and different aspects of cultural charachteristics of hunter-gatherers to which Zarzi is attributed; and second because what is already understood regarding their subsistence, economic and social relations is not exclusively limited to Zarzian sites and could be defined in a wider framework as every EP culture. Accordingly, for the moment and until new evidence, we have to limit the attribution only to lithic industry with specific characteristics mentioned in the article.

    Keywords: Epipalaeolithic, Zarzian, lithic Industry, Central Zagros
  • Reza alipoor* Pages 105-124
    Introduction

    The Main Recent Fault (MRF) is a seismic structure on the northwestern boundary of the Zagros belt and southern border of the Sanandaj-Sirjan belt. This fault as a major strike-slip fault consists of several segments in the Zagros collision zone. The seismic activity of the southwestern segments is greater than the northwestern segments. Several earthquake events have occurred along the MRF zone in the past decade, as the largest was the 1909 Silakhor earthquake with 7.4 magnitude. Several structural studies have been done along the MRF from the southwest segment (Dorud fault) to northwestern segments (Marivan and Piranshahr segments), because of the seismicity importance of this fault zone. However, there is no any structural and morphotectonics studies along this fault in the Sarvabad region. Therefore, in this research, the relative tectonic activity of the MRF in the Sarvabad region has been investigated based on field studies and measurements of the morphometric indicators.

     Materials and methods

    In this study, six morphometric indicators were measured in the basins of the study area, to assessment of the tectonic activity related to the MRF fault zone in the Sarvabad region. These indicators include: stream length-gradient index (SL), asymmetry factor index (Af), basin shape index (Bs), hypersometric integral index (Hi), valley height-width index (Vf) and topographic symmetry factor index (T). These indicators have been extracted using digital elevation model (DEM) and geological maps of the study area. Then, for a detailed study of the relative active tectonic using analytical hierarchy process (AHP), we first considered weight of each index based on its importance, and finally, weighted average of indicators has been analyzed for data standardization using fuzzy logic.

    Results and discussion

    In the northwest basins of the study area and along the MRF zone, SL index indicates high values, according to the SL map and related graphs. According to the Hi index diagrams, the basins of the study area are classified in three categories. Category 1 (young topographic and convex curve shape), category 2 (sigmoid curve shape and mature basin) and category 2 (concave curved shape) and nine measured basins are classified in the first category. Three categories for the Af index are considered in the study area. The basins of the central part of the study area indicate the highest asymmetry, because of the strike-slip activity of the MRF. Almost half of the basins of the study area are classified in class 1 and 2, according to Bs index classification map. The values of the Vf index is decreased in the basins along the active strike-slip fault in the study area. The T index in the most basins of the study area shows 1 and 2 classes, indicating an asymmetric region in the central part and along the active strike-slip fault systems. In this study, we used a weighting system for morphotectonic indices to calculate the exact relative tectonic activity. morphotectonic indicators affected by tectonic structures have the most weights and indices controlled by topography and mineralogy are less weights. The weight of each indices is multiplied in the measured map of each basin, after weighing the indices in the studied area. Then the finalized weight maps are shown separately for the indices. All values of the weighted map have been converted into the same range from zero to one using the fuzzy method, in order to standardize the values of the indices. Then, six index maps was combined using a simple additive weighting (SAW) model. Then the final map and, in fact, the output of the SAW model, are classified into 3 classes of relative tectonic activity from high to low. Based on this model, the Southeastern and West parts of the region show a higher relative tectonic activity related to the Northwestrn parts.

     Conclusion

    Based on final map obtained from the SAW model Basins with high relative tectonic activity is located in the Southeastern and West parts and in northwest-southeast line trend along the MRF zone. Field evidence indicate that the recent tectonic activities in the study area are visible as V-shaped valleys, linear fault valleys, and fault planes. In the northern part of the MRF zone in the Sarvabad region, the strike-slip movement of the fault indicates an extensional component. This extensional component is visible as normal faults and the formation of veins. In the southwestern part of the study area, the strike-slip fault movements indicates compressive component, as reverse faults and flower structures.

    Keywords: MRF, Sarvabad, active tectonic, earthquake
  • Shahriar Mahmoudi*, Ali Mohammad Khajei Pages 125-142
    Introduction

    Petrogenesis of continental magmatic arc is more complicated than oceanic arcs. Because some various parameters affect the composition of magmatism in the congenital margin, such as continental crust contamination, mixing with crustal magmas and the deformation phenomena from primary mantle magma (Martin et al., 2005; Eyuboglu et al., 2018; Pawley and Holloway, 1993). From a historical point of view, adakite is initially known as a special rock on the Adak island, described by Kay, (1978), called by Mackenzie as andesite. The unusual geochemical features of these rocks are: (SiO2 ≥ 56 wt%، Al2O3 ≥ 15 wt%، K2O/Na2O < 0.5 wt%، Sr > 400 ppm، Y ≤ 18 ppm و Nb < 10 ppm). The low content of HREE due to the presence of hornblende or garnet in the adakites melting source. Negative anomalies of Nb and Ti are also the properties of the magmas drifted from subduction zones. Totally, it can be said that the abundance of the major and rare elements in volcanic rocks of the Darehzereshk’s Hassanabad correlate with the average chemical composition of adakites in other parts of the world. According to the Martin and Moyn (2003) classification, the study adakites are classified as high silicic adakites (HSA).

    Method and materials

    From the study area was collected more than 100 samples. From 40 samples were created tine-section microscopic. petrography has done by Zeiss research microscopy in Kharazmi microscope lab. In order to study the geochemical characteristics of the igneous rocks in the area, 35 samples of outcrops, granodioritic intrusive rocks, dykes, and xenoliths were selected and 8 of them were analyzed by ICP-MS at Zarazma company. XRF analysis has done in the Laboratory of Damghan University. The results are presented in Table, 1. EPMA  data got in the Iran Minerals Processing Research Center.

    Results and discussion

    The Darehzereshk’s Hassanabad volcanic complex located in the microcontinental Iran block, along the Urmia-Dakhtar volcanic belt and 80 kilometers west of Yazd city (Fig,1 A,B). After field geology and sample collection, petrography and XRD, ICP/MS and EPMA analyses were done. Based on collected data, the volcanic rocks in study area include diorite-andesitic dikes and intrusive body, trachyte, dacite and rhyolite lava and domes. In the outcropes and specimens, these rocks are bright, light-gray to dark gray color. Andesite-diorite dikes are subvolcanic (Fig. A3), and often show the microlitic porphyry and glomero porphyry texture. In the dacite lava, plagioclase crystals are often characterized by zoning and unstable core (Fig. C3). Also the amphiboles present in the microscopic sections of these samples are sometimes chemically zoned (Fig. D3). the plagioclase crystals mostly have reaction margin (Fig. E3). In rhyolite and rhyodacite, 5 to 15 percent quartz is present and shows corrosion gulf (Fig. F3).
    The whole rock chemical composition of volcanic rocks and dikes in the classification diagrams (e.g. Le Bas et al, 1986) plotted in the andesite, dacite and trachyte areas (Fig. A4). Sub-volcanic rocks included intrusive and xenoliths plotted in the range of granodiorite and gabbro areas. These rocks with the sub-alkaline nature located in the calc-alkaline magma series. The contained rare light earth elements (LREE) are enriched and heavy rare earth elemental (HREE) depleted (Tab-1). In addition, there is a negative anomaly of Nb and Ti (Fig-D4), which is one of the indices of the calc-alkaline adikatic magma in subduction zone. The continuous pattern of the major and rare elements of the samples in the Harker diagrams (Harker, 1909) indicates the same origin and the role of crystalline differentiation in the magma evaluation (Rolinson, 1983). Other geological evidence, such as the enrichment of large ion lithophile elements such as K, Rb, Th, U, also approved this opinion (Fig. D4). Based on the Sr/Y ratio against Y (Defant and Drummond, 1990), all volcanic samples are the adakite (Fig. A5). In the SiO2/MgO diagrams against K/Rb (Fig. B5) (Avdeiko and Bergal, 2015) and the Sr diagram against CaO+Na2O (Castillo, 2012), these rocks are located in the high-silicic adakite (HAS) (Fig. C5). On the other hand, the xenoliths that are present in the volcanic rocks originated from melts due to metasomatism of the mantel wedge by the influence of oceanic crust-derived fluids, which indicates the deeper sources than relative to the adakits (Tatsumi et al. 1986). The results of EPMA from the plagioclase show the end members of these crystals in between (An 47-26) (Fig. A6). The amphibole crystals analyses illustrated calcific compound (Fig. B6) and are within the range of ferro-hastingsite composition (Fig. C6). Also, amphiboles composition indicates the low-to-moderate ƒO2 pressure conditions that are associated with the mantel sources. Thermo-barometric calculations based on the chemical composition of plagioclase and alkali-feldspar crystals (Putritka, 2008), show the magma generates at a temperature between 895° C and 1080° C and a pressure of 10 to 12 kbar. This property illustrated crustal- mantel boundary at a depth of 30 to 36 km.

    Conclusion

    Based on petrography and geochemistry data, igneous rocks in the Hassan bad are divided into two group. The first group is associated with continental arc environments and is part of the intrusive body and xenoliths. This rocks crystalized under the 7.5 to 8.8 Kabr pressure. The second group, which includes the adakits of the region under study, is mainly silica-saturated rocks that originate from enrichment fluids from magma at a relatively high depth (30-36 km depp and 985 to 1080 °C) indicating metasomatic activity in the lower crust and upper mantle in the western part of the Yazd block.

    Keywords: Adakite, Tectonic setting, Dacite, Magma mixing Central Iran Zone, Yazd Block