فهرست مطالب

نشریه کواترنری ایران
پیاپی 5 (بهار 1395)

  • تاریخ انتشار: 1395/03/23
  • تعداد عناوین: 7
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  • مرتضی دلاوری، عطا شاکری صفحات 1-14
    کوه تفتان در جنوب شرق ایران یکی از مراکز آتشفشانی فعال قوس ماگمایی مکران در محدوده زمانی نئوژن- کواترنری است. تفتان از نظر تقسیم بندی ساختاری در زون جوش خورده سیستان قرار گرفته و قاعده آن مجموعه سنگ های افیولیتی، فلیش و سنگ های آتشفشانی (عمدتا کرتاسه تا ائوسن) است. مجموعه های فنوکریستی سنگ ها شامل پلاژیوکلاز + کلینوپیروکسن + هورنبلند ± ارتوپیروکسن ± بیوتیت است. شواهد عدم تعادل در کانی ها بویژه در پلاژیوکلاز و هورنبلند بر تغییرات شرایط فیزیکوشیمیایی تبلور همچون دما، فشار و ترکیب شیمیایی دلالت دارد. از نظر تنوع شیمیایی گدازه های ترم بازیک تا اسیدی حضور دارند؛ اگرچه عمده گدازه ها و مواد پیروکلاستیک تفتان ترکیب آندزیتی تا داسیتی دارند. اختصاصات شیمیایی ولکانیسم تفتان همچون بالابودن تمرکز Sr (> 645 ppm)، بالا بودن نسبت La/Yb (>14) و Sr/Y (> 40) سازگار با مذاب های شبه آداکیتی مرتبط با حواشی فعال قاره ای دارای پوسته ضخیم است. بر اساس شواهد شیمیایی و کانی شناسی دخالت فرایندهای مختلف گوشته ای و پوسته ای در ژنز مذاب تفتان قابل استنباط است. ابتدا ذوب گوه گوشته لیتوسفری نسبتا غنی زیرقاره ای که تحت تاثیر فرایندهای زون فرورانش قرار گرفته است. سپس تجمع مذاب های گوشته ای در عمق پوسته ضخیم قاره ای که توام با ذوب بخشی پوسته ای، آلایش و همگن شدن بوده است. در نهایت فرایندهای پوسته ای کم عمق تر شامل هضم پوسته ای و تحولات مرتبط با مخزن ماگمایی همچون تغییرات فیزیکوشیمیایی مذاب و تبلور تفریقی که باعث تحول بیشتر مذاب شده است.
    کلیدواژگان: سنگ های آتشفشانی، شبه آداکیتی، تفتان، مکران، جنوب شرق ایران
  • مهدی تلخابلو، سیدمحمود فاطمی عقدا، زمان مهرگان صفحات 15-25
    با توجه به اهمیت مناطق صنعتی در اجرای پروژه های مهندسی، لزوم بررسی ویژگی های ژئوتکنیکی در جلوگیری از رخدادهای ناخواسته امری اجتناب ناپذیر است. منطقه ویژه اقتصادی پتروشیمی بندر ماهشهر در استان خوزستان، شهرستان ماهشهر و در مجاورت بندر امام خمینی واقع شده که ازلحاظ تقسیم بندی رسوبی- ساختاری در زون زاگرس قرارگرفته است. در این پژوهش بر اساس نتایج آزمایش های شناسایی (هیدرومتری، آتربرگ، دانه بندی) خاک منطقه موردنظر طبقه بندی شده است. همچنین نتایج آزمایش حدود آتربرگ، حد روانی و شاخص پلاستیسیته خاک ها نیز تعیین گردیده و تغییرات مدول الاستیسیته بر اساس نوع خاک ها محاسبه گردیده است. در تعیین نوع ساختگاه بر اساس آزمایش های لرزه ای از پارامتر سرعت متوسط موج برشی استفاده شده است. همچنین ضمن بررسی ویژگی های ژئوتکنیکی نهشته های کواترنری منطقه به بررسی روابط بین پارامترهای مدول الاستیسیته حاصل از آزمایش های لرزه ای با عدد نفوذ استاندارد و نیز زاویه اصطکاک داخلی خاک به دست آمده از آزمایش سه محوری با عدد نفوذ استاندارد در محدوده بندر ماهشهر پرداخته شده است. مقایسه نتایج حاصله با روابط مربوط به دیگر محققین نشان دهنده این است که روابط حاصل از این تحقیق مقادیر کمتری برای زاویه اصطکاک داخلی نهشته های کواترنری بندر ماهشهر به دست می دهد که ناشی از وجود رس در رسوبات منطقه است.
    کلیدواژگان: آزمایش های لرزه ای، زون زاگرس، سرعت موج برشی، عدد نفوذ استاندارد، مدول الاستیسیته
  • طیبه اکبری، راضیه لک، رضا شهبازی، کتر مهرنوش قدیمی، اشرف اسدی، فریبا کرمی، پیتر ویگاند، کمال الدین علیزاده، دکنتر هرمان بهلینگ صفحات 27-40
    در این تحقیق با مطالعه مغزه رسوبی سه متری از دریاچه گهر واقع در زاگرس مرتفع، محیط رسوبی گذشته با استفاده از شاخص های ژئوشیمی و پالینولوژی مورد بررسی قرار گرفت و با تفسیر تغییرات پوشش گیاهی به دست آمده از نمودار گرده دریاچه گهر، تغییرات آب و هوایی گذشته بازسازی شد. نتایج نشان داد که منطقه مورد مطالعه به طور متناوب شرایط آب و هوایی سرد و مرطوب و خشک و گرم را در گذشته تجربه نموده است. از مهمترین دستاوردهای این تحقیق می توان به کاربرد شاخص ژئوشیمی نسبت وانادیوم به کروم (V/Cr) برای تفسیر شرایط آب و هوای گذشته اشاره نمود. وجود سه بیشینه در شاخص V/Cr و هماهنگی آن با درصد فراوانی گرده های گیاهان مانداب و درختی نظیر بلوط و علفی مانند خانواده چتریان می تواند شاهدی بر وجود سه دوره با افزایش بارش در منطقه مرتفع زاگرس باشد. به نظر می رسد که سن نسبی مغزه رسوبی بر اساس تطابق داده های بارش و دمای بازسازی شده حاصل از مدل کلان مقیاس طبیعیMCM و تغییرات فراوانی گرده درختان بلوط حدود هولوسن میانی تا زمان کنونی را پوشش دهد. تحلیل خوشه ایفراوانی گرده های گیاهی درختی و درختچه ای و علفی، چهار زون مجزا در طول مغزه رسوبی بصورت GHA ،GHB ،GHC و GHD را نشان داد که منطقه همزمان با دو زون GHA وGHB دارای پوشش گیاهی از نوع جنگلی- استپی با چیرگی بلوط بوده است.در مجموع تغییرات فراوانی گرده های بلوط و ریش بز در طول مغزه رسوبی ناشی از تغییرات شرایط رطوبتی و دمایی محیط می تواند باشد. همچنین شواهدی همانند گرده های درختی دست کاشت بهمراه گرده های گیاه بارهنگ می تواند نشانه دخالت انسان در منطقه مورد مطالعه باشد.
    کلیدواژگان: آب و هوای گذشته، ایران، تحلیل رسوب، شاخص وانادیوم به کروم، گرده شناسی
  • مهران مقصودی، سید محمد زمانزاده، اصغر نویدفر، ایوب محمدی، روح الله یوسفی زشک صفحات 41-51
    در سال های اخیر مطالعات ژئومورفولوژی با رویکرد زمین باستان شناسی با هدف بررسی زمینه های ظهور و فروپاشی تمدن ها و نیز عوامل موثر بر آنها جهت پیدا کرده است. در این پژوهش از دستگاه غربال برای دانه سنجی ذرات بالای 63 میکرون و برای ذرات زیر 63 میکرون از روش پیپت و از نرم افزار گرداستیت[1] برای تحلیل آماری رسوب ها بهره گرفته شد. در کنار آن از نتایج کانی شناسی رسی، کلسیمتری و رنگ نیز استفاده شد. بر اساس نتایج گرانولومتری رودخانه کرج در دو بازه زمانی تغییر بستر داده و رسوبات مربوط به دشت سیلابی برجای گذاشته است. ساکنین تپه مافین آباد با توجه به اینکه با فاصه بیشتری نسبت به کانال استقرار پیدا کرده بودند، به نظر می رسد متروکه شدن این سکونتگاه بصورت ناگهانی تحت سیلاب رودخانه نباشد. در مقابل ساکنین تپه میمنت آباد بدلیل استقرار در فاصله کم نسبت به رودخانه تحت تاثیر رژیم رودخانه قرار گرفته اند. بر اساس نتایج کانی شناسی رسی قبل از استقرار ساکنین شرایط آب و هوایی گرم با میزان آبشویی متوسط بر منطقه حاکمیت داشته است. بطور کلی بدلیل نقش ناهمواری های بین رودخانه شور و کرج در جابجایی عرضی بستر رودخانه کرج، ساکنین تپه میمنت بیشتر متاثر شده اند.
    1- Gradistat
    کلیدواژگان: تپه باستانی، تحلیل رسوب، تغییرات محیطی، رودخانه کرج
  • کورش شیرانی، محبوبه خوش باطن صفحات 53-65
    شناسایی و تاثیر زمین لغزش های فعال به عنوان یکی از جلوه های فرسایش در تهدید مناطق مسکونی، مزارع و تخریب جاده های ارتباطی از اهمیت ویژه ای برخوردار می باشد. بدین منظور فن تداخل سنجی تفاضلی راداری (DInSAR) با برخوردار بودن از پوشش زمینی وسیع و نیز قدرت تفکیک زمانی و مکانی زیاد، به عنوان یکی از دقیق ترین و کم هزینه ترین فنون سنجش از دور، برای شناسایی و نمایش جابجایی های به وجود آمده در سطح زمین ارائه شده است. هدف از انجام این پژوهش شناسایی مقدماتی محدوده لغزشی نقل و برآورد میزان فعالیت ناشی از این توده لغزشی می باشد. بنابراین در این پژوهش میزان جابجایی سطحی ناشی از زمین لغزش نقل واقع در 70 کیلومتری جنوب شهر حنا در شهرستان سمیرم، با استفاده از تکنیک تداخل سنجی تفاضلی راداری محاسبه شد. بدین منظور، تعداد 10 تصویر راداری از سنجنده ASAR ماهواره ENVISAT انتخاب و به روش DInSAR پردازش گردید. در نتیجه پردازش های اولیه، از بین زوج های تصویری تشکیل شده، مجموعا تعداد 9 زوج تداخل سنج در سال های 2004، 2010 و 2011 میلادی مناسب پردازش های بعدی شناخته شد. بر اساس نتایج پردازش تصاویر راداری، بیشترین میزان جابجایی صورت گرفته در سطح توده لغزشی نقل مربوط به زوج تصویری سوم آگوست 2011 و 31 دسامبر 2011 با بازه زمانی 150 روزه، معادل 8 سانتی متر برآورد گردید. نتایج این پژوهش حاکی از فعال بودن توده لغزشی نقل در طول مدت زمان اخذ تصاویر راداری می باشد. هم چنین نتایج این پژوهش نشان داد، داده های راداری و روش پردازش تداخل سنجی تفاضلی از پتانسیل خوبی برای شناسایی، پایش زمین لغزش ها و محاسبه میزان جابجایی آن ها برخوردار می باشد.
    کلیدواژگان: تصاویر راداری، روش DInSAR، زمین لغزش نقل، سنجنده ASAR، ماهواره ENVISAT
  • غلامعباس آروان، فریبرز قریب، معصومه خلج معصومی صفحات 67-78
    استفاده از داده های سنجش از دور، از جمله راهکارهای موثر در پایش و تجزیه و تحلیل مخاطرات زمین ساختی و از جمله زمین لغزش می باشد. در ایران پایش فرایندهای زمین ساختی از قبیل فرونشست و زمین لغزش غالبا با تصاویر راداری انجام می شود. در این مطالعه، برای اولین بار در ایران، از تصاویر VNIR سنجنده ASTER به منظور تشخیص و آشکارسازی محدوده های زمین لغزش منطقه پشت بادام شهرستان درود استفاده شد. تصاویر مربوط به قبل و بعد از زمین لغزش با استفاده از افزونه COSI-Corr که در نرم افزار ENVI توسعه داده شده است، پردازش شدند. پروسه پیش پردازش تصاویر مربوطه شامل ، رجیستر کردن ، عملیات انطباق و تصحیح سه بعدی انجام شد. به منظور بررسی تغییرات در دو بازه زمانی، با استفاده از افزونه مذکور، عمل انطباق بین دو تصویر انجام گرفت و با انتخاب گزینه نمونه برداری مجدد سینوسی با اندازه زاویه 25 درجه، موتور انطباق فرکانسی، اندازه پنجره 32، اندازه گام 4 و آستانه 90 ، این انطباق انجام شد. خروجی آن به صورت، جابجایی در راستای خاور- باختر، شمالی- جنوبی و نسبت سیگنال به نویز است که ترکیب آنها، تصویر مناطقی است که در بازه زمانی 2001 تا 2008 دچار تغییر شکل سطحی شده، و جابجایی زمین لغزش ها به صورت بخش های انطباق نیافته (پیکسلی) در زمینه ای از تصویر انطباق یافته (بدون پیکسل)، آشکارسازی شده اند.
    کلیدواژگان: زمین لغزش، تصاویر VNIR سنجنده ASTER، افزونه COSI، Corr
  • سعید رضاییان لنگرودی، راضیه لک، سعید مهدلو ترکمانی صفحات 79-91
    مطالعه رسوبات و شورابه پلایا از جنبه های اقتصادی با توجه به وجود ذخایر تبخیری و از نظر اثرات آن بر اکولوژی و محیط زیست و آبهای منطقه حائز اهمیت خاص می باشد. سطح آب دریاچه حوض سلطان با گستره آبگیر حدود 195 کیلومترمربع متاثر از حجم آبهای وارده به آن اعم از آبهای زیرزمینی، رودهای فصلی و بارندگی می باشد. به منظور مطالعه هیدروژئوشیمی شورابه، در این پلایا، تعداد 25 نمونه شورابه از بخش های مختلف دریاچه برداشت شد. پارامترهای فیزیکوشیمیایی در محل اندازه گیری و آنالیز شیمیایی شورابه ها انجام شد. همچنین، برای مطالعه رسوب شناسی، کانی شناسی و تعیین شوری، از محل برداشت شورابه، 100 نمونه رسوب، بوسیله اوگر دستی تا عمق بیشینه 2 متر برداشته شد. با انجام آزمایشات ژئوشیمیایی، ترکیب یونی شورابه ها و با آنالیز کانی شناسی رسوبات، نوع کانی های موجود در رسوبات مشخص گردید. ترتیب فراوانی کاتیون های موجود در شورابه به ترتیب شامل سدیم، منیزیم، کلسیم و پتاسیم و آنیونها شامل کلر، سولفات و بیکربنات می باشد. کانی های تبخیری موجود در رسوبات را کلسیت، ژیپس، هالیت، کارنالیت، هگزاهیدریت، تناردیت و باسانیت تشکیل می دهند. بررسی هیدروژئوشیمی آبهای ورودی بیانگر این است که نسبت مولی یون ها از نوع HCO3 < Ca + Mg بوده و در نمودار تکاملی ژئوشیمیایی شورابه ها، مسیر ژئوشیمیایی (II) را طی نموده و پس از جدایش کانی های مختلف، تیپ شورابه دریاچه Na-Ca-(Mg)-Cl می گردد که قابل مقایسه با دریاچه مهارلو، دریاچه نمک بریستول و دریاچه بزرگ نمک آمریکا است.
    کلیدواژگان: هیدروژئوشیمی، تکامل شورابه، کانی های تبخیری، پلایا، دریاچه حوض سلطان
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  • Pages 1-14
    Taftan volcano, located in the southeastern Iran, is one of the active volcanic centers of the Makran magmatic arc during Neogene-Quaternary. The Makran arc is an east-west trending Neogene- Quaternary volcanic edifice (Pang et al., 2014) lying in the north of the Makran accretionary prism. Three major volcanic centers in the north of Makran from west to east are the Bazman, Taftan and Koh-i-Sultan volcanoes, respectively, form a ca. 300 km long magmatic arc. Regarding structural zones, the Taftan volcano locates in Sistan suture zone and its basement rocks include ophiolite, flysch and volcanic rocks (mostly Upper Cretaceous to Eocene). In this paper, we present petrographic and whole rock geochemical signatures of the Taftan volcanic rocks with the aims of better understanding of petrogenesis and tectonic implications of magmatism in the Makran arc.
    Materials And Methods
    The rock samples were crushed into centimeter-sized chips. After crushing, they handpicked in order to eliminate altered parts and remove any visible impurities. The samples were powdered by Tungsten Carbide in the sample preparation laboratory of the Iranian Mineral Processing Research Center (IMPRC). Whole-rock major and trace elements were obtained by Inductively Coupled Plasma-Emission Spectrometry (ICP-ES) using a Spectro Ciros Vision instrument and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) on Perkin Elmer Elan 6000 instruments at Acme Labs. The major elements and also Cr and Ba were determined by ICP-ES and the remaining trace elements by ICP-MS. Powdered rock samples were mixed with LiBO2/Li2B4O7 flux and fused in crucibles in a furnace. The quenched bead was dissolved in ACS grade nitric acid. Loss-on-ignition (LOI) was determined by heating a sample split to 1000°C.
    Result and
    Discussion
    In the Taftan volcanics, phenocrystic assemblage consists of plagioclase clinopyroxene hornblende ± orthopyroxene ± biotite. Disequilibrium micro-textures of minerals, including sieve-texture, resorption surfaces, fine- sieve zones and regrowth bands of plagioclase and sieve- texture and opacity rim of hornblende suggest changes in physico-chemical conditions of the system (T, P, PH2O, melt chemistry). Geochemically, Taftan volcanics comprise basic to acidic compositions, although dominated by intermediate andesitic to dacitic lava and pyroclastics. Based on K2O-SiO2 diagram, the samples plot within medium- to high- K series. Except two samples showing low Mg# [100*Mg/(Mgᗭ)] (~17 and 24), the others are characterized by approximately high Mg# (> 50). In Harker variation diagrams, despite scatters of some data points, a continuous and nearly linear trends can be observed suggesting genetic relationships among the samples and melt evolutionary trend. In these diagrams some elements including MgO, TiO2, CaO, FeOT, Mg# and Cr represent negative correlation with SiO2 enhancement. These variations are consistent with fractional crystallization of ferromagnesian phases (clinopyroxene hornblende), plagioclase and Fe- Ti oxides. The volcanics display chondrite-normalized fractionated rare earth element (REE) patterns with (La/Yb)N, (Sm/Yb)N, (La/Sm)N ratios in the ranges of 9.9- 19.7, 2.4- 3.7, 3.6- 5.8, respectively. Primitive-mantle normalized multi-element diagrams are characterized by light ion lithophile element (LILE) such as Rb, K and Ba enrichment and high field strength element (HFSE) such as Ta and Nb depletion which could be interpreted as subduction zone magmatic signatures. Furthermore, geochemical characteristics of the Taftan volcanics are consistent with adakitic signatures. These include high Sr (> 645 ppm), Sr/Y (> 40) and La/Yb (>40). High Sr/Y and La/Yb ratios as well as low Y content of “adakites” has been interpreted as melt equilibration with amphibole garnet and lack of plagioclase in melt source. This mineralogy corresponds to high pressure (>10 kb) condition. Scenarios that match these requirements for adakite generation include partial melting of thickened arc or thickened post-collisional continental crust (e.g. Chung et al., 2003; Petford and Atherton, 1996; Topuz et al., 2011), partial melting of subducted slab (Defant and Drummond, 1990; Drummond and Defant, 1990), low degree partial melting of metasomatized mantle (Gao et al., 2007) or high-pressure fractional crystallization involving garnet (e.g. Macpherson et al., 2006). In the case of Taftan volcano, partial melting of subducted slab seems to be impossible because both the subduction zone and subducted slab are too old (pre- Cretaceous). Moreover, geochemistry of Taftan volcanics including trace element and isotopic characteristics are different from slab- derived adakites. Therefore, it is more realistic to consider Taftan volcanics as “adakite- like” melts generated in continental arc setting with thickened crust. Consistently, geophysical studies show thick continental crust (> 50 km) beneath Taftan volcano. In arc settings, during interaction of mantle melts with deep lower crust and as a result of complex magmatic processes such as melting-assimilation-storage-homogenization (MASH) and assimilation-fractional-crystallization (AFC), “adakitic melts” could be produced (Richards and Kerrich, 2007).
    Conclusion
    Bringing together all of petrographic and chemical evidence, here we propose following successive processes for the genesis of the Taftan volcanics:1. Partial melting of sub-continental lithospheric mantle wedge. This mantle source is reasonably more enriched than sub-oceanic depleted mantle. In addition, slab-derived materials including fluids and/or sediment melts would increase LILE content and enhancement of LILE/HFSE ratio in melt source.
    2. Interaction of mantle melts with deep continental crust and assimilation processes. Melt equilibration with high pressure crustal lithology (amphibole ± garnet – plagioclase) would reinforce the adakitic signature of the melt.
    3. Melt ascent and mid to upper-crustal processes including storage, refilling of magma chamber, magma mixing and fractional crystallization of plagioclase and ferromagnesian minerals.
    Keywords: adakitic, Makran, southeastern Iran, Tatan, volcanic rocks
  • Pages 15-25
    Regarding to the importance of the industrial region in engineering project execution, assessment of Geotechnical characteristics is essential to prevent undesired problems. Because of the uprising number of oil and gas industry structures, the Mahshahar Special Industrial Region is very important. So, the Geotechnical investigation in this region is necessary. Executing these investigations guaranties the implementation of any construction projects and prevents any unwanted detrimental events.
    The study area is located in Mahshahar Port near in southwest of Iran. This port is one of the important industrial ports of Iran. Mahshahr port is located in area between 49º04´-49º06´E and 30º25´-30º31´N.
    Materials And Methods
    Based on Sedimentary-structural division of Iran, this area is located in Zagros zone. This zone is limited to Sanandaj-Sirjan zone from the northeast, to the Makran Zone from the southeast, to the highlands of northeastern Iraq and southeast Turkey from the northwest and to Arabian Plate from the south and southwest. Based on geological data, the properties of Zagros zone varies in different areas and this zone is divided to some subzones that Abadan Subzone, in which the study area has located. This subzone is located in the southwestern part of Zagros.
    To investigate the Geotechnical characteristics of Quaternary sediments in the study area, eight boreholes data, performed by continuous coring method, with depth 11 to 25m were studied. The seismic downhole test and Standard Penetration Test (SPT) were done in all boreholes. The laboratory tests are included the index tests on soil samples (particle size distribution, Hydrometer, Atterberg test), consolidation, direct shear, uniaxial and triaxial tests. Strata were classified using index tests.
    To reveal the stratification of site, the Seismic Downhole test was performed in all boreholes, in which the source was in surface (blow on a plate placed in 2-3m distance from borehole) and the P-wave was measured in geophones installed in different depth of boreholes (1m intervals), so whole depths of borehole were investigated. To measure the S-waves, the blows were stroked in a horizontal direction on timber to generate S-waves. Finally, the relationship between elasticity modulus in downhole and SPT tests and also the relationship between friction angles in triaxial tests with NSPT values were assessed.
    Results And Discussion
    The plasticity of soil has investigated using Atterberg test results, performed applying standard ASTM D4318 on all samples. The results show that the Liquid Limit and plasticity index vary between 25-40% and 10-20%, respectively, showing the low to medium plastic characteristic of soil.
    The elastic modulus and also the relationship between the elastic modulus on downhole and NSPT tests were investigated in the study area. Based on the results, the elastic modulus of quaternary sediments of Mahshahar varies between 100-350 Mpa. In general the relative density and the seismic wave velocity of soil strata were increased with depth in this area.
    Also, the fitting curve of NSPT values and elastic modulus in downhole tests show the R2=0.80, in which the NSPT values were corrected to N60.
    Soil classification of the site, regarding the average S-wave velocity of soil up to 30m depth, was performed based on the Iranian Building Code (IBC) 2800. The recorded mean S-wave velocity in all boreholes is less than 375m/Sec so the ground type III (based on IBC 2800) is recommended to be taken into account in the design.
    Estimating of friction angle of soils, some researchers like Hunt (1984) have been published some reference tables. In this study, to have a simple equation to estimate the friction angle of quaternary sediments, the results of NSPT and consolidated undrained triaxial test (CU) have been used. The result shows the R2=0.85 for fitting curve. Regarding the results, it can be concluded that because of overestimating of friction angles, the presented tables by Hunt (1984) is not applicable to Mahshahr quaternary sediments. It seems that the main reason comes from remarkable existence Clay soils in the sediments.
    Conclusion
    In this research, based on data from boreholes, the general characteristics of quaternary sediments were revealed and also the strata were classified based on the Unified System as ML, CL and SM. To determine the elastic modulus of soil, the results of the seismic downhole test were used. Based on these results the elasticity of soil varies from 100 to 350MPa. The relationship between mentioned above elasticity and NSPT was assessed and an equation was determined. In general the relative density and seismic velocity increase with depth in this site. S-wave velocity in Seismic downhole test results were used to determine the site or ground type. This parameter was less than 375 m/Sec in all boreholes. So, the ground type III (IBC2800) is recommended for the whole site. Finally, an equation was concluded for relationship between NSPT and UC triaxial friction angle which can be more useful than other published relationships (like those by Hatanaka & Uchida) and Hunt’s tables, because these published ones overestimate the friction angle; the main reason of this case is the existence of the great amount of Clay in soil in this site.
    Keywords: Atterberg limits, elastic modulus, Mahshahr port, NSPT, quaternary sediments, seismic tests
  • Pages 27-40
    Dynamic change and great endangered oak forests have characterized the Zagros Mountain as an attractive site to study. There are some palynological and geochemical studies in the north and northwest of Iran where is located in a moderate elevation. The motivation for this study is to reconstruct the past environment of high part of Zagros Mountain in order to find the climate change.
    Materials And Methods
    This research is a sedimentological and palynological study of a three meter’s sediment core from Lake Gahar located in high Zagros Mountain in Lorestan Province. In order to study the paleoclimatic condition in this region a multi-proxy approach consist of geochemistry and palynology has done. We used Auger corer device for sampling two cores GH1& GH2 in vicinity of each other from 49ₒ16'23"E, 33ₒ18'00"N for palynology and sedimentology separately in summer 2014. The sub-samples from GH2 used by 20 cm interval distance for geochemical process and analyzed by inductively coupled plasma emission spectroscopy (ICP) method and the indices have analyzed. In this study 30 samples of GH1 were used with interval distance equal 10 cm for palynology. The pollen extraction followed the chemical treatment methods based on Moor et al. (1991). The chemical treatment carried out at department of Palynology and Climate Dynamics situated at Georg-August-University of G ttingen, Albrecht-von-Haller-Institute for Plant Sciences (Göttingen, Germany). Pollen determinations were performed by using the institute pollen reference slides collection and pollen atlases of Reille (1992, 1995, 1998), Beug (2004) and pollen morphological descriptions by Van Zeist and Bottema (1977). Then, during microscopic analysis, we identified and counted the pollen grains by magnification equal 400X by Zeiss. The pollen diagram was drawn by the aide of Tilia (version 1.7.16) software. The radiocarbon dating method was used for samples and the data of annual precipitation and temperature reconstructed based on MCM model during 8000 yrs. BP.
    Results And Discussion
    According to the pollen percentage diagram of Lake Gahar (Figs. 6 to 8), four main local pollen assemblage zones consisting of two older zones GHA (depth of 300 to 290 cm), GHB (290 to 110 cm depth) and two earlier zones GHC (depth 110 to 50 cm) and GHD (depth 50 to 0 cm) were identified. Then geochemical analysis was performed for the second core in Geological Survey of Iran. Three major ratios consist of V/Cr, V/Mo, and Co/Ni calculated based on ICP results. The V/Cr ratio considered as an indicator for the interpretation of past sedimentary environment of study region and also climate change and supported by pollen analysis results. The maximum amounts of V/Cr ratio were found in three major depths of 40-60,120-140, and 200-220 cm. Cluster analysis for the pollen frequency indicated four distinct zones; from base to the top are respectively GHA, GHB, GHC and GHD. This zonation was induced based on arboreal and/ or none arboreal pollen.
    Conclusions
    The results showed that the two zones GHA and GHB coincide with expansion of forest-steppe vegetation of oak as the dominant species. It seems that the positive fluctuation of temperature caused more frequency of arboreal pollen.
    In this research the geochemical results are more significant. The V/Cr index demonstrated three significant pick throughout the core which is in conjunction with abundance of aquatic plants (Sparganium and Cyperaceae) and also trees and herbs such as oak and grass pollens. It seems that the disappearing of arboreal pollen, especially Quercus at a depth of 50 and 60 cm at the boundary between GHC and GHD is associated with unfavorable temperature conditions for plant growth however V/Cr ratio is in highest amount during this period. In addition the minimum amount of V/Cr ratio can be as a sign of warm and dry period with decrement of annual precipitation. It is also concluded that the maximum V/Cr ratio can be an indicator of increasing annual precipitation during three major time phases in high Zagros Mountains.
    Keywords: Iran, Paleoclimate, Palynology, Sedimentology, V, Cr ratio
  • Pages 41-51
    Reconstruction of the landscape response to climate change in the long-term geological scattered data due to the lack or shortage of sediment and age sediment controls is very dificult. Grain size analysis can be used to identify sediments in environments and different facies, that this in turn gives us some information about sedimentation processes and flowing type. Recognizing the many economic and environmental aspects of early humans due to their dependence on natural factors is not possible without knowing the environmental elements.in this paper we try to study Karaj and Shadchay regime changes and its effects on Meymanatabad and Mafinabad settlements.
    Methodology
    Due to analyzing and reconstruction of depositional conditions in both Karaj and Shadchay rivers (a branch that is connected to the Karaj River), Sampling was attempted. Considering that the aim of the study was to examine two ancient hills Meymantabad and Mafynabad. Therefore, the sampling location after repeated field visits to the region, a situation that was chosen to be the width of the cluster. We considered in sampling of river terraces the Sediments resize and change colors. Shadchay River terraces in height of 4:40 m 11cases and from Karaj River terraces in height 7 m 12 cases Samples were taken. Firstly, all samples were analyzed by using a screening device, the second step to obtain deposition below 63 microns in size, moving the pipette method was used.
    Results And Discussion
    Based on granolomtry results for samples of Tow Rivers, Karaj River in two cases were changed and has left the floodplain sediments. In most cases the particle distribution between classes is above 1000 and below 63 microns. The mean average of particle is 410.76 microns. Depositional environment is constantly changing from calm to energetic; On the one hand it can be because of increase and decrease the power of the river and on the other because of the bed movement. Against the distribution of Shadchay sediments is mostly above 63 microns and rivers has high discharge by then. The average of particle diameter is between 1001.12 microns. campared to Karaj River bed changes not occurred, and are entirely river sediments. Overall, all samples were evaluated for high-energy depositional environment.
    •Calcymetry
    In general, a process diagram for Karaj River is approximately constant. Only layer of 3:40 to 5:60 have the greatest amount of calcium carbonate. According to survey data, we see in this layer, there is only clay and a sand particle was not found in this layer. In a depth that mixtures of clay and sand particles are deposited (in flooding cases) the amount of calcium carbonate is more. Based on Klsymtry data ersults for the Shadchay River, calcium carbonate has not favorable conditions to be deposited, but an increasing or decreasing trend from low to high exist, in other words, carbon dioxide pressure was high, in general the environment was acidic. In Meymanatabad Hill the most of calcium carbonate belongs to latest ancient layer.
    •Color
    According to Clay Mineralogy sample results that indicate wetter conditions, and due to the location of the study area and the current situation to the first theory, based on warm and humid conditions it is appearance that brown and red precipitates were exist. According to the latest Mineralogy of clay that is related to LN108 is belonging to chlorite samples so that this mineral belongs to moderate condition and mild leaching conditions. In fact in temperate conditions and mild leaching rate and location of the inner part of the premountain is somehow confirming the theory of hot and humid condition in the South West of Tehran plane in the Silk period.
    Conclusion
    Based on granolumetry results of samples from two rivers, Karaj river bed changed in two cases and has left sediments of floodplain type. In most cases the particle distribution between classes is above 1000 and below 63 microns. The average particle is between 410.76 microns. Depositional environment is constantly changing from calm to energetic; On the one hand it can be because of increase and decrease the power of the river and on the other because of the bed movement. Considering that the main channel of the river in the mafinabad cluster has not much changed so Cluster residents have long been living in margins of rivers. Seems to suddenly abandoned these settlements have not been effected by devastating floods because residents were deployed with greater distance. Against the distribution of Shadchay sediments is mostly above 63 microns and rivers has high discharge.
    Keywords: Ancient cluster, Environmental changes, Sediment analysis, Karaj River
  • Pages 53-65
    Landslide is defined as the downward movement of rock masses, debris and earth materials. This condition occurs where shear stress of materials exceeds its shear strength and is commonly known as slope failure. In other words, landslides are surface processes occuring in mountainous areas to various scales. Based on the kind and scale, landslides have significant effects on the environment. Identification and the effect of active landslides as one of the aspects of erosion threatening residential areas, farmlands, dams and destruction of roads have great significance. Launching satellites with Synthetic Aperture Radar (SAR) sensors onboard, is purposely built for differential interferometry (DInSAR) applications opening new opportunities for mapping and monitoring slow ground deformations and even high speed landslides. For this purpose, the technique of differential interferometry synthetic aperture radar containing extensive and constant earth coverage with great time and place resolution as one of the most accurate and least expansive remote sensing techniques has been presented to identify and illustrate displacement on the earth surface. This research is aimed to identify active domain of Noghol landslide and to estimate its activities done due to the sliding mass in the area.
    Materials And Methods
    Padena area in Semirom is situated in the southern part of Esfahan province. This area due to its special geological, climatic and geomorphological characteristics provides favorable condition for occurrences of various mass movements. The Noghol landslide is also situated in Padena- Semirom. The study area is located at about 300 km south of Esfahan in 51° 39' 10" E and 30° 52' 39" N.
    Thus, the surface displacement done by landslide in Hanna city, 70 km south of Semirom by using differential interferometry synthetic aperture radar (DInSAR) technique has been calculated. For this purpose 10 RADAR images of ASAR sensor from ENVISAT satellite have been chosen and then processed with DInSAR method.
    Results And Discussion
    Consequently, the preliminary processing consist of paired images totally 9 interferometer images have been identified to be processed in 2004, 2010 and 2011 to be considered as a base to provide landslide displacement maps. Based on the results obtained from the ASAR RADAR images processed in the current research, the maximum displacement of Noghol landslide related to pairs images on 3 August 2011 and 31 December 2011 with a period of 150 days has been estimated 8 cm. Also, the average displacement rate among the interferogram built during the years 2004, 2010 and 2011 due to this landslide has been estimated about 2 cm per month. Within the research, in addition to monitor and figure out the amount of displacement due to sliding mass during the obtaining RADAR images, the results taken from analyzing images during different time periods, indicate the landslide displacement. Also, increasing the domain of the landslide gradually and with simultaneous increasing in time period between pairs interferometry during the image dates have been used so that the least displacement done on the sliding mass was related to pair images of 20 May 2010 and 24 June 2010 with a period of 35 days and about 3 cm. So, we can say that the domain of the slide activity is bound from north and north east of sliding mass toward center and south and ultimately to the south west side of the sliding mass along the Marbor river. With expanding the active domain of landslide, the amount displacement of landslide has been grown up. The above issue can be an indication the activity of Noghol landslide during obtaining the RADAR images within the study in various steps. It can also be mentioned that the results obtaining from the differential interferometry of ASAR RADAR images with respect to activity domain of the landslide with the greatest displacement within the Noghol sliding mass have been in accord with the field observations. So, based on the above conclusions and with respect to the surface of rupture and slip materials resulted from field observations and movement patterns and monitoring of landslide obtained from the analyses of phase to displacement maps of landslide and also with respect to the landslide activities during the various steps so far, it can be stated the Noghol landslide would be a kind of complex rotational slide (slump). According to the above conclusions, the total movement orientation of the landslide would be toward the river from the east to the west.
    Conclusion
    The research results implies the activity of Noghol landslide during obtaining the RADAR images in the area. So that this landslide occupies an area of about 11 hectares. Due to the occurrence of landslide in rural areas and farmlands especially apple orchards have affected and heavy damages have been incurred and a large amount of productive farming soil destroyed. Since the landslide is adjacent with the hydrological network of the area, it is considered as the main source of sedimentation. The results of the research indicates that the radar images as well as differential interferometry contain significant potential to identify slope unstable areas, monitoring landslides and also estimating the amount of displacement. Meanwhile, RADAR images (ASAR) contain superior capability for providing displacement maps of differential interferometry with more details about the area landslide because of containing shorter wavelength (c band).
    Keywords: ASAR sensor, DInSAR method, ENVISAT satellite, Noghol landslide, radar images
  • Pages 67-78
    One of the natural events which takes place due to environmental conditions of each place, caused by different reasons, is mass movement of components of earth`s surface, and its occurrence leading to many environmental and economic consequences. Compared with other natural disasters, landslides are more controllable, hence, monitoring and detection of their variations and displacements has an important role in development planning. Remote sensing as a modern approach for investigating and monitoring natural disasters in extensive dimensions and short periods is a big progress in controlling natural disasters and decreasing their environmental effects.
    Monitoring of unstable masses to evaluating displacement value of active landslides in different time periods is one of the important issues in studying sliding masses. It can be considered as the most important issue in constructing and retrofitting engineering projects. In this study, optical satellite images of ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) sensor have been used as a new instrument to detecting movements of sliding masses rather than radar images. Poshte-Ghaleh Sliding zone in Doroud is caused by activity of Doroud fault, therefore, considering the large extent of sliding zone, low-cost and short duration of this method, its behavioral monitoring using optical satellite images instead of other methods (such as earth`s surveying and radar interferometry) increases importance of this research. Thus, we can use this present technology, so survey the region in a shorter duration.
    Material and
    Method
    In present study we use the newly developed COSI-Corr (Co-Registration of Optically Sensed Images and Correlation) extension to assessing ground deformation. It is essential to check this newly developed method for its wider use in earth science’s related problems like detection of changes (caused due to different dynamic processes of the earth). The study of geological hazards using satellite data is a very practical and valuable method. Investigation the radar data is common, but in this method which is applied for the first time in Iran, the optical data of satellite sensors are used to detect the landslide. At this point a newly developed technique of sub-pixel correlation of optical images (from push broom sensors) before and after the event can definitely help for the measurement of land surface deformation. For this purpose, the level- 1A satellite images produced by the ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) satellite sensor before and after the occurrence of landslide at Posh-Ghaleh were applied. The imagery level 1A is required for carrying out sub-pixel correlationby COSI-Corr. Radiance of ASTER imagery is automatically done when ASTER imagery is opened with ENVI versions 4.2 and higher. The ASTER.hdf file format is adopted as input for COSI-Corr. ASTER band VNIR 3N (nadir viewing) is used (as recommended) for the estimation of ground deformation, though, any other band (VNIR, SWIR, TIR) can also be used. The ancillary file contains the positions, attitudes, and look directions of the satellite while acquiring the image, along with number of lines and columns, nominal ground resolution, and solar azimuth and elevation. This file was prepared from the given ASTER .hdf file for nadir looking VNIR (3N) band using COSI-Corr software. Therefore, the images were correlated using the COSI-Corr extension applied on ENVI 4/8 version and sub-pixel correlation technique.
    Result and
    Discussion
    The sub-pixel correlation of pre- and post-landslide ASTER images provided an image of displacements caused by landslide. Sub-Pixel correlation of two orthorectified pre - and post-landslide optical images affords horizontal ground displacements through an iterative, unbiased process of estimating phase plane in the Fourier domain. At first, the pre-processing of image data including the radiance correction was performed automatically using COSI-Corr extension. Then, co-registration and orthorectification of ASTER images before and after the landslide were performed. The image was prepared in orthorectification with optimization of ground control points to preserve the pixel value in resampling method. In order to investigating the displacement during the two time intervals, the two images were correlated by COSI-Corr, which was selected as an optimized method. Two correlation methods are available for sub-pixel correlation of optical imagery which are frequency and statistical. Frequency method works in Fourier domain while statistical is based on statistical approaches. For comparison of the performance of correlation methods in measuring ground displacement. The correlation was performed using sinc25 resampling, frequency correlation engines, and window size 32 with a step size 4 and threshold90. The output image include displacement in direction east-west, north-south and Signal to Noise Ratio that components, the image of regions as an output having the surface deformation between 2001 and 2008 .Finally, the displacement of landslide was detected as the decorrelation patches (pixel- based) in texture the correlated image (no pixel).
    Conclusion
    Sub-pixel correlation of optical images can give valuable information for terrain change monitoring and estimating ground deformation. The assessment of a newly established sub-pixel correlation technique (COSI-Corr) can give a better understanding of the process characterizing the change. The sub-pixel correlation of optical images technique measures horizontal displacement component in E-W and N-S direction, and its results are more precise at shorter wavelength, whereas the InSAR provide results in measuring the vertical component of the displacement. Both techniques can complement the information to have a complete characterization of landslide. The sub-pixel correlation of pre- and post-landslide ASTER images provided an image of displacements caused by landslide.
    Keywords: COSI, Corr, correlation, Ground Control Point, optimization
  • Pages 79-91
    Introduction
    The study of sediments and brine of playa, from economic aspects, has special significance with respect on evaporate deposits and its effect on ecology, environment and regional water. Examinations of sedimentologic and mineralogic characteristics of the closed-basin cores due to the very high susceptibility to precipitation and evaporation balance are beneficial for determination and evolution of late Quaternary sedimentary specification. Hoz-e-Soltan Lake with a 195km2 catchment area, 25-50 cm depth, located at 35 km of north of Qom, in Central Part of Iran. It is sited between 34º56´ and 35º31´ north and 50º53´ and 51º20´ east at western-north of Hoz-e-Masileh. It is surrounded by Ali-Abad and Kushk-e-Nosrat mountains in north and northeast, Manzarieh and Chahar mountains in west and Mohammad-Abad and Badamcheh mountains in south and southeast. This Lake is influenced by the volume of input water including groundwater, intermittent streams and precipitation.
    Materials And Methods
    In order to study hydrogeochemistry of brine in the playa, 25 samples of brine were taken from different parts of the Lake. Physic-chemical parameters were measured in the site and chemical analysis of brines was performed. Also, to study sedimentology and mineralogy and to determine salinity, 100 sediment samples were obtained up to 2 m depth by manual auger. By implementing geochemical experiments, ionic compositions of brines were recognized and by mineralogical analysis of sediments, types of minerals which occurred in deposits were determined. Samples were collected in good quality polyethylene bottles of one-liter capacity. Each sample was divided into two separate samples before being sent to the laboratory to enhance the accuracy of the results.At the time of sampling, the chemical and physical parameters of the water samples including pH, EC, TH and TDS were measured using a Hach SensIons system model 156 multi-parameter following a standard operating procedure explained by California State Water Resources Control Board (2002). In order to determination of cations and anions amounts in brine, different methods were used, such as flame photometry for sodium and potassium, atomic absorption for calcium and magnesium, silver nitrate for chlor, alkalinity polls for bicarbonate, and measurement turbidity methods for sulfate. The analytical precision for the measured major ions was within ±5%. All of analyses were done in the laboratory of Geological Survey of Iran.
    Results And Discussion
    The average acidity of brine of the sediment area equals to 8 which indicates alkaline nature of brine. The EC values of the samples vary from 1250 to 14280. Inlet (input) waters of Hoz-e-Soltan Lake are poor in bicarbonate ion and its mole ratio is ((HCO3
    Conclusion
    Hydrochemical studies of inlet waters indicate that mole ratio of ions is HCO3
    Keywords: brine evolution, evaporate minerals, Hoz, e, Soltan Lake, hydrogeochemistry, Playa