فهرست مطالب

  • پیاپی 16 (زمستان 1397)
  • تاریخ انتشار: 1397/12/10
  • تعداد عناوین: 7
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  • مریم بیاتی *، فریبا کرمی، بهروز ساری صفحات 361-375

    دشت تبریز، که بخش مهمی از آذربایجان شرقی است، در طول تاریخ تغییرات اقلیمی مهمی را پشت سر گذاشته و پس روی و پیش روی توده های آبی مهم، مانند دریاچه ارومیه، بر سطح آن رخ داده است. شواهدی از این تغییرات اقلیمی و پس روی و پیش روی توده های آبی در سطوح دشت بر جای مانده است که می توان بخشی از این شواهد را در رسوبات دشت تبریز پیگیری کرد. در این مقاله، برای پاسخ به سوالات طرح شده در زمینه نوع و نحوه تغییرات گذشته، سعی شده است در محدوده های مشخص، که داده هایی از ویژگی های فیزیکی و شیمیایی سازندها قابل دسترس بوده اند و بر اساس این داده ها لایه ها قابل تفسیرند و از نظر ژئوکرونولوژی اهمیت زیادی دارند، چینه ها و لایه ها بررسی شوند. همچنین در مواردی برخی ویژگی های لایه ها مورد آزمایش خاک قرار گرفتند. در این تحقیق، از داده های سازمان قطار شهری بهره گیری شد و از متخصصان مربوطه اطلاعات لازم به دست آمد. همچنین سعی شد با حضور در محدوده هایی که حفاری ها و گودبرداری ها صورت گرفته همه لایه ها از نزدیک مورد بازدید میدانی قرار گیرند و در موارد لازم اندازه گیری ها در محل صورت گیرد. برای رسیدن به هدف، از نتایج آزمایش های SPT، روش های پالئوپدولوژی، و نتایج آزمایش دانه بندی و ph استفاده شد. نتایج بررسی ها نشان داد در بخش های مهمی از دشت تبریز عمق 2/5 تا 10 متری عموما از لایه های متشکل از رس سیلت دار سفت تا بسیار سفت همراه یک لایه شن رس دار و عمق 10 تا 18/5 متری از لایه ها متشکل از ماسه سیلت/ رس دار بسیار متراکم تشکیل شده است. در بعضی از قسمت های دشت نیز ماسه های بادی دیده می شود که از حاکمیت شرایط خشک در محدوده دشت حکایت می کند. بررسی دانه بندی لایه ها نشان می دهد دشت تبریز دوره هایی را با شرایط اقلیمی مرطوب تا خشک پشت سر گذاشته است. گسترش دریاچه ارومیه تراس هایی را در این دشت بر جای گذاشته که خود از وقوع تغییرات اقلیمی مهم در محدوده دشت تبریز حکایت می کند.

    کلیدواژگان: تغییرات اقلیمی، تغییرات محیطی، دشت تبریز، کواترنر، نهشته های رسوبی
  • رحیم دبیری*، حبیب ملایی، میترا غفاری، عبدالله یزدی صفحات 377-394

    سنگ‌های آتشفشانی شمال‌شرق ورزقان در کمربند ماگمایی اهر‌‌ ارسباران فوران کرده‌‌اند. این مجموعه پلیوکواترنری شامل بازالتی‌آلکالن، تراکی‌بازالت، بازالتیک‌تراکی‌آندزیت، تراکی‌آندزیت، آندزیت، داسیت، و ریوداسیت است. بررسی شیمی‌کانی‌های سنگ‌های بازیک منطقه نشان می‌دهد ترکیب بلورهای الیوین از نوع کریزولیت (XFo: 0.74-0.84)، پیروکسن از نوع اوژیت و دیوپسید (Wo42-48، En37-45، Fs10-16) و پلاژیوکلاز کلاسیک تا حد‌ واسط (XAn: 31-93) است. بر پایه محاسبات شیمی‌کانی، دما‌فشار‌سنجی، و تعادلات فازی (بر اساس روش‌های ترکیب خمیره سنگ، ترکیب کلینوپیروکسن، تعادل کلینوپیروکسن‌ مذاب، ترکیب الیوین و تعادل الیوین‌ مذاب) دمای تشکیل سنگ‌های بازیک منطقه بین 1170 تا 1270 درجه سانتی‌گراد و فشار تبلور کلینوپیروکسن‌های منطقه در حدود 8 کیلوبار (پوسته میانی‌ زیرین) تخمین زده می‌شود. ترکیب کلینوپیروکسن‌ها نشان می‌دهد بازالت‌های منطقه در محدوده مربوط به محیط کششی و با سرشت آلکالن قرار می‌گیرند. همچنین ترکیب پیروکسن‌های منطقه نشان می‌دهد ماگمای والد این سنگ‌ها از یک منشا غنی یا کمترتهی‌شده نشئت گرفته و کمتر دچار تحول شده‌اند.

    کلیدواژگان: تعادلات فازی، دمافشارسنجی، کلینوپیروکسن، کواترنری، ورزقان
  • عذرا خسروی، سیدرضا حسین زاده*، مرتضی فتاحی، محمد خانه باد صفحات 395-412

    رسوبات کواترنری مخروط ‏افکنه ‏ها اطلاعات مهمی از شرایط اقلیمی گذشته و تحولات محیطی حوضه آبریز بالادست خود ارائه می‏کنند. در این پژوهش نویسندگان به بررسی تکامل الگوی رسوبی بر سطح مخروط‏افکنه کال شور پرداختند تا با استفاده از تفسیر نتایج حاصل از آنالیزهای ژئوفیزیکی و ژئوشیمیایی این رسوبات محیط رسوب گذاری این رسوبات در دوره کواترنر را بررسی کنند. مخروط ‏افکنه کال شور یک مخروط کوچک و نسبتا متقارن در شمال شرق ایران و در دامنه جنوبی رشته کوه بینالود است که بر پایه ویژگی‏های رنگ و بافت و اندازه ذرات و مطالعات میدانی سطح آن به 8 سطح مورفو رسوبی با نام های A1 تا A8 تقسیم شده است. بر پایه مطالعات رسوب‏شناسی، رسوبات مخروط‏افکنه کال شور دارای جورشدگی بد و بسیار بد، کج شدگی متقارن (تقریبا متقارن تا بسیار مثبت)، کشیدگی (متوسط و پهن)، و بافت گراول و گراول شنی هستند. در تفسیر ویژگی‏های ژئوفیزیکی، اندازه‏های میانه، نمونه‏های A2 و A5 و A6 و A7 دارای میانه پایین تر، جورشدگی ضعیف، و کشیدگی بیشتر نسبت به بقیه رسوبات اند. همچنین، بر حسب نتایج آنالیزهای شیمیایی حاصل از آزمایش XRF، میزان عناصر اکسیدهای کلسیم و آلومینیوم و سیلیس و همچنین نسبت عناصر منیزیم به کلسیم و منگنز به کلسیم به ترتیب در نمونه‏های A1 و A3 و A8 کاهش و در نمونه‏های A6 و A2 و A5 و A7 کاهش می‏یابد که به ترتیب نشان‏دهنده شرایط اقلیمی سرد و خشک و گرم و مرطوب است. به طور کلی، با توجه به نتایج آنالیزهای ژئوفیزیکی و ژئوشیمیایی سیلاب حمل‏ کننده در نمونه‏های A6 و A2 و A5 و A7 دارای سرعت بسیار زیاد (و نه لزوما دبی بالاتر) است. همچنین این سیلاب‏ها در محیط‏هایی با اقلیم سرد و خشک و با حاکمیت تخریب فیزیکی رخ داده‏‏ اند و در نمونه‏ های A4 و A1 و A3 و A8 اقلیم گرم و مرطوب با سیلاب‏های مداوم، اما، با انرژی کمتری رخ داده اند. بنابراین 4 سطح رسوبی در نتیجه اقلیم سرد و خشک و 4 سطح رسوبی در نتیجه اقلیم گرم و مرطوب در سطح این مخروط قابل مشاهده است.

    کلیدواژگان: شمال شرق ایران، کنترل های اقلیمی، کواترنر، مخروط افکنه، ویژگی های مورفو رسوبی
  • روناک گراوند*، رحیم معصومی صفحات 413-434

    سیالات زمین‏گرمایی ظاهرشده در اطراف آتشفشان سبلان ترکیب شیمیایی متفاوتی را نشان می‏دهند. تفاوت‏های ثبت شده، هم به لحاظ فراوانی آنیون‏های اصلی هم از نظر ترکیب عناصر کمیاب، حائز اهمیت است. بسته به موقعیت جغرافیایی رخداد سیالات زمین‏گرمایی، انواع سیالات، اعم از سدیم کلریدی (شمال‏غرب سبلان) و اسید سولفاته (شرق سبلان) و بی‏کربناته و سدیم کلریدی (جنوب سبلان)، شناسایی شده‏اند. این سیالات به لحاظ محتوای عناصر کمیاب و سنگین نیز حائز اهمیت اند. عنصر بور (B)، که یکی از عناصر رایج در سیالات زمین‏گرمایی است، در برخی از چشمه‏های آب‏گرم اطراف سبلان (جنوب سبلان) و نمونه‏های برداشته شده از چاه‏های اکتشافی (شمال‏غرب سبلان) مقادیر نسبتا بالایی را نشان می‏دهد. محتوای بور در نمونه‏های مطالعه شده از منطقه جنوب سبلان 19 تا 33 میلی‏گرم بر لیتر و در نمونه ‏های مطالعه شده از چاه‏های شماره 1 و 4 به طور متوسط 22 میلی‏گرم بر لیتر است. نظر به اینکه اغلب یک رابطه مستقیم و خطی بین بور و دما وجود دارد، در نمونه‏های مطالعه شده نیز اغلب این قاعده حکم فرماست. تمرکز بور نسبت به pHهای مختلف نیز الگوهای خاصی را نشان می‏دهد؛ به گونه ای که گستره pH 6-9 بیشترین فراوانی را نشان می‏دهد و در این محدوده pH گونه B(OH)4 غالب است. از نظر زیست محیطی، تمرکزهای بالای بور می‏تواند مخاطره آمیز باشد. اختلاط آب‏های زمین‏گرمایی حاوی بور بالا با آب رودخانه‏ها، دریاچه‏ها، آب شرب، و آب پشت سدها می‏تواند سبب به وجود آمدن مشکلات جدی بهداشتی شود. این اتفاق در برخی از رودخانه‏های اطراف سبلان، از جمله خیاوچای، قابل مشاهده است که با محتوای بور 7 میلی‏گرم بر لیتر مقدار نسبتا بالایی را نشان می‏دهد.

    کلیدواژگان: آثار زیست محیطی، بور، ژئوشیمی، سبلان، سیالات زمین گرمایی
  • دارا داس برزین، خلیل رضایی*، راضیه لک، مهدی محمدی ویژه، حامد مسلمی صفحات 435-456

    شناسایی آبرفت ها، رسوبات، و محیط رسوبی دیرینه ته نشست آن ها در حالتی که در مطالعه آن ها از روش‏ های ترکیبی استفاده شده همواره اهمیت بالایی دارد. این گونه مطالعات ترکیبی معمولا به روش مستقیم (نمونه‏برداری) و روش غیرمستقیم (روش‏های ژئوفیزیکی) انجام می‏شود. هدف اصلی این تحقیق شناسایی رسوبات و محیط ‏رسوبی دیرینه آبرفت های منطقه کوچ صفهان با تلفیق داده ‏های رسوب‏ شناسی حاصل از چاهک‏ ها و روش راداری نفوذی به زمین (GPR) بود. برای این ‏منظور، داده های رادار نفوذی به زمین به طول 11 کیلومتر در امتداد جاده کوچ صفهان به سمت لشت ‏نشا برداشت شد. سپس، با توجه به پروفیل‏ های راداری 7 گمانه رسوبی با عمق متوسط 2/7 متری جهت تلفیق با داده ‏های رسوب‏ شناسی حفاری شد. بررسی‏ های انجام‏شده به شناسایی 5 رخساره راداری شامل خطوط راداری به صورت گسسته و غیر‏موازی مقعر محدب، خطوط راداری به صورت منحنی های پیوسته موازی، خطوط راداری با شیب های متفاوت به صورت گسسته، خطوط راداری به صورت ناپیوسته موازی با شیب‏ کم، خطوط راداری ناپیوسته موازی با شیب‏ کم و میرایی شدید و 8 رخساره رسوبی ماسه بسیار ریز سیلتی، ماسه ‏ریز، گراول ماسه ای، ماسه ریز گراولی، مواد آلی، ماسه درشت سیلتی، ماسه درشت، ماسه گلی با کمی گراول انجامید که نشان دهنده قسمت ‏های مختلف محیط های رودخانه ‏ای بود. در این منطقه میزان ذرات‏ دانه ریز رسوبی و مواد آلی از جنوب به سمت شمال منطقه افزایش می‏یابد.

    کلیدواژگان: رادار نفوذی به زمین (GPR)، رخساره های راداری، رخساره رسوبی، رسوب شناسی، محیط رسوبی دیرینه
  • زهرا بوسلیم، هادی جعفری* صفحات 457-472

    بررسی رابطه الگوی جریان و کیفیت آب از عوامل مهم کمک کننده در مدیریت کمی و کیفی آب‏های زیرزمینی است. تحقیق حاضر به منظور استفاده از شواهد هیدروشیمیایی و ایزوتوپی در تعیین الگوی جریان آب زیرزمینی در آبخوان شاهرود و بررسی آثار هیدروژئولوژی بر کیفیت آب منطقه انجام گرفت. جهت جریان کلی آب در آبخوان شاهرود از مناطق شمال شرقی به  جنوب غربی است. به وجود آمدن یک خط تقسیم آب در منطقه باعث ایجاد تغییراتی در جهت جریان کلی آب در برخی بخش ‏ها و انحراف جریان به سمت شرق شده است. بررسی‏های هیدروشیمیایی 120 نمونه آب نشان داد در این آبخوان پیوستگی ژئوشیمیایی، به ویژه در بخش جنوب شرقی، وجود ندارد؛ به گونه ‏ای که بخش شرقی و بخش جنوب شرقی اختلاف کیفیت فاحشی با بخش ‏های شمالی، غربی، و مرکزی نشان می‏دهد. جریان ورودی قوی تر از مرز شمالی همراه خط تقسیم آب زیرزمینی باعث جدا افتادن و ساکن شدن آب‏های شور جنوب شرق منطقه شده‏ است. در نتیجه، به مرور زمان، تغییر تیپ آب از سولفاته به کلروره در این توده آب نسبتا راکد رخ داده است. جدا افتادن جریان آب در بخش جنوب شرقی باعث شده آب شور آن تاثیر چندانی بر شیمی آبخوان نگذارد. آنالیز 3 نمونه تریتیوم وجود حداقل دو منبع تغذیه با سنین مختلف در آبخوان را اثبات می‏کند. نمونه‏های شور جنوب شرقی با میزان تریتیوم کمتر از TU0/8 نشان دهنده آب نسبتا قدیمی تغذیه شده قبل از سال 1952 است؛ درحالی که آب شیرین شمال منطقه با میزان تریتیوم TU 2/2 آبی است که به تازگی تغذیه شده است. سن بیشتر آب در بخش جنوب شرقی به دلیل عدم ارتباط هیدرولیکی با آب‏ های جوان، سرعت کمتر جریان، و نیز عدم خروج آب قدیمی از این بخش از آبخوان به دلیل کم بودن میزان بهره ‏برداری است.

    کلیدواژگان: ناپیوستگی هیدروژئوشیمیایی، هیدروژئولوژی، هیدروشیمی
  • حسین حاجی علی، مهسا عبداللهی، سعید محمدصبوری* صفحات 473-481

    در این تحقیق برآورد خطر لرزه‏ای شهر ساوه به روش احتمالاتی انجام شد. محدوده شهر ساوه در زون ایران مرکزی واقع شده و فعالیت لرزه ای متوسط دارد. بر اساس مطالعات لرزه خیزی و لرزه زمین ساخت انجام گرفته در این تحقیق، نزدیک ترین چشمه لرزه زا به این شهر گسل البرز است که از مرکز شهر ساوه عبور می کند و انتظار می رود بیشینه شتاب را برای این شهر ایجاد کند. اما پس از تحلیل های مربوط به جدایش خطر لرزه‏ای، مشخص شد که گسل ایندس، با فاصله های 21 کیلومتر از شهر، 45/12درصد خطر برای شهر ساوه را تحت کنترل خود دارد و در واقع زمین لرزه کنترل کننده در دوره بازگشت 475 سال را به وجود آورده است.

    کلیدواژگان: جدایش خطر زمین لرزه، روش احتمالاتی، شهر ساوه، گسل ایندس، لرزه زمین ساخت
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  • Fariba Karami, Maryam Bayati *, Behrooz Sari Pages 361-375

     Sediments provide a continuous, sensitive record of changing conditions of environment and processes within plain and in the surrounding plain, thus they contain significant archives of past environmental change on the continents. Valuable informations on regional and global scale patterns of past climate
    variability in the Azarbayjan region have been documented by numerous paleoclimate studies, but some of these may partly explain the contradictory palaeoclimate histories. Although paleoclimate changes in the eastern Azarbayjan during the late Pleistocene to Holocene are well constrained in terms of proxy-climate data. In this study the data were collected, the sub-bottom profilers. In this study with aim of monitoring of past environmental changing of Tabriz plain, widely used indicators of Quaternary paleoclimates. In particular, the geochemical ”archives” contained in sediments provide long and high-resolution proxies of terrestrial records. However, such geochemical proxies especially those gathered from the holes , can only be indirect indicators of past climates and may be influenced, to different degrees, by several independent factors. In order to overcome this indirectness, multi-proxy methods are widely used. Spt methods ,Granolometry,and textural methods are these used method. Also used Ph analyzing for explain of Quaternary history of Tabriz plain. The result of this study suggested of the Tabriz plain hade very different paleoclimate conditions. The amount of clay and soft grain sediment in depth of ground is high. Our results indicate that the region was relatively cold and wet during the late glacial, and some times were dry. During the beginning of the Holocene, while precipitation values were high, the temperature gradually increased than , the region was warm but extremely dry.

    1-Introdution

    Sediments are sensitive to climatic (global and local)and tectonic, and sedimentological changes,providing clear sedimentary records about them. Shore deposits are generally composed of loose, unconsolidated sediments, ranging from very fine sand up to pebbles and cobbles in terms of sediment size. They receive their sediments from rivers draining a catchment area and the erosion of nearby cliffs and foreshore outcrops. fluvial sediment capacity transported to the coastal area. Shore systems deal with the nteractions between depositional and erosional processes as waves, currents, rivers, tides, and winds). The Tabriz plain undergone significant modification associated with water level changes related to climatic conditions and tectonism since its formation
    The East Azarbayjan plain is situated on basement rocks consisting of Mesozoic metamorphic rocks,
    Triassic limestones, Upper Cretaceous ophiolites, and Miocene turbidites. These rocks are unconformably overlain by Quaternary volcanics and coeval lacustrine sediments. The basin infilling ends with Late Quaternary travertines and recent unconsolidated fluvial sediments. To restructure the past climate and environmental conditions is crucial in terms of understanding the living conditions of previous communities. On the other hand, the accurate interpretation of human impact on past environmental conditions is very important in terms of fully understanding the dimensions of man's pressure on nature and the changes in land use. Human impact emerges as an important and constant factor that regulates the vegetation dynamics in the lands occupied especially in the Late Holocene. In general, the climatic changes experienced in the Eastern Azarbayjan region and Tabriz plain are consistent with the hole layer data. This is impoErtant in terms of reflecting effects of global climatic changes in the study area.
     

    2-Materials and methods.


    To restructure the past climate and environmental conditions in the Eastern Ayjan region in the Late Pleistocene and Holocene investigated by grianology analysis. In this study ,used of Geocronology data ,sediment layer and pedology property for experting of environmental changes in Tabriz plain. In field study is measured and is analysed grain of sediment in laboratory. Also used spt method for investigation on soft grains in sediment. Investigation on PH of sediment and deposits were other methods for understanding of past environment condition.
     

    3-Results and discussion

    Extensive paleoclimatic studies have provided evidence that the Holocene is characterized by wet and dry climatic fluctuations and rapid shifts worldwide. We propose that, the sedimentary record of Tabriz plain
    provides a suitable geological archive for understanding the changes in this climate sensitive coastal area. The work reported here is predominantly focused on lithological observations, inorganic parameters and basic organic matter characteristics. The field work were collected from of the sediment cores. The latter technique has been used to obtain geochemical profiles, which are interpreted to identify local climate signals, distinguish internal and external effects on the environment such as physical dynamics, chemical
    characteristics of the soil column. This study also aims to analyse the effect of main global climate trends on the environment of plain such as the Early Holocene humid phase, the Middle Holocene dry conditions and various Late Holocene events including organic matter rich sedimentation. Investigation on sediment layer show that from 15 to 35 meter is formed by clay ,sandy –silt and silt. This composition is suggested of low energy in past environment. Changes of sediment property is show that climate changed. Investigation on soil sampels and analysied by spt method show that most of grains is soft in deep of layers. In between of layer can see wind sands. Percent of Clay grain is decrease in eastern part of plain.

    4-Conclusion

    The study of distribution of soft grain materials in Tabriz plain show that most part of area in 20 meter of deep is formed by soft grains. 50 percent of this soft grains are clay and silt. Northern part of plain is formed by red soils that sources of his soil is Quaternary sediment. Thick layer of clay suggested of dry condition continued length time . Yellow soil is evidence of cold and dry condition in Tabriz plain. Old landslides in between layer show that in plain wet condition some time were governed. Especially the signal of the Early Holocene humidity is documented in sedimentary record. Such investigations which are now in progress will provide further insight into climate-induced changes in the sediment.
    Thick of wind sand layer suggested that the warm period is governed 400 year in plain. This period marked by color layer in around of Tabriz.

    Keywords: Environmental changes, climatic changes, Tabriz plain, Sediment, Quaternary
  • Rahim Dabiri*, Habib Mollai, Abdollah Yazdi, Mitra Ghaffari Pages 377-394
    1-Introduction

    The studied area is situated in northeast Varzeghan in East Azerbaijan Province. In the classification of the structural unites of Iran, this area is a part of Ahar-Arasbaran magmatic arc. The Cenozoic magmatism in the Ahar-Arasbaran region started in the Eocene with an intensive volcanic activity that produced widespread basic to felsic rocks and continued in the Oligo-Miocene with the emplacement of large granitoid plutons. The Plio-Quaternary basaltic and trachyandesitic rocks cover the older magmatic units, particularly in the Varzaghan area. This Quaternary alkaline volcanism in northwest Iran occurred after late Miocene calc-alkaline magmatism.

    2-Materials and methods

    Minerals from representative samples were analyzed at University of Tasmania (UTAS), Australia with a Cameca Sx-100 electron microprobe with combined WDS and EDS systems. A range of natural minerals were used as standards. The microprobe operated with a 5μm beam diameter, an accelerating voltage of 20 kV and a beam current of 15 nA. Precision, as indicated by replicate determinations on an in-house standard, was better than 2% for the major elements.

    3-Results and discussion

    Volcanic rocks consist of alkali basalts, trachybasalts , basaltic tracyandesite, tracyandesite, andesite, dacite and rhyodacite. Alkali basalts and trachybasalts display microlithic porphyritic texture with phenocrysts of Chrysolite (XFo: 0.74-0.8), Diopside and Augite (Wo42-48، En37-45، Fs10-16), and plagioclase (XAn: 31-93) in microlithic groundmass. The Olivine composition shows that these minerals are not in equilibrium with liquids similar to the whole-rock composition.  According to melt and clinopyroxene compositions and olivine and clinopyroxene -melt equilibrium, estimated crystallization temperature varies between 1170 C to ~1270 C. The equilibrium pressure calculated using clinopyroxene compositions is close to 8kbar which corresponds to an approximate depth of ~25 km.

    4-Conclusion

    The clinopyroxene compositions of the basic rocks display an alkaline nature which indicates an extensional setting. Also, clinopyroxene compositions indicate that parental magma this rocks origin from enriched and primitive source. The petrographic and mineral chemistry evidences reveal that magma evolution processes have been occurred in open-system thermodynamics and fractional crystallization has played the most vital role in the evolution of basaltic magma.

    Keywords: Fuzzy equilibrium, Thermobarometry, Clinopyroxene, Quaternary, Varzeghan
  • Azra Khosravichenar, Sayed Reza Hosseinzade*, Morteza Fattahi, Mohammad Khanebad Pages 395-412
    1- Introduction

    Climate has an important role in the sedimentation of quaternary fans. In the dry climate of the present time, the surface materials of the hills have deposited during the wet or cold periods, but these deposits have been transferred to alluvial fans during the transition to dry or warm periods of Quaternary (Bull, 1991). Instead, in the present basins that are located in semi-arid climates, sediments have been transferred to fans during the wetter or colder period. Alluvial fan’s deposits are sensitive to hydrological conditions, and the study of these sediments provides worthwhile information from paleo climate. Quaternary sediments of the alluvial fans offer important information about paleoclimates conditions and paleo environmental changes of their catchments.

    2-Materials and methods

    In this research, the authors have studied the evolution of sedimentary pattern using the results of geophysical and geochemical analyses on the surface of the Kalshour Fan in the Northeast of Iran, during the Quaternary period. The Kalushshour fan is a small and relatively symmetrical fan in the southern slopes of the Binaloud Mountain Range in North eastern Iran (Fig.1 and 2). This area is closed to city of Neyshabour (20 km) at latitude with latitude 36 ° 10'35 "N to 36 ° 12'36" N and longitude 58 ° 59 '6 "E to 59 ° 0' 11 "E. The mean annual precipitation in the region surrounding the study area is 15 to 28 cm/year(source: Meteorological Organization of Khorasan Razavi, Iran ), suggesting that the study area lies in the arid to semiarid transitional zone. The focus of this research is on the Kalshour basin on the southern slopes of the Binaloud mountains and alluvial fan and terraces. And attempts to compare the dispersion of the major and trace element oxides with the standard averages of these sediments present.
    The first map of the study area was prepared in the ArcGIS 10.3 software based on aerial photographs, topographic maps and satellite images to study the alluvial fan surface. Then different levels of geomorphological surfaces were determined according to the colour, texture and grain size parameters. Then, during the field trips, the accuracy of the map Validated with the reality on the ground and its bugs were met.
    Eight samples were collected from the surface of the alluvial fan for studding of their geophysical and geochemical characteristics. Chemical analyses were performed for eight samples. Analyses were performed by x-ray influence spectrometer and inductively coupled plasma-mass spectrometry (ICP-MS) at the Bespar Payesh (Mining Material Research Co), Analytical Laboratories Ltd. in Ferdowsi university of Mashhad, Iran. The main oxides are in% and trace elements in ppm. Based on morpho-sedimentry characteristics, the surface of this fan is classified into 8 levels, called A1 to A8.
    After drying the sediment in the oven, sediments were weighted at intervals of 0.5 to 5 phi. Then, other parameters related to the sediment texture, sedimentation, degradation, sorting, etc. were determined, and the associated analyses and diagrams, such as percentage cumulative graphs, percentages, etc. were mapped using the Gradistate software. To ensure the results obtained, the graphs of the name and texture of the sediment were re-constructed in the 3Dplot software environment. To improve the achievement, the corresponding graphs in the Corel DRAW Graphic Suitee software environment were restored and Set up. At the next step. Their findings were compared together.

    3-Results and discussion

     Based on the geophysical analysis, A2, A5, A6, and A7 samples are poorly sorted and stretchy than the rest of the sediments. Elemental geochemistry well describes the temperature and precipitation of paleo conditions. Also according to the geochemical analysis, the amount of calcium, aluminum, and silica oxide elements and the ratio of magnesium to calcium and manganese to calcium in samples A1, A3 and A8 were decreased and in s A6, A2, A5 and A7 samples were decreased Which in turn reflects the cold - dry and warm - humid climate. In general, according to the results of geophysical and geochemical analyses, carrier flood in the A6, A2, A5 and A7 sediment samples had been passed with very high speed. Also, these floods occurred in a climatic environment with a physical watering regime. In A4, A1, A3 and A8 samples, warm and humid climate were associated with continuous but less energetic floods. Thus, four sedimentary levels due to the cold and dry environment and four sedimentary levels due to the warm and humid environment are visible at the surface of the cone.

    Keywords: Alluvial fan, Morpho-Sedimentary Features, Quaternary, Climatic Control, Northeastern Iran
  • Ronak Geravand*, Rahim Masoumi Pages 413-434

     The manifested geothermal fluids around Sabalan volcano show different compositions. These compositional differences are observable in both the anionic composition and the concentration of trace elements. Regarding to the geographic distribution of geothermal fluids and hot springs, Na-Cl fluids (NW Sabalan), Acid Sulfate fluids (East of Sabalan), and HCO3 fluids (South of Sabalan) have been recognized. These fluids are also considerable regarding to the trace element and heavy metal contents. Boron as a common component in geothermal fluids shows relatively high concentrations in some hot springs of Sabalan area (South of Sabalan) and the obtained samples from the drilled wells (NW Sabalan). The studied samples of South of Sabalan area show 19-33 mg/l Boron content and the well samples show 22 mg/l Boron values in on average. With a regard to theIn generals there is a linear and positive relation between Boron and temperature in many geothermal fluids, this positive relation is also seen in the studied samples. The correlation of B-pH for the studied samples displays a special pattern. The highest concentration of Boron can be seen in 6-9 pH range. In this pH range, B(OH)4 is the dominant species. The high concentration of Boron can be dangerous from the environmental point of view. The contamination of high-Boron geothermal fluids with in the rivers, lakes, dams, and drinking waters can may cause health problems. This phenomena currently happens currently in some rivers such as Khiyav chay (7 mg/l Boron content) around the Sabalan volcano.  

    Introduction

    Boron is the 51th element in of the earth’s crust with 8 ppm average concentration (Cotton et al., 1999; Jansen 2003). Boron is a non-metal element and is usually found with Oxygen compositions and never found as a free element (Cotton et al., 1999). More thane 200 Boron bearing minerals have been found till now. and Borax (Na2[B4O5(OH)4]•8H2O), Kernite (Na2B4O7•4H2O), Colemanite (Ca2B6O11•5H2O), and Ulexite (NaCaB5O9•8H2O) are the main Boron minerals. This element is a basic micronutrient for most of plants, animals, and even humans (Rainey et al., 1999, 2002).     
    Method of investigation
    In order to investigate the Boron content and distribution patterns of this element in geothermal fluids in Sabalan area several stages were anticipated and carried out.
    The chemical analyses of these samples for determination of major and trace elements as well as stable isotopes were carried out in hydrogeochemistry lab at Bremen University (Germany).
    The stable isotope analyses (δD and δ18O) were carried out by using LGR DLT-100 Laser Spectrometer (Los Gatos Research). The analytical precisions for δ18O and δD were ±0.2‰ and ±1‰, respectively.

    Results and Discussion

    From the geological point of view the study area is located in a volcanic setting which belongs to the Cenozoic era. This area is a small part of western Alborz-Azerbaijan geologic zone. The main lithological units of Sabalan geothermal system consist of igneous rocks such as andesite, basalt, dacite, trachyte, and monzonite.
    The geothermal manifestations such as hot springs are observable in most parts around Sabalan volcano and include different types of geothermal fluids such as Na-Cl, Acid Sulfate, and Bicarbonate waters. These waters show a relatively high Boron contents especialy in the southern Sabalan geothermal field.    

    Conclusions

    Several conclusions have been obtained from our investigation:-  

             The studied samples show different Boron concentrations which include 20-33 mg/l in Southern Sabalan and 20-22 mg/l Boron in the drilled wells in NW Sanalan.
    -           There is a positive and strong relation between temperature and Boron content of most studied geothermal fluids. In some of the studied samples, this positive relation is not seen which can be thought as the occurrence of mixing process.
    -           The high content of Boron in Khiyav-Chay  can be dangerous for the environment and may cause health problems in the area.

    Keywords: Geochemistry, Geothermal Fluids, Boron, Sabalan, Environmental Impacts
  • Dara Dasbarzin, Khalil Rezaei*, Razyeh Lak, Mehdi Mohammadivijeh, Hamed Moslemi Pages 435-456
    Introduction

    Sedimentary environments are the best place to keep records of past events and evidence of fundamental events occurring on the surface of the earth within sedimentary units and their discontinuities. The identification and separation of these sedimentary units have often been the goal of many geological projects with different scientific and practical objectives. Detection of the alluvial deposit has always been of high importance when combined with their study. These hybrid studies are usually carried out in direct (sampling) and indirect methods (geophysical methods). In previous studies, in almost all researches, the necessity of carrying out sedimentology studies to better interpret the identified sequences and their adaptation to GPR studies has been emphasized by the researchers. This combination of studies, in addition to separating different units in terms of grain size, may include other factors such as the presence the quality and depth of fluid (ground water and water table), uniformity of particle size (sorting), particle size, and sedimentary structures. The main objective of this research is to identify sediments and ambient environments of alluvial soils by integrating the data from sedimentation from wells and GPR. The study area is located in Guilan province, between Kouchesfahan and Lasht-e-Nesha cities in the coastal plain of the Caspian Sea. The climate of the study area is humid and the annual rainfall is an average of 800 mm. From geomorphology point of view, the northern boundary of the Alborz is in accordance with the cluster of tertiary deposits and the coastal plain of the Caspian Sea. Under the sea terraces and alluvial plain covers, there are the Miocene-Pliocene-Quaternary marine rocks that have been displaced by the retreat of the Caspian Sea.

    Material and Methods

    Firstly, GPR data (using 100 megahertz antenna, MALA) was taken to 11 km long land along the Kouchesfahan road to the Lasht-e-Nesha. Then, according to the radar profiles, they were drilling 7 sedimentary boreholes for media depth 2.7m to combine with sedimentology data. Global Positioning System is used to determine the location. the resulting data for the processing stages entered the Reflex-W software. After performing the necessary processing considering the radar facies and the depth of penetration of the waves in the radar profiles, suitable points for drilling boreholes were selected for a sampling of subsurface sediments (7 stations). The average depth of the drilled boreholes is 7.2 m. 42 Sediment samples were taken in each well based on the visible changes, including sediment type, grain size, color, moisture, and organic matter content. In the laboratory, grading experiments were carried out after the preparation of the samples (drying and separating organic matter), direct measurement of the dimensions with morphoscopy, dry sieving, and hydrometric method. In addition to the initial analysis of grain size, other statistical parameters such as the average of diameter, mean, sorting, skewness were measured.

    Results and Discussion

    Investigations have led to the identification of five radar facies (Reflectors no-continuous undulating with concave-convex pattern, Reflectors continuous with concave-convex pattern, Reflectors no-continuous with different angle, Reflectors no-continuous parallel with low angle, Reflectors no-continuous with low angle and attenuation high and nine sedimentary facies; silty very fine Sand (Zs), fine Sand (s), sandy Gravel (sG), gravely fine Sand (gS), organic matter (O), silty coarse Sand (zs), coarse Sand(S), muddy slightly gravelly sand (g)Ms, which represent different parts of the river environment, including the river canal and floodplain. In this region, the amount of fine-grained particles and organic matter increases from the south to the north. The facies are likely to be part of the old channel of the Sefidrud River when the channel has been redirected to the east. Changes in the percentage of grain size in the boreholes have irregular variations, which the number of fine grain particles is increased from the upstream to downstream of the region. Grains tend to be coarser from the bottom to the top of the boreholes and finer toward the shore. Sorting are bad and very bad in most samples, which indicates the deposition of finer grain particles among coarse grains. From the upstream side, in most drilled boreholes, sediments show a finning and a coarsening upward sequence that indicates the energy fluctuations of the environment over time.

    Conclusion

    The results of this study showed that wet, fine-grained with high organic matter content environments cause the destruction of the wave and including the radar method's limitations. Also, in urban environments and through the passageways, vehicle overpasses and power rails affect radar profiles and cause the radar profile to be illegible. In the studied area, the depth of effective influence of the waves is not more than 3 meters. In this research, based on valid scientific classification, 5 radar facies and 9 sedimentary facies related to different sedimentary environments were identified. The results showed that radial facies, with respect to depth, particle size, moisture, organic matter and evaporates content limitations, can be very good for identification of various sediments, especially at low and near depths. By performing this research and matching the sedimentary and radial facies, the ability of the two methods in another interpretation was also identified and such adaptations can be applied in other areas with great confidence.

    Keywords: Ground Penetration Radar (GPR), Paleo-Depositional Environment, Radar Facies, Sedimentary Facies, Sedimentology, Guilan
  • Zahra Boosalik, Hadi Jafari* Pages 457-472
    Introduction

    One of the main factors in quantitative and qualitative management of groundwater in different regions is investigation the relationship between flow pattern and water quality, in other words, studying the effects of hydrogeology on aquifers hydrochemistry. Meanwhile, the Shahrood aquifer is one of the most distinctive aquifers in showing hydrogeological effects on aquifers hydrochemistry. The Shahrood alluvial Aquifer, is a single-layered and unconfined aquifer which its main inputs are recharge from rainfall, sewage return flow from urban areas, agricultural return flow and underground water flow from adjacent karstic aquifers. The diversity of recharge sources of Shahrood aquifer and the distribution of exploitation wells have caused complexity in the pattern of groundwater flow in this aquifer. The general flow direction of groundwater in the Shahroud aquifer is from the northern, eastern, and southeast regions to the central, western and southwest areas. But the creation of a water distribution line in the eastern and southern parts of the region has caused changes in the overall flow of water in these parts. So that the flow takes direction to the east, around the villages of Royan and Hussein Abad. The more distance between potential lines in the southern part indicates lower hydraulic gradient and, consequently, less flow rate in this part of the aquifer. The purpose of this study is useing of hydrochemical and isotopic evidence in determining the pattern of groundwater flow in Shahrood alluvial aquifer and also to study the effects of hydrogeology on water quality and geochemical anamolies in the region.
     

    Method and material


     For hydrochemical studies, 120 samples of groundwater were analyzed at Shahrood University of Technology. Also, 3 samples were analyzed for determining the amount of tritium isotopes at the University of Ottawa.
     

    Discussion  and Result

    Hydrochemical studies were showed that the EC value in shahrood aquifer varies from 671 μs / cm in the north of the aquifer to 12000 μs/cm in the east and southeast. There is no geochemical continuity in this aquifer, especially in the southeast. In other words, there are two different salinity anamolies in the Shahrud aquifer. These anamilies are related to the eastern-northeast and southeastern parts of the aquifer, that show a significant difference in the quality rather to the north, west and central parts. For example, the EC in sample W109 is 9000 μs / cm, but near and upstream this sample, in W59 sample, EC is about 1200 μs/cm. The groundwater type is sulfate, bicabonate and chlorine in the eastern entrance to the central northern, western parts and southern areas, respectively. Bicarbonate samples are related to karstic Formations in the north of the region. While the emergence of sulfate and chlorine types are associated with the dissolution of marl and gypsum outcrops in the east and south eastern parts. Given that Marl and Gypsum Formations are the same in eastern and southeast regions, it is expected that their water type to be similar and mainly sulfate-type. But the all waters are chlorine in the southern part of the aquifer. This can be due to the longer resident time of water in the southern part and the achievement of geochemical evolution due to reaction with aquifer rocks over time. In fact, the largest volume of inflow and recharg in the Shahroud plain comes from the north and Bastam Plain. The volume of this input flow is very impressive rather than the volume of the inflow from the south-east of the region, and it prevents the entering flow of southern saline water, and reduces the velocity or stagnation of the inflow water from the southeastern border. This strong inflow from northern boundary, along with the water distribution line in the southeastern part of aquifer, causes separation and isolation of saline flows from the south-east of the region. Consequently, over time, changing the type of water from sulfate to chlorine occurs in this stagnant water mass. The southern saline water has not much effect on the Shahrood aquifer chemistry due to the stagnant or slow water flow in the southeastern part. In fact, the hydrogeological control has an important role in changing the water type in the Shahrood aquifer. According to tritium analysis, there are at least two different recharge sources in the aquifer. The southern saline samples with a tritium content less than 0.8 TU indicate relatively old water fed before 1952, While the freshwater from the north of the area with a tritium content about 2/2 TU, is a mixture of relatively old water and modern water. The southeastern waters to become older, due to the lack of hydraulic communication with young water and the less velocity of water flow.

    Keywords: Hydrogeochemical discontinuities, Hydrogeology, Hydrochemistry
  • Mahsa Abdollahi, Saeed Mohammad Saburi*, Hossein Hajiali Pages 473-481

    the study area of this study is located in central iran and part of the Urmia-Dokhtar volcanic belt.  It is the oldest rock in the region, depending on the median eocen. there are several earthquakes in this area caused numerous earthquakes. in general, an earthquake risk analysis study consists of several steps that will be addressed in this chapter. Two basic parts are important here. first, the recognition of tectonic Source that includes the recognition of seismic Source and knowledge of their main characteristics.  these features can include length, distance, dip and dip direction, Siesmic potential, active faults, quaternary deposits. The second part deals with the seismic activity of the region. in this part, we identify and analyze the seismic status of the region as we identify prehistoric earthquakes (benefiting from the historical data of seismology). Such investigations resulted in the identification of valuable information, such as the  Siesmic rate of Gutenberg- Richter coefficients, and  seismic pattern. finally, the combination of these two parts in the form of a comprehensive model is modeled as the seismic model and can be considered as input data Research Method.

    Methodology

     in this study, advanced EZ - Frisk software has been used for analyses. since in such studies it is necessary to apply at least a suitable  Atteniuation relation. regard to features and geological conditions,  tectonics and Siesmotectonic of this area  in Iran,  have finally used four new generations to calculate the seismic velocity parameters of the region by considering equal weight for each relationship. the probabilistic approach for determining the Siesmic parameters of this study is the probabilistic approach of risk analysis. in the PSHA method, using probabilistic models from Siesmic Source (point, line, path, or region), the maximum amount of seismicity values of the  pick Ground Acceleration is calculated while using probabilistic models from  Siesmic Sourse (point, line, path, or region).

    Analyses

     Important faults of this area are Alborz, Kushke-e-Nosrat, Indes, qom – Zefreh, and Ipak. the Ipak fault over 100 km, along with east - west, is the most active element of  Siesmotectonic in this range. The earthquake event of 1962 with magnitude 7.2 has occurred as the largest instrument event in the region, relating to the activity of the Ipak fault. Alborz fault, 2 km distance, is the closest Siesmotectonic element to the  Saveh city. this fault has overturned the from south east on quaternary deposit. according to the explanations that have been studied in the study section, the PSHA diagram for the Saveh city is calculated based on Fig. 3. therefore, the 0.22 acceleration for Saveh city is evident in the period of 475 years. The most probable magnitude during the 475  year period is 5 / 5 and at a distance of approximately 21 km. the results clearly show that although Alborz fault is located near the middle of the Saveh city, it is not the main factor in the production of earthquakes for this city and produces only 8.5 percent of total risk. Instead of the Kushk-e-Nosrat and Indes, respectively, at 18 and 21 km, respectively, have 90 % of the risk for the  Saveh city.

    Conclusion

     It was thought that the acceleration was the result of Alborz Fault that is almost from the middle of the Saveh city . therefore, the risk separation calculation was performed to determine the validity of this issue. but it was found that the main factor in the earthquake production was not for the city. After magnitude-distance deaggregation analysis, it is clear that the Indes fault with 21 km distance from Saveh city create the 45.12% of hazard within its activity. In fact the controlling earthquake at 475 year return period is associated with Indes fault.

    Keywords: Saveh city, Probabilistic, seismotectonic, magnitude-distance deaggregation, Indes fault