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استفاده از روش لومینسانس نوری جهت تعیین سن رسوبات لسی اطراف شهر میبد و تفسیر شرایط تشکیل آنها | ||
| فیزیک زمین و فضا | ||
| مقاله 4، دوره 44، شماره 2، تیر 1397، صفحه 307-319 اصل مقاله (520.82 K) | ||
| شناسه دیجیتال (DOI): 10.22059/jesphys.2018.253856.1006986 | ||
| نویسندگان | ||
| مرتضی فتاحی* 1؛ داریوش مهرشاهی2 | ||
| 1دانشیار، گروه فیزیک زمین، موسسه ژئوفیزیک دانشگاه تهران، ایران | ||
| 2دانشیار، دانشکده جغرافی، دانشگاه یزد، یزد، ایران | ||
| چکیده | ||
| نهشته‌های لسی تاریخچه آب‌و‌هوایی و وضعیت جریان گردوغبار جوی دوران گذشته را در خود ضبط کرده‌اند و وجود آنها در یک منطقه، مراحل مختلفی از تغییر اقلیم در دوره زمین‌شناسی «کواترنر» را نشان می‌دهد؛ اما جهت استفاده مناسب از این منبع اطلاعات، نیاز به تعیین سن این نهشته‌ها و میان لایه‌های کهن خاک بین آنها داریم. جهت سنیابی رسوبات لس توسط لومینسانس برانگیخته نوری (OSL) به دو پارامتر دز معادل دز طبیعی محیط و دز سالانه نیاز است. به‌منظور اندازهگیری دز معادل معمولاً از روش SAR استفاده می‌شود. اما در این مطالعه به دلیل خالص نبودن کوارتز پس از دو مرحله شستشو با اسید فلوریدریک به دلیل تولید سیگنال مادون قرمز، از روش نور آبی پس از مادون قرمز ([Post IR] OSL) استفاده شد. در این بررسی دز معادل دز طبیعی نمونههای برداشت شده با تحلیل دادهها در برنامه آنالیست به روش هیستوگرام محاسبه شد. دز سالانه محیط توسط روش ICP و سن نمونه یا آخرین زمان رسوبگذاری آن 3900 ± 34600 سال پیش به دست آمد. با توجه به این سن، زمان رسوبگذاری ذرات سیلت معادل اواسط دوره وورم بوده است که به آخرین عصر یخچالی مربوط می‌شود. به این دلیل رسوبگذاری این لس‌ها در ایران مرکزی در شرایط سرد و خشک بوده و با وزش بادهای شدیدی که منجر به ایجاد کوهریگ‌هایی نیز در مناطق اطراف دشت یزد شده بودند مطابقت دارد. | ||
| کلیدواژه‌ها | ||
| سنیابی؛ لومینسانس برانگیخته نوری؛ لس؛ دیرینه اقلیم کواترنر؛ میبد | ||
| عنوان مقاله [English] | ||
| OSL Dating of Maibod Loess deposits and their formation interpretation | ||
| نویسندگان [English] | ||
| morteza Fattahi1؛ Dariush Mehrshahi2 | ||
| 1Associate Professor, Department of Earth Physics, Institute of Geophysics, University of Tehran, Iran | ||
| 2Associate Professor, Faculty of Geography, University of Yazd, Yazd, Iran | ||
| چکیده [English] | ||
| Loess deposits mainly of silt particles with different mineralogical sources have covered about 10 percent of the Earth land area. World-wide studies on loess deposits show that most of the loess deposits accumulated during the Glacial ages while during the inter-glacial phases their accumulation has stopped or dramatically lessened. Loess deposits have recorded the past climatological history within their grains which can be used to distinguish possible climate changes during the Quaternary period. Dating of paleo-proxy records such as loess sediments also have the potential for understanding the chronology of paleo environmental events including tectonic activities. Loess deposits around the world were among the first sediments to be used for luminescence dating particularly within the arid and semi-arid areas. The development of luminescence dating techniques and our understanding of loess palaeosol sequences have progressed over the past 35 years with both fields of study supporting the development and understanding of the other. Luminescence dating dosimeters are grains of feldspar and quartz, which are both typically abundant in loess, and, because loess is a fine-grained aeolian deposit and its nature implies medium-to-long transport distances, any previous luminescence signal should be reset (or ‘removed’) prior to deposition. Luminescence dating is also an important tool for developing numerical chronologies for loess deposits, providing comparison of different records and the study of correlations between records. Furthermore, the event being dated is the last exposure of the sediments to daylight, which directly relates the luminescence age to the time of deposition of the sediment. Study and dating of loess deposits from different parts of Iran can help to test this hypothesis. Several investigations on loess deposits from North and North-eastern Iran (including North of Alborz Mountains, Gorgan and Gonbad Kavous) led to limited chronological results. On the other hand, although loess sediments have been distinguished in different parts of central Iran (i.e. Kerman and Yazd provinces) there was not a single study of loess deposits in this area so far. As a result, we decided to attempt a research on loess deposits of central Iran. One of important areas of loess remains in central Iran is Maibod area located in central part of Yazd Province. Maibod is located in the main high-way towards the Persian Gulf region. Loess deposits formed as local ridges accumulated on an extended fault-erosional terrace in southern side of Maibod. Since study and dating of such deposits can clarify parts of tectonic history of Maibod area the outcome from such research is correct can be crucial. Furthermore, investigation on loess deposits of such dating-free location can significantly add to its Quaternary Paleoenvironmental/Paleoclimatological knowledge. Consequently, we extracted a sample from parts of loess deposits over the Maibod terrace. The extraction point is located on the western side of Maibod City where the loess sediments becoming very hard and they formed wide varieties of yardang to interfluve ridges with a few meters height. Contaminated Quartz grains of 90–180 μm and the post IR single-aliquot regenerative-dose protocol were employed for De determination. Experiments were carried out in Oxford University using a Riso TA-15a automated TL/OSL system (Botter-Jensen, 1997) incorporating an IR laser diode (400mW, 830±5 nm), and a Strontium-90 beta source. After laboratory works and dating of the sample (at 30000 to 39000 years ago) the accumulation period has been distinguished at around the middle of the last glacial age (Wurm). Considering the major water erosion over both top loess (late Quaternary) and its green marl basement (Neogene) and due to the distinct slope escarpment (terrace-like feature) we can conclude that the accumulation phase was after the last fault activity. In other words, most active seismic event has happened earlier than loess deposition before 3000 to 39000 years ago. Due to the relatively intact feature of nearby ancient Narin castle (3000 years old) we can conclude that the most sever tectonic activities in the area occurred between 3000 to 40000 years ago approximately. Such single conclusion needs to be evaluated with more studies and many OSL dating on loess deposits of central Iran. | ||
| کلیدواژه‌ها [English] | ||
| Dating, OSL, loess, quaternary paleoclimate, meibod | ||
| مراجع | ||
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اسلامی، م.، 1393، مطالعه مورفولوژیکی و منشأیابی تراس‌های طبیعی شهر میبد. دانشگاه آزاد اسلامی میبد؛ دانشکده منابع طبیعی و کشاورزی، گروه ژئومورفولوژی؛ رساله کارشناسی ارشد. علیجانی، ب.، 1369، چگونگی تشکیل فرابار سیبری و تأثیر آن بر اقلیم شرق ایران. فصلنامه تحقیقات جغرافیایی مشهد، بنیاد پژوهش‌های آستان قدس رضوی، شماره 17، 52-41. فتاحی، م.، کریمی مؤید، ن.، واکر، ر. و طالبیان، م.، 1392، استفاده از لومینسانس نوری پس از مادون قرمز جهت اندازهگیری نرخ لغزش گسل گوک. مجله فیزیک زمین و فضا، 39 (2)، 13-28. کریمی، ع.، خادمی، ح.، و جلالیان، ا.، 1390، لس: ویژگیها و کاربردهای آن برای مطالعات اقلیم گذشته. پژوهش‌های جغرافیای طبیعی (دانشگاه تهران)؛ شماره 76، تابستان، 20-1.
Aitken, M. J., 1985, Thermoluminescence dating. Academic Press, London. Akram, H., Yoshida, M. and Ahmad, M. N., 1998, "Rock magnetic properties of the late Pleistocene Loess-Paleosol deposits in Haro River area, Attock basin, Pakistan: Is magnetic susceptibility a proxy measure of paleoclimate?", Earth, Planets and Space, 50, 129-139. Berberian, M., 2014, Earthquakes and Coseismic Surface Faulting on the Iranian Plateau. Elsevier, series: Developments in Earth Surface Processes (Book 17). Frechen, M., Kehl, M., Rolf, C., Sarvati, R. and Skowronek, A., 2009, Loess chronology of the Caspian Lowland in northern Iran. Quatern Int., 198, 220–233. Gerasimenko, N. and Rousseau, D. D., 2008, Stratigraphy and Paleoenvironments of the Last Pleniglacial in the Kyiv Loess Region (Ukraine). Quaternaire, 19(4), 293-307. Karimi, A., Khademi, H., Kehl, M. and Jalalian, A., 2009, Distribution, lithology and provenance of peridesert loess deposits in northeastern Iran. Geoderma, 148, 241–250. Kehl, M., Frechen, M. and Skowrenk, A., 2005, Paleosols derived from loess and loess-like sediments in the Basin of Persepolis, Southern Iran. Quaternary International, 1v.40-141, 135-149. Kehl, M., 2009, Quaternary Climate Change in Iran: The State of Knowledge. Erdkunde 63(1), 1-17. Lateef, A. S. A., 1988, Distribution, provenance, age and paleoclimatic record of the loess in Central North Iran. In: Eden, D.N., Furkert, R.J. (Eds.), Loess – its Distribution, Geology and Soil. Proceeding of an International Symposium on Loess, New Zealand, 14–21 February 1987. Balkema, Rotterdam, 93–101. Liu, T. and Ding, Z., 1998, Chinese loess and the paleomonsoon. Annual Review of Earth Planetary Science, 26: 111–145. Lowe, J. and Walker, M., 2015, Reconstructing Quaternary Environments. Routledge, Oxon (U.K.). Muhs, D. R., Roskin, J. and Tsoar, H., 2013, Origin of Sinai-Negev erg, Egypt and Israel: mineralogical and geochemical evidence for the importance of the Nile and sea level history. Quaternary Science Reviews, 60, 28-48. Murray, A. S. and Wintle, A. G., 2000, Luminescence dating of quartz using an improved single-aliquot regenerative-dose protocol. Radiation Measurement, 32, 57-73. Okhravi, R. and Amini, A., 2001, Characteristics and provenance of the loess deposits of the Gharatikan watershed in Northeast Iran. Global and Planetary Change, 28, 11-22. Pashaei, A., 1997, Physicochemical properties of loess deposits in Gorgan area. Geology Science Journal, 23-24, 67-78. Pecsi, M., 1990, Loess Is Not Just the Accumulation of Dust. Quaternary International, 7-8: 1-21. Pecsi, M., 1991, Problem of Loess Chronology. GeoJournal, 24(2), 143-150. Pecsi, M., 1995, The Role of Principles and Methods in Loess-Paleosol Investigations. GeoJournal, 36(2-3), 117-131. Pye, K., 1984, Some Perspectives on Loess Accumulation. Loess Letter, 11, 5-10. Pye, K., 1987, Aeolian Dust and Dust Deposits. 312 pp. Academic Press, London. Pye, K., 1995, The nature, origin and accumulation of loess. Quaternary Science Reviews, 14, 653–667. Roberts, H. M., 2008, The development and application of luminescence dating to loess deposits: a perspective on the past, present and future. Boreas, 37(4), 483-507, DOI 10.1111/j.1502-3885.2008.00057.x. Shackleton, N. J., 1977, The oxygen isotope stratigraphic record of the late Pleistocene. Philos. Trans. R. Soc. London, Ser. B., 280, 169-182. Smalley, I. J. and Vita-Finzi, C., 1968, The formation of fine particles in sandy deserts and the nature of ‘desert’ loess. Journal of Sedimentary Petrology, 38, 766–774. Stokes, S., Bailey, R. M., Fedoroff, N. and O’Marah, K. E., 2004, Optical dating of aeolian dynamism on the West African Sahelian margin. Geomorphology, 59(1), 281-291, DOI 10.1016/j.geomorph.2003.07.021. Thomas, D. S. G and Goudie, A., 2011, The Dictionary of Physical Geography. 3rd Edition, Blackwell, Oxford (U.K.). Thomas, D. S. G., Bateman, M. D., Mehrshahi, D. and O’Hara, S., 1997, Development and environmental significance of an eolian sand ramp of Last-Glacial age, central Iran. Quaternary Research, 48: 155-161. Thomas, D. S. G and Burrough, S. L., 2011, Climatic Frameworks: Legacies from the past. In: Arid Zone Geomorphology, Etd: Thomas, D. S. G. Wiley-Blackwell, Oxford, 27-52. Van Zeist, W. and Wright, H. E., 1963, Preliminary pollen studies at Lake Zeribar, Zagros Mountains, southern Iran. Science, 140, 65-67. Wintle, A. G., 1981, Thermoluminescence dating of Late Devensian loesses in southern England. Nature, 289, 479–480. Wintle, A. G., 1982, Thermoluminescence properties of fine-grain minerals in loess. Soil Science, 134, 164–170. Wright, J. S., 2001, Desert" loess versus "glacial" loess: quartz silt formation, source areas and sediment pathways in the formation of loess deposits. Geomorphology, 36, 231-256. | ||
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