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ثبت تغییرات اقلیم کواترنر پسین در پذیرفتاری مغناطیسی لس‌های آزادشهر | ||
| پژوهش های جغرافیای طبیعی | ||
| مقاله 2، دوره 48، شماره 2، تیر 1395، صفحه 175-191 اصل مقاله (1.27 M) | ||
| نوع مقاله: مقاله کامل | ||
| شناسه دیجیتال (DOI): 10.22059/jphgr.2016.59354 | ||
| نویسندگان | ||
| وحید فیضی1؛ حبیب علیمحمدیان2؛ قاسم عزیزی* 3؛ حسین محمدی4؛ علی اکبر شمسی پور5 | ||
| 1دانشجوی دکتری جغرافیا، اقلیم‌شناسی، دانشگاه تهران | ||
| 2استادیار گروه زمین‌شناسی (گرایش محیط مغناطیس)، سازمان زمین‌شناسی و اکتشافات معدنی کشور | ||
| 3دانشیار، گروه جغرافیای طبیعی، اقلیم‌شناسی، دانشگاه تهران | ||
| 4استاد، گروه جغرافیای طبیعی، اقلیم‌شناسی، دانشگاه تهران | ||
| 5استادیار، گروه جغرافیای طبیعی، اقلیم‌شناسی، دانشگاه تهران | ||
| چکیده | ||
| در این پژوهش، برش رسوبی نوده واقع در شمال شرق ایران برای بررسی وضعیت آب‌وهوایی گذشته بررسی شده است. تلفیقی از مرور سامان‌مند منابع کتابخانه‌ای و میدانی و کارهای آزمایشگاهی در این تحقیق استفاده شده است. به‌منظور انجام کار با بررسی‌های میدانی متوالی، محل و روش نمونه‌برداری مشخص شد. 237 نمونه به فواصل 10 سانتی‌متری از برش نوده نمونه‌برداری شد. پذیرفتاری مغناطیسی تمامی نمونه‌ها اندازه‌گیری شد و بر اساس نتایج به‌دست‌آمده از این آزمایش، نمونه‌های دارای نوسانات شدید افزایش یا کاهش میزان پذیرفتاری مغناطیسی، برای مطالعة سایر پارامترهای مغناطیسی انتخاب شد. نتایج این تحقیق نشان می‌دهد که میزان پذیرفتاری مغناطیسی، پسماند مغناطیسی طبیعی، پسماند مغناطیسی ایزوترمال اشباع‌شده و HIRM در لایه‌های لس کمتر از لایه‌های خاک دیرینه است. در مقابل، میزان S_0.3 در لایه‌های لس بیشتر از خاک‌های دیرینه است. نتایج این تحقیق نشان می‌دهد که برش رسوبی نوده در طول 150 هزار سال گذشته، حدود هشت دورة آب‌وهوایی گرم و مرطوب (لایه‌های خاک دیرینه و شبه‌خاک دیرینه با میزان پذیرفتاری مغناطیسی بالا) در بین دوره‌های سرد و خشک (لایه‌های لس با میزان پذیرفتاری پایین) را تجربه کرده است. | ||
| کلیدواژه‌ها | ||
| برش رسوبی نوده؛ پارامترهای مغناطیسی؛ تغییرات اقلیم؛ رسوبات لس | ||
| عنوان مقاله [English] | ||
| Records of late quaternary climate changes in magnetic susceptibility of Azadshahr Loess | ||
| نویسندگان [English] | ||
| Vahid Feizi1؛ Habib Alimohammadian2؛ Ghasem Azizi3؛ Hossain Mohammadi4؛ Ali Akbar Shamsipour5 | ||
| 1PhD Candidate, Faculty of Geography, Climatology, University of Tehran, Iran | ||
| 2Assistance Professor, Environment Magnetic Laboratory, Department of Geology and Mineral Exploration, Iran | ||
| 3Associate Professor, Faculty of Geography, Climatology, University of Tehran, Iran | ||
| 4Professor, Faculty of Geography, Climatology, University of Tehran, Iran | ||
| 5Assistance Professor, Faculty of Geography, Climatology, University of Tehran, Iran | ||
| چکیده [English] | ||
| Introduction In general, loess sediments are one of the most widespread forms of aeolian sediments. During the past few decades, loess stratigraphy studies played key role in the investigation about global climate changes. These sediments are usually yellowish in color and silt makes 70 to 90 percent of its volume. In Iran, loesses outcrop are often in northeast part of south Caspian Sea. The previous studies revealed that loess/paleosol sequences correspond to cold/ warm period of climate, especially during quaternary period. Therefore, loess deposits are the most important natural archive of climate changes and are ideal for reconstruction of paleoclimate and geomorphological change in Quaternary. The thick loess/paleosol sequences of northeast Iran provide unique opportunity to reconstruct the terrestrial paleoclimate changes recorded in these sediments. A number of loesse-paleosol sequences contain a magnetic record of palaeoclimate through the Quaternary period. Anisotropy of magnetic susceptibility (AMS) was mentioned as a good tool to determine paleocurrent or paleodirection. AMS measurements were mostly used in the investigation of igneous, metamorphic and sedimentary rocks with an increasing number of applications in Quaternary loess and paleosol studies since the end of the1980s. The sediment magnetic properties depend on the magnetic content and characteristics of the source material and post-depositional weathering/soil formation processes. Loess in north of Iran is part of world loess belt and evidence of paleoclimate changes in continent. Materials and Methods In this study, Azadshar (Nowdeh Loess Section) was selected to reconstruct Late Quaternary climate change. The Nowdeh loess section with about 24 m thickness was sampled in 10 cm intervals for magnetometry analysis. For this aim, sampling location and method was determined after consecutive study area. This study used reformed review of library references and lab practices combination. Magnetic susceptibility of all samples was measured in Environmental and Paleomagnteic laboratory based on Geological Survey of Iran. All samples were placed in an 11 cm3 plastic cylinders to be used in magnetic measurement instruments. Magnetic susceptibility was measured using AGICO company made Kappabridge model MFK1-A instrument. Magnetic susceptibility of all samples was measured. Based on results of this study, samples with high frequency in magnetic susceptibility (increasing or decreasing) were selected for other studies of magnetic parameters. Results and Discussion The variation of magnetic susceptibility signal in the Nowdeh section suggests variation in climate conditions and mechanisms during the Late Quaternary. The magnetic susceptibility relationship with Loess/paleosol deposits resulted in low magnetic susceptibility values in cold and dry climate periods (Loess) and high magnetic susceptibility values in warm and humid climate periods (paleosoil). Therefore, one can say that Loess and paleosol sequences of this area were formed in glacial and interglacial periods and under different climate condition. Results of this study indicated that Magnetic Susceptibility, Natural remanent magnetization, Saturation isothermal remanent magnetization and HIRM in loess was less than paleosol. Instead, the amount of S_0.3 in loess layers was more than paleosol. Results of this study show that Nowdeh section has seen 8 periods of hot and humid climate (paleosol layers and similar paleosol layers with high magnetic susceptibility) in cold and dry periods (loess layers with low magnetic susceptibility) during past 150 ka. Conclusion This study was conducted to investigate and evaluate the capability of magnetite properties in reconstruction of Late Quaternary paleoclimate condition recorded in loess/paleosol deposits of Nowdeh section in Golestan province, northeast Iran. Nowdeh loess/paleosol sequence is an indicator for periodic dry-cool (deposition of loess) and moist-warm (formation of paleosol) conditions. Formation of the studied loess and paleosols has probably taken place in glacial and interglacial cycles with different climatic conditions, respectively. Nowdeh section magnetic properties are completely matched with Neka sediment result that has obtained by Mahdipour et al. (2013). In 20 to 48 ka of past years, in two sediment sections magnetic susceptibility was similar and wherever increased, hot and humid period are integrated with paleosol layer formation. The results of this research are also in accordance with Bear and Storm (1995) in saturation of beryllium in Xifeng section and isotope δ18 of marine sediment. This indicate that climate change event in two section are simultaneous. Finally, we should say that magnetic properties depending on sensible mineral to climate change, is a very useful variable for climate change reconstruction. | ||
| کلیدواژه‌ها [English] | ||
| climate change, magnetic parameters, Nowdeh outcrop, loess sediments | ||
| مراجع | ||
10. Ghazanchaei, R.; Pashaei, A.; Khormali, F. and Ayoubi, Sh. (2008). Investigation on micromorphological properties of a loess-paleosol sequence in Naharkhoran, Gorgan, Agricultural Science and Nature Resources, 15(2).
11. Karimi, A., Khademi, H. and Jalalian, A. (2011). Loess: Characterize and application for paleoclimate study, Geography Research, 76: 1-20.
12. Mehdipour, F.; Alimohammadian, H. and Sabori, J. (2013). The Reconstruction of Late Quaternary Climatical Conditions in Part of North Iran (Neka Loesses) Using Magnetic Parameters and Geochemistry, Scientific Quarterly Journal of Geosciences, 23(89).
13. Nabavi, M. (1976). Introduction geology of Iran, 1-109pp.
14. An, Z.S.; Kukla, G.; Porter, S.C. and Xiao, J.L. (1991). Magnetic susceptibility evidence of monsoon variation on the Loess Plateau of Central China during the last 130,000 years. IEEE International Geoscience and Remote Sensing Symposium, Boston, Massachusetts, pp. II1227-30.
15. Balsam, W.; Ji, J.F. and Chen, J. (2004). Climatic interpretation of the Luochuan and Lingtai loess sections, China, based on changing iron oxide mineralogy and magnetic susceptibility. Earth and Planetary Science Letters, 223: 335-348
16. Beer, J. and Sturm, M. (1995). Dating of lake and loess sediments, Radiocarbon, 37(P): 81-86.
17. Bloemendal, J., King, J.W., Hall, F.R., and Doh, S.J., 1992. Rock magnetism of late Neogene and Pleistocene deep–sea sediments: Relationship to sediment source, diagenetic processes, and sediment lithology. Journal of Geophysical Research, Vol. 97, pp. 4361–4375.
18. Bloemendal, J., Liu, X.M., Sun, Y.B., Li, N.N., 2008. An assessment of magnetic and geochemical indicators of weathering and pedogenesis at two contrasting sites on the Chinese Loess Plateau. Palaeogeogr. Palaeoclimatol. Palaeoecol. 257, 152–168.
20. Dekkers, M.J. (1997). Environmental magnetism: an introduction, Geology, Mijnbouw, 76: 275-320.
21. Ding, Z.L.; Xiong, S.F.; Sun, J.M.; Yang, S.L.; Gu, Z.Y. and Liu, T.S. (1999). Pedostratigraphy and Paleomagnetism of a ~7.0 Ma Eolian Loess-red Clay Sequence at Lingtai, Loess Plateau, North-central China and the Implications for Paleomonsoon Evolution, Palaeogeography Palaeoclimatolohy Palaeoecology, 152: 49-66.
22. Frechen, M.; Kehl, M.; Rolf, C.; Sarvati, R. and Skowronek A. (2009). Loess Chronology of the Caspian Lowland in Northern Iran, Quaternary International, 198: 220-233.
25. Guo, X.; Liu, X.; Lu, X.; Guo, H.; Chen, Q.; Liu, Z. and Mingming, M. (2013). The magnetic mechanism of paleosol S5 in the Baoji section of the southern Chinese Loess Plateau, Quaternary International, 306: 129-136.
26. Guo, Z.T.; Ruddiman, W.F.; Hao, Q.Z.; Wu, H.B.; Qiao, Y.S.; Zhu, R.X.; Peng, S.Z.; Wei, J.J.; Yuan, B.Y. and Liu, T.S. (2002). Onset of Asian desertification by 22 Myr ago inferred from loess deposit in China, Nature, 416: 159-163.
27. Heller, F. and Evans, M.E. (1995). Loess magnetism. Reviwe Geophysical, 33: 211-240
28. Heller, F. and Liu, T.S. (1984). Magnetism of Chinese loess deposits", Geophysical Journal of the Royal Astronomical Society, 77: 141-125.
29. Heslop, D.; Langereis, C.G. and Dekkers, M.J. (2000). A new astronomical timescale for the loess deposits of Northern China. Earth and Planetary Science Letters, 184: 125-139.
30. Jahn, B.; Gallet, S. and Han, J. (2001). Geochemistry of the Xining, Xifeng and Jixian sections, Loess Plateau of China: eolian dust provenance and paleosol evolution during the last 140 ka, Chemical Geology, 178: 71-94.
31. Jia, J.; Xia, D.; Wang, B.; Zhao, S.; Li, G. and Wei, H. (2013). The investigation of agnetic susceptibility variation mechanism of TienMountains modern loess: Pedogenic or wind intensity model? Quaternary International, 296: 141-148.
32. Karimi, A.; Khademi, H. and Ayoubi, A. (2013). Magnetic susceptibility and morphological characteristics of a loess–paleosol sequence in northeastern Iran, Catena, 101: 56-60.
33. Karimi, A.; Khademi, H.; Kehl, M. and Jalaian, A. (2009). Distribution, Lithology and Provenance of Peridesert Loess Deposits in Northeast Iran, Geoderm, 148: 241-250.
34. Kehl, M.; Frechen, M. and Skowronek, A. (2005). Paleosols Derived from Loess and Loess-like Sediments in the Basin of Persepolis, Southern Iran, Quaternary International, 140/141: 135-149.
35. Kehl, M.; Sarvati, R.; Ahmadi, H.; Frechen, M. and Skowronek, A. (2006). Loess / Paleosolsequences along a Climatic Gradient in Northern Iran, Eisxeitalter und Gegenwart, 55: 149-173.
36. Maher, B.A. (2011). The magnetic properties of Quaternary aeolian dusts and sediments, and their palaeoclimatic significance. Aeolian Research, 3: 87–145.
37. Mullins, C.E. (1977). Magnetic susceptibility of the soil and its significance in soil science- A review, Journal of Soil Science, 28: 223-246.
38. 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.
39. Pashaei, A. (1996). Study of Chemical and Physical and Origin of Loess Deposits in Gorgan and Dasht Area, Earth Science, 23/24: 67-78.
40. Peck, J.A.; King, J.W.; Colman, S.W. and A.kravchinsky, V. (1994). A rock magnetic record from Lake Baikal, Siberia: Evidence for Late Quarternary climatechange, Earth Planet Sci. Lett., 122: 221-238.
41. Pécsi, M. (1990). Loess is not Just the Accumulation of Dust, Quaternary International, 7/8: 1-12.
42. Qin Huang, C.; Feng Tan, W.; KuangWang, M. and Koopal, L.K. (2014). Characteristics of the fifth paleosol complex (S5) in the southernmost part of the Chinese Loess Plateau and its paleo-environmental significance, Catena, 122: 130-139.
43. Robinson, S.G.; Maslin, M.A. and McCave, I.N. (1995). Magnetic-susceptibility variation in upper Pleistocene deep-sea sediment of the NE Atlantic- Implications for ice rafting and paleocirculation at the last glacial maximum, Paleoceanography, 10: 221-250.
44. Song, Y.; Shi, Z.; Dong, H.; Nie, J.; Qian, L.; Chang, H. and Qiang, X. (2008). Loess Magnetic Susceptibility in Central Asia and its Paleoclimatic Significance. IEEE International Geoscience & Remote Sensing Symposium, II 1227-1230, Massachusetts.
45. Spassov, S. (2002). Loess Magnetism, Environment and Climate Change on the Chinese Loess Plateau. Doctoral Thesis, ETH Zürich, 1-151pp.
46. Stocklin, J. (1968). Structural history and tectonics of Iran: a review. American Association of Petroleum Geologists Bulletin, 52(7): 1229-1258.
47. Thouveny, N.; de Beaulieu J.L.; Bonifay, K.M.; Creer, J.; Guiot, M.; Icole, S.; Johnsen, J.; Jouzel, M.; Reille, T. Williams and Williamson, D. (1994). Climate variations in Europe over the past 140 kyr deducedf rom rock magnetism, Nature, 371: 503-506.
48. Van Oorschot (2001). Chemical distinction between lithogenic and pedogenic iron oxides environmental magnetism, Faculty of aardwetenschappen, University Utrecht, 28:185.
49. Roberts, A.P., Cui, Y., and Verosub, K.L., 1995, Wasp–waisted hysteresis loops: Mineral magnetic characteristics and discrimination of components in mixed magnetic systems. Journal of Geophysical Research, Vol. 100, pp. 17909–924.
50. Wang, Y.; Evans, M.E.; Rutter, N. and Ding, Z.L. (1990). Magnetic susceptibility of Chinese loess and its bearing on paleoclimate,. Geophysical Research Letters, 17(13): 2449-2451.
51. Zech, M.; Zech, R.; Zech, W.; Glaser, B.; Brodowski, S. and Amelung, W. (2008). Characterisation and palaeoclimate of a loess-like permafrost palaeosol sequence in NE Siberia, Geoderma, 143: 281-295.
52. Ziyaee, A.; Pashaei, A.; Khormali, F. and Roshani, M.R. (2013). Some physico-chemical, clay mineralogical and micromorphological characteristics of loess-paleosols sequences indicators of climate change in south of Gorgan, Journal of Water and Soil Conservation, 20(1). | ||
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