کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8912808 | 1639830 | 2018 | 59 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Coarse- versus fine-grain quartz OSL and cosmogenic 10Be dating of deformed fluvial terraces on the northeast Pamir margin, northwest China
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله

چکیده انگلیسی
Along the NE Pamir margin, flights of late Quaternary fluvial terraces span actively deforming fault-related folds. We present detailed results on two terraces dated using optically stimulated luminescence (OSL) and cosmogenic radionuclide 10Be (CRN) techniques. Quartz OSL dating of two different grain sizes (4-11â¯Î¼m and 90-180â¯Î¼m) revealed the fine-grain quartz fraction may overestimate the terrace ages by up to a factor of ten. Two-mm, small-aliquot, coarse-grain quartz OSL ages, calculated using the minimum age model, yielded stratigraphically consistent ages within error and dated times of terrace deposition to â¼9 and â¼16 ka. We speculate that, in this arid environment, fine-grain samples can be transported and deposited in single, turbid, and (sometimes) night-time floods that prevent thorough bleaching and, thereby, can lead to relatively large residual OSL signals. In contrast, sand in the fluvial system is likely to have a much longer residence time during transport, thereby providing greater opportunities for thorough bleaching. CRN 10Be depth profiles date the timing of terrace abandonment to â¼8 and â¼14 ka: ages that generally agree with the coarse-grain quartz OSL ages. Our new terrace age of â¼13-14 ka is broadly consistent with other terraces in the region that indicate terrace deposition and subsequent abandonment occurred primarily during glacial-interglacial transitions, thereby suggesting a climatic control on the formation of these terraces on the margins of the Tarim Basin. Furthermore, tectonic shortening rates calculated from these deformed terraces range from â¼1.2 to â¼4.6 mm/a and, when combined with shortening rates from other structures in the region, illuminate the late Quaternary basinward migration of deformation to faults and folds along the Pamir-Tian Shan collisional interface.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Quaternary Geochronology - Volume 46, June 2018, Pages 1-15
Journal: Quaternary Geochronology - Volume 46, June 2018, Pages 1-15
نویسندگان
Jessica A. Thompson, Jie Chen, Huili Yang, Tao Li, Bodo Bookhagen, Douglas Burbank,