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DOI	10.1016/j.quageo.2016.06.003
	ESR dating of glacial moraine deposits: Some insights about the resetting of the germanium (Ge) signal measured in quartz
	Yi, Chaolu; Bi, Weili; Li, Jianping
通讯作者	Yi, CL (通讯作者)
发表日期	2016
ISSN	1871-1014
EISSN	1878-0350
起始页码	69
结束页码	76
卷号	35
英文摘要	The electron spin resonance (ESR) dating of tills using germanium-doped (Ge) paramagnetic centers in quartz has advantages over other dating techniques, as quartz is common, processing is easy, and the technique has the potential for dating features several hundreds of thousands years old. ESR dating of moraines is based on the supposition that either subglacial comminution or exposure to sunlight resets the signal. However, actual dating suggests that a signal that is initially present cannot be bleached to zero by grinding alone. We found that grinding coarse samples (0.5-1 mm in diameter) to the mean grain size of fine sand (0.125-0.193 mm) reduced the signal intensity to 53-69% of its original value. From the value of the signal difference, one can devise a correction factor for ESR ages of subglacial sediment. Polymineralic grains are commonly present in till. Exposure of them to sunlight for several days can reduce the signal intensity to 7-8% of its original value within 1-2 mm thick of the sediment surface. However, within 5-8 mm of the sediment surface, exposure to sunlight for over one week only reduced the signal intensity to mean plateau values of 42-50% of the initial value. Mixing upper and lower layers of the samples during exposure to sunlight changed the signal intensity. This suggests that the amount of bleaching varies spatially. Sediments initially deposited at the margins of ice caps or ice sheets and subsequently overridden may have been sufficiently exposed to sunlight to allow ESR dating of moraines. The purity of the quartz and the grain size have significant impacts on signal intensity; intensive purification and the use of a uniform fine sand fraction are thus recommended. (C) 2016 Elsevier B.V. All rights reserved.
关键词	GRAIN-SIZE DISTRIBUTIONS UPPER URUMQI RIVER TIAN-SHAN QUATERNARY GLACIATION TIEN-SHAN CHINA TILL AREA MOUNTAINS EVOLUTION
英文关键词	ESR dating; Laboratory bleaching; Glacial moraine
语种	英语
WOS研究方向	Physical Geography ; Geology
WOS类目	Geography, Physical ; Geosciences, Multidisciplinary
WOS记录号	WOS:000381325500008
来源期刊	QUATERNARY GEOCHRONOLOGY
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/258647
推荐引用方式 GB/T 7714	Yi, Chaolu,Bi, Weili,Li, Jianping. ESR dating of glacial moraine deposits: Some insights about the resetting of the germanium (Ge) signal measured in quartz[J]. 中国科学院青藏高原研究所,2016,35.
APA	Yi, Chaolu,Bi, Weili,&Li, Jianping.(2016).ESR dating of glacial moraine deposits: Some insights about the resetting of the germanium (Ge) signal measured in quartz.QUATERNARY GEOCHRONOLOGY,35.
MLA	Yi, Chaolu,et al."ESR dating of glacial moraine deposits: Some insights about the resetting of the germanium (Ge) signal measured in quartz".QUATERNARY GEOCHRONOLOGY 35(2016).