气候变化领域集成服务门户(CCPortal): Landscape evolution of a bedrock peneplain on the southern Tibetan Plateau revealed by in situ-produced cosmogenic Be-10 and Ne-21

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DOI	10.1016/j.geomorph.2012.02.024
	Landscape evolution of a bedrock peneplain on the southern Tibetan Plateau revealed by in situ-produced cosmogenic Be-10 and Ne-21
	Strobl, M.; Hetzel, R.; Niedermann, S.; Ding, L.; Zhang, L.
通讯作者	Strobl, M (通讯作者)
发表日期	2012
ISSN	0169-555X
EISSN	1872-695X
起始页码	192
结束页码	204
卷号	153
英文摘要	Low-relief bedrock surfaces that occur at high altitude are a common feature of Cenozoic mountain belts and have often been used to infer a significant amount of rock uplift after their generation at low elevation. The timescale over which such surfaces can be preserved at high elevation and the rate at which they are modified by weathering and erosion are poorly known. Here we use cosmogenic Be-10 and Ne-21 to quantify the landscape evolution of a bedrock peneplain in southern Tibet that occurs at an altitude of similar to 5300 m. The peneplain is developed in Cretaceous granitoids and Jurassic metasediments of the northern Lhasa block (90 degrees E, 31 degrees N) and originally had a minimum extent of similar to 150 km east-west and similar to 75 km north-south. It has been dissected by small rivers that generated a few hundred meters of relief and formed additional bedrock surfaces of limited extent at lower elevation. Local denudation rates for the peneplain and the lower bedrock surfaces - based on Be-10 concentrations in grus samples and amalgamated quartz clasts - cluster between 5 and 11 m Ma(-1) (mean = 8.1 m Ma(-1)) and are thought to be representative for the long-term rate of downwearing of these surfaces. Samples from bedrock outcrops and bedrock blocks yield more variable rates (3-20 m Ma(-1)), which partly overestimate the long-term lowering rate, presumably due to block tilting and bedrock inhomogeneity. Spatially averaged Be-10 denudation rates for small river catchments range from 9 to 16 m Ma(-1) (mean = 11.8 m Ma(-1)) and are only slightly higher than the local denudation rates. Hence, the incision and widening of valleys proceeds at low rates, which demonstrates that the landscape of the peneplain region is remarkably stable. The combined Ne-21 and Be-10 data in a subset of the samples suggest that the bedrock surfaces have experienced a simple exposure history without periods of burial. Thus, our data do not provide any evidence for extended periods of shielding by ice during past glaciations, which is consistent with the absence of erratic boulders and moraines in the peneplain region. (C) 2012 Elsevier B.V. All rights reserved.
关键词	LOWER CRUSTAL FLOW EROSION RATES NAM CO QUATERNARY GLACIATION HYDROLOGICAL CHANGES TERRESTRIAL ROCKS SURFACE UPLIFT EXPOSURE AGES SHEAR ZONE HALF-LIFE
英文关键词	Tibet; Peneplain; Denudation rate; Cosmogenic Be-10; Cosmogenic Ne-21
语种	英语
WOS研究方向	Physical Geography ; Geology
WOS类目	Geography, Physical ; Geosciences, Multidisciplinary
WOS记录号	WOS:000303294800017
来源期刊	GEOMORPHOLOGY
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/258052
推荐引用方式 GB/T 7714	Strobl, M.,Hetzel, R.,Niedermann, S.,et al. Landscape evolution of a bedrock peneplain on the southern Tibetan Plateau revealed by in situ-produced cosmogenic Be-10 and Ne-21[J]. 中国科学院青藏高原研究所,2012,153.
APA	Strobl, M.,Hetzel, R.,Niedermann, S.,Ding, L.,&Zhang, L..(2012).Landscape evolution of a bedrock peneplain on the southern Tibetan Plateau revealed by in situ-produced cosmogenic Be-10 and Ne-21.GEOMORPHOLOGY,153.
MLA	Strobl, M.,et al."Landscape evolution of a bedrock peneplain on the southern Tibetan Plateau revealed by in situ-produced cosmogenic Be-10 and Ne-21".GEOMORPHOLOGY 153(2012).