地质学
地堑
结壳
高原(数学)
岩石圈
构造学
马来西亚令吉
地震学
地幔(地质学)
大陆地壳
古生物学
数学分析
生物化学
化学
数学
基因组
基因
作者
P. Blisniuk,Bradley R. Hacker,Johannes Glodny,Lothar Ratschbacher,BI Si-wen,Zhenhan Wu,Michael McWilliams,Andy Calvert
出处
期刊:Nature
[Nature Portfolio]
日期:2001-08-01
卷期号:412 (6847): 628-632
被引量:413
摘要
Tectonic models for the evolution of the Tibetan plateau interpret observed east–west thinning of the upper crust to be the result of either increased potential energy of elevated crust1 or geodynamic processes that may be unrelated to plateau formation2,3,4,5,6. A key piece of information needed to evaluate these models is the timing of deformation within the plateau. The onset of normal faulting has been estimated to have commenced in southern Tibet between about 14 Myr ago7 and about 8 Myr ago8 and, in central Tibet, about 4 Myr ago9. Here, however, we report a minimum age of approximately 13.5 Myr for the onset of graben formation in central Tibet, based on mineralization ages determined with Rb–Sr and 40Ar–39Ar data that post-date a major graben-bounding normal fault. These data, along with evidence for prolonged activity of normal faulting in this and other Tibetan grabens, support models that relate normal faulting to processes occurring beneath the plateau. Thinning of the upper crust is most plausibly the result of potential-energy increases resulting from spatially and temporally heterogeneous changes in thermal structure and density distribution within the crust and upper mantle beneath Tibet. This is supported by recent geophysical and geological data10,11,12,13,14,15,16,17, which indicate that spatial heterogeneity exists in both the Tibetan crust and lithospheric mantle.
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