The Zedong Window: A record of superposed Tertiary convergence in southeastern Tibet

	The Zedong Window: A record of superposed Tertiary convergence in southeastern Tibet
	Harrison, TM ; Yin, A ; Grove, M ; Lovera, OM ; Ryerson, FJ ; Zhou, XH
刊名	JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
	2000-08-10
卷号	105 期号:B8 页码:19211-19230
ISSN号	2169-9313
文献子类	Article
英文摘要	Determining the timing, magnitude, and location of deformation due to the Indo-Asian collision is widely acknowledged as an important step in understanding how the lithosphere responds during continental collision. A puzzling result of geological investigations of the Lhasa Block over the past 2 decades has been the apparent lack of significant Tertiary deformation there. Perhaps the most important structural feature of the Lhasa Block is the south directed Gangdese Thrust System, which developed along its southern edge. The thrust system, which separates the Andean-type batholith of southern Asia from rocks of Indian affinity, is obscured at most locations across southeastern Tibet by back thrusts of the younger, north directed Renbu Zedong Thrust System. The best documented site where both thrusts are exposed occurs near Zedong (Zedong Window). Systematic geochronologic analyses were conducted in this area. U-Pb zircon dating of three samples of a synkinematically to postkinematically deformed hanging wall granitoid (the Yaja granodiorite) cut by the Gangdese Thrust indicates a crystallization age of 30.4+/-0.4 Ma (2 sigma), thus placing an upper bound on the initiation of the thrust, U-Pb zircon dating of granitoid samples structurally higher in the Gangdese hanging wall yields emplacement ages of 42.5+/-1.0 Ma and 48.9+/-0.8 Ma (2 sigma), similar to other magmatic complexes within the Gangdese are. Geochemical results are consistent with these plutons forming in the same environment as precollisional intrusions within the Gangdese batholith, suggesting a significant post-collisional input of juvenile heat. The Ar-40/Ar-39 thermochronology of samples from a vertical section through the hanging wall within the Yaja granodiorite, coupled with results of a numerical thermal model, indicate an average slip rate along the Gangdese Thrust of 7 mm/yr between 30 and 23 Ma and a minimum displacement of similar to 50 km, Farther east in the Zedong: Window, thermal effects produced by later north directed thrust sheets of the Renbu Zedong system appear to have obscured thermal history signatures in the Gangdese hanging wall related to earlier south directed thrusting. Thermochronological results from this region indicate that thermal overprinting related to the north directed thrusting occurred between 25 and 10 Ma, consistent with previous estimates.
WOS关键词	INDIA-ASIA COLLISION ; SOUTHERN TIBET ; U-PB ; INVERTED METAMORPHISM ; THERMAL EVOLUTION ; ACTIVATION-ENERGY ; VOLCANIC-ROCKS ; LHASA BLOCK ; MAGMATISM ; HIMALAYA
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	AMER GEOPHYSICAL UNION
WOS记录号	WOS:000088794600022
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/75778]
专题	中国科学院地质与地球物理研究所
通讯作者	Harrison, TM
作者单位	1.Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA 2.Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA 3.Univ Calif Lawrence Livermore Natl Lab, Inst Geophys & Planetary Phys, Livermore, CA 94550 USA 4.Acad Sinica, Inst Geol, Beijing 100029, Peoples R China
推荐引用方式 GB/T 7714	Harrison, TM,Yin, A,Grove, M,et al. The Zedong Window: A record of superposed Tertiary convergence in southeastern Tibet[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,2000,105(B8):19211-19230.
APA	Harrison, TM,Yin, A,Grove, M,Lovera, OM,Ryerson, FJ,&Zhou, XH.(2000).The Zedong Window: A record of superposed Tertiary convergence in southeastern Tibet.JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,105(B8),19211-19230.
MLA	Harrison, TM,et al."The Zedong Window: A record of superposed Tertiary convergence in southeastern Tibet".JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 105.B8(2000):19211-19230.