气候变化领域集成服务门户(CCPortal): Transition from extrusion to flow tectonism around the Eastern Himalaya syntaxis

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DOI	10.1130/B31811.1
	Transition from extrusion to flow tectonism around the Eastern Himalaya syntaxis
	Chiu Y.-P.; Yeh M.-W.; Wu K.-H.; Lee T.-Y.; Lo C.-H.; Chung S.-L.; Iizuka Y.
发表日期	2018
ISSN	167606
起始页码	1675
结束页码	1696
卷号	130 期号:2021-09-10
英文摘要	Two contradictory plate-kinematic models, (1) collision extrusion and (2) mid- to lower-crustal-level flow, have been proposed for inducing crustal deformation surrounding the eastern Tibetan Plateau in response to the Cenozoic collision of India-Eurasia. A hybrid tectonic model indicating extrusion followed by crustal flow is established by new structural, petrological, and geochronological data obtained from the Gaoligong shear zone in western Yunnan, China. The 40Ar/39Ar ages for muscovite (34-31 Ma), biotite (23 Ma), and K-feldspar (33-21 Ma) mineral separates from the Gaoligong group, and a matrix crosscutting quartzofeldspathic dike produce a cooling path. By interlinking the synkinematic metamorphic conditions with the reconstructed cooling path, we find that the temperature dropped from 550 °C around ca. 34 Ma to 350 °C at ca. 32 Ma, and dropped again to 275 °C around ca. 22 Ma. The timing and kinematic mechanism of four ductile deformation events, followed by brittle deformation, is deciphered. The earliest D1 event deformed the Early Cretaceous granite (zircon U-Pb ages of 118-78 Ma), forming WNW-ESE-striking upright folds during the closure of the Neo-Tethyan ocean. The D2 event was associated with large-scale eastward thrusting and folding with top-to-the- N/NE sense of shear under upper-amphibolite- facies conditions between 50 and 35 Ma due to India-Eurasia continent-continent collision. D3 formed moderate NE-dipping, NW-SE-striking, left-lateral shear zones that accommodated the southeastward extrusion of Indochina around 35-28 Ma. The sinistral sense of shear S/C fabrics defined by muscovite folia with foliation-bounded myrmekite indicates that deformation occurred under middle- to lower-amphibolite-facies metamorphic conditions. The 28 Ma to 15 Ma steep N-S-trending, right-lateral Gaoligong shear belt (D4) is the dominant structural feature in this region. Chloritization of biotite and boudinaged sillimanite along S/C2 fabrics indicate that the crystalline rocks retrograded from amphibolite-facies into greenschist- facies conditions. This coincided with clockwise cataclastic flow around the Eastern Himalaya syntaxis due to gravitational collapse after delamination of the thickened Tibetan Plateau. © 2018 Geological Society of America.
语种	英语
来源期刊	Bulletin of the Geological Society of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/185083
作者单位	Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan; Center for General Education, National Taiwan Normal University, Taipei, Taiwan; Department of Geosciences, National Taiwan University, Taipei, Taiwan; Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan
推荐引用方式 GB/T 7714	Chiu Y.-P.,Yeh M.-W.,Wu K.-H.,et al. Transition from extrusion to flow tectonism around the Eastern Himalaya syntaxis[J],2018,130(2021-09-10).
APA	Chiu Y.-P..,Yeh M.-W..,Wu K.-H..,Lee T.-Y..,Lo C.-H..,...&Iizuka Y..(2018).Transition from extrusion to flow tectonism around the Eastern Himalaya syntaxis.Bulletin of the Geological Society of America,130(2021-09-10).
MLA	Chiu Y.-P.,et al."Transition from extrusion to flow tectonism around the Eastern Himalaya syntaxis".Bulletin of the Geological Society of America 130.2021-09-10(2018).