Structural and geochronological constraints on the tectono-thermal evolution of the Danba domal terrane, eastern margin of the Tibetan plateau

Zhou, Mei-Fu, Yan, Dan-Ping, Vasconcelos, Paulo M., Li, Jian-Wei and Hu, Rui-Zhong (2008) Structural and geochronological constraints on the tectono-thermal evolution of the Danba domal terrane, eastern margin of the Tibetan plateau. Journal of Asian Earth Sciences, 33 5-6: 414-427. doi:10.1016/j.jseaes.2008.03.003


Author Zhou, Mei-Fu
Yan, Dan-Ping
Vasconcelos, Paulo M.
Li, Jian-Wei
Hu, Rui-Zhong
Title Structural and geochronological constraints on the tectono-thermal evolution of the Danba domal terrane, eastern margin of the Tibetan plateau
Journal name Journal of Asian Earth Sciences   Check publisher's open access policy
ISSN 1367-9120
Publication date 2008-08-25
Sub-type Article (original research)
DOI 10.1016/j.jseaes.2008.03.003
Open Access Status DOI
Volume 33
Issue 5-6
Start page 414
End page 427
Total pages 14
Editor Bor-ming Jahn
Place of publication Kidlington, Oxford, UK
Publisher Pergamon/Elsevier Science Ltd
Language eng
Subject C1
970104 Expanding Knowledge in the Earth Sciences
040303 Geochronology
Abstract The Songpan-Ganze terrane of the Tibetan plateau is underlain by Neoproterozoic crystalline basement rocks of the Yangtze block. These basement rocks are exposed as a series of extensional tectonic domes that form a nearly north–south trending extensional belt more than 1000 km long in the eastern margin of the Tibetan plateau. In the Danba area, detachment faults separate the basement core complexes (e.g., the Gezong and Gongcai complexes) from the Paleozoic strata which have been thinned or removed completely. The cover sequences have undergone upper greenschist to lower amphibolite facies metamorphism to form the Danba schist and are overlain by the Triassic Xikang Group, a thick flysch sequence. Both the basement rocks and the Paleozoic rocks have undergone multiple stages of deformation and thus provide an excellent opportunity to study the tectono-thermal evolution of the eastern margin of the Tibetan plateau. Two stages of deformation, corresponding to three generations of foliation (S1, View the MathML source, and View the MathML source), have been recognized on the basis of structural and microscopic observations. We selected amphibole and biotite separates associated with distinct generations of foliation for 40Ar/39Ar dating using laser microprobe incremental heating technique to place numerical constraints on the major tectono-thermal events within the Danba area. The geochronogical results reveal an earliest metamorphic event at 258.6 ± 0.5 Ma (S1 biotite) and 263.6 ± 0.8 Ma (S1 amphibole), coinciding temporally with the mantle plume that produced the voluminous Emeishan flood basalts. The second event was a progressive extensional deformation first occurred at 159–166 Ma (View the MathML source amphibole) responsible for the earlier tectonic doming of the crystalline basement, and then the final tectono-thermal overprint recorded by View the MathML source foliation and View the MathML source metamorphism locally in the core complexes at 47–58 Ma for the Gezong complex and 64–81 Ma for the Gongcai complex. This major post-orogenic extensional event is believed to be a consequence of collision between the North China and South China blocks. The apparent discrepancy of the 40Ar/39Ar ages observed between localities suggests a slow cooling process associated with progressive uplift.
Keyword Eastern margin of the Tibetan plateau
Structure
Geochronology
Mantle plume
Post-orogenic extension
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2009 Higher Education Research Data Collection
School of Earth Sciences Publications
 
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Created: Fri, 17 Apr 2009, 06:37:06 EST by Ms Christine Sinclair on behalf of School of Earth Sciences