Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by King, J. Articles by Zhang, H. F. Search for Related Content GeoRef GeoRef Citation

First field evidence of southward ductile flow of Asian crust beneath southern Tibet

¹ Department of Earth Sciences, The Open University, Milton Keynes MK7 6AA, UK
² Department of Geology, University of Leicester and Natural Environment Research Council Isotope Geosciences Laboratory, British Geological Survey, Keyworth NG12 5GG, UK
³ Department of Earth Sciences, The Open University, Milton Keynes MK7 6AA, UK
⁴ State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China

There is lively debate on whether Asian plate material was involved in southward flow of mid-lower crust in a ductile channel beneath southern Tibet. One argument against such involvement is the apparent absence of material derived from Asian lithosphere within the High Himalayan Series (Indian plate) that could represent the putative channel. A north-south–trending mid-Miocene dike swarm that intrudes the Tethyan sedimentary cover of the Sakya gneiss dome (Indian plate) yields new Sr-Nd isotopic data (⁸⁷Sr/⁸⁶Sr = 0.7071–0.7079; _Nd –4 to –6) indicating that these melts share the same source as Miocene dacitic dikes from north of the Indus-Tsangpo suture. Moreover, dikes on both sides of this suture represent crustal melts derived largely from mid-lower crust of the Asian plate, exposed today as the Nyainqentanglha gneisses that underlie the Gangdese batholith. We infer that melting of the Asian lithosphere extended south of the surface trace of the suture, requiring southward propagation of anatectic Asian middle crustal material during the Miocene. The emplacement ages of the southern dike swarm (12–9 Ma) thus delimit the timing of active southward ductile flow of Asian material.

Key Words: Himalaya • isotope geochemistry • tectonics • channel flow

This article has been cited by other articles:

				G.H.-N. Chan, D.J. Waters, M.P. Searle, J.C. Aitchison, M.S.A. Horstwood, Q. Crowley, C.-H. Lo, and J.S.-L. Chan Probing the basement of southern Tibet: evidence from crustal xenoliths entrained in a Miocene ultrapotassic dyke Journal of the Geological Society, January 1, 2009; 166(1): 45 - 52. [Abstract] [Full Text] [PDF]