Age and origin of the Bulangshan and Mengsong granitoids and their significance for post-collisional tectonics in the Changning–Menglian Paleo-Tethys Orogen

Wang, Changming, Deng, Jun, Santosh, M., Yu, Longjun, McCuaig, T. Campbell, Carranza, Emmanuel John M., and Wang, Qingfei (2015) Age and origin of the Bulangshan and Mengsong granitoids and their significance for post-collisional tectonics in the Changning–Menglian Paleo-Tethys Orogen. Journal of Asian Earth Sciences, 113 (Part 2). pp. 656-676.

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Abstract

The subduction and collision tectonics in the Sanjiang region provide important insights into the evolution of the Paleo-Tethyan Orogen. Here we present LA-ICP-MS zircon U–Pb ages, Sm–Nd and Lu–Hf isotopic data, whole-rock major and trace element compositions of the Late Triassic magmatic rocks from the Mengsong and Bulangshan granitoids in this region. Zircon U–Pb dating of the Bulangshan and Mengsong granitoids yields crystallization age of 216–228 Ma, with zircon εHf(t) values ranging from −15.2 to −1.5. These granitoids are high-K calc-alkaline and muscovite-bearing. The rocks show peraluminous nature, and are enriched in large ion lithophile elements (Rb, K, U, and Th) and depleted in high field strength elements (Nb and Ti). They also display enrichment in light rare earth elements with strong negative Eu anomalies (δEu = 0.16). The geochemical and isotopic features suggest that the primary magma of the Bulangshan and Mengsong granitoids most likely originated from partial melting of the underlying Proterozoic metasedimentary rocks. The granitoid magmatism is correlated with post-collisional tectonics, and provides important constraints on the timing of closure of the Paleo-Tethyan Ocean.

Item ID: 41370
Item Type: Article (Research - C1)
ISSN: 1878-5786
Keywords: zircon U–Pb geochronology; geochemistry; Nd–Hf isotope; post-collision; Paleo-Tethys; Sanjiang
Funders: National Basic Research Program of China, China Scholarship Council (CRC), Fundamental Research Funds for the Central Universities (FRFCU), Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China (PCSIRT)
Projects and Grants: NBRP No. 2015CB452603, NBRP No. 2009CB421008, CRC No. 201406405006, FRFCU No. 2652013034, PCSIRT 111 Project No. B07011
Date Deposited: 02 Dec 2015 02:10
FoR Codes: 04 EARTH SCIENCES > 0402 Geochemistry > 040203 Isotope Geochemistry @ 35%
04 EARTH SCIENCES > 0402 Geochemistry > 040202 Inorganic Geochemistry @ 30%
04 EARTH SCIENCES > 0403 Geology > 040303 Geochronology @ 35%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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