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Geoscience ›› 2018, Vol. 32 ›› Issue (06): 1263-1271.DOI: 10.19657/j.geoscience.1000-8527.2018.06.14

• Petrology • Previous Articles     Next Articles

Zircon U-Pb Age and Lithogeochemical Characteristics of Late Triassic Dacite in Sanchahe Area, Fengqing County, Western Yunnan Province

LI Guochang(), WANG Wei, YANG Ligang, TIAN Yinggui, FEI Zhibin, LI Weizhong   

  1. Yunnan Exploration Institute of Geology & Mineral Resources,Kunming,Yunnan 650051,China
  • Received:2018-03-19 Revised:2018-07-28 Online:2018-12-10 Published:2018-12-20

Abstract:

Volcanic rocks in Sanchahe area are mainly composed of dacite. LA-ICP-MS zircon U-Pb dating indicates that the dacite was formed in 209.7-218.8 Ma. Many inherited zircon cores of different periods were found, suggesting that the dacite have had complex magma source. The dacite contains high Si and Al contents, and belongs to high-K calc-alkaline series. The rocks show strongly fractionated REE pattern, medium negative Eu anomalies, depletions of Ta, Ba, Nb and Sr and enrichments of Rb and Th. This suggests that the dacitic magma was originated from the anatexis of crustal source. Integrating geochemical and geochronological results, we propose that the Sanchahe dacite formed in a post-collision extensional setting after the Paleo-Tethys closure.

Key words: Changning-Menglian suture zone, paleo-Tethys, dacite, zircon U-Pb dating, geochemistry

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