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Geoscience ›› 2021, Vol. 35 ›› Issue (02): 492-503.DOI: 10.19657/j.geoscience.1000-8527.2020.074

• Petrology • Previous Articles     Next Articles

Geochronology,Geochemistry and Tectonic Significance of Songkarsu Granites in Karamali,Eastern Junggar

YANG Shuo(), LIU Ge, JIN Liuyuan, ZHENG Haifeng   

  1. Xinjiang Institute of Geological Survey, Urumqi,Xinjiang 830000,China
  • Received:2019-08-01 Revised:2020-09-20 Online:2021-04-25 Published:2021-05-25

Abstract:

The Eastern Junggar region was magmatic active and intrusive rocks were extensively developed.The Songkarsu pluton is located in the eastern margin of Junggar and the southern side of the Karamaili tectonic belt. The small pluton is composed mainly of monzogranite and syenite granite. Zircon U-Pb dating yielded a formation age of (410.2±2.2) Ma(MSWD=0.30),representing the first Early Devonian granite reported in the southern margin of the Karamaili belt. The rocks are alkaline granitic,and are featured by high Si,low Ti,high Al,alkali-rich,Ca-poor,and weakly peraluminous. The granites belong to A2-type,and are (primitive mantle-normalized) enriched in large ion lithophile elements (LILEs, e.g., Rb,Th,U, and K) with obvious negative Sr,P and Ti anomalies. Based on regional geological data analysis, we considered that the Songkarsu pluton was formed under continuous expansion and growth after the initial opening of the Karamaili ocean basin.The Karamaili area was under extensional tectonic regime during the Early Devonian.

Key words: Devonian granite, geochronology, geochemistry, tectonic setting, Eastern Junggar, Karamaili

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