Earth Science Frontiers ›› 2022, Vol. 29 ›› Issue (2): 146-163.DOI: 10.13745/j.esf.sf.2021.7.14

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Composition of the Fukeshan magmatic arc in the northern Great Xing’an Range: Constraints on the southward subduction of the Mongol-Okhotsk oceanic plate

LI Wenlong1(), YANG Xiaoping2,*(), QIAN Cheng2, LI Chenglu1, LÜ Mingqi1, CHENG Zhaoxun1, WANG Lijia1   

  1. 1. Heilongjiang Institute of Natural Resources, Harbin 150036, China
    2. Shenyang Center of Geological Survey, China Geological Survey, Shenyang 110034, China
  • Received:2021-04-15 Revised:2021-06-25 Online:2022-03-25 Published:2022-03-31
  • Contact: YANG Xiaoping

Abstract:

The Fukeshan magmatic arc extends north-east in Fukeshan-Gulianhe area, northern Great Xing’an Range. Its material composition, formation age and spatial distribution pattern are very important for studying the Late Triassic tectonic evolution of the Mongol-Okhotsk ocean. In this paper, the petrology, geochemistry and zircon U-Pb dating of gabbro, diorite and granodiorite from the Fukeshan magmatic arc are reported, aiming to furthering our understanding of the tectonic setting of the northern Great Xing’an Range during the Late Triassic. LA-ICP-MS zircon U-Pb dating yielded the crystallization ages of (205.7±2.2) Ma and (203.2±2.5) Ma for gabbro and granodiorite, respectively, which correspond to the tectonic-magmatic event in the Late Triassic. Petrological and geochemical study indicate that the gabbro and diorite belong to tholeiite and calc-alkaline transition series rocks with high Na, Al, Ca, Mg and Mg# contents and low Ti contents. They are enriched in large ion lithophile elements (LIFE) and light rare earth elements (LREE). The granodiorite belongs to calc-alkaline transition series rocks with high Si, Na and Al contents and low Mg contents. The rock has low content of Y and Yb, with no obvious negative Eu anomaly and belongs to O-type adakite. The Fukeshan magmatic arc has a distribution pattern from north to south, and the corresponding lithologic variation indicates the Mongol-Okhotsk ocean has a polarity of southward subduction.

Key words: northern Great Xing’an Range, Fukeshan magmatic arc, Late Triassic, Mongol-Okhotsk ocean, southward subduction

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