Welcome to visit Geoscience!

Geoscience ›› 2021, Vol. 35 ›› Issue (04): 940-954.DOI: 10.19657/j.geoscience.1000-8527.2020.107

• Petrology • Previous Articles     Next Articles

Late Devonian Tectonic Transition in South Altyn Tagh: Constraints from Geochronology and Geochemistry of the Suoerkuli Monzogranite

YUAN Yaping1(), LIU Xiangdong2(), ZHANG Zhenkai2, ZENG Zhongcheng2, HE Yuanfang2   

  1. 1. Shaanxi Hydrogeology Engineering Geology and Environment Geology Survey Center, Xi’an,Shaanxi 710068, China
    2. Shaanxi Mineral Resources and Geological Survey Center, Xi’an,Shaanxi 710068, China
  • Received:2020-04-16 Revised:2020-12-01 Online:2021-08-10 Published:2021-09-08
  • Contact: LIU Xiangdong

Abstract:

Whole-rock major, rare earth and trace element compositions, as well as LA-ICP-MS zircon U-Pb ages of monzogranites from Suoerkuli in the Altyn Orogen are newly presented. LA-ICP-MS zircon U-Pb dating indicates that the monzogranites were formed at (377.5±1.6) Ma and (377.4±2.1) Ma. Geochemically, the rocks are characterized by relatively high Si (72.55%-76.41%) and total alkaline (K2O+Na2O=7.32%-8.59%), normal aluminum saturation index (A/CNK=0.92-1.08), and high TFeO/MgO (2.57-6.47), suggesting that the rocks are high-K calc-alkaline. These rocks have relatively high LREEs and remarkable negative Eu anomalies. Furthermore, they are enriched in elements of Rb, Th, Y, Zr, Hf and depleted in Ba, Sr, P, Ti. According to the geochemical characteristics, it is suggested that the monzogranites are classified as A1-type. The monzogranites were likely generated by the fractionation of the parental magma, which was produced by the partial melting of felsic crustal rocks led by mantle-derived material underplating. Based on the regional geological investigations and spatial-temporal distribution of the igneous rocks, we considered that the monzogranite was emplaced in an intraplate extensional environment, and generated in the transition from post-orogenic to intraplate tectonic regime in the Late Devonian.

Key words: zircon U-Pb geochronology, A-type granite, intraplate extension, Altyn Tagh

CLC Number: