Welcome to visit Geoscience!

Geoscience ›› 2020, Vol. 34 ›› Issue (05): 1015-1027.DOI: 10.19657/j.geoscience.1000-8527.2020.033

• Petrology • Previous Articles     Next Articles

Geochronological, Geochemical and Geological Significance of Huilong Gabbroic Pluton in Southeastern Guangxi

LI Daixian1(), KANG Zhiqiang1,2(), LIU Di1, CHEN Huan1, CAO Yan1, WEI Naishao1, WEI Tianwei1, WANG Rui1, LIU Dongmei1, ZHOU Tong1, LAN Haiyang3   

  1. 1. College of Earth Science, Guilin University of Technology, Guilin, Guangxi 541004, China
    2. Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration, Guilin, Guangxi 541004, China
    3. Liaoning Metallurgical Geological Exploration Research Institute Co, LTD, Anshan, Liaoning 114038, China
  • Received:2019-07-15 Revised:2020-05-15 Online:2020-10-28 Published:2020-10-29
  • Contact: KANG Zhiqiang

Abstract:

Early Mesozoic tectonics of South China has been disputed for decades. There are two prevailing view points for tectonic attributes: oceanic-continental subduction/collision or intracontinental tectonics. Previous studies mainly focus on the granitic rocks, causing multiple interpretations on its tectonic setting. The LA-ICP-MS zircon U-Pb age of Huilong gabbros is (245.8±1.7) Ma, showing that Huilong pluton was formed in the Early Triassic. The Huilong gabbros have relatively low contents of SiO2 (47.42%-48.80 %) and MgO (2.24%-2.62 %), and relatively high contents of TFe2O3 (18.24%-21.49 %), P2O5 (0.38%-0.88%) and TiO2 (1.66%-2.04%). The rocks are enriched in large ion lithophile elements (LILEs, such as Ba, Rb, and U) and depleted in high field strength elements (HFSEs, such as Nb, Ta, Zr, Hf, and Ti, (La/Yb)N=3.85-5.99), showing a significant positive Eu anomaly (δEu=1.04-1.48). Sr-Nd isotope characteristics, including ( 87Sr/ 86Sr)i=0.717,658 - 0.718,405 and εNd(t)=-10.30 to -10.71, demonstrate affinity to the EM II enriched mantle, and imply an enriched mantle source formed under the influence of ancient subduction events at Yunkai. Based on previous studies, the Huilong pluton was probably generated from the partial melting of an enriched mantle source under the backarc spreading of paleo-Pacific subduction beneath South China, with fractionation of mafic minerals.

Key words: gabbro, zircon U-Pb age, EM II enriched mantle, Huilong pluton, southeastern Guangxi

CLC Number: