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Geoscience ›› 2022, Vol. 36 ›› Issue (01): 333-346.DOI: 10.19657/j.geoscience.1000-8527.2022.01.30

• Geochemistry • Previous Articles     Next Articles

Geochemistry, Zircon U-Pb Chronology and Lu-Hf Isotope Characteristics of Monzogranites from Aishan Pluton in Jiaodong Peninsula

LI Xiuzhang1(), WANG Ligong1(), LI Yixin2, WANG Yingpeng1, YU Xiaowei1, ZHANG Wen1, GUO Ruipeng1, LIU Handong1   

  1. 1. Shandong Institute of Geological Survey, Jinan, Shandong 250013, China
    2. College of Earth Sciences, Guilin University of Technology, Guilin, Guangxi 541006, China
  • Received:2021-03-31 Revised:2021-09-03 Online:2022-02-10 Published:2022-03-08
  • Contact: WANG Ligong

Abstract:

The large-scale gold mineralization in Jiaodong Peninsula occurred from 125 to 110 Ma. Early Cretaceous Aishan pluton, coincided with the gold mineralization, is distributed in the eastern margin of North China Craton. Aishan pluton is composed of deep-facies quartz diorite-porphyry monzonitic granite and shallow-facies diorite porphyry, granite porphyry, etc., and develops mafic enclaves. Based on the studies of the petrography, geochemistry, zircon LA-ICP-MS U-Pb dating and Lu-Hf isotopic constitution of Aishan monzogranites, this paper discusses the petrologic classification, forming age, magmatic source and petrogenesis. Zircon U-Pb age of Aishan pluton is( 115±1)Ma. Aishan pluton is characterized by Na2O>3.47, A/CNK<1.35, high Y content (8.2×10-6-210.5×10-6), low Sr/Y ratio (19.5-67.3), with obvious rare earth element fractionation (LREE/HREE=28.43-34.72, (La/Yb)N=46.38-56.74), and negative Eu anomaly (δEu=0.75-0.83). Aishan pluton is a set of quasi-aluminous-weak peraluminous high-potassium calc-alkaline rock series, showing the characteristics of I-type granite. Aishan monzogranites have zircon εHf(t) values of -19.7 to -16.0, and two-stage Hf model ages (TDM2) vary in range of 2.18-2.42 Ga. According to the petrology, geochemistry and Lu-Hf isotopic constitution, combined with the results of previous studies on the genesis of Weideshan granite, the authors hold that Aishan monzogranites are a production of mixture between crustal acid magma and mantle intermediate-basic magma. The magma mainly derived from ancient Proterozoic and Neoarchean continental crust material.

Key words: Aishan pluton, monzogranite, zircon U-Pb age, Lu-Hf isotope, Jiaodong Peninsula

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