Earth Science Frontiers ›› 2022, Vol. 29 ›› Issue (1): 342-363.DOI: 10.13745/j.esf.sf.2021.1.63

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Deep magmatic process of the Fushan complex in the southern section of Taihang Mountain, Hebei Province and its tectonic significance

CUI Xiaoliang1,2(), SU Shangguo2,*(), ZHANG Yanan2, CHEN Xuegen2, SI Xiaobo2, HUO Xiaoyan2   

  1. 1. School of Water Conservancy and Hydropower, Hebei University of Engineering, Handan 056038, China
    2. School of Earth Sciences and Resources, China University of Geoscience (Beijing), Beijing 100083, China
  • Received:2020-05-16 Revised:2021-01-10 Online:2022-01-25 Published:2022-02-22
  • Contact: SU Shangguo

Abstract:

The complex deep crust-mantle interaction in the magmatic process, and the deep magma chamber system during the Mesozoic lithospheric thinning of the North China Craton, is poorly understood, and the shallow response of the deep magma process is also controversial. In this study the Fushan complex in the Han-Xing area in central North China Craton is studied. A detailed petrographical, mineralogical, geochemical and geochronological analysis was carried out to investigate the multiple magma chamber system, the deep magmatic process and its shallow response. Zircon U-Pb dating results show that the age of the fine-grained monzonite from the early Fushan complex suite is 129 Ma, and the age of the porphyritic monzonite from the late porphyry complex suite is 122 Ma. Petrographic observation and back scatter electron (BSE) images indicate both amphiboles and plagioclases in the Fushan complex have a complex annulus structure. Through the analysis of the crystal growth process and discussion on the origin of crystal zoning, we show that the crystal growth environment and process are rather complex. The high Mg, K and Sr contents in the Fushan complex and the origin of crystal zoning in hornblende and plagioclase provided proof that the deep magma underwent strong magmatic mixing and multiple magma chamber process controlled by the activity of magmatic fluids. The depth of the early intrusive suite of the Fushan complex is 7 km, and the emplacement depth of the late suite is 1.5 km, which shows that the crust was uplifted by 5.5 km at 7 Ma. Most of the intrusive rocks in the Fushan complex have high Sr, low Y and positive δEu, indicating they might be formed from partial melting of the thickened continental crust. These observations support the existence of an eastern plateau of China in the Late Mesozoic.

Key words: Fushan complex, mineral zoning, magma mixing, multiple magma chambers, eastern plateau

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