Earth Science Frontiers ›› 2020, Vol. 27 ›› Issue (2): 420-441.DOI: 10.13745/j.esf.sf.2020.3.30

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Confirmation and metallogenesis of the Neoproterozoic rift in the western section of the northern margin of the North China Craton

PENG Runmin(), WANG Jianping   

  1. School of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing 100083, China
  • Received:2020-03-02 Revised:2020-03-10 Online:2020-03-25 Published:2020-03-25

Abstract:

The Langshan-Zha'ertaishan metallogenic belt, consisting of the Tanyaokou, Huogeqi, Dongshengmiao and Jiashengpan large-superlarge Zn-Pb-Cu-Fe sulphide deposits hosted in the Proterozoic Zha'ertaishan Group, is an important hydrothermal mineralization belt of the Proterozoic passive continental margin in an extensional structural regime in the western section of the northern margin of the North China Craton. Most areas of the mineralization belt distribute in the Langshan Mountain district. Three of the four typical deposits, the Huogeqi, Dongshengmiao and Tanyaokou deposits, occur in this region. It becomes an important scientific issue whether all the Mesoproterozoic Zha'ertaishan Group in the Langshan Mountain's core area and the three deposits hosted in the Zha'ertanshan Group be re-classified as the Neoproterozoic, after the 2010 discovery of acidic volcanic rocks with zircon ages of 816-805 Ma in the southwestern Langshan Mountain. Evidence includes (1) the minimum detrital zircon age of 1155 Ma for the meta-sedimentary rocks of the Precambrian strata with calcite marble from southern Langshan Mountain, (2) the detrital zircon age peaks at 1862-1762 (youngest age 1732 Ma) and 2448 Ma for the Liuhongwan Formation of the Zha'ertaishan Group with dolomate marble in the Tanyaokou district, (3) the occurrence of Neoproterozoic (887.4±9.1 Ma) meta-mafic volcanic rocks in the host formation of the Langshan Group in the north side of the Langshan Mountain, and (4) the “interbedding” of siliceous bands containing barite and microcrystal feldspar with pyrites, sometimes sphalerites and pyrrhotite and galena, with δ34S values of these four sulfide minerals varying between 17.60‰ and 21.97‰ and showing the characteristics of hydrothermal exhalation. Based on the evidence, we suggest the following: (1) the Zha'ertaishan Group hosting dolomite marble in the Tanyaokou district, and the Precambrian strata (formerly called the Zha'ertaishan Group) hosting acidic volcanic rocks and calcite marbles in southwest Langshan, were deposited in two different rift basins; (2) the Mesoproterozoic rifts and hydrothermal metallogenic systems in the south side of the Langshan Mountain developed the Tanyaokou and Dongshengmiao deposits in the Mesoproterozoic Zha'ertaishan Group; and (3) the Neoproterozoic rift and hydrothermal metallogenic system in the north side of the Langshan Mountain developed the Huogeqi orefield in the Neoproterozoic Langshan Group. The Huogeqi deposit hosted in the Neoproterozoic Langshan Group obviously appears to be a transitional type of mineral deposits between the SEDEX and VMS types with a bias towards SEDEX type.

Key words: Mesoproterozoic rift, Neoproterozoic rift, the western section of the northern margin of the North China Craton, Langshan, Inner Mongolia

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