Earth Science Frontiers ›› 2022, Vol. 29 ›› Issue (1): 176-199.DOI: 10.13745/j.esf.sf.2021.8.12

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Metallogenic patterns and ore deposit model of the tin polymetallic deposits in the southern segment of Great Xing’an Range

ZHOU Zhenhua(), MAO Jingwen   

  1. MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, CAGS, Beijing 100037, China
  • Received:2021-01-20 Revised:2021-05-22 Online:2022-01-25 Published:2022-02-22

Abstract:

The tin polymetallic ore belt of southern Great Xing’an Range (SGXR) is the most important tin ore belt in northern China. Here, aiming to promote regional tin/silver prospecting, we systematically summarized the spatiotemporal distribution and metallogenic characteristics and proposed the deep dynamics and metallogenic models of the tin polymetallic deposits in SGXR. These deposits were formed in an extensional environment, with obvious spatial and temporal aggregation characteristics. They are located between the Erlian-Hegenshan, Huanggang-Ganzhu’ermiao and Xilamulun fault zones and formed mostly between 150-130 Ma, although multi-stage mineralization likely occurred in some large and medium-sized ore deposits. Even though tin mineralization is extensive, few highly differentiated ore-bearing granites are exposed so far, due probably to high background of ore-forming elements in the area, but also likely they are hidden in the depth. The tin polymetallic ore is mainly composed of tin, lead, zinc and silver, with few concurrent or accompanied tungsten mineralization. Multi-stage, multi-type mineralization is a result of multi-stage magma extrusion from a deep magma chamber, which produced ore-forming fluids with similar or different properties. Meanwhile, reactions between ore-forming fluids and surrounding rocks could also affect the fluid composition and evolution. Magma fluid exsolution, stratigraphic activation and extraction, mantle material, atmospheric precipitation, hot brine and metamorphic hydrothermal fluid all played a part in mineralization. Especially in the high temperature, low pressure environment, deep mafic magma degassing not only provided heat source for the mineralization, but also might provide an abundance of ore-forming element and volatile component. During the mineralization process, the main contributing factors for the super enrichments of metal elements were decreasing fluid temperature/pressure, mixing of fluids from different sources, immiscibility of supercritical fluids, multiple boiling of the fluids and water-rock interaction.

Key words: tin polymetallic deposits, spatiotemporal distribution, fluid exsolution, crust-mantle interaction, super enrichment mechanism, southern segment of the Great Xing’an Range

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