Genesis and geological significance of hydrothermal Pb-Zn orebodies in the Xiarihamu mining area, East Kunlun Mountains, China

被引：0
|
作者：
Chen X. [1 ]
Wang H. [1 ]
Mao J. [1 ,2 ]
Yu M. [3 ]
Qiao J. [4 ]
Wang Z. [4 ]
机构：
[1] School of Earth Sciences and Resources, Chang’an University, Xi’an
[2] Ministry of Natural Resources Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing
[3] School of Geosciences and Info-Physics, Central South University, Changsha
[4] Qinghai No.5 Geological Mineral Exploration Institute, Xining
来源：
Earth Science Frontiers | 2023年 / 30卷 / 02期
关键词：
East Kunlun; ore genesis; Pb-Zn deposit; skarn; Xiarihamu;
D O I：
10.13745/j.esf.sf.2022.2.76
中图分类号：
学科分类号：
摘要：
The Xiarihamu deposit is a giant magmatic Ni-Co sulfide deposit discovered recently in the East Kunlun metallogenic belt. With the advancement of deep, peripheral ore prospecting, however, some distinct hydrothermal Pb-Zn-(Cu, Ag) orebodies—which are obviously different from the magmatic sulfide deposit—have been found at the Xiarihamu mining area, with nearly 100,000 tons of proven reserves. In order to further reveal their genesis and production background, a systematic study of the mineral alteration characteristics and metallogenic chronology of the newly discovered hydrothermal orebodies is carried out. The hydrothermal orebodies are mainly stratified in the marble/gneiss interlayer structural belt of the Paleoproterozoic Baishahe Formation of the Jinshuikou Group. The main metallic minerals are galena and sphalerite, followed by chalcopyrite, and the gangue minerals are pyroxene, garnet, epidote, chlorite, titanite, apatite, quartz, calcite, etc. According to EPMA analysis, the pyroxene is mainly composed of the diopside-hedenbergite series, with the end component mainly Di65.44-79.01Hd18.55-30.78Jo1.63-0.51; the garnet belongs to the andraditespessartine series, with the end component mainly Gro24.93-92.17And3.29-9.95(Spe + Alm)1.68-67.29; and the epidote and chlorite in the skarn are both characterized by high Mn contents. Based on the above results it is considered that the hydrothermal orebodies are of skarn type. The trace element composition of the hydrothermal titanite from the skarn is similar to that of typical hydrothermal titanite according to LA-ICP-MS analysis. It has relatively low ΣREE, is enriched in LREE, with small LREE/HREE fractionation, and has a Th/U ratio of 0.23-1.97 (averaging 0.94). By LA-ICP-MS in-situ U-Pb dating the 206Pb/238U weighted mean age (after 207Pb correction) of the hydrothermal titanite is (413.3 ± 3.6) Ma (n = 23, MSWD = 0.96), and for the hydrothermal apatite it is (414 ± 13) Ma (n = 17, MSWD = 1.03). These results indicate that mineralization of the skarn orebodies occurred in the Early Devonian, which is consistent with the metallogenic age (within the error range) of the magmatic Ni-Co sulfide ore body. Combined with the regional metallogenic geological conditions, this paper considers that there are two temporospatially related metallogenic systems-magmatic and hydrothermal systems-developed in the Xiarihamu mining area. Briefly, under the extensional background the upwelling of the mantle-derived magma results in the partial melting of rocks in the middle-upper crust to form a felsic magmatism chamber; the melts then rise along the extensional structure zone and differentiate to produce the ore-forming fluids which then react with Paleoproterozoic marble or calcareous siltstone to form the Pb-Zn-(Cu, Ag) orebodies. This paper provides direct metallogenic and chronological evidences for the existence of Devonian Pb-Zn skarn deposits in the East Kunlun metallogenic belt. It is of theoretical and practical significance, therefore, to consider the coexistence of magmatic and hydrothermal ore-forming systems in the region and carry out a comprehensive prospecting evaluation accordingly. © 2023 Science Frontiers editorial department. All rights reserved.
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页码：347 / 369
页数：22
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