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Lithogeochemical characteristics and metallogenic mechanism of the Hetaoshu rich-PGE magmatic sulfide deposit in the Xiaoguanhe region, Panxi TEXT SIZE: A A A

The Hetaoshu rich-PGE magmatic sulfide deposit is located in Xiaoguanhe area, Huili County, the ore-bearing lithofaciy is a mafic-ultramafic intrusion, which is one of the magma sulfide deposits rich in PGE content in the Emeishan Large Igneous Province (ELIP). This paper will provide a basic study on major elements, trace elements and platinum-group elements for various rocks and ores in the intrusion, and we discussed the characteristic of magma source and parental magma, the degree of partial melting of the mantle, and the process of rock-forming and ore-forming. The study show that the Hetaoshu mafic-ultramafic rocks are products of tectonic-magmatic activity in the ELIP and belong to tholeiitic evolution trend, which have the similar characteristics with Emeishan basalts from the ratio of the trace elements. Primitive mantle-normalized patterns of Ni-Cu-PGE are similar with Jinbaoshan with the low ratio of Pd/Ir (1.5 similar to 13. 1), relative to the Ni and Cu, PGE is undepletion, relative to Os, Ir,, Ru and Rh, Pt and Pd are enrichment. By estimating, the parental magma was produced by fractional crystallization from picritic-like magmas generated by relatively high degrees (about 20. 17%) of partial melting of an OIB-type mantle source, with the composition of 11. 93% in MgO, 49. 88% in SiO2, 2. 61% in TiO2 and 13. 71% in FeOT. In comparison with several types of Ni-Cu-PGE magmatic sulfide deposits from the composition of PGE and sulfide segregation in the Xiaoguanhe area, the enrichment of platinum group elements and low of Cu/ Pd of the Hetaoshu deposit is similar with Jinbaoshan, this kind of characteristic indicated that, the sulfide might segregate from the PGE undepleted picritic-like magmas. By analysis of the mechanism of diagenesis and mineralization, in the early stage of magmatic evolution, the accumulation of mafic minerals which represented as olivine (about 12. 7%) occurred after the picritic-like magmas intruded deep-level chamber, and formed high-Mg basalt magma; affected by factors such as temperature reduction and crustal contamination, the partial residual high-Mg basaltic magma have undergone segregation (R = 2000 similar to 50000) when they flowed from deep to high level chamber; then the sulfide melt mixed with olivine, which form in magma conduit. Finally, under the impacts of tectonic compression, the olivine-sulfide mixtures formed rich-PGE intrusion by accumulation in high-level chamber, its highly variable R factor are corresponding with the wide range of PGE contents.

Publication name

 ACTA PETROLOGICA SINICA, 33 (7):2225-2240; JUL 2017

Author(s)

 Zhu FeiLin; Bai Mei; Tao Yan

Corresponding author(s) 

 ZHU Feilin 
 zhufeilin2000@163.com  
 - Chengdu Univ Technol, Coll Earth Sci, Chengdu 610059, Sichuan, Peoples R China
 - Appl Nucl Technol Geosci Key Lab Sichuan Prov, Chengdu 610059, Sichuan, Peoples R China

Author(s) from IGCAS   TAO Yan

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