Ore genesis of the unusual Talate Pb–Zn(–Fe) skarn‐type deposit, Altay, NW China: constraints from geology, geochemistry and geochronology

Abstract

The Talate ore field is located in the Abagong polymetallic metallogenic belt of the Altay Orogen, NW China. Lenticular ore bodies occur in the Kangbutiebao Formation, a package of intermediate-felsic marine volcanic rocks and terrigenous clastic sedimentary-carbonate rocks. Skarn alteration (mainly garnet) is present in both ore and wall rocks, especially the carbonate rocks. The mineral assemblages and crosscutting relationships of veins allow the alteration and mineralization process to be divided into four stages. From early to late, these are the early skarn (E-skarn), the late skarn with quartz-magnetite veins (QM), the quartz-sulphide (QS) and the quartz-carbonate (QC) assemblages. Quartz crystals are important gangue minerals in the latter three stages, in which four distinct compositions of fluid inclusions are identified based on petrography, microthermometry and laser Raman microspectroscopy, namely aqueous inclusions (W-type), pure CO 2 inclusions (PC-type), CO 2 -rich inclusions (C-type) and daughter mineral-bearing inclusions (S-type). Microthermometric data and laser Raman analyses show that the quartz crystals from the QM stage contain all four inclusion types, with the W-type being predominant. Homogenization temperatures range between 271 and 426°C. The salinities of the W-and C-type fluid inclusions range from 0.5 to 22.4 wt.% NaCl eqv., whereas the S-type fluid inclusions in the QM stage range from 31 to 41 wt.% NaCl eqv. Daughter minerals in the fluid inclusions include halite, sylvite, pyrite and calcite. Quartz from the QS stage (main mineralization stage) contains the W-, C-and PC-type inclusions, which are homogenized at temperatures of 204-269°C, with salinities of 0.2-15.6 wt.% NaCl eqv. Only W-type fluid inclusions have been identified in the QC stage. These yielded homogenizing temperatures of 175-211°C and salinities of 1.1-9.9 wt.% NaCl eqv. The C-type fluid inclusions of the main (QS) mineralization stage yield trapping pressures of 107-171 MPa, corresponding to a depth of 4-6 km. The sulphur isotope values (À1.7‰ and À6.6‰) imply that the QS stage may not be directly associated with the early skarn (À7.4‰) and quartz-magnetite stages (À4.8‰ and À5.0‰), though the QS stage is probably dominated by magmatic-hydrothermal fluids.40 Ar/ 39 Ar isotope plateau ages of 227.6 and 214.1 Ma for biotite separated from the QM and QS stages are significantly younger than the host Kangbutiebao Formation (ca. 410 Ma). The Talate Pb-Zn(-Fe) deposit is interpreted to be an unusual skarn-type system formed in a continental collision orogeny.

Geochemistry, zircon U–Pb analysis, and fluid inclusion 40Ar/39Ar geochronology of the Yingchengzi gold deposit, southern Heilongjiang Province, NE China

“…Thus, the Yingchegnzi mineralizing event was driven by the late Permian–Early Triassic continental collision regime between the North China and Siberia cratons, a tectonic event that generated ductile–brittle shear zones and faults within the Songnen–Zhangguangcai Range Massif which controlled the gold orebodies of Yingchengzi deposit. And this collision ultimately results in widely regional metamorphism, which was usually followed by intensive hydrothermal activities and triggered a large amount of mineralization of the CABO (Chen et al ., 2004, 2005, 2008, 2012, 2014a,b; D. F. Li et al ., 2014; Han et al ., ; J. Zhang et al ., 2014; Mao et al ., ; Wu et al ., ; Z.J. Zhang et al ., 2014; Zhang and Li, ).…”

Petrogenesis and tectonic setting of the Middle Permian A‐type granites in Altay, northwestern China: Evidences from geochronological, geochemical, and Hf isotopic studies

“…The sillimanite‐bearing metapelitic schist (635–670 °C and 5.8–6.8 kbar) was dated as 299.2 ± 3.4 Ma (Wang, Wei, Zhang, Chu, Zhao, & Liu, ). Recently, two ~280‐Ma pelitic granulites were identified, and the P–T estimates indicate peak conditions of >940 °C and 7.8–10 kbar and 970 °C and ~8 kbar, respectively (Li, Zhang, Chen, Zheng, Hollings, Wang, & Fang, ; Tong, Xu et al, ). These HT to ultrahigh‐temperature and low‐pressure metamorphic rocks reflect a high heat flow in the extensional environment in the Chinese Altay orogen during the Permian. Mafic–ultramafic rock: Permian mafic–ultramafic intrusions or dykes are widely distributed only along the Irtish suture zone, and they comprise, from west to east, the Hongguleneng mafic–ultramafic complex (273.3 ± 2.6 Ma; Zhang et al, ), the Qiemuqieke hornblende‐bearing gabbro (276.0 ± 2.1 Ma; Wan et al, ), the Kekesazi gabbro (281.2 ± 1.8 Ma) and mafic dykes (279.6 ± 3.6 Ma; Zhang, Zou et al, ), the Bayituobie gabbro (282.2 ± 2.8 Ma), the Jungeleke gabbro (283.6 ± 1.8 Ma), and the Palasier River gabbro (283.4 ± 1.4 Ma; Zhang, Zou et al, ), the Kalatongke mafic–ultramafic complex (287 ± 5 Ma; Han et al, ), and the Mayinebo gabbro (272.5 ± 2.4 Ma) and the Dasazi gabbro (269.4 ± 2.5 Ma; Zhang et al, ).…”

“…The sillimanite-bearing metapelitic schist (635-670°C and 5.8-6.8 kbar) was dated as 299.2 ± 3.4 Ma (Wang, Wei, Zhang, Chu, Zhao, & Liu, 2014b). Recently, two~280-Ma pelitic granulites were identified, and the P-T estimates indicate peak conditions of >940°C and 7.8-10 kbar and 970°C and~8 kbar, respectively (Li, Zhang, Chen, Zheng, Hollings, Wang, & Fang, 2014a;Tong, Xu et al, 2014a). These HT to ultrahigh-temperature and low-pressure metamorphic rocks reflect a high heat flow in the extensional environment in the Chinese Altay orogen during the Permian.…”

Indosinian tectonics and mineral systems in China: an introduction

“…The paper by D. F. Li et al (2014) presents age data from biotite separated from the quartz-magnetite ore and quartzsulphide ores at the Talate Pb-Zn(ÀFe) deposit which show 40 Ar/ 39 Ar plateau ages of 227.6 and 214.1 Ma, respectively, significantly younger than the host Kangbutiebao Formation (ca. 410 Ma), that is a package of intermediate-felsic volcanic rocks, clastic sediments, and carbonates.…”