Epithermal deposits in North Xinjiang, NW China

Abstract

The North Xinjiang region (NW China) is an important part of the Central Asia Orogenic Belt, situated at the junction of Siberia, Tarim and Kazakhstan plates. It is an area characterized by multiple stages of Phanerozoic continental growth, during which several porphyry and epithermal systems were formed. The relationship of these mineral systems to the geodynamic evolution of the region has not yet been well understood. In this paper, we list the main geological characteristics of 21 significant epithermal precious and base metal deposits in North Xinjiang, and classify them into high-sulfidation and low-sulfidation styles, with the latter being predominant. We have selected seven epithermal deposits representing different styles formed under different tectonic regimes and discuss their geology and geochemistry in some detail. The depositscale geology and geochemistry of epithermal systems in North Xinjiang are essentially similar to those in other parts of the world. All epithermal deposits in North Xinjiang are hosted in volcanic rocks with ages ranging from Devonian to Triassic, with the Early Carboniferous volcanic sequences being the most important, followed by the Permian and Triassic. The Devonian-Early Carboniferous host rocks belong to the calc-alkaline series that developed in pre-collisional arc-back-arc basin systems; whereas the Permian-Triassic host volcanic rocks of shoshonite series formed in post-subduction regimes. Available isotopic ages of these epithermal systems cluster in two periods: Early Carboniferous ([320 Ma) and Late Carboniferous-Triassic (320-220 Ma), reflecting two metallogenic episodes that occurred during subductionrelated accretion and post-subduction collision regimes, respectively. Accordingly, three groups of epithermal deposits in North Xinjiang can be recognized as (1) precollisional deposits without or with negligible collisionalrelated modification, (2) deposits formed in collision regime and (3) ore systems strongly overprinted by fluid flow in post-subduction collision regime.

Geochronology and geochemistry of igneous rocks in the Bailingshan area: Implications for the tectonic setting of late Paleozoic magmatism and iron skarn mineralization in the eastern Tianshan, NW China

“…The eastern Tianshan region is an approximately 300 km wide orogenic collage that is bounded by the Junggar block to the north and Chen et al, 2012). (b) Geologic map of the eastern Tianshan (modified after Mao et al, 2005;Wang et al, 2006).…”

“…the Tarim craton to the south ( Fig. 1a; Chen et al, 2012). The northern Dananhu-Tousuquan arc is situated between the Kanggur and Dacaotan Fault (Fig.…”

Metamorphosed Pb–Zn–(Ag) ores of the Keketale VMS deposit, NW China: Evidence from ore textures, fluid inclusions, geochronology and pyrite compositions

“…The CAOB is an orogenic collage comprising ophiolite suites, magmatic arcs, Precambrian microcontinental massifs and several accretionary terranes, which resulted from the collision between the Siberia and TarimSinoKorean plates along the Solonker suture that progressively closed eastward from the end of Early Carboniferous to the Early Triassic (Chen, 2000;Chen et al, 2012;Sengor and Natal'in, 1996;Xiao et al, 2003Xiao et al, , 2009. In spite of diachronous oceanic closure, the CAOB is generally accepted as a late Paleozoic (320 to 256 Ma) or Hercynian (Variscan) orogenic belt .…”

Geology and fluid evolution of the Wangfeng orogenic-type gold deposit, Western Tian Shan, China

“…The Western Chinese Tian Shan is an important part of the CAOB as it is favorable for orogenic-type mineralization when considering metallogenic models for either subduction-related accretionary orogeny (Goldfarb et al, 1991(Goldfarb et al, , 2001 or continental collisional orogeny (Chen and Fu, 1992;Chen et al, , 2012aPirajno, 2009). However, so far only the Tianger gold belt has been reported to be orogenic-type in this area Zhu et al, 2007), which makes the Tianger gold belt (including the Wangfeng gold deposit) a useful window for providing insight into orogenic-type mineralization in the Western Chinese Tian Shan.…”