A review of mineral systems and associated tectonic settings of northern Xinjiang,NW China

Geoscience Frontiers  2011年02期
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In this paper we present a review of mineral systems in northern Xinjiang,NW China,focussing on the Tianshan,West and East Junggar and Altay orogenic belts,all of which are part of the greater Central Asian Orogenic Belt(CAOB).The CAOB is a complex collage of ancient microcontinents,island arcs,oceanic plateaux and oceanic plates,which were amalgamated and accreted in Early Palaeozoic to Early Permian times.The establishment of the CAOB collage was followed by strike-slip movements and affected by intraplate magmatism.linked to mantle plume activity,best exemplified by the 250 Ma Siberian Traps and the 280 Ma Tarim event.In northern Xinjiang,there are numerous and economically important mineral systems.In this contribution we describe a selection of representative mineral deposits, including subduction-related porphyry and epithermal deposits,volcanogenic massive sulphides and skarn systems.Shear zone-hosted Au lodes may have first formed as intrusion-related and subsequently re-worked during strike-slip deformation.Intraplate magmatism led to the emplacement of concentrically zoned(Alaskan-style) mafic—ultramafic intrusions,many of which host orthomagmatic sulphide deposits. A huge belt of pegmatites in the Altay orogen,locally hosts world-class rare metal deposits.Roll-front.