Metallotectonics And Geochemistry Of The Baishiya Iron-Polymetallic Deposit, Dulan, Qinhai, China

Locating in the eastsouthern uplift edge of the Qaidam basin, Dulan, Qinhai, China, Baishiya Iron-Polymetallic Deposit is a skarn deposit controlled by the contact zones between granitic intrusive bodies and Carboniferous sedimentary to early Triassic volcanic rocks.Based on the metallgonenic geological setting of the Dulan region, and the theories of tectonometallogeny, geochemistry and metallogenic prognosis, the author has surveyed into ore geology of M1-M18 ore sections in Baishiya deposit, studied metallotectonic features and geochemistry of ores and wallrocks, proposed a metallogenic model, and points out the direction for further exploration. The main results are as follows:(1) The key cause of the coexistence of iron-copper-cobalt, copper-lead-zinc and tungsten-tin-molybdenum minerilizations is its special geological setting:the intersection of the North Qaidam Metallogenic Belt and North Kunlun Metallogenetic Belt, the junction among the deep fault in the northern edge of Qaidam Basin, middle Kunlun deep fault and Wahongshan deep fault, the North-South-trending tectonic-magmatic uplift between Qaidam Basin and the Gonghe Basin.(2) Baishiya iron-polymetallic deposit occurred in skarns from Carboniferous sedimentary to early Triassic volcanic rocks, related to the granitic magma intrusion (or hidden granite), belong to the exsoskarn type or distal skarn type, characterized with the mineralization zoning of upper magnetite phase and under sulfide phase.(3) Iron-Copper-Cobalt mineralizations are associated chiefly with the basement rocks and meta-basic granodiorite and dioritic rocks, whereas copper-lead-zinc and tungsten-tin-molybdenum mineralizations are mainly related to the cover rocks and the meta-acidic rocks such as biotitic granite, reflecting the fact of the former one with more mantle-derived elements and the latter one with more continental composition, as well as the evolution law of magma.(4) The granitic intrusion is the main source of ore-forming kinetics and ore-forming metals in the deposit. Contact skarn-type ore bodies are main explorating targets future in the Baishiya deposit.