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Abstract:A group of mafic_ultramafic plutons in East Tianshan Mountain intruded into the Lower Carboniferous turbudite of Gandun Formation and Middle Carboniferous basic volcanic rocks of Wutongwozi Formation (or Qi'e_shan Formation). Some of them are spatially and temporally associated with Cu-Ni sulfide deposits. Heated argument exists on the genesis of the suite of the mafic-altramafic rocks: some consider them to be post orogenic intrusions, while others hold that they should be ophiolites; therefore, the origin of the mineralization is still a problem of much controversy. The authors chose seven different types of Cu-Ni sulfide ore samples from the representative Huangshandong deposit to conduct Re-Os dating. The seven measured points defined an isochronal age of 282±20 Ma(2σ) with an initial 187Os/188Os of 0.24±0.04(MSWD) and a correction coefficient of 0.9987. The data suggest that the ore_forming age is younger than that of Early Carboniferous turbudite and Middle Carboniferous volcanic rocks which host the mafic_ultramafic rock intrusions, corresponding to the extension stage. They share the same mineralization time with the extensively developed orogenic gold and epithermal gold deposits and are younger than the porphyry copper system in the same area. Their initial 187Os/188Os value of 0.25±0.04 and mean γOs value of 99 indicate that abundant crustal substances were mixed with the Cu_Ni sulfide ore system during their formation process.
keywords:geochemistry Huangshandong Cu_Ni sulfide deposit East Tianshan Mountain Re_Os dating Permian
.2002.Re-Os Dating of Cu-Ni Sulfide Ores from Huangshandong Deposit in Xinjiang and Its Geodynamic Significance [J].Mineral Deposits21(4):323~330