Metallogenesis of Batebakebulake iron deposit in Altay, Xinjiang
Yang Junjie1, Chai Fengmei1, Yang Fuquan2, Zhang Zhixin3
1. Xinjiang Key Laboratory for Geodynamic Processes and Metallogenic Prognosis of the Central Asian Orogenic Belt, Xinjiang University, Ürümqi 830049;
2. Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037;
3. Xinjiang Research Center for Mineral Resources, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Ürümqi 830011
The Batebakebulake iron deposit occurs in metavolcanite-sedimentary sequence of the Upper Silurian-Lower Devonian Kangbutiebao Formation, with the host rocks being garnet skarn, hornblende-plagioclase leptynite, leptite. Ore bodies are largely concordant with the bedding of the strata, and occurs as stratiform-like, lenses and irregular shapes, the distribution of the ore bodies is spatially related to skarn. Research shows that fluid inclusions in garnet of skarn stage are pure vapor inclusions, vapor inclusions, liquid inclusions, daughter mineral-bearing inclusions and melt mineral-bearing inclusions. Retrogressive metamorphism stage is liquid inclusions and a little vapor inclusions. Quartz-sulfide stage is main liquid inclusions, three-phase CO2-type inclusions and a little pure vapor inclusions, vapor inclusions, daughter mineral-bearing inclusions. Homogenization temperatures of fluid inclusions in skarn stage vary from 217 ℃ to 499 ℃, with the peak around 255 ℃, salinity ranges from 8.68% to 22.65% NaCl equiv. Homogenization temperatures of fluid inclusions in retrogressive metamorphism stage vary from 181 ℃ to 432 ℃, with the peak around 225 ℃, salinity ranges from 12.85% to 22.65% NaCl equiv. Homogenization temperatures of fluid inclusions in quartz-sulfide stage vary from 140% to 482 ℃, with the peak around 155 ℃, salinity ranges from 0.18% to 42.40% NaCl equiv. The δ18 OSMOW values of garnet, quartz and calcite range from 1.8‰ to 7.1‰, with the corresponding δ18 OH2O values between -4.79‰ and 4.57‰, and δDSMOW values of fluid inclusions between -128‰ and -84‰. The combined isotopic data imply that the ore-forming fluids of the skarn stage in the Batebakebulake iron deposit were mainly derived from magmatic fluids, with a minor part from the meteoric water, and in quartz-sulfide stage meteoric water increased obviously. The δ13 CV-PDB values of calcite from the Batebakebulake iron deposit define a narrow range of -3.2‰ to -2.0‰, indicating that the carbon in the fluids was mainly derived from the mantle or a deep-seated place.