新疆阿尔泰薄克土巴依铁锰矿地质特征及成矿作用

新疆薄克土巴依铁锰矿床赋存于下泥盆统康布铁堡组变质火山-沉积岩系中。本研究利用流体包裹体显微测温、氢和氧同位素以及年代学数据，探讨该矿床的成矿流 体性质及来源、成矿时代和成矿作用。结果表明，矿体呈层状，与地层产状一致，矿石具有块状、条带状、条纹状、细脉状和浸染状构造，矿化具有喷流沉积特征。成矿流体属中温(集中在200~320 ℃) 、低盐度(1.05%~4.49%)、中低密度的Na₂O-H₂O体系。重晶石的δD值为-129‰~-116‰，δ¹⁸O值变化于10.4‰~11.6‰，δ¹⁸O_H2O值为5.7‰~10.3‰，表明成矿流体来自深循环的海水与岩浆水的混合。矿体围岩变质安山岩的锆石LA-ICP-MS U-Pb年龄为(398.8±1.3) Ma，限定成矿时代在399 Ma左右，即为早泥盆世成矿。

Geological Characteristics and Metallogenesis of the Boketubayi Iron-Manganese Deposit in Altay,Xinjiang

The Boketubayi iron-manganese deposit is hosted in metavolcanic-sedimentary sequence of the Lower Devonian Kangbutiebao Formation. Fluid inclusion microthermometry, H-O isotopes, and geochronological dating have been carried out to investigate the nature and source of ore forming fluids, mineralization age, and ore-forming mechanism of this deposit. Geological features of the deposit indicate that the ore body was layered, which is consistent with formation occurrence. In addition, massive, banded, striped, thin veins, and disseminated ores were observed in this study, suggesting the mineralization has exhalative-sedimentary characteristics. Fluid inclusions belong to medium-temperature (cluster between 200 and 320 ℃), low salinity (1.05% to 4.49%), and low-to medium-density Na₂O-H₂O system. Stable isotope analysis of barite yielded δD values of -129‰ to -116‰, δ¹⁸O_SMOW values of 10.4‰ to 11.6‰, and _δ¹⁸O_H2O values of 5.7‰ to 10.3‰, respectively,indicating ore forming fluids derived from the mixing of deep circulation seawater and magmatic water. The LA-ICP-MS zircon U-Pb dating yielded an age of (398.8±1.3) Ma for ore-hosted metamorphic andesite, which indicates the ore forming age of Boketubayi deposit is around 399 Ma in Early Devonian.