Metallogenesis of the Tuomoerte Fe-(Mn) Deposit in Altay, Xinjiang

The Tuomoerte medium type iron deposit can be found in the metavolcanic-sedimentary sequence of the upper Kangbutiebao Formation from the Upper Silurian to Lower Devonian. The source of ore materials, mineralogenetic epoch and metallogenesis were studied by S stable isotope and geochronology and are reported in this paper. Three periods of mineralization can be distinguished on the basis of field evidence and petrographic analyses: volcano-sedimentation, magmatic-hydrothermal, and regional metamorphism. The majority of the Fe-Mn metallogenic activity occurred during the volcano-sedimentation period, some Fe and the majority of Cu mineralization occurred during the magmatic-hydrothermal period. The δ³⁴S values of pyrite from the volcano-sedimentation period ranged from 6.2‰ to 13.1‰ and -20‰, indicating that the sulfur was mainly derived from the volcanic rocks, with some minor contributions from the bacteria-reduced sulphate in the seawater. The δ³⁴S values of pyrite from the magmatic-hydrothermal period ranged from -1.8‰ to 8.5‰ and cluster between -1.8‰ to 3.8‰, indicating that the sulfur was mainly derived from the biotite granite porphyry dyke. The zircon U-Pb age by Laser Ablation-Multicollector Inductively Coupled Plasma-Mass Spectrometry (LA-MC-ICP-MS) of the meta-rhyolite of the Third Member of upper Kangbutiebao Fm is (406.7±4.3) Ma, and the age of biotite granite porphyry dyke, which intrude into Fe orebody, is (401.6±0.6) Ma. The zircon U-Pb ages indicate that the Fe-Mn mineralization period during the volcano-sedimentation and magmatic-hydrothermal periods coincides with early Devonian timing (401-407 Ma). The Fe-Mn and Fe-Cu mineralization were found to be related to volcanic eruption deposition and magma intrusion activities, respectively.