The Characteristics and Geological Significance of Calcite in-situ U-Pb Chronology,Pyrite Trace Elements and Sulfur Isotopes in the Shaping Uranium Deposit,Fenggang,Guizhou Province
To determine the mineralization age and material source of the Shaping uranium deposit,laser ablation inductively coupled plasma mass spectrometer(LA-ICP-MS)was used to conduct U-Pb dating of calcite,in-situ micro area analysis of trace elements and sulfur isotopes in pyrite.The results show that calcite and pyrite were formed in both the early and late mineralization stages of this deposit.The U-Pb dating of early mineralization cal-cite(Cal1)is(74.1±1.4)Ma,and late calcite(Ca12)is(22.1±0.8)Ma.The contents of elements such as Co,Se,Mo,Pb in the early mineralization of pyrite(Py Ⅰ),and Ni,As,Sb,Tl in late stage mineralization of pyrite(PyⅡ)are relatively high.The δ34S values are from-3.66‰ to+4.77‰(the average value is-0.42‰)in Py Ⅰ,and from-9.13‰ to-7.47‰(the average value is-8.49‰)in PyⅡ.The studies show that pyrite was formed in the medium-low temperature mineralization stage.Sulfur mainly was originated from deep sedimentary strata and metamorphic basement,carried to the metallogenic site by deep ore-forming fluids,and formed pyrite through thermochemical sulfate reduction.Under the background of the late Yanshan-Himalayan orogenic move-ment,the deep fluids transported upward and extracted the uranium in the Cambrian black rocks,which was min-eralized by hydrocarbon fluid pyrolysis and differentiation in the ore-forming favorable parts.The Shaping uranium deposit was controlled by deep organic fluid and composite structure.
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