【摘要】：喀來(lái)子大型鋇-鐵礦床位于新疆西昆侖塔什庫(kù)爾干地區(qū),礦體賦存于原"布倫闊勒群"變火山-沉積巖序列中。作為西昆侖地區(qū)獨(dú)有的鋇-鐵礦床,其礦石具條紋-條帶狀構(gòu)造,礦石礦物以磁鐵礦和重晶石為主。礦區(qū)出露圍巖主要為變泥質(zhì)碎屑沉積巖(含石榴石二云石英片巖),并夾少量變火山熔巖(黑云斜長(zhǎng)變粒巖和黑云斜長(zhǎng)片麻巖等)。礦體夾層黑云斜長(zhǎng)片麻巖LA-ICP-MS鋯石U-Pb年齡顯示原火山熔巖的形成年齡為(537.2±6.4)Ma,從而間接約束了喀來(lái)子鋇-鐵礦床的成礦年齡。依此,本文建議"原古元古界布倫闊勒群"應(yīng)分離出一套寒武紀(jì)(火山)沉積-成礦系列。礦石中磁鐵礦氧同位素(δ18 O=5.0‰~9.2‰)、硫酸鹽(δ34S=39.3‰~41.4‰)和黃鐵礦硫同位素(δ34S=17.0‰~23.5‰)特征表明,喀來(lái)子鋇-鐵礦床為經(jīng)歷細(xì)菌還原作用(BSR)的熱液噴流沉積型礦床(SEDEX)。具體成因機(jī)制可能為:在早寒武世半封閉的海水環(huán)境中,富含鐵鋇的海底熱液沿?cái)嗔训葮?gòu)造噴流至海底,與周圍溫度較低的海水混合導(dǎo)致溫度、pH和氧逸度等因素發(fā)生突變,從而促使相關(guān)礦物沉淀。其中,重晶石為熱液流體中鋇與經(jīng)BSR作用后殘余的SO_4~(2-)反應(yīng)生成,黃鐵礦為含鐵熱液與SO_4~(2-)還原產(chǎn)物H_2S相結(jié)合形成。當(dāng)H_2S消耗完全后,富鐵熱液在弱氧化條件下沉淀于海底形成磁鐵礦。
[Abstract]:The Kalaizi large barium iron deposit is located in Tashkurgan area, West Kunlun, Xinjiang, and the orebody occurs in the original "Blunkaule Group" altered volcanic-sedimentary rock series. As a unique barium iron deposit in the West Kunlun area, its ore is striped and striped, and its ore minerals are mainly magnetite and barite. The exposed rocks of the mining area are mainly argillaceous clastic sedimentary rocks (including garnet quartz-quartz schist) and a small amount of metamorphic lava (black-cloud plagioclase and black-cloud plagioclase gneiss etc.). The LA-ICP-MS zircon U-Pb age of the La-ICP-MS gneiss in the intercalation of the orebody shows that the age of formation of the original lava is (537.2 鹵6.4) Ma, which indirectly constrains the metallogenic age of the Kalaizi barium iron deposit. It is suggested that a series of Cambrian (volcanic) sedimentation-metallogenic series should be separated from the Proterozoic Blunkole Group. The oxygen isotopes of magnetite (未 18O ~ (5.0 鈥，

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