本文關(guān)鍵詞： 老廠VMS礦床 昌寧-孟連縫合帶 流體包裹體 硫同位素 成礦作用　出處：《巖石學(xué)報》2017年07期 　論文類型：期刊論文

【摘要】：老廠Pb-Zn多金屬塊狀硫化物礦床是西南三江特提斯造山帶內(nèi)目前唯一報導(dǎo)的與OIB火山巖有關(guān)的VMS礦床,關(guān)于其成礦流體性質(zhì)和成礦物質(zhì)來源,以及由此約束的成礦作用過程依然值得深入研究。本文基于對該礦床Ⅰ號礦體群塊狀礦體和網(wǎng)脈狀礦化系統(tǒng)的野外觀察和礦相學(xué)研究基礎(chǔ)上,選取部分塊狀礦石中的方解石和網(wǎng)脈狀礦化中的石英開展流體包裹體熱力學(xué)研究,并對各類礦石的硫化物進(jìn)行硫同位素分析。結(jié)果顯示,兩類礦石的原生流體包裹體均屬于NaCl-H_2O體系,塊狀礦石成礦流體溫度110~158℃,鹽度13.2%~18.7%NaCleqv;網(wǎng)脈狀礦化成礦流體溫度186~371℃,集中在246~339℃,鹽度3.6%~19.8%NaCleqv,集中在6.9%~16.8%NaCleqv。從下部網(wǎng)脈狀礦化到上部塊狀礦體的成礦溫度降低,反映較高溫度的成礦熱液沿噴流通道上升至海底面與海水作用并降溫。該過程中流體鹽度并未發(fā)生明顯下降,推測成礦前海底可能已存在較高鹽度的鹵水。各類礦石硫化物δ~(34)S值基本一致,均在-0.69‰~1.32‰,組成穩(wěn)定(極差僅2.01‰),呈集中于零值的分布特征。共生硫化物對中δ~(34)S黃鐵礦閃鋅礦方鉛礦,說明硫同位素基本達(dá)到分餾平衡。硫化物集中零值的硫同位素組成,既不同于由海水硫酸鹽無機還原造成的明顯正δ~(34)S值,也不同于有機(細(xì)菌)還原造成的明顯負(fù)δ~(34)S值,因此提出硫來源于礦體下盤基性火山巖,通過海水循環(huán)淋濾含礦巖系或者直接源于淺部巖漿房的釋氣作用。綜合前人C-H-O-Pb同位素組成研究結(jié)果,認(rèn)為老廠VMS型礦床形成過程中發(fā)生過巖漿釋氣作用,為成礦提供了硫和金屬成礦物質(zhì)、以及初始成礦流體。
[Abstract]:Laochang Pb-Zn polymetallic massive sulphide deposit is the only VMS deposit related to OIB volcanic rocks reported at present in the Sanjiang Tethys orogenic belt in southwest China. Its ore-forming fluid properties and ore-forming material sources are discussed. This paper is based on the field observation and mineralogical study of the block orebody and the network vein mineralization system of the No. 1 ore body group of the deposit. The thermodynamic study of fluid inclusions is carried out by selecting calcite from some massive ores and quartz from reticulated vein mineralization, and sulfur isotopic analysis of sulfides of all kinds of ores is carried out. The results show that. The primary fluid inclusions of the two types of ores belong to the NaCl-H_2O system. The ore-forming fluid temperature of the massive ore is 110 ~ 158 鈩，

本文編號：1493711