滇西老厂隐伏斑岩-矽卡岩型钼矿床成矿过程与物质来源

发布时间：2018-07-07 13:40

  本文选题：老厂 + 斑岩-矽卡岩型钼矿床　； 参考：《岩石学报》2017年07期

【摘要】：滇西老厂新生代隐伏斑岩-矽卡岩矿床位于西南三江特提斯南段昌宁-缝合带内,是缝合带内目前发现唯一的钼矿床。前人的研究主要围绕新生代岩体展开,而对于有关的斑岩-矽卡岩成矿作用的研究尚待深化。本文对老厂斑岩-矽卡岩型钼矿床进行了岩相学、电子探针和硫同位素分析,探讨成矿物理化学条件和物质来源。斑岩型矿床成矿过程包括成岩期、钾化期与硅化期,矽卡岩型成矿过程包括进矽卡岩期、早退矽卡岩期和晚退矽卡岩期。斑岩与矽卡岩最终都经历了低温热液的改造。矿物学和电子探针分析表明:角闪石结晶温度为730~790℃,氧逸度NNO+1.6~2.5,成岩阶段具有高温和相对还原的特点;钾化及硅化阶段黑云母结晶温度从650℃逐步降低为450℃,然而相应的氧逸度由QMF+1.9升高为QMF+2.5。斑岩内辉钼矿的富集以及矽卡岩内金属硫化物的沉积,均与温度下降和氧逸度升高关系密切。已知斑岩全岩δ~(34)SVCDT(+3.00‰~+11.00‰)与无矿化斑岩全岩δ~(34)S组成一致,表明成矿物质主要来源于岩浆。金属硫化物δ~(34)SVCDT(-1.96‰~+1.99‰)组成与低氧逸度斑岩矿床的δ34S组成特征符合。本文为老厂钼矿床成矿机制提出了客观合理的解释,为丰富西南三江特提斯新生代斑岩-矽卡岩成矿系统的研究提供了新的参考。
[Abstract]:The Laochang Cenozoic concealed porphyry-skarn deposit in western Yunnan is located in the Changning-suture zone of the south section of Sanjiang Tethys in southwest China and is the only molybdenum deposit found in the suture zone at present. Previous studies mainly focus on the Cenozoic rock mass, but the study of porphyry skarn mineralization needs to be deepened. In this paper, the petrography, electron probe and sulfur isotope analysis of the Laochang porphyry skarn type molybdenum deposit are carried out, and the metallogenic physicochemical conditions and material sources are discussed. The ore-forming process of porphyry deposit includes diagenetic period, potassium stage and silicification stage, and skarn type metallogenic process includes skarn entry stage, early decaying skarn stage and late skarn stage. Porphyry and skarn both underwent the transformation of cryogenic hydrothermal solution. Mineralogy and electron probe analysis showed that the crystallization temperature of amphibole was 730 ~ 790 鈩，

本文编号：2105131