张家坪子金矿床成矿机制及矿化富集特征
发布时间：2018-12-07 10:13
【摘要】：浅成低温热液型金矿床是中国重要的金矿床类型之一,为我国国民经济的发展提供着黄金资源的支持,从储量及金矿数量上相比国外虽有较大的差距,但随着我国地质找矿工作的不断开展,这类矿床的发现也将不断增加。张家坪子金矿地处扬子准地台西南缘与松潘-甘孜地槽接壤部位的冕西金矿集中区的茶铺子-盐源-巴折金成矿带,是我国著名的青藏-三江浅成低温热液金矿成矿区。该矿床历经数年勘查,局部控制深度超过500m,品位向深部变高,矿体深部仍有变富、变厚的可能。区内虽已查明金矿床(矿化点)多处,前人虽对该金矿的地质特征和找矿方向进行了初步探讨,但对成矿机制的认识并不统一;缺乏相应的研究资料。本文通过野外地质调查,查明了研究区地层、构造、岩浆岩及矿体的特征,结合同位素、流体包裹体等样品的实验数据,系统分析了张家坪子金矿床的成矿物质、成矿流体来源;并以板块构造成矿理论和幔源成矿理论为指导,综合前人研究资料,分析了研究区金矿床的成矿机制及矿化富集特征;为张家坪子金矿床“攻深找盲”提供理论依据;同时也为该地区相应类型的矿床研究工作提供指导。取得如下主要成果:(1)研究区三叠系中统的蚀变交代白云岩为金矿体的主要赋存岩性;矿体以似层状与透镜状呈南北展布,矿石矿物主要为黄铁矿和方铅矿,其次为黝铜矿与闪锌矿,少量的黄铜矿等;矿石多为网脉状构造和块状构造,属于低硫化物型矿石,主要载金矿物为黄铁矿;围岩蚀变主要有绿泥石化、碳酸盐化、黄铁矿化、硅化和绢云母化;褐铁矿化是表生作用的产物,可作为找矿的标志。(2)根据C、O、H、S稳定同位素及流体包裹体的研究,成矿热液为以变质水为主,夹杂少量岩浆水的混合源;金成矿物质主要来源于地幔。金矿床成矿温度集中于200℃-280℃之间,成矿深度集中于1.5-2.4km之间;矿床类型应属于浅成低温热液型金矿床。金成矿作用主要发生于1.54Ma-38Ma之间的喜山期,其主成矿年龄约为25Ma。(3)研究区金矿体主要位于司依诺背斜西翼的张家坪子剪切片理化蚀变带中三叠统内,矿体的产出状态完全受到张家坪子韧性剪切带的唯一控制;区内金矿体矿化富集比较集中的部位为张家坪子韧性剪切带内陡、缓交替的地段,围岩绿片岩形成圈闭构造的地段,也是金矿体富集的部位;另外,在区内小断层、劈理、节理、面理和片理构造发育处,也多有富矿的存在。(4)通过对S16号勘探线成矿元素原生晕的圈定,发现矿体出露位置均见有Hg、Sb、As等前缘元素富集,而中部(Pb、Cu、Zn)以及尾部(Bi、Mo、W)指示元素未见富集,深部仍有富矿体存在的可能,建议下一步向深部开展工作“攻深找盲”,扩大找矿成果。
[Abstract]:The epithermal hydrothermal gold deposit is one of the important types of gold deposits in China, which provides the support of gold resources for the development of China's national economy. However, with the development of geological prospecting in China, the discovery of these deposits will increase. Zhangjiapingzi gold deposit is located at the southwestern margin of Yangzi quasi platform and the contiguous part of Songpan-Ganzi geosyncline. It is a famous low-temperature hydrothermal gold mineralization area of Qinghai-Sanjiang in China. After several years of exploration, the local control depth of the deposit is over 500 m, the grade of the deposit is higher and the ore body is still rich and thicker. Although many gold deposits (mineralization sites) have been identified in the area, although the geological characteristics and prospecting direction of the gold deposit have been preliminarily discussed, the understanding of the metallogenic mechanism is not uniform, and the corresponding research data are lacking. Based on the field geological investigation, the characteristics of strata, structures, magmatic rocks and orebodies in the study area have been found out. Combined with the experimental data of isotopes and fluid inclusions, the ore-forming materials of the Zhangjiapingzi gold deposit have been systematically analyzed. Source of ore-forming fluid; Under the guidance of plate tectonics and mantle-derived metallogenic theory, the metallogenic mechanism and mineralization enrichment characteristics of gold deposits in the study area are analyzed based on the previous research data, which provide theoretical basis for "deep exploration blind" of Zhangjiapingzi gold deposit. It also provides guidance for the study of the corresponding types of ore deposits in this area. The main results are as follows: (1) the altered metasomatic dolomite of the Triassic in the study area is the main host lithology of the gold deposit; The ore bodies are layered and lenticular. The ore minerals are mainly pyrite and galena followed by tetrahedrite and sphalerite a little chalcopyrite and so on. The ore is mostly reticulated vein structure and block structure, belongs to low sulphide type ore, the main gold bearing material is pyrite, the wall rock alteration mainly includes green mud petrification, carbonization, pyrite, silicification and sericite. Limonitization is the product of epigenesis and can be used as a sign of prospecting. (2) according to the study of stable isotopes and fluid inclusions of OHN, the ore-forming hydrothermal solution is a mixed source of metamorphic water and a small amount of magmatic water; The gold-forming minerals are mainly derived from the mantle. The ore-forming temperature of gold deposit is between 200 鈩，
本文编号：2367041
[Abstract]:The epithermal hydrothermal gold deposit is one of the important types of gold deposits in China, which provides the support of gold resources for the development of China's national economy. However, with the development of geological prospecting in China, the discovery of these deposits will increase. Zhangjiapingzi gold deposit is located at the southwestern margin of Yangzi quasi platform and the contiguous part of Songpan-Ganzi geosyncline. It is a famous low-temperature hydrothermal gold mineralization area of Qinghai-Sanjiang in China. After several years of exploration, the local control depth of the deposit is over 500 m, the grade of the deposit is higher and the ore body is still rich and thicker. Although many gold deposits (mineralization sites) have been identified in the area, although the geological characteristics and prospecting direction of the gold deposit have been preliminarily discussed, the understanding of the metallogenic mechanism is not uniform, and the corresponding research data are lacking. Based on the field geological investigation, the characteristics of strata, structures, magmatic rocks and orebodies in the study area have been found out. Combined with the experimental data of isotopes and fluid inclusions, the ore-forming materials of the Zhangjiapingzi gold deposit have been systematically analyzed. Source of ore-forming fluid; Under the guidance of plate tectonics and mantle-derived metallogenic theory, the metallogenic mechanism and mineralization enrichment characteristics of gold deposits in the study area are analyzed based on the previous research data, which provide theoretical basis for "deep exploration blind" of Zhangjiapingzi gold deposit. It also provides guidance for the study of the corresponding types of ore deposits in this area. The main results are as follows: (1) the altered metasomatic dolomite of the Triassic in the study area is the main host lithology of the gold deposit; The ore bodies are layered and lenticular. The ore minerals are mainly pyrite and galena followed by tetrahedrite and sphalerite a little chalcopyrite and so on. The ore is mostly reticulated vein structure and block structure, belongs to low sulphide type ore, the main gold bearing material is pyrite, the wall rock alteration mainly includes green mud petrification, carbonization, pyrite, silicification and sericite. Limonitization is the product of epigenesis and can be used as a sign of prospecting. (2) according to the study of stable isotopes and fluid inclusions of OHN, the ore-forming hydrothermal solution is a mixed source of metamorphic water and a small amount of magmatic water; The gold-forming minerals are mainly derived from the mantle. The ore-forming temperature of gold deposit is between 200 鈩，
本文编号：2367041
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