1 康定长岩窝金矿矿床成因分析
摘要
四川省甘孜藏族自治州康定县长岩窝金矿是该县的一处小型金矿床,有着三个矿区狮子岩、长岩窝、双牛棚。该矿床属于石英脉型金矿床,矿石主要赋存于石英脉中,大致为东西走向,受断裂构造的控制;矿区位于扬子准地台和松潘-甘孜地槽褶皱系两个Ⅰ级大地构造单元的接合部、道孚-康定三岔裂谷系的中心,也是南北向安宁河深断裂、北西向鲜水河深断裂、北东向茂汶深断裂和北川-映秀深断裂四大断裂带的交汇处。矿区出露于“康定杂岩”西缘的志留系沉积盖层中。矿床产于晚太古-晚元古界变质岩系中,其中常有不同时代的花岗岩侵入,最重要的是中生代燕山期花岗岩类。岩石中含水矿物及碳酸盐岩等发生去水脱碳形成流体并与大气降水混合形成高温流体, 沿剪切带运移, 并从围岩中卒取Au, Sb, As, Bi, S 等成矿物质, 形成含金的成矿流体;使矿区内金等成矿元素在动力、热力和韧性剪切构造作用下发生活化、迁移和初步富集成矿;在以后的围岩蚀变作用下,围岩中的金被进一步卒取、活化、迁移和富集;由于温度与压力的极聚降低, 含金成矿流体中的金开始在剪切带中的有利构造部位沉淀、富集成矿。最终形成中低温热液多金属硫化物型金矿床。
关键词:石英脉型金矿床 康定杂岩 多金属硫化物
The genesis analysis of gold at
Changyanwo in Kangding county
2 Abstract
The genesis of Changyanwo is a Small-scale gold deposit at Kangding County,
Ganzi Tibetan Autonomous Prefecture in Sichuan Province,there are three Mining
areas ,Shiziyan Changyanwo and shuangniupeng. The deposit is a quartz vein-type
gold deposits, the ore mainly occurs in quartz veins,it roughly the east-west,it is
controlled by faults; The mine is located in two tectonic units of grade Ⅰ a juncture is
the Yangtze platform and the quasi-Songpan - Ganzi geosyncline fold system, the
center of the Daofu - Kangding trigeminal rift system, the NS at Anling River deep
fracture,NW at Xianshuihe deep fracture,NE at Maowen deep fracture and the
Beichuang -- Yingxiu deep fracture,so The mine is located in the intersection of the
four faults. The mine is exposed in the sedimentary cover layer of
silurian-carboniferous in the western "Kangding Melange ".Deposits are occured in
the late Archean - late Proterozoic metamorphic rocks, Which are frequently invaded
by granites of different ages, The granitoids in Yanshan of the Mesozoic is the most
important. The water-bearing minerals and carbonate rocks in rocks are occurred
dehydration and decarbonization form fluids with the mixture meteoric water
formed the high-temperature fluid. movemented by shear zone, and jailer took the
Ore-forming materials as Au, Sb, As, Bi, S and so on from the surrounding rock,
formed ore-forming fluids by gold-bearing. So that the endogenous gold and other in
mining area ore-forming elements by the power, heat and ductile shearing are
occurred to activation, migration and initial mineralization; In the later wall-rock
alteration effect , the golden of the country rock was jailer took further, activation,
migration and enrichment, As temperature and pressure decreased very Poly. the
golden form the gold-bearing ore-forming fluids began to precipitation, mineralization
in favorable structural positions In the shear zone. The final formation the gold
deposits which is the low-temperature hydrothermal polymetallic sulphides.
Key words: Quartz vein-type gold deposits Kangding Melange Polymetallic
sulfide
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4 第一章 引言
1.1 选题依据
我国的采金历史悠久,据考证,早在4000多年前久开始了采金活动,采金坑、挖金 、淘金遗迹遍布全国各地。纵观我国地质环境,具有形成多种类型金矿的地质条件和找矿前景,金矿化成群出现,成带展布,资源较为丰富,为我国发展黄金事业提供了良好的物质基础。
关于金矿的成因研究许多学者专家都提出了很多的成因理论,这些理论也日趋成熟,为找矿提供理论方向。以板块构造理论为指导,依据矿床在成矿作用、主要控矿因素、矿石建造和组构、容矿岩石建造等方面的特征对已知金矿划分为6个系列17种成因类型,并且可以根据各类金矿在不同岩石建造中的表现样式,将所有金矿归结为内生和外生两个群。其中有造山带型金矿理论、与侵入岩有关的金矿成因、变质地体中脉金矿床的研究等。在本次实习的康定长岩窝金矿是脉状金矿中的一种对与其成矿的理论的分析对指导找矿有重大的意义,也是对大学中所学知识的总结。
1.2 自然地理
矿区位于四川省康定县雅拉乡境内,南起狮子岩-金台子,经长岩窝-红海子,北至双牛棚,,呈北北东-南南西的带状。矿权由14个拐点构成,面积为33.97 km2。其拐点坐标为(表1-1):
拐点编号 东 经 北 纬
1 102°00′00″ 30°06′00″
2 102°01′15″ 30°06′00″
3 102°01′15″ 30°08′30″
4 102°02′00″ 30°08′30″
5 102°02′00″ 30°09′15″
6 102°04′00″ 30°09′15″
7 102°04′00″ 30°11′15″
8 102°04′15″ 30°11′15″
5 9 102°04′15″ 30°12′30″
10 102°02′30″ 30°12′30″
11 102°02′30″ 30°10′30″
12 102°01′00″ 30°10′30″
13 102°01′00″ 30°09′00″
14 102°00′00″ 30°09′00″
地理坐标为:东经102°00′00″-102°04′15″,北纬30°06′00″-30°12′30″。矿区近中部,西侧的狮子岩卡子-三滴水-腰战棚为东西向分水岭,地表水分别向南和向北泾流排泄出矿区。海拔高度最低3040米(金台子矿段南东边清水沟),最高5087米(长岩窝矿段西边山头),相对高差达2047米,属青藏高原东缘-川西高原和四川盆地过渡区的深切割高山区地貌类型,区内气候属北亚寒带干旱气候,总体特征为气温低。每年11月至次年4月为冰雪期,5-10月可开展野外地质工作,6-8月为雨季,占全年降雨量的70%以上。
1.3 交通与经济
矿区外部交通较方便,自成都有108国道接318国道直达康定县城,行程320千米。康定至矿区有12千米简易公路,尔后有约10千米马道到达矿区。研究区内各矿段间均有马道通行(图1-1)。
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图1-1 矿区交通位置图
雅拉乡居民以藏族为主,少量汉族,矿区内荒无人烟。居民以农业为主,牧业次之。农作物以玉米、小麦、豆类、马铃薯为主。矿区内无工矿企业,所需生产、生活物资都依赖康定县城及外地供给。
1.4金矿的研究现状
1.4.1 国内外研究现状
关于金矿的成因研究个国的专家学者都提出了不同的理论及成矿模式。Groves 等在1998年对加拿大的Abitibi和澳大利亚 Golden Mile地区的绿岩带