太仆寺旗沙子沟多金属矿区岩石矿物特征与矿床成因研究.doc

太仆寺旗沙子沟多金属矿区岩石矿物特征与矿床成因研究 【中文摘要】沙子沟矿区位于内蒙古太仆寺旗北部,是2006年发现的新矿产地,主要资源为金属钨、钼。矿区处于华北地台北缘构造带的正镶白旗多伦金铅锌多金属找矿区内,该区是寻找金、银、锌、钨、钼多金属矿产资源的十分有利的一个找矿远景区。由于基础工作薄弱,该矿点的发现是该远景区找矿工作的一次重大突破。矿区以王家营子南北向的东沟为界,划分成东矿区和西矿区。东矿区为钨矿脉分布区和钨钼矿脉分布区,其中钨矿脉在浅部,钨钼矿脉和钼矿脉在深部。西矿区主要是钼矿分布区。矿床赋存于一套以云母片岩为主的区域变质岩中。本文以为,矿区内发生过多期次的岩浆活动,部分区域变质岩受到改造发生边沿混合岩化,并在后期构造运动中产生有利于成矿的裂隙系统,成为重要的控矿因素。钼矿床的矿化密集程度与混合岩化强度呈正相关。变质相研究表明,矿区内变质程度较邻近区域偏高,基性变质岩达高角闪岩相,变质温压条件变化较大,局部可能叠加了由岩浆和混合岩化引起的高温变质作用。综合大地构造环境、矿床地质特征和矿脉特征等,本文以为沙子沟矿床应属于与岩浆有关的浅成脉型钼.多金属矿床,但至今尚未确定与成矿有关的岩体。; 【Abstract】 A multi-metal deposit has been found in Shazigou, north Taipusiqi of the Inner Mongolia Autonomous Region in 2006, which is a significant breakthrough in the Zhengxiangbaiqi-Duolun multi-metal prospect for Au, Ag, Zn, W, Mo. The lead resource of Shazigou deposit are Mo contact metamorphic rocks include diopsidite, aposandstone and skarn; a kind of dynamo-metamorphic rock known as mylonite.Granites\intrusion mainly occurred in late Hercynian and early Yenshan stage, all of them are lime-alkali rocks, which are high in SiO_2 with a average of 73.04 and alkalinity, that is, K_2O Na_2O2.45-8.65 K_2ONa_2O, low in CaO, MgO and have a supersaturation of Al. All in all, they are high in acidity and had undergone a thorough differentiation, which are propitious to deposits of W, Mo.Most of the regional metamorphic rocks near and in the deposit, especially mica-schists, have been changed in a migmatization course which are likely to be caused by granite intrusive mass. The migmatites, most of which been observed are stripped migmatite and ophthalmite, are considered as the most important adjoining rock of the ore bodies. At the same time when migmatization occurred, a huge number of pegmatite veins ed and been transported to terrene as we can see today. The veins, which could be considered as a part of migmatites, called leucosome, are known as a result of partial fusion of the regional metamorphic rocks.For ascertaining rocks\ metamorphic grade of this deposit, this *** focuses on the characteristics of chief mineral constituents and metamorphic P-T condition of issite and amphibolites. Metamorphic grade has been restricted by Ti-AlIV Na_2OK_2O -TiO_2 relationship diagrams of amphiboles and metamorphic P-T condition has been calculated by using the amphibole-plagioclase couple. Amphiboles in amphibolites are showing high Al_2O_3 and high K_2O in composition, while the FeOMgO content are rather constant, FeO MgO are showing negative relationship. All amphiboles belong to calcic- amphibole series according to Leak\s classification and 5 mineral species could be subdivided. Plagioclases from amphibolites are all andesine. The metamorphic type corresponds to medium-high temperature regional metamorphism, while the metamorphic grade is high amphibolite facies.In author\s opinion, Shazigou ore deposit can be classified as a epithermal deposit, migmatization made the regional metamorphic rocks a rigid body, tectonic movement like faults and folds destroyed the rocks and made innumerable cracks, a granite intrusive mass brought heat and boiled waters nearby to hytrothermal deposit.