【作者】 张海；

【导师】 何明友； 刘应平；

【作者基本信息】 成都理工大学 ， 地球化学， 2011， 硕士

【摘要】 本文以野外地质研究及室内测试数据为依据,在详细研究了四川石棉大水沟碲矿床的区域地质地球化学背景和矿床地质特征基础上,通过研究大水沟碲矿床元素地球化学、矿石矿物Pb、S同位素、不同成矿期矿物包裹体H、O同位素地球化学特征,探索成矿环境、物质来源、成矿流体来源等,研究结果表明:1、大水沟碲矿床的形成与深部地质过程密切相关。碲矿床发育在板块拼接部位,深大断裂构造活动强烈,深大断裂发育,这无疑为后期的构造-岩浆活动及大量成矿物质向浅部输送提供了良好通道。同时,其伴生的次级或低级别的断裂构造则为后期的成矿热液的运移、成矿作用的发生及碲矿床的形成提供了有利的通道和良好的储矿空间。2、大水沟碲矿床具有良好的多金属矿集区的区域成矿地球化学背景,是铜、金、银等多金属矿集区。该矿床处于贫碲的地球化学场内,在大面积贫碲环境中碲之所以能局部富集成矿,表明成矿元素碲主要来源于深部物质。3、碲矿床发育在志留系通化组一段的变基性火山岩中,产于大水沟热穹窿构造翼部,受NNE组脆性等间距破裂带控制。表明热穹窿构造为碲矿床的发育塑造了良好的储矿场所,而后期脆性构造发育,使得储矿层破碎充分,无疑大大增加其与成矿热液反应的比表面积,同时为成矿物质提供通道和反应场。使得成矿物质在大水沟热穹窿内反应充分,并大量富集成矿。4、大水沟碲矿床常微量元素特征显示,大水沟碲矿床变质围岩原岩为大陆拉斑玄武岩,矿石与围岩的成岩成矿氧化还原环境截然不同,有利于成矿。更为重要的是区内出露有一定规模的花岗岩,研究表明这种花岗岩具有明显的陆壳改造型花岗岩的微量元素特征,且相对富Bi、Ag等成矿元素。而Bi、Ag则是碲的最佳沉淀剂元素(刘英俊,1987)。由此可见,区内中酸性岩浆活动与花岗岩的成岩作用对碲矿床的形成具有密切的成因联系。5.同位素特征显示碲及其矿化剂、含矿流体,主要来自深源岩浆热液。成矿过程中,成矿环境较为封闭。综合上述,认为大水沟碲矿床的形成与构造-岩浆活动、动力变质作用、大水沟热穹窿构造+次级脆性构造、赋矿围岩与成矿物质的化学差异等具有密切的成因联系,同时表明该矿床具有动力变质岩浆改造成矿的特征。更多还原

【Abstract】 Based on large geological investigations in the field and a lot of analytical data gained in the laboratory, the author researched the regional geological-geochemical background and the geological features by studying the element geochemistry, the isotope of Pb, S in ores, and the isotope of H, O of fluid inclusions of different stages of mineralization, in order to discuss the ore-forming environment, the sources of materials and the sources of the ore-forming fluid. The result showed that:1. The Dashuigou tellurium deposit is formed in the site where the plates splice, the structure with deep fracture, and the magma intense activity. Multiple stages of the deep fracture provide passages for the latter magma. Minerals react fully and precipitation in the fragmentation zone which caused by plate collision. This is conducive to the formation of tellurium deposit.2. The Dashuigou tellurium deposit is located in area with regional geochemical background of polymetallic ore enrichment. It is the polymetallic ore enrichment area of Cu, Au, Ag, and so on. Lying in the geochemical field with barren Te, the enrichment of the Te (up to 7-8 orders of magnitude) in partial geologic bodies where the whole area is poor of Te in the geological environment indicated that the Te may source from the deep.3. The deposit is formed in the Triassic metabasic volcano rock of Tonghua group of Silurian in the Dashuigou thermal dome, and under the control of NNE group of brittle rupture zones with equal interval. The thermal dome structure provided favorable storage place for the development of Te deposit. The later development of brittle structure made the ore bed crash fully, which greatly increased the surface area of reaction between the ore-forming hydrothermal and it, provided passage and reaction field for ore-forming materials so that they reacted adequately and enriched into deposit in the Dashuigou thermal dome.4.The features of the trace elements showed that the origin of the metamorphic wall rocks are continental tholeiite. The redox environment of the deposit and the wall rocks are very different which is conducive to mineralization. The granite exposed in the area is rich of Bi and Ag, which has the trace element characteristics of continental crust-type granites. The limestone of Tonghua group of Silurian is obviously erosion of magmatism which is enrichment of Co, Ni, Sc, In, Ga. The ore-forming elements of Te and Bi are rich in metamorphic rocks, especially in slate, schist, fine - banded marble and rocks with low metamorphic degree.5.The features of isotopes show that Te and its mineralizer, ore-bearing fluid mainly come from the deep magmatic hydrothermal. The environment of ore-forming is isolated with the outside.In summary, it is believed that the form of Gashuigou Te deposit is closely related with tectonic-magmatic activities, dynamic metamorphism, Dashuigou thermal dome structure and brittle substructure, chemical differences between ore-hosting wall-rocks and ore-forming materials. It indicates this deposit has the features of dynamic metamorphic magmatic mineralization.更多还原