| 驼路沟喷气沉积型钴(金)矿床的地质-地球化学 |
| 点此下载全文 |
| 引用本文：.2002.Geology and Geochemistry of Tuolugou Exhalative-Sedimentary Co-Au Deposit, Qinghai Province [J].Mineral Deposits,21(3):213~222 |
| Hits: 3058 |
| Download times: 2171 |
|
| 基金项目:国土资源部“九五”科技发展计划项目(95_02_005)和国家地质调查项目(K1.1.3.1及200110000001) |
|
| 中文摘要:驼路沟矿床是容矿于震旦—寒武纪富钠火山-沉积岩系中的钴(金)矿床。矿床地质-地球化学特征、矿体的产态、矿石结构构造以及金属矿物的标型表明，驼路沟钴(金)矿床主要与震旦—寒武纪海底喷气沉积成矿作用有关，在加里东和晚华力西—印支碰撞造山过程中，喷气沉积型矿体被构造改造，并导致金在局部地段进一步富集。元素地球化学研究揭示，Au、As、Pb、Cu、Zn、Mo、Co是圈定含矿层的化探异常元素组合，而Co-Ni-Au-Pb-Mo-As组合异常可以指示矿体。建议在矿床勘查的初期注意可能出现于喷气沉积成矿中心附近的铜钴矿。 |
| 中文关键词:钴矿床 喷气沉积矿床 驼路沟 东昆仑 |
| |
| Geology and Geochemistry of Tuolugou Exhalative-Sedimentary Co-Au Deposit, Qinghai Province |
|
|
| Abstract:The Tuolugou cobalt-gold deposit, located in the central part of the East Kunlun orogen, serves as the first example of exhalative_sedimentary deposits in this region and is now under exploration. Lithologies of Co- and Au-bearing formation in the Tuolugou ore district include detrital and volcanic rocks of four lithostratigraphic sub_units, which are from bottom to top black shale(Z-DC-a), tuff-sandstone(Z-DC-b), volcano-sedimentary rocks (Z-DC-c) and sandstone (Z-DC-d). There are no intrusive rocks involved in the Tuolugou ore district. Volcanics in four sub_units are intermediate to acidic and show a chemical affinity of active continental margin or island arc. The cobalt-gold ore bed is hosted by volcano-sedimentary rocks (Z-DC-c), whose sequence is mainly composed of metamorphosed pelitic siltstone with interbeds of tuff and exhalite (quartz albitite). U_Pb dating data (570 Ma) obtained from zircon of quartz albitite indicate an age between Sinian and Cambrian. Co-Au orebodies are in stratiform and lenticular forms. They extend conformably in strata, forming an over 7 km-long mineralization zone. Individual orebodies are 100 to 1000 m long and 0.86 to 4.45 m thick, with average grades of 0.024%～0.108% Co and 0.3～0.78 g/t Au. The ores display laminar, banded, disseminated and massive textures. The gangue minerals include quartz, albite, carbonate (siderite, ankerite and calcite), sericite, chlorite and tourmaline (dravite), whereas the ore minerals are composed of pyrite (>30%), small amounts of arsenopyrite, chalcopyrite, sphalerite pyrrhotite, bornite, and trace cobalt pentlandite, cobalt pyrite, linnaeite, carrollite, cattierite and gold. Cobalt is contained in pyrite in the ore. The multiple orogeny during Caledonian and Late Variscan to Indosinian produced extensive metamorphism and deformation, and led to the development of folds that evolved into thrusts. This caused reformation of exhalative_sedimentary orebodies and partial emplacement of gold orebodies. The complex ore-forming process mentioned above finds expression in variable generations of pyrite in Co-Au ores. Pyrite of early generation is anhedral, fine_grained and fragmented, with quartz, calcite and gold filled in microfractures. Pyrite of early generation is sometimes seen to be elongated into spindle_shaped crystalloblasts. Pyrite of late generation is of a lower proportion relative to early pyrite, and is subhedral to euhedral and coarse_grained in form with no fragmentation. Microprobe analyses show that early pyrite has high average content of Co and Ni, and low Au (2.44% Co, 0.49% Ni and 0.01% Au) relative to late pyrite (0.1% Co, 0.1% Ni and 0.14% Au). All this suggests that early pyrite and late pyrite were formed before regional metamorphism and deformation (exhalative-sedimentary stage) and during metamorphic and deformation stage, respectively, and that cobalt mineralization is mainly related to exhalative-sedimentary mineralization, whereas gold is mainly an epigenetic product related to collisional orogeny. |
| keywords:cobalt deposit, exhalative-sedimentary mineralization,Tuolugou, East Kunlun |
| View Full Text View/Add Comment Download reader |
|
|
|
