| 一个海底基性火山喷流成因的银锑矿床地质特征 |
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| 引用本文：.1996.Main geological characteristics of a submarine basic volcanic effusive silver-antimony deposit[J].Mineral Deposits,15(3):238~248 |
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| 中文摘要:广东梅县嵩溪宝山是个产于具裂谷性质的永-梅裂陷槽南段翼部裂陷火山-沉积盆地内的一个海底基性火山喷流成因的银锑组合大型银矿。文中阐述以下问题：容矿层位岩性组合、建造和相及层位地球化学特征、矿区地质构造；海底基性熔岩——玄武岩的地质、地球化学、稀土元素特征及其构造环境与成矿意义；矿体（层）形态、产状、矿石结构构造、矿物共生组合、地球化学、稀土元素、同位素、包裹体等。 |
| 中文关键词:裂陷槽 基性熔岩 气液喷流 喷流碎屑岩 银锑组合 广东宝山 |
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| Main geological characteristics of a submarine basic volcanic effusive silver-antimony deposit |
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| Abstract:The Baoshan deposit in songxi, Meixian County, Guangdong Province, is an independent large-sized silver deposit with silver-antimony assemblage. Being of submarine basic volcanic effusive origin, it occurs in a rift-fault volcanic-sedimentary basin within a rift-fault trough of rift valley character. The host horizon, namely argillaceous-arenaceous rock of Lower Jurassic Songling Formation, is characterized by the existence of effusive fragments and high Ag and Sb abundances. The ore district is a NW-striking plunging anticline, and NW-striking and SW-dipping F1is the ore-control growth fault. In the ore district, the major igneous rocks are synsedimentary submarine effusive basic lava —— basalt and sed-pyro-clastic rocks. Lava occurs mostly in multi-layer form, being olivine basalt-picritic basalt. δEu averages l.29, (87Sr/86Sr), of whole rock is 0.7088; the rocks are relatively close to continental rift alkaline basalt in chemical composition and REE contents. Silver-antimony orebodies occur along bedding in stratiforrn of stratoid form, and the principal orebody group adhering to the basalt bed extends persistently. Strata, basalt and ore bed are parallel to each other and folded synchronously, and the ores assuming primary laminared and banded structures consist mainly of pyrite, stibnite, arsenopyrite and sphalerite. Eight sorts of silver minerals have already been recognized; individual pyrite minerals are rich in As, Sb and Ag, Co/Ni>l, and S/Se averages 510 000. Ore-forming fluids are of Na+ - Ca2+ - Cl- - HCO- type, with average salinity 7.89×10-2. Hydrogen and oxygen isotopic compositions of inclusions show ore-forming fluids to be submarine hot brine and metalllogenic temperature to be 130～190℃. The similarity in REE curves between basalt ore and individual pyrite mineral implies their cognate nature. Average pyroelectric coefficient of pyrite is +374.6 mV/C, indicating Type P. Minor lead isotope compositions of pyrite, stibnite and arsenopyrite demonstrate their plutonic nature, whereas minor lead isotope compositions of shale etc. in host horizon exhibit crust-derivative nature，δ34S values of sulfides in ores vary in the wide range of -3.0‰～+14.3‰ and hence show high degree of discretization, suggesting characteristics of a submarine volcanic effusive and sedimentary deposit. |
| keywords:rift-fault trough, basic lava, gas-liquid effusion, silver-antimony assemblage, effusive clastic rock |
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