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澳大利亚西部太古代浅层脉型金矿床产于葡萄石-绿纤石岩相至低级绿片岩相岩石中,具有以下特征:(1)矿床主要赋存在火山作用和构造活动期后形成的脆性剪切带中;(2)矿脉赋存于角砾岩中;(3)含银硫盐、辉锑矿和早期的玉髓等低温矿石和脉石矿物;(4)矿体内金属具有垂向分带性。成矿流体温度介于150℃-325℃之间,推测的就位深度<5km。石英、绢云母、绿泥石等蚀变矿物的同位素分析结果与另一些具有相同构造活动周期的太古界脉金矿中的热液流体测试数据相比表明:本矿床含金热液流体中δD_(流体)值较高(与海水平均比值SMOW相比1σ;n=19,为-6‰±9‰);而δ~(18)O_(流体)值较低(与SMOW相比1σ;n=167,为4.4‰±2.3‰)。地表水的浅层渗入作用以及这些地表水与平流迁移的变质-岩浆水的相互作用,均能合理地解释矿床中流体包裹体及稳定同位素的组成特点及玉髓的存在。
The Archean shallow-vein gold deposits in Western Australia are produced in the gravel-greenstone-lithofacies to low-grade greenschist facies and have the following characteristics: (1) The deposits mainly consist of volcanism and brittle shear formed during the tectonic activity (2) the veins are hosted in breccia; (3) low-temperature ores and gangue minerals such as silver and sulfur salts, stibnite and early chalcedony; (4) With sexual. The temperature of ore-forming fluid is between 150 ℃ and 325 ℃, and the assumed in-situ depth is less than 5km. The results of isotope analysis of alteration minerals such as quartz, sericite, chlorite and other hydrothermal fluids in the Taiyuanjiemai gold deposit show that the δD_ (Fluid) values were higher (1σ compared to the average seawater ratio SMOW; n = 19, -6 ‰ ± 9% o); and the values of δ ~ (18) O_ (fluid) = 167, 4.4 ‰ ± 2.3 ‰). The shallow infiltration of surface water and the metamorphism-magmatic water interaction between surface water and advection can all reasonably explain the composition of fluid inclusions and stable isotopes and the presence of chalcedony in the deposit.