| 黔西南区微细金矿地质特征及成因探讨 |
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| 引用本文：.1987.A Tentative Discussion On Geologic Characterisncs And Genesis Of Fine-Grained Gold Deposits In Southwestern Guizhou[J].Mineral Deposits,6(3):49~56 |
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| 中文摘要:黔西南区微细金矿沿广西裂谷及下甘河断裂分布，主要赋存于中三叠统许满组，上二叠统龙漳组、长兴组及下三叠统夜郎组粉-细砂岩、水云母粘土岩、泥质白云岩、泥晶灰岩中。矿体呈似层状、透镜状、分枝状、囊状产出。金呈胶体金和超（次）显微金存在于水云母等粘土矿物和黄（白）铁矿中。根据矿床的碳、氧同位素组成、矿物包裹体测温和含盐度测定资料以及区内系统岩石地球化学测量，认为该区微细金矿系壳源中低温地下热（卤）水溶滤金矿床。 |
| 中文关键词:微细金矿 地质特征 金的赋存状态 矿床成因 黔西南 |
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| A Tentative Discussion On Geologic Characterisncs And Genesis Of Fine-Grained Gold Deposits In Southwestern Guizhou |
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| Abstract:Gold deposits in this area lie at the southwestern margin of the Yarrgtze Paraplatform, controlled by the Guangxi rift and the Xiaganhe fault (Fig. 1). Orebodies are present bi clayey siltsone, fine sandstone, siltstone, hydromica claystone, breccia, shale, argillaceous dolomite and micrite of Middle Triassic Xumart Formation, Upper Permian Longtan Formation and Ch&gxing FomatioⅡas well as lower Triassic Yeland Formation (Fig.2, Fig. 3). Orebodies occur in stratoid (Fig. 3), lenticular (Fig. 4), branching and chambered forms and can contain as high as 50.7-89.44 g/t gold in the richest part, with the general concentration being 2.31-16.42 g/t. Of the near 50 species of ore minerals so far identified, the major gold-bearing minerals are clay minerals dominated by hydromica (containing 5.2-7.5 g/t gold) and pyrite or marchasite (with 45.9-93.2 g/t gold). Gold in clay minerals is of colloidal form (Photo 5 ), while that in pyrite (marchasite) is supermicroscopic gold. Gold is of high fineness and ores are capable of being dressed. Pyrite from Banqi and Yata deposits has δ34S value of +5.9 ~ +16.6‰; δ18O value of quartz and calcite varies in the range of +9.61-+26.07‰ (Table 3 ); the inclusions in pyrite, quartz and stibnite have decrepitation and homogenization temperature 180-290 t, salinity 7.01-48.00% and pH value 6.28- 6.4l; pyrite has Co/Ni ratio 0.30-0.41 and S/Se ratio 46287-153033. The strata containing gold 5-15.5 times higher than the Clarke value include siltstone and claystone of early Middle Triassic broad seabasin hilly facies, which has 17.4-20.37 ppb gold on the average, and siltstone and claystone of early Late Permian semi-confined sea plateau facies, which averagely contain 44.71-54.33 ppb gold (Table l). Based on characteristics of ore deposits, geochemical data on rocks and various analyses, the author considers that ore materials must have been derived from the strata, and the gold deposits genetically belong to leaching type of mesothermal- epithermal underground brine of crustal series. |
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