兴仁县紫木的凼金矿外围地区基岩含金量与地层，岩石和沉积相的关系

Relationship of An Background Abundance in Surrounding Area to Stratigraphy, Rocks, and Sedimentary Factes at Zimudang Gold Deposit in Xingren County, Southwest Guizhou

一比五万大山、贞丰、者相三区调图幅基岩取样分析的统计结果表明：基岩的含金量，在地层上，全区以上二叠统＂大厂层＂含金最高，是区域内找金的重要标志，其次是上二叠统地层和中三叠统的藻灰岩；在岩石上，以硅质岩最高，其次是碎屑岩和生物碳酸盐岩，特别是含玄武岩碎属的岩石；沉积相上，则以潮坪相最高，其次是台缘藻滩相、开阔台地相、三角洲相和泻湖相；而在区域上，则以大山幅最高，特大型的紫木凼金矿的出现与其有关。

In order to examine the gold background abundance respectively in stratigraphy,rocks, and sedimentary factes surrounding the Zimudang gold deposit in Xingren County of Southwest Guizhou, the rock samples collected during the geologic mapping, at 1: 50,000. of three quadrangles, Zhenfeng, Dashan and Zhexiang, have'been analysed for gold.The study shows that gold is stratigraphically the most abundant in the 'Dachang Horizon', a sillcious rock bed of the Permian age, which is a criterial for gold prospecting and is also well known for producing stibnite ores, secondly in the late Permian stata and in the algal limestone bed of the middle Triassic age. Lithologically, there is the presence of gold with the highest background in silicious rocks; besides, with relatively higher value in biocarbonate rocks, and in elastic rocks, especially basaltic clasts. Of all the sedimentary factes, the tidal flat factes is the highest in An background, subsepuently, a decrease in the gold abundance begins from the bank-inset algal factes, through the factes of broad platform and of delta, to lagoonal factes. In general, geological map of Dashan quadrangle strongly reveals a dependence of the formation of the super-large Zimudang gold deposit on the highest background abundance in gold.