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天生桥地区为云南省东南部文山县的重要矿区之一,在二叠世吴家坪阶早期,岩相古地理格局及微地形变化成为控制该地区形成沉积型铝土矿的主要因素。在野外露头、探槽和钻孔岩芯剖面资料和室内分析的基础上,通过对研究区晚二叠世吴家坪阶早期主要岩石类型及沉积特征的系统研究,利用单因素分析多因素综合作图法绘制岩相古地理图。本文认为该时期天生桥地区总体处于泥质低能海岸的古地理背景,沉积相包括海岸相和局限浅海相,可细分为沼泽、潮坪、局限浅海上部、局限浅海下部亚相及潮上带、潮间带、潮下带微相。特别是,本次研究新增加了隆起与泻湖两个微相。潮下带、泻湖和局限浅海上部为铝土矿沉积的最有利环境,可考虑将其列入文山天生桥地区晚二叠世吴家坪早期沉积型铝土矿成矿的远景区。
The Tianshengqiao area is one of the most important mined areas in Wenshan County, southeastern Yunnan Province. In the early Permian Wujiaping stage, the lithofacies palaeogeographic pattern and microtopography have become the main factors that control the formation of sedimentary bauxite in this area. On the basis of the data of outcrops, trenches and core profiles of drills and laboratory analyzes, the author systematically studied the main Late-Permian Wujiaping-type rock types and sedimentary characteristics in the study area, and used the univariate analysis of multi-factor comprehensive mapping Law to draw lithofacies paleogeography map. This paper argues that the Tianshengqiao area is generally paleogeographed with muddy low-lying coasts. The sedimentary facies include the coastal facies and the confined shallow marine facies, which can be subdivided into swamps, tidal flats, confined shallow-water upper part, confined shallow-sea subfacies and tidal flats, Intertidal zone, tidal zone with micro-phase. In particular, two microfacies of uplift and lagoon have been newly added in this study. The sub-sea belts, lagoons and the confined shallow-water upper part are the most favorable environments for the deposition of bauxite. Consider including it in the prospect of the late Permian Wujiaping early sedimentary-type bauxite mineralization in the Tianshengqiao area of Wenshan.