山西省中石炭世本溪早期(铁铝岩段)岩相古地理与成矿规律之探讨

本溪早期地层(铁铝岩段)在山西省分布甚广,矿产资源丰富,不仅有铝土矿、粘土矿,而且还赋存有铁矿、黄铁矿等,是本省的重要含矿层位之一。近年来,笔者参加了山西省石炭纪岩相古地理编图工作,对本溪早期岩相古地理特征及各类矿产成矿规律有些粗浅认识,借此与同行们共同探讨。一、地层概况本溪早期地层自下而上由铁质岩、铝质岩和泥质岩三种基本岩石类型所组成。由于受下伏碳酸盐岩古风化壳的制约,岩层厚度变化较大(图1);基底地形低凹处厚度大,凸起处变

A Preliminary Study of Sedimentary Facies,Palaeogeograpgy and Mineralization Regularity in Shanxi during the Early Benxian(the Fe-Al-Bearing Rock Members)of Middle Carboniferous Times

This paper deals with sedimentary facies and palaeogeography in Shanxi during the early Benxian of Middle Carboniferous times in light of the criteria for recognition of sedimentary facies such as sedimentary structures. fossil assemblages, trace elements and isotopic data. During the period, oldland and islands were confined to the southern and northern ends of Shanxi, respectively, whereas the central part of it was generally occupied by the barriered tidal flat-lagoon system which may be divided into twelve lagoon districts and five swamp districts. The mineralization regularity has also been discussed in terms of sedimentary facies and palaeogeography. Bauxite, iron and pyrite deposits are all associated with ancient lagoons. Pyrite deposits tend to occur in the central facies of the lagoons, whereas iron deposits in the marginal facies. Bauxite deposits are dominantly related to the lagoon beach facies. For example, the rough bauxite ores often lie in the lower part of the subtidal zone; the clastic and oolitic bauxite ores in the upper part of the subtidal zone and intertidal zone, and the compact massive ores in the supratidal zone and swamp facies.