豫西郁山铝土矿床沉积环境分析

豫西郁山铝土矿床是河南省新发现的一大型隐伏铝土矿,属华北地台G层铝土矿。以系统的中—深部钻探工作为基础,根据含铝岩系的岩性组合、沉积构造和地球化学特征,将郁山矿区内上石炭统一段分为2个相和4个微相。提出郁山铝土矿床含铝岩系形成于滨海泻湖潮坪环境,铝土矿主要赋存于豆鲕状(含砂砾屑)铝土矿微相中,为局限潮下带上部环境;认为郁山矿床含铝岩系经历了3期规模不断增大的突发海侵到缓慢海退的沉积环境演化旋回,并形成矿床的3个铝土矿层,最后一次大规模海侵—海退事件形成了区内最连续的铝土矿层(体)。通过研究,进一步完善了华北地台本溪组铝土矿成矿理论。

Sedimentary Environment Research for the Yushan Bauxite Ore Deposit in Western Henan Province, China

The Yushan bauxite ore deposit in the western Henan Province is a large concealed deposit discovered by Henan Institute of Geological Survey in 2005,which belongs to layer-G bauxite of North China Platform.The deposit-bearing strata of the Upper Carboniferous can be divided into two facies and further to four microfacies according to the systemic analysis of drilling data,i.e.lithologic association,sedimentary structure and chemistry feature of the allite series.The allite series of Yushan bauxite is formed in sedimentary environment of the shallow marine such as the coastal,the tidal flat or the lagoon,and the bauxite is mainly developed with the microfacies of oolitic(or classic) deposit that is formed in the upper part of restricted subtidal zone.Importantly,the allite series of the Yushan bauxite is the product resulting from a complex process of three cycles from the rapid transgression to the slow regression that form three bauxite sequences from the bottom to the upper part correspondingly,and the bauxite sequence with the large-scale distribution is formed in the last large-scale transgression-regression cycle.Therefore,this study is a good complement for the theory of bauxite formation in Carboniferous Benxi Formation in the North China Platform.