安徽南部地区奥陶纪海相红层的分布及时代

Distribution and age of the Ordovician marine red beds in southern Anhui Province

在充分收集前人奥陶系地层学、古生物学和沉积学等资料的基础上,对安徽南部地区奥陶系进行了系统梳理,开展皖东地1井和贵池冯村剖面奥陶纪海相红层系统研究,为地层对比、古气候和古地理恢复提供重要的科学依据。研究表明:奥陶纪海相红层主要分布于紫台组、牯牛潭组、大田坝组、宝塔组、汤头组和胡乐组,时代为早奥陶世弗洛晚期至晚奥陶世凯迪中期;主要岩石类型为碳酸盐岩(瘤状泥质灰岩、网纹状灰岩、含生物碎屑灰岩和泥微晶灰岩等),少量碎屑岩(泥岩、含粉砂质泥岩、含粉砂质页岩);大多数属半深水海相红层,局部为浅水和深水海相红层;自北西向南东呈现一层式→二层式→三层式→二层式→一层式→零层式的横向变化,出现时代凯迪期→达瑞威尔期→弗洛期的纵向变化,海相红层的分布与沉积环境、古水温和不同地区构造性质密切相关;研究区海相红层不仅具有区域性(与湖北宜昌奥陶系具有对比性),而且具有全球性(中国主要块体),在地层划分与对比上具有重要的研究价值。

On the basis of fully collecting the previous Ordovician stratigraphy,paleontology,sedimentology and other data,the Ordovician system has been systematically combed,and systematic research has been carried out on the Ordovician marine red beds of well WDD1 and the Fengcun section in Guichi in southern Anhui Province,which provides an important scientific basis for stratigraphic correlation,paleoclimate and paleogeographic restoration.The research shows that the Ordovician marine red beds are mainly distributed in the Zitai Formation,Guniutan Formation,Datianba Formation,Baota Formation,Tangtou Formation and Hule Formation,and the age is from the late time of the Early Ordovician Floian Age to the middle time of the Late Ordovician Katian Age.The main rock types are carbonate rocks(nodular argillaceous limestone,reticulated limestone,bioclastic limestone and micrite limestone),and a small amount of clastic rock(mudstone,silty mudstone,silty shale).Most of the marine red beds belong to the semi-deep marine red beds,with some being shallow and deep marine red beds.From northwest to southeast,there is a horizontal variation of one layer type,two layer type,three layer type,two layer type,one layer type,and zero layer type,with a vertical variation of the Katian Age,Darriwiliaan Age and Floian Age.The distribution of marine red beds is closely related to the sedimentary environment,ancient water temperature,and structural properties of different regions.The marine red beds in the study area not only have regional characteristics,but also have global characteristics,which have important research value in stratigraphic correlation.