江西修水地区第四纪地层序列

QUATERNARY STRATIGRAPHIC SEQUENCE IN THE XIUSHUI AREA, JIANGXI

根据岩石地层学与地貌地层学特征，将江西修水地区的第四系划分为５个岩石地层单位。由老到新为：①赣县组为一套暗红色强风化砾石层，组成修水河第五级阶地，形成时代大于１０ＭａＢＰ；②进贤组分上、下两段。下段为棕红色强网纹化红土和砂砾层，组成第四级河流阶地；上段为一套褐红色网纹化亚粘土与砂、砂砾石组合，组成第三级阶地。进贤组形成的年龄大致为０９～０１ＭａＢＰ；③莲塘组岩性以厚层的褐黄色砂砾石层与薄层亚砂土为主，组成第二级阶地，中上部ＯＳＬ年龄为６５０×１０３ａＢＰ；④联圩组为褐灰、黄灰色砂砾、砂及亚砂土，组成第一级阶地，中部的Ｃ１４年龄为８０×１０３ａＢＰ；⑤赣江组为灰白色粗砂砾石层，顶部发育薄层灰色亚砂土。

On the basis of large amounts of field surveys and according to the lithostratigraphic and morphostratigraphic features, the Quaternary system in the Xiushui area, Jiangxi, is divided into five lithostratigraphic units: (1) The Ganxian Formation consists of a dark red conglomerate bed, comprising terrace V of the Xiushui River, formed at >1.0 Ma B.P. (2) The Jinxian Formation may be divided into the upper and lower members. The lower member is composed of brownish red reticulate laterite and sandy conglomerate, forming terrace IV; while the upper member is made up of brownish red reticulate loams, sands and gravels, forming terrace III. According to the intergrated thermoluminescence (TL), photoluminescence (OSL) and paleomagnetic dating, the age of this formation is 0.9～0.1 Ma. (3) The Liantang Formation consists dominantly of thick bedded brownish yellow gravels and thin bedded sandy loams, forming terrace II, and the OSL age of its middle and upper parts is 65.0×10 3a. (4) The Lianyu Formation is composed chiefly of brownish gray and yellowish gray gravels, sands and loams, forming terrace I. The C 14 age of the middle part is 8.0×10 3 a. (5) The Ganjiang Formation is marked by grayish white coarse sands and gravels with thin bedded sandy loams at the top.