鄂尔多斯盆地下白垩统含水层储水岩石特征与介质结构研究

本文采用沉积学与水文地质学交叉研究的思路,对鄂尔多斯盆地下白垩统含水层储水岩石特征与含水介质结构进行了研究。下白垩统是由宜君-洛河、华池-环河、罗汉洞-泾川三套含水岩组组成的一个厚达1300m、具多层结构的巨型碎屑岩地下水系统,发育以长石砂岩、长石石英砂岩为主的多类型储水砂岩,其沉积形成于以河流、沙漠为主的多种陆相沉积环境。由于受沉积、成岩及后期剥蚀等作用的控制,各含水岩组储水岩石的类型、厚度及分布,以及储水空间的类型和发育程度、储水孔隙介质结构均有明显变化;在与其它水文地质条件的共同影响下,下白垩统地下水赋存和富集条件总体呈现"盆地北好南差、北部上好下差、南部下好上差"的宏观分布规律。

Structure of water-bearing media and characteristics of water-bearing rocks of the Lower Cretaceous aquifer in the Ordos Basin

From the viewpoints of sedimentology and hydrogeology,structure of water-bearing media and characteristics of water-bearing rocks of the Lower Cretaceous aquifers in the Ordos Basin are analyzed in this paper.The Lower Cretaceous is composed of Yijun-Luohe,Huachi-Huanhe and Luohandong-Jingchuan water-bearing complex,and becomes a huge multilayered clastic aquifer system of 1300 meters thick.In this system,there are abundant and varied types of water-bearing sandstones which are mainly feldspathic sandstone and feldspathic quartzose sandstone.The sandstones are formed in varied continental depositional environments,most of which are of fluvial and desert facies.Under the control of sedimentation,diagenesis and later corrosion,the types,thickness and distribution of water-bearing rocks in each water-bearing complex are different,and the types and developing degree of water-bearing spaces and the structure of water-bearing media in each water-bearing complex are also variable.Affected jointly by sedimentation,diagenesis,later corrosion and other hydrogeological conditions,the groundwater occurrence and abundance of the Lower Cretaceous in Ordos Basin collectively are good in the north and poor in the south,and good in the upper part and poor in the lower part in the north,and good in the lower part and poor in the upper part in the south.