巴楚隆起先巴扎三维区鹰山组岩溶特征及成因

Karst characteristic and origin analysis for Yingshan Formation in Xianbazha 3D area of the Bachu uplift

巴楚隆起西部剥蚀区先巴扎三维区鹰山组在加里东中期长期暴露地表接受大气淡水淋滤发生岩溶作用。以加里东中期岩溶古地貌为基础,结合精细相干和地震属性分析,对研究区古水系进行精细刻画,类比研究区与西克尔露头的岩溶特征,总结造成这种岩溶特征的成因。研究区地表各水系从干流到分支河谷发育且成熟而稳定,树枝状水系发育,表明该区具有丰富的大气淡水补给和良好的岩性-构造条件,地表岩溶相当发育;而地下水系主要以地表主干水系为排泄基面,其基本围绕地表水系分布且分支少,说明地下水没有形成系统的水文网络,地下岩溶的发育受到一定限制。研究区缺乏良好的径流和排泄系统,岩溶洞穴分布有限,以孤立分散洞穴为主,很少发育大的洞穴或暗河。地下岩溶发育程度低的原因包括岩溶发育不彻底、洞穴充填和溶蚀孔洞层发育。

There are karst fractured/caverned reservoir formed by multi-phase karstification in Tabei uplift and Tazhong lower uplift of Tarim basin, but large scale karst-cave layer have not yet been found in the Bachu uplift. The Yingshan Formation in Xianbazha 3D area of the western Bachu denudation area is directly covered by the Silurian formation. During the middle-Caledonian, the Yingshan Formation exposed to surface for a long time and developed karst cave after atmospheric water eluviation. The branch-like river was mature and had steady valley, which indicates a good lithologic-structural condition and abundant atmospheric fresh water in this area.Therefore, the surface karst is quite developed; drainage for the subterranean rivers, which had a few branches, was mainly controlled by the distribution of the trunk of surface rivers and scattered depressions. It is suggested that the subterranean rivers did not form a system of hydrologic groundwater network, so that underground karst development is confined. Based on analyses of karst characteristics in this area and analog study of karst in Xikeer outcrop, the reasons for the low level of underground karst development were summarized as follows:1 incomplete karst development; 2 cavern filling; 3 layers having developed solution pore and cave.