中扬子区构造特征及勘探方向建议

中扬子区经历了印支-喜山期四个构造变形、变位发展阶段:印支运动结束海相沉积,并形成了黄陵、潜江、洪湖古隆起,早燕山期全区挤压,奠定了本区中、古生界的基本构造格局,晚燕山期,构造负反转,中、古生界构造发生叠加改造,喜山期,构造正反转,总体表现为隆升挤压。印支期以来多期构造运动的叠加改造,形成了南、北两个弧形构造体系,平面上构造展布特征具有明显的差异性:北部(大洪山)弧形构造系呈现南北分带、东西分块的构造格局,南部弧形构造系东西差异明显,东部具双重结构特征,西部为"隔槽式"构造格局。近期应以江汉平原南部、湘鄂西区桑植石门复向斜为勘探重点,同时围绕深化地质认识,解剖区域结构,加强地震攻关,积极准备中扬子南、北逆冲推覆带勘探。

THE TECTONIC CHARACTERISTICS AND THEIR SIGNIFICANCE FOR HYDROCARBON EXPLORATION IN MID-YANGTZE AREA

The Mid-Yangtze area experienced four development stages of tectonic deformation and position change, including Indosinian tectonic movement which ended the sedimentation of marine deposition, creating paleo-uplifts of Huangling, Qianjiang and Honghu, the Early Yanshanian compression in the entire area, forming the basic structural framework of the Mesozoic and Paleozoic, the Late Yanshanian tectonic movement, resulting in negative inversion of structures and superimposition of Paleozoic and Mesozoic structures, the Himalayan tectonic movement resulting in positive inversion of structures because of uplifting and compression. The structural superimposition and deformation occurred because of multi-phase tectonic movement since Indosinian, forming two-arc structural system in the south and north parts that show distinct difference in horizontal structural distribution. The northern (Da Hongshan) arc structural system shows north-south zonation and east-west segregation in structural framework, while the southern arc structural system is characterized by dual structures, showing obvious difference in the east and west, with the west having the "separated trough type" structural framework. Therefore, recent hydrocarbon exploration should be focused on the southern part of Jianghan plain and Shangzhi-Shimen synclinorium in Hunan and the western part of Hubei. Meanwhile, a more in-depth geologic understanding shall be attained toward this area and further analysis shall be made in regard to the regional textures. Seismic survey and data interpretation should be strengthened in order to make preparations for hydrocarbon exploration in the southern and northern overthrust nappe belts in the Mid-Yangtze area.