准噶尔盆地南缘阿什里地区地质构造基本特征

Geological structures in the Ashi region,Xinjiang

关键词:  北天山  阿什里  逆掩推覆构造  准噶尔盆地

Key words:  North Tianshan Mountains  Ashili  overthrust nappe structure  Junggar Basin

摘要:

准噶尔盆地南缘阿什里地区紧邻北天山造山带前缘,受北天山造山系逆冲构造作用的影响,区内构造变形十分强烈。野外地质调查和地震勘探证实,该区逆掩推覆构造现象普遍,阿什里地区头屯河构造西侧较大范围的石炭系露头为逆冲推覆、遭受剥蚀后残留的外来岩块。结合前人对准南地区侏罗纪沉积演化、盆地格局和三叠系、侏罗系沉积特征和沉积相分析研究成果,笔者建议对准南地区盆地边界南扩,以侏罗系分布范围划定盆地南界。除前人普遍认识到北天山前缘存在三排背斜构造带之外,证实紧靠北天山盆山结合部还存在一排以头屯河背斜为代表的背斜构造带,对提升该地区的油气勘探前景具有重要意义。

Abstract:

The geological structures in the Ashi region,southern Junggar Basin,Xinjiang are highly deformed under the influence of thrusting of the North Tianshan orogenic systems.The overthrust nappes occur on a great range of scales in the study area,as indicated by field geological survey and seismic exploration.The widespread Carboniferous outcrops in the western part of the Toutunhe structures in the Ashi region are interpreted as the exotic blocks left over by overthrusting and erosion.Referenced to the previous research on the sedimentary evolution,basin framework,deposition of the Triassic and Jurassic strata,and sedimentary facies analysis during the Jurassic,the authors contend that the southern boundary of the Junggar Basin should be moved further southwards to the extent of the Jurassic strata.Except the pre-existing three anticline zones,another anticline zone represented by Toutunhe anticline should be added at the basin-range junction right near North Tianshan Mountains.