新生代伊犁盆地与周缘山脉耦合关系研究

In order to reveal the intracontinental tectonic process of Tianshan that corresponds to the remote effect of the India and Eurasia plate collision, many scholars have carried out a lot of research work on basin-mountain coupling from foreland basins both in front of north and south Tianshan, respectively. However, the Yili basin was less concerned, there are some controversies about the Cenozoic tectonic deformation pattern and period of Tianshan, and less concerned on the intermountain basin. The Yili basin, as a large intermountain basin, is controlled by the south and north Tianshan, and is a key location which can resolve intracontinental tectonic process of Tianshan. In recent years, a large amount of drilling cores and geophysical data have been obtaining, which provide a new opportunity to research the Tianshan intracontinental tectonics deeply. Based on basin-mountain coupling, structural deformation and chronostratigraphy work will be researched from several typical natural profiles and drilling cores to determine a new and fine stratigraphic time scale. Meanwhile, the Cenozoic detrital apatite fission track and basin provenance will be carried out under the new time scale, which could reconstruct the Cenozoic tectonic evolution of the Yili basin. Moreover, basin-mountain coupling process will be discussed from a perspective of large-type intermountain basin in the Tianshan orogen after India-Eurasia collision, which would provide a rigorous constraint on intracontinental orogenic process of the Tianshan orogen.

围绕印度与欧亚板块碰撞远程效应这一科学命题，前人在天山南北两侧前陆盆地开展了大量盆山耦合研究工作，以揭示天山陆内构造过程，而对大型山间盆地关注较少，且在新生代构造变形方式和时间等方面仍存较大争议。伊犁盆地作为大型山间盆地，同时受南、北天山构造控制，是解决天山造山带陆内构造过程的关键地区，尤其是近年来，我们获得大量区域地质调查积累的钻孔岩芯及物探资料，为深入研究陆内构造过程提供了新的契机。本申请拟从盆山耦合角度，对新生代典型地层剖面开展构造变形研究，同时对典型新生代地层天然剖面和深钻孔岩芯开展年代地层学工作，建立新生代地层精细时间标尺；最后，结合新生代以来地层的碎屑磷灰石裂变径迹热年代学和盆地物源分析，开展伊犁盆地新生代构造演化研究。并在此基础上，探索天山造山带大型山间盆地在印度和亚洲大陆碰撞远程效应下盆地沉积与山体隆升的耦合过程，为探讨天山造山带陆内造山过程提供约束。

天山作为典型陆内造山带，是研究热点地区之一。目前在新生代构造变形方式和时间等方面仍存较大争议，伊犁盆地作为天山造山带内部的大型山间盆地，同时受南、北天山造山带演化构造控制，是解决天山造山带陆内构造过程的关键地区，盆内发育的新生代沉积物是记录天山造山带内部构造运动的重要载体。项目收集了大量的区域地质调查积累的钻孔岩心资料，重点对3个钻孔岩芯开展了精细的磁性地层年代学工作，建立了晚新生代地层精细时间标尺，发现沉积速率在~1.77Ma的峰值，是北天山构造隆升的直接响应，与北天山山前的地壳缩短相吻合。同时，项目对天然剖面新生代地层尤其是第四纪沉积地层开展了大量热释光、ESR测年和沉积古地理工作。结果表明第四纪以来伊宁盆地周缘控盆断裂存在多期次强烈活动，控制了盆地的形成演化。早更新世晚期，伊犁盆地北缘断裂强烈活动，下更新统及前第四纪地层发生褶皱，盆地北部大幅度抬升，导致中更新统沉积中心向南迁移；中更新世末，乌孙山北缘断裂向北逆冲，晚更新世末，伊犁盆地北缘断裂和乌孙山北缘断裂对冲，区域地壳整体抬升，伊犁盆地构造地貌定型。这种盆山格局对晚更新以来中亚地区的气候环境有重要的影响。通过对盆地河流冲积物和风成沉积多种环境指标综合分析，结果表明该区晚第四纪气候变化除对区域尺度气候事件存在响应外，全新世时期气候变化也受到该区盆-山地貌组合的影响。