柴达木盆地阿拉尔断层几何学、运动学及其演化

Geometry, Kinematics and Evolution of Alar Fault in Qaidam Basin

柴达木盆地多个油气田发现于阿拉尔断层上、下盘地层,阿拉尔断层几何学、运动学及其演化特征对深入研究油气成藏规律具有重要意义。本文利用地震资料阐述阿拉尔断层几何学构造样式,提出断点移动法在垂向、横向和沿断面三向定量解释阿拉尔断层各时期移动距离、移动速率和移动角度,综合分析断层几何学和运动学进而探讨断层的演化特征。研究发现阿拉尔断层几何学构造样式具有分段性,各分段具有不同的运动类型,断层西段主要以抬升-挤压为主,断层中段出现明显的走滑-推覆特征,东段为断层上盘抬升及走滑运动所形成的派生断层。阿拉尔断层运动学特征具有多样性、分段性和推覆-抬升交互式。阿拉尔断层的整个演化过程经历了抬升、挤压、走滑、推覆等多种运动类型,正是在这种演化背景下,阿拉尔断层几何学和运动学在不同时期和不同位置存在多样性和分段性。

Multiple oil and gas fields were found upperwall and footwall of Alar fault in Qaidam Basin, but the research results of geometry, kinematics and evolution of Alar fault were weak. Detailed research of Alar fault is significative to hydrocarbon accumulation. In this paper, using seismic data to elaborate geometry of Alar fault, presenting breakpoint moving method to interpret the moving distance, rate and angle of Alar fault quantitatively from vertical direction, lateral direction and along fault plane（three-direction） in each period, finally analyzing to evolution of Alar fault with characteristic of geometry and kinematics. The study found that geometry of Alar fault structural style was different characteristic of motion with segmentation. The whole fault can be divided into western segment, middle segment and eastern segment. The three-direction moving distance of Alar fault was maximum on middle segment and minimum on eastern segment. Alar fault has characteristic of intermittent climbing in each period. The activity intensity of Alar fault on middle segment was sharper than both ends, and the moving rate of fault was larger in Late Oligocene and in late Pliocene. The moving angle of Alar fault was about 45 degree in every period, and western segment was bigger. Alar fault had experienced uplift, extrusion, strike slip and thrust nappe movement forms in the whole evolution. In this tectonic evolution background, Alar fault are developed in multi-period, the characters are complicated and the spreads are in segments.