【摘要】 乌鲁木齐市西部地区处于北天山地震带中,是准噶尔含油气盆地的南缘中部的一部分。本研究于2010年5月至10月在该区域部署了20个微地震观测台站。通过对记录的天然微地震资料的分析发现:研究区微地震活动比较频繁,但总体分布比较离散,没有明显沿着某条或某几条断裂成带状集中分布。说明北天山地震带在研究区内的地震活动主要受控于多级构造,也是研究区处于宽缓盆山转换带的一个典型特征。利用三维地震层析成像反演获得了区域上地壳三维纵波速度结构,并利用统计分辨率矩阵分析方法获得了反演模型的三维空间分辨率分布。所获得的波速结构显示:属于准噶尔盆地的乌鲁木齐山前凹陷比柴窝堡凹陷沉积地层厚,而柴窝堡凹陷与博格达复背斜具有相似的地层特征。分割乌鲁木齐山前凹陷与柴窝堡凹陷的东西走向构造块体边界断裂较发育,倾向南,倾角较缓,该断裂应该是北天山地震带的主断裂;分割柴窝堡凹陷与博格达复背斜的近南北走向构造块体边界断裂不发育。此外,柴窝堡凹陷北部5～10km深度范围内存在一个局部隆起区,可能具有良好的油气资源勘探前景。更多还原

【Abstract】 The present study deployed 20 micro-seismic stations in an area of～1 200km2 in west Urumqi,in the North Tianshan seismic zone and central-south boundary of the Jungar Basin,during May and October of 2010.The observations recorded by the seismic stations show that thestudy region is seismically active,but micro-earthquakes are scattered and do not concentrate along any regional fault belt.This distribution suggests that the regional seismicity is simultaneously controlled by different-order tectonics,which is typical for a wide and smooth basin-mountain transition zone where the study region located.A 3D P-wave velocity model was inverted by micro-seismic tomography,and statistic resolution lengths were inverted for the 3D model.The P-wave velocity model provides uppercrustal structure information beneath the study region.The Urumqi piedmont depression has larger sedimentary thickness than the Chaiwopu depression,while the Chaiwopu depression has similar sedimentary thickness to the Bogeda anticlinorium.An east-west striking fault separating the former two blocks develops very well and the fault dips to the south.This fault may be the main fault of the north Tianshan seismic zone.A north-south striking fault separating the latter two blocks does not develop well.Besides,a local uplift is found at the depth range of 5～10km in the northern Chaiwopu depression,which may indicate a good prospect of oil and gas exploration.更多还原