新疆伽师强震群区基底界面结构特征
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摘要
用射线分布分析法对伽师强震群区的高分辨折射地震剖面资料进行了更进一步的分析处理,得到了伽师强震群区更完整的基底界面结构特征.结果表明,在伽师强震群区地壳上部存在两个明显的结构界面:第一个界面的结构连续、完整,其埋深变化不大,在2.6～3.3km之间,为一向天山方向逐渐抬升、近平直的倾斜界面;第二个界面的埋深变化较大,在8.5～11.8km之间,为古老的塔里木盆地结晶基底.在约37km桩号附近结晶基底有近2.5km的深度突变,推断可能是伽师强震群区超基底断裂所致.以该断裂为界,结晶基底分为西南、东北两段.每段内界面的埋深变化不大,西南段的埋深约11.5km,东北段的埋深约为8.5～9.0km,该段在从西南向东北整体抬升的背景上略有上隆,反映出在塔里木地块西北缘特殊的构造环境下上部地壳的变形特征.
The seismic data obtained from high resolution seismic refraction profile in Jiashi strong earthquake swarm area in Xinjiang China were further processed with ray hit analysis method and more complete basement interface structural characteristics beneath Jiashi strong earthquake swarm area were determined.The results show that there are two clear basement interfaces at the upper crust in Jiashi strong earthquake swarm area.The first one with buried depth ranging from 2.6 km to 3.3 km presents integral and continuous structure,and it appears an inclined plane interface and smoothly rises up toward Tianshan mountain.The second basement interface with buried depth from 8.5 km to 11.8 km,is the antiquated crystalline basement of Tarim basin.Near the post number of 37 km,the buried depth of the crystalline basement changed abruptly by 2.5 km,which maybe result from an ultra crystalline basement fault.If taking this fault as a boundary,the crystalline basement could be divided into two parts,i.e.the southwestern segment with buried depth about 11.5 km,and the northeastern segment with buried depth approximately from 8.5 km to 9.0 km.That is to say,in each segment,the buried depth changes not too much.The northeast segment rises up as a whole and upheaves slightly from southwest to northeast,which reflects the upper crustal deformation characteristics under the special tectonic background at the northwestern edge of Tarim basin.
The seismic data obtained from high resolution seismic refraction profile in Jiashi strong earthquake swarm area in Xinjiang China were further processed with ray hit analysis method and more complete basement interface structural characteristics beneath Jiashi strong earthquake swarm area were determined.The results show that there are two clear basement interfaces at the upper crust in Jiashi strong earthquake swarm area.The first one with buried depth ranging from 2.6 km to 3.3 km presents integral and continuous structure,and it appears an inclined plane interface and smoothly rises up toward Tianshan mountain.The second basement interface with buried depth from 8.5 km to 11.8 km,is the antiquated crystalline basement of Tarim basin.Near the post number of 37 km,the buried depth of the crystalline basement changed abruptly by 2.5 km,which maybe result from an ultra crystalline basement fault.If taking this fault as a boundary,the crystalline basement could be divided into two parts,i.e.the southwestern segment with buried depth about 11.5 km,and the northeastern segment with buried depth approximately from 8.5 km to 9.0 km.That is to say,in each segment,the buried depth changes not too much.The northeast segment rises up as a whole and upheaves slightly from southwest to northeast,which reflects the upper crustal deformation characteristics under the special tectonic background at the northwestern edge of Tarim basin.
引文
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郑显华.1995.塔里木盆地西部巴楚一麦盖提地区石油地质特征及勘探建议[J].石油试验地质,17(2):114-120.
朱令仁,苏乃秦,杨马陵.1998.1997年新疆伽师强震群的三次成功预报[J].中国地震,14(2):101-115.
贾承造.1999.塔里木盆地构造特征与油气聚集规律[J].新疆石油地质,20(3):177-183.
刘启元,陈九辉,李顺成,等.2002.新疆伽师强震群区三维地壳上地幔S波速度结构及其地震成因的探讨[J].地球物理学报,43(3):356-365.
徐朝繁,张先康,朱金芳,等.2002.复杂介质结构中折射界面的哈格多恩原理波前成像[J].地震地质,24(4):542-548.
徐朝繁.2005.伽师强震群区、西秦岭阿尼玛卿缝合带上部地壳精细结构:复杂结构中的地震波前成像方法及其应用[D]:[学位论文].中国地震局地球物理研究所:56-61.
徐朝繁,张先康,刘宝金,等.2005.高分辨折射地震资料处理方法及其应用[J].地球物理学进展,20(4):1052-1058.
徐朝繁,张先康,段永红,等.2006a.新疆伽师强震群区上部地壳精细结构的高分辨折射地震探测研究[J].地震学报,28(1):60-69.
徐朝繁,张先康,张建狮,等.2006b.射线数分布分析法及其在复杂地壳结构探测中的应用[J].地震学报,28(2):167-175.
杨卓欣,张先康,嘉世旭,等.2006.伽师强震群区震源细结构的深地震反射探测研究[J].地球物理学报,49(6):1701-1708.
张先康,赵金仁,张成科,等.2002.帕米尔东北测地壳结构研究[J].地球物理学报,37(6):356-365.
郑显华.1995.塔里木盆地西部巴楚一麦盖提地区石油地质特征及勘探建议[J].石油试验地质,17(2):114-120.
朱令仁,苏乃秦,杨马陵.1998.1997年新疆伽师强震群的三次成功预报[J].中国地震,14(2):101-115.
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