INDEPTH Ⅳ深反射地震揭示的东昆仑造山带隆升过程  

East Kunlun Orogeny′s uplift uncovered by deep reflection seismic data in INDEPTH Ⅳ

作　　者：刘志伟[1] 赵文津[1] 吴珍汉[1] 史大年[2] 宋洋[1] 邓世广 

机构地区：[1]中国地质科学院,北京100037 [2]中国地质科学院矿产资源研究所,北京100037

出　　处：《地球物理学报》2016年第9期3211-3222,共12页Chinese Journal of Geophysics

基　　金：中国地质调查局项目"青藏高原深部过程与资源环境效应研究"(1212011220903);美国自然科学基金委员会(NSF);德国GFZ地学研究中心联合资助

摘　　要：INDEPTH Ⅳ深反射地震数据处理的重点和难点是近地表风化壳静校正和异常振幅噪音衰减,通过初至波剩余折射静校正技术、异常振幅噪声衰减技术和CRS优化叠加技术获得了信噪比较高的地震剖面.由INDEPTH Ⅳ深反射地震剖面揭示,东昆仑造山带上地壳地层具有挤压走滑、断展褶皱等动力学特点,岩石圈上、下地壳之间存在不连续的松潘—甘孜古洋壳反射特征,东昆仑山下偏南局部Moho面以上低频异常反射特征指示局部熔融、低速高导体存在.综合INDEPTH Ⅳ深反射地震剖面和其他地球物理数据分析认为,东昆仑造山带隆升过程非常复杂,隆升过程至少经过两次主期变形,一期是中生代三叠纪松潘—甘孜洋向北俯冲引发被动大陆边缘造山,另一期是新生代古近纪印度—欧亚板块碰撞致使羌塘地块北移造成的上地壳挤压隆升.利用INDEPTH Ⅳ深反射地震单炮、速度和叠加剖面等成果,综合解译数据,最终提出东昆仑造山带隆升过程的另一种模式,以有助于深化对东昆仑造山模式的认识.A great challenge in INDEPTH Ⅳ′s deep-reflection seismic processing is to deal with nearsurface statics and noise attenuation,and a seismic profile with high signal-noise-ratios has been obtained by means of first-break refraction residual statics,abnormal amplitude noise suppression and CRS stacking.The new interpreted profile uncovers that the upper crust of East Kunlun Orogenic belt obviously possess dynamical characteristics of compressional strike-slips and fault-propagation folds,Songpan-Garzêancient oceanic crust′s reflection discontinuously exists between the upper and lower crusts of lithosphere,and abnormal low-frequency reflectionresponses may attribute to a partially molten block with lower-velocity and high-conductivity properties.INDEPTH Ⅳ′s seismic profiles and other geophysical data prove that the complex uplift process in East Kunlun orogeny experienced twice principal-stage deformations at least,first deformed in one northern subduction of Songpan-GarzêOcean during the Triassic period and second triggered by a compressional stress from Qiangtang Block moving northward since Cenozoic era.Finally,based on INDEPTH Ⅳ′s shot gathers,velocity and stacking profiles presently interpreted,a new uplifting model comes forward to enhance much knowledge to east Kunlun Orogenic belt.

关 键 词：深反射地震 东昆仑造山带 松潘—甘孜洋壳 INDEPTH Ⅳ 

分 类 号：P541[天文地球—构造地质学]