松潘地块与西秦岭造山带下地壳的性质和关系——深地震反射剖面的揭露
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摘要
松潘地块位于青藏高原的东缘,处于中国大陆东西向构造与南北向构造的结合部位,特殊的构造环境使其长期控制并影响着中国大陆的形成与演化。探测松潘地块的岩石圈细结构,揭示其与东昆仑-西秦岭造山带的关系,既可为研究青藏高原东北缘板块碰撞的深部过程奠定基础,同时又关联着松潘地块的油气远景评价。2004年完成了第一条横过松潘地块北缘若尔盖盆地和西秦岭造山带的长约257km的深地震反射剖面,首次揭露出若尔盖盆地和西秦岭造山带岩石圈的细结构,发现若尔盖盆地和西秦岭造山带同属统一的稳定的大陆地块,并且下地壳均以北倾的强反射为主要特征。这种北倾的反射为松潘地块向西秦岭下地壳俯冲提供了地震学证据。近于平坦的Moho反射特征反映出西秦岭造山带在造山后又经历了强烈的伸展作用。
Lying at the northeastern Qinghai-Tibet Plateau, the Songpan block is tectonically located at the junction between the E-W- and N-S-trending tectonics of continental China. The Songpan block has long controlled and affected the formation and evolution of continental China owing to its special tectonic environment. Understanding the fine structure of the lithosphere beneath the Songpan block and revealing its relation to the East Kunlun-West Qinling orogen not only laid a foundation for studying the deep processes of plate collision at the northeastern margin of the Qinghai-Tibet Plateau but also are concerned with petroleum prospect evaluation in the Songpan block. A ～257-km-long, deep seismic reflection profile across the Zoigê basin on the northern margin of the Songpan block and the West Qinling orogen were for the first time surveyed in 2004. The profile has revealed the fine lithospheric structure of the Songpan block and the West Qinling orogen and found that both the Songpan block and the West Qinling orogen belong to the same stable continental block, and that their lower crusts are both characterized by north-dipping strong reflection. The north-dipping reflection constitutes seismic evidence for the northward subduction of the lower crusts of the Songpan block and West Qinling orogen. The nearly level Moho reflections of the Zoigê basin and the West Qinling orogen show that they underwent intense extension after collisional orogeny.
Lying at the northeastern Qinghai-Tibet Plateau, the Songpan block is tectonically located at the junction between the E-W- and N-S-trending tectonics of continental China. The Songpan block has long controlled and affected the formation and evolution of continental China owing to its special tectonic environment. Understanding the fine structure of the lithosphere beneath the Songpan block and revealing its relation to the East Kunlun-West Qinling orogen not only laid a foundation for studying the deep processes of plate collision at the northeastern margin of the Qinghai-Tibet Plateau but also are concerned with petroleum prospect evaluation in the Songpan block. A ～257-km-long, deep seismic reflection profile across the Zoigê basin on the northern margin of the Songpan block and the West Qinling orogen were for the first time surveyed in 2004. The profile has revealed the fine lithospheric structure of the Songpan block and the West Qinling orogen and found that both the Songpan block and the West Qinling orogen belong to the same stable continental block, and that their lower crusts are both characterized by north-dipping strong reflection. The north-dipping reflection constitutes seismic evidence for the northward subduction of the lower crusts of the Songpan block and West Qinling orogen. The nearly level Moho reflections of the Zoigê basin and the West Qinling orogen show that they underwent intense extension after collisional orogeny.
引文
黄汲清,任纪舜,姜春发,等.中国大地构造基本特征.地质部地质科学院,1962.
张先康.阿尼玛卿缝合带东段基底结构——马尔康-碌曲-古浪地震宽角反射/折射剖面阶段结果.青藏高原东北缘西秦岭-松潘及其邻区大陆动力学学术研讨会,西安,2005.
高锐,等.松潘地块北缘岩石圈结构及其与东昆仑-西秦岭造山带的关系(国家自然科学基金会2004年度汇报).北京,2004.
高锐,等.深地震反射剖面探测初步成果.青藏高原东北缘西秦岭-松潘及其邻区大陆动力学学术研讨会论文摘要,西安,2005.
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[2]许志琴,侯立玮,王宗秀,等.中国松潘-甘孜造山带的造山过程[M].北京:地质出版社,1992:1-190.
[3]张国伟,郭安林,姚平安.中国大陆构造中的西秦岭-松潘大陆构造结[J].地学前缘,2004,11(3):23-32.
[4]任纪舜,姜春发,张正坤,等.中国大地构造及其演化[M].北京:科学出版社,1980.
[5]Seng7r A M C.The Cimmeride orogenic system and the tec-tonics of Eurasia[J].Geol.Soc.Am.Spec.Pap.,1984,195:1-82.
[6]Burchfield B C,Chen Z,Liu Y,et al.Tectonics of the Long-men Shan and adjacent regions,central China[J].Int.Geol.Rev.,1995,37:661-735.
[7]Yin A,Harrison T M.Geologic Evolution of the Himalayan-Ti-betan orogen[J].J.Ann.Rev.Earth Planet.Sci.,2000,28:211-280.
[8]崔作舟,陈纪平,吴苓.阿尔泰-台湾岩石圈地学断面综合研究:花石峡-邵阳深部地壳的结构和构造[M].北京:地质出版社,1996.49-168.
[9]李松林,张先康,张成科,等.玛沁-兰州-靖边地震测深剖面地壳速度结构的初步研究[J].地球物理学报,2002,45(2):210-217.
[10]王椿镛,韩渭宾,吴建平,等.松潘-甘孜造山带地壳速度结构[J].地震学报.2003,25(3):229-242.
[11]Ross A,Brown L,Passakorn P,et al.Deep reflection survey-ing in central Tibet:lower-crustal layering and crustal flow[J].Geophysical Journal International,2006,156:115-128.
[12]卢占武,高锐,李秋生,等.中国青藏高原深部地球物理探测与地球动力学研究[J].地球物理学报,2006,49(3):753-770.
[13]Rui Gao,Zhanwu Lu,Qiusheng Li,et al.Geophysical survey and geodynamic study of crust and upper mantle in the Qing-hai-Tibet Plateau[J].Episodes,2005,28(4):263-273.
[14]张季生,高锐,李秋生,等.松潘甘孜和西秦岭造山带地球物理特征及基底构造研究[J].地质学报,2007,待刊.
[15]高锐,董树文,贺日政,等.莫霍面地震反射图像揭露出扬子陆块深俯冲过程[J].地学前缘,2004,11(3):43-49.
[16]Brown L D,Wille D M,Zheng L,et al.COCORP:New per-spectives on the deep crust[J].Geophys.J.R.AstrSoc,1987,89:47-54.
[17]Brown L D.Lower continental crust:Variations mapped by COCORP deep profiling[J].Annal.Geophy.,1987,5:325-332.
[18]高锐,黄东定,卢德源,等.横过西昆仑造山带与塔里木盆地结合带的深地震反射剖面[J].科学通报,2000,45(17):1874-1879.
[19]高锐,肖序常,刘训,等.新疆地学断面深地震反射剖面揭示的西昆仑-塔里木结合带岩石圈细结构[J].地球学报,2001,22(6):547-552.
[20]马永生,陈跃昆,苏树桉,等.川西北松潘—阿坝地区油气勘探进展与初步评价[J].地质通报,2006,25(9-10):1046-1049.
[21]王海燕,高锐,马永生,等.深地震反射剖面揭示的松潘地块若尔盖盆地与西秦岭造山带岩石圈尺度的构造关系[J].地球物理学报,2007,待刊.
张先康.阿尼玛卿缝合带东段基底结构——马尔康-碌曲-古浪地震宽角反射/折射剖面阶段结果.青藏高原东北缘西秦岭-松潘及其邻区大陆动力学学术研讨会,西安,2005.
高锐,等.松潘地块北缘岩石圈结构及其与东昆仑-西秦岭造山带的关系(国家自然科学基金会2004年度汇报).北京,2004.
高锐,等.深地震反射剖面探测初步成果.青藏高原东北缘西秦岭-松潘及其邻区大陆动力学学术研讨会论文摘要,西安,2005.
[1]许志琴,侯立玮,王宗秀.松潘-甘孜造山带构造研究新进展[J].中国地质,1991,12:14-16.
[2]许志琴,侯立玮,王宗秀,等.中国松潘-甘孜造山带的造山过程[M].北京:地质出版社,1992:1-190.
[3]张国伟,郭安林,姚平安.中国大陆构造中的西秦岭-松潘大陆构造结[J].地学前缘,2004,11(3):23-32.
[4]任纪舜,姜春发,张正坤,等.中国大地构造及其演化[M].北京:科学出版社,1980.
[5]Seng7r A M C.The Cimmeride orogenic system and the tec-tonics of Eurasia[J].Geol.Soc.Am.Spec.Pap.,1984,195:1-82.
[6]Burchfield B C,Chen Z,Liu Y,et al.Tectonics of the Long-men Shan and adjacent regions,central China[J].Int.Geol.Rev.,1995,37:661-735.
[7]Yin A,Harrison T M.Geologic Evolution of the Himalayan-Ti-betan orogen[J].J.Ann.Rev.Earth Planet.Sci.,2000,28:211-280.
[8]崔作舟,陈纪平,吴苓.阿尔泰-台湾岩石圈地学断面综合研究:花石峡-邵阳深部地壳的结构和构造[M].北京:地质出版社,1996.49-168.
[9]李松林,张先康,张成科,等.玛沁-兰州-靖边地震测深剖面地壳速度结构的初步研究[J].地球物理学报,2002,45(2):210-217.
[10]王椿镛,韩渭宾,吴建平,等.松潘-甘孜造山带地壳速度结构[J].地震学报.2003,25(3):229-242.
[11]Ross A,Brown L,Passakorn P,et al.Deep reflection survey-ing in central Tibet:lower-crustal layering and crustal flow[J].Geophysical Journal International,2006,156:115-128.
[12]卢占武,高锐,李秋生,等.中国青藏高原深部地球物理探测与地球动力学研究[J].地球物理学报,2006,49(3):753-770.
[13]Rui Gao,Zhanwu Lu,Qiusheng Li,et al.Geophysical survey and geodynamic study of crust and upper mantle in the Qing-hai-Tibet Plateau[J].Episodes,2005,28(4):263-273.
[14]张季生,高锐,李秋生,等.松潘甘孜和西秦岭造山带地球物理特征及基底构造研究[J].地质学报,2007,待刊.
[15]高锐,董树文,贺日政,等.莫霍面地震反射图像揭露出扬子陆块深俯冲过程[J].地学前缘,2004,11(3):43-49.
[16]Brown L D,Wille D M,Zheng L,et al.COCORP:New per-spectives on the deep crust[J].Geophys.J.R.AstrSoc,1987,89:47-54.
[17]Brown L D.Lower continental crust:Variations mapped by COCORP deep profiling[J].Annal.Geophy.,1987,5:325-332.
[18]高锐,黄东定,卢德源,等.横过西昆仑造山带与塔里木盆地结合带的深地震反射剖面[J].科学通报,2000,45(17):1874-1879.
[19]高锐,肖序常,刘训,等.新疆地学断面深地震反射剖面揭示的西昆仑-塔里木结合带岩石圈细结构[J].地球学报,2001,22(6):547-552.
[20]马永生,陈跃昆,苏树桉,等.川西北松潘—阿坝地区油气勘探进展与初步评价[J].地质通报,2006,25(9-10):1046-1049.
[21]王海燕,高锐,马永生,等.深地震反射剖面揭示的松潘地块若尔盖盆地与西秦岭造山带岩石圈尺度的构造关系[J].地球物理学报,2007,待刊.
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