深地震反射剖面揭示的天山北缘乌鲁木齐坳陷地壳结构和构造
摘要
已有活动构造研究结果表明,天山北缘具有典型的大陆内部活动构造特征,表现为多排平行山体的背斜和逆断裂.为了研究乌鲁木齐坳陷区的地壳细结构、主要断裂展布和深、浅构造关系,2004年底,在乌鲁木齐西部的天山与准噶尔盆地之间的过渡带上,完成了一条近SN向的长度为78 km的深地震反射探测剖面.结果表明,该区地壳以双程走时9~10.5 s左右的强反射带为界分为上地壳和下地壳,上地壳厚约26~28 km,下地壳厚约23~25 km.双程走时5 s以上,反射层位丰富,构造形态清晰,且在剖面横向上具有明显不同的构造特征;在西山以南的区域,为一系列近东西向展布、南北向排列的逆冲背斜构造和一组自南向北逆冲的断裂,它们在深部均受到滑脱带的控制;在西山和王家沟一带,为一套向北陡倾的反射层系和一组沿层间滑动的断裂;剖面北部显示出了典型的沉积盆地图像,沉积盆地最深处约为10~12 km.双程走时6~9 s之间,为一些延续长度较短、反射能量较弱、且无规律可寻的凌乱反射,表明这部分地壳结构具有明显的"反射透明"性.Moho过渡带出现的时间位于双程走时14~17 s,对应壳幔过渡带厚度约为9~10 km.本区Moho面自北向南逐渐加深,剖面北部其深度约为50~52 km,在靠近北天山附近,其深度约为54~55 km.在剖面中部的西山附近,上、下地壳分界面反射和Moho过渡带反射变得模糊,且浅部地层还出现隆起和褶皱,推测与准噶尔盆地和天山的挤压过程有关.
It is known from the active tectonic research results that the northern margin of Tianshan mountains is characterized with typical intra-continental active tectonics,which has thrust faults and anticlines with multiple parallel mountains.In order to investigate the fine crustal structures and the main fault geometries as well as the deep-shallow tectonic relations in rümqi depression,a deep seismic reflection profile of 78 km long,running in nearly SN direction,was completed in 2004.This profile is located in the transition zone between Tianshan mountains and Junggar Basin of the western rümqi.The results show that the crust beneath the investigated area is divided into upper and lower crusts by a strong reflective zone with about 9～10.5 s TWT.The thicknesses of the upper and lower crusts are about 26～28 km,23～25 km,respectively.There are rich reflective layers and clear tectonic patterns above 5s TWT while presenting obviously different tectonic features along the profile.In the southern region of Xishan,the stacked deep seismic reflection section has a series of thrust anticlines extending in the EW direction and arranging in the SN as well as a group of faults thrusting from south to north.All of those are influenced by the deep detachment zone.In the Xishan and Wangjiagou area,it shows a set of steeply north-dipping reflective layers and a group of faults slipping along the layers.The northern part of the profile shows the images of typical sediment basin and its deepest depth is about 10～12 km.Between 6 and 9 s TWT,the stacked deep seismic reflection section shows disordered reflections with comparatively short continuing time and weak energy.These indicate that this part of the crust is evidently possessed with "reflection transparence".The Moho transition zone occurs at 14～17 s TWT,and the zone thickness is about 9～10 km.In the studied area,the Moho discontinuity gradually deepens from north to south.Its depth is about 50～52 km at the northern segment of the profile and is about 54～55 km near north Tianshan.In the neighbourhood of Xishan at the middle profile,the reflections from the boundary between upper and lower crusts as well as Moho transition zone become misty while the shallow stratums show signs of uplift and fold,which may have something to do with the extrusions between Junggar basin and Tianshan mountains.
It is known from the active tectonic research results that the northern margin of Tianshan mountains is characterized with typical intra-continental active tectonics,which has thrust faults and anticlines with multiple parallel mountains.In order to investigate the fine crustal structures and the main fault geometries as well as the deep-shallow tectonic relations in rümqi depression,a deep seismic reflection profile of 78 km long,running in nearly SN direction,was completed in 2004.This profile is located in the transition zone between Tianshan mountains and Junggar Basin of the western rümqi.The results show that the crust beneath the investigated area is divided into upper and lower crusts by a strong reflective zone with about 9～10.5 s TWT.The thicknesses of the upper and lower crusts are about 26～28 km,23～25 km,respectively.There are rich reflective layers and clear tectonic patterns above 5s TWT while presenting obviously different tectonic features along the profile.In the southern region of Xishan,the stacked deep seismic reflection section has a series of thrust anticlines extending in the EW direction and arranging in the SN as well as a group of faults thrusting from south to north.All of those are influenced by the deep detachment zone.In the Xishan and Wangjiagou area,it shows a set of steeply north-dipping reflective layers and a group of faults slipping along the layers.The northern part of the profile shows the images of typical sediment basin and its deepest depth is about 10～12 km.Between 6 and 9 s TWT,the stacked deep seismic reflection section shows disordered reflections with comparatively short continuing time and weak energy.These indicate that this part of the crust is evidently possessed with "reflection transparence".The Moho transition zone occurs at 14～17 s TWT,and the zone thickness is about 9～10 km.In the studied area,the Moho discontinuity gradually deepens from north to south.Its depth is about 50～52 km at the northern segment of the profile and is about 54～55 km near north Tianshan.In the neighbourhood of Xishan at the middle profile,the reflections from the boundary between upper and lower crusts as well as Moho transition zone become misty while the shallow stratums show signs of uplift and fold,which may have something to do with the extrusions between Junggar basin and Tianshan mountains.
引文
[1]邓起东,冯先岳,张培震等.天山活动构造.北京:地震出版社,2000Deng Q D,Feng X Y,Zhang P Z,et al.Active Tectonics of ChineseTianshan Mountains(in Chinese).Beijing:Seismological Press,2000
[2]邓起东,冯先岳,张培震等.乌鲁木齐山前坳陷逆断裂-褶皱带及其形成机制.地学前缘,1999,6(4):191~199Deng Q D,Feng X Y,Zhang P Z,et al.Reverse fault and fold zonein the Urumqi range-front depression of the northern Tian-shan and itsgenetic Mechanism.Earth Science Frontiers(in Chinese),1999,6(4):191~199
[3]冯先岳,邓起东,石监邦等.天山南北缘活动构造及其演化.见:国家地震局地质研究所编.活动断裂研究(1).北京:地震出版社,1991.1~16Feng X Y,Deng Q D,Shi J B,et al.Active tectonics of the southernand northern Tianshan mountains and its tectonics evolution.In:Institute of Ceology,SSB eds.Research on Active Faults(1)(inChinese).Beijing:Seismological Press,1991.1~16
[4]Allen M B,Vencint S J,Wheller P J.Late Cenozoic tectonics of theKepingtage thrust zone Tianshan and Tarim Basin,Northwest China.Tectonics,1999,18(4):639~654
[5]郭飚,刘启元,陈九辉等.中国境内天山地壳上地幔结构的地震层析成像.地球物理学报,2006,49(6):1693~1699Guo B,Liu Q Y,Chen J H,et al.Seismic tomography of the crustand upper mantle structure underneath the Chinese Tianshan.ChineseJ.Geophys.(in Chinese),2006,49(6):1693~1699
[6]胥颐,Steven W Roecker,魏若平等.天山中部的地震定位和地壳活动性分析.地球物理学报,2005,48(6):1308~1315Xu Y,Steven W Roecker,Wei R P,et al.Analysis of seismic activityin the crust from earthquake relocation in the central Tianshan.Chinese J.Geophys.(in Chinese),2005,48(6):1308~1315
[7]Avouac J P,Papponnier P T,Bai M,et al.Active thrusting andfolding along the northern Tianshan,and Late Cenozoic rotation of theTarim relative to Dzgungaria and Kazakhstan.Journal ofGeophysical,1993,98(B4):6755~6804
[8]Burchfiel B C,Brown E T,Deng Q,et al.Crustal shortening on themargins of the Tianshan,Xinjiang,China.International GeologyReview,1999,41:665~700
[9]Molnar P,Brown E T,Burchfiel B C,et al.Quaternary climatechange and formation of river terraces across growing anticlines on thenorth flank of the Tianshan.J.Geology,1994,102:583~602
[10]Windly B F,Allen M B,Zhang C,et al.Paleozoic accretion andCenozoic redeformation of the Chinese Tianshan range,central Asia.Geology,1990,18:128~131
[11]张培震,邓起东,杨晓平等.天山的晚新生代构造变形及其地球动力学问题.中国地震,1996,12(2):127~138Zhang P Z,Deng Q D,Yang X P,et al.Late Cenozoic tectonicdeformation and mechanism along the Tianshan Mountain,Northwestern China.Earthquake Research in China(in Chinese),1996,20(3):127~138
[12]冯先岳.天山全新世活动断裂及古地震研究.内陆地震,1995,9(3):217~225Feng X Y.Holocene active faults and paleo-earthquakes of TianshanMountain.Inland Earthquake(in Chinese),1995,9(3):217~225
[13]沈军,汪一鹏,李莹甄等.中国新疆天山博阿断裂晚第四纪右旋走滑运动特征.地震地质,2003,25(2):184~192Shen J,Wang Y P,Li Y Z,et al.Late quaternary right-lateral strike-slip faulting along the Bolokenu-Aqikekuduke fault in ChineseTianshan.Seismology and Geology(in Chinese),2003,25(2):184~192
[14]杨晓平,邓起东,张培震等.北天山地区活动逆断裂-褶皱带构造与潜在震源区估计.地震地质,1998,20(3):193~198Yang X P,Deng Q D,Zhang P Z,et al.Active reverse fault-fold zoneand estimation of Potential earthquake sources in northern Tian-shan.Seismology and Geology(in Chinese),1998,20(3):193~198
[15]赵瑞斌,杨主恩,周伟新等.天山南北两侧山前坳陷带中新生代构造特征与地震.地震地质,2000,22(3):295~304Zhao R B,Yang Z E,Zhou W X,et al.Mesozoic-Cenozoic structuralcharacteristics and seismicty of the depressions on the southern andnorthern of the Tian-shan mountains.Seismology and Geology(inChinese),1998,22(3):295~304
[16]王椿镛,邹景文,史刚等.反射地震剖面解释的天山北缘地壳构造.见:中国地震局地质研究所编.活动断裂研究(8).北京:地震出版社,2001.1~8Wang C Y,Zou J W,Shi G,et al.Structure and tectonic of the crustin the northern Tianshan mountains revealed by seismic reflectionprofiles.In:Institute of Geology,CSB eds.Research on ActiveFaults(8)(in Chinese).Beijing:Seismological Press,2001.1~8
[17]杨晓平,顾梦林,孙振国等.1906年新疆玛纳斯大震区的多层次逆冲构造与深部结构.地震地质,2002,24(3):303~313Yang X P,Gu M L,Sun Z G,et al.Multilayered reverse faults anddeep structure of 1906 Manas earthquake area in Xinjiang.Seismology and Geology(in Chinese),2002,24(3):303~313
[18]渥伊尔马滋著.地震数据处理.黄绪德,袁明德译.北京:石油工业出版社.1994Yilmaz O.Seismic Data Processing(in Chinese).Huang X D,YuanM D translate.Beijing:Petroleum Industry Press,1994
[19]邵学钟,张家茹,范会吉等.天山造山带地壳结构和构造:乌鲁木齐-库尔勒地震转换波测深剖面.地球物理学报,1996,39(3):336~345Shao X Z,Zhang J R,Fan H J,et al.The crust structure and tectonicof Tianshan orogenic belt:a deep sounding work by converted wavesof seismic along Urumqi-Korla profile.Chinese J.Geophys.(inChinese),1996,39(3):336~345
[20]胥颐,刘福田,刘建华等.天山地震带的地壳结构与强震构造环境.地球物理学报,2000,43(2):184~193Xu Y,Liu F T,Liu J H,et al.Crustal structure and tectonicenvironment of strong earthquakes in the Tianshan earthquake belt.Chinese J.Geophys.(in Chinese),2000,43(2):184~193
[21]滕吉文,张中杰,白武明等.岩石圈物理学.北京:科学出版社.2004.142~144Teng J W,Zhang Z J,Bai W M,et al.Lithospheric Physical(inChinese).Beijing:Science Press,2004.142~144
[22]赵俊猛,刘国栋,卢造勋等.天山造山带与准噶尔盆地壳幔过渡带及其动力学含义.中国科学(D辑),2001,31(4):272~282Zhao J M,Liu G D,Lu Z X,et al.Crust-mantle transitional zone ofTianshan orogenic belt and Junggar Basin and its geodynamicimplication.Science in China(Series D)(in Chinese),2001,31(4):272~282
[23]王椿镛,楼海,魏修成等.天山北缘的地壳结构和1906年玛纳斯地震的地震构造.地震学报,2001,23(5):460~469Wang C Y,Lou H,Wei X C,et al.Crustal structure in northernmargin of Tianshan mountains and seismotectonics of 1906 Manasearthquake.Acta Seismologica Sinica(in Chinese),2001,23(5):460~469
[2]邓起东,冯先岳,张培震等.乌鲁木齐山前坳陷逆断裂-褶皱带及其形成机制.地学前缘,1999,6(4):191~199Deng Q D,Feng X Y,Zhang P Z,et al.Reverse fault and fold zonein the Urumqi range-front depression of the northern Tian-shan and itsgenetic Mechanism.Earth Science Frontiers(in Chinese),1999,6(4):191~199
[3]冯先岳,邓起东,石监邦等.天山南北缘活动构造及其演化.见:国家地震局地质研究所编.活动断裂研究(1).北京:地震出版社,1991.1~16Feng X Y,Deng Q D,Shi J B,et al.Active tectonics of the southernand northern Tianshan mountains and its tectonics evolution.In:Institute of Ceology,SSB eds.Research on Active Faults(1)(inChinese).Beijing:Seismological Press,1991.1~16
[4]Allen M B,Vencint S J,Wheller P J.Late Cenozoic tectonics of theKepingtage thrust zone Tianshan and Tarim Basin,Northwest China.Tectonics,1999,18(4):639~654
[5]郭飚,刘启元,陈九辉等.中国境内天山地壳上地幔结构的地震层析成像.地球物理学报,2006,49(6):1693~1699Guo B,Liu Q Y,Chen J H,et al.Seismic tomography of the crustand upper mantle structure underneath the Chinese Tianshan.ChineseJ.Geophys.(in Chinese),2006,49(6):1693~1699
[6]胥颐,Steven W Roecker,魏若平等.天山中部的地震定位和地壳活动性分析.地球物理学报,2005,48(6):1308~1315Xu Y,Steven W Roecker,Wei R P,et al.Analysis of seismic activityin the crust from earthquake relocation in the central Tianshan.Chinese J.Geophys.(in Chinese),2005,48(6):1308~1315
[7]Avouac J P,Papponnier P T,Bai M,et al.Active thrusting andfolding along the northern Tianshan,and Late Cenozoic rotation of theTarim relative to Dzgungaria and Kazakhstan.Journal ofGeophysical,1993,98(B4):6755~6804
[8]Burchfiel B C,Brown E T,Deng Q,et al.Crustal shortening on themargins of the Tianshan,Xinjiang,China.International GeologyReview,1999,41:665~700
[9]Molnar P,Brown E T,Burchfiel B C,et al.Quaternary climatechange and formation of river terraces across growing anticlines on thenorth flank of the Tianshan.J.Geology,1994,102:583~602
[10]Windly B F,Allen M B,Zhang C,et al.Paleozoic accretion andCenozoic redeformation of the Chinese Tianshan range,central Asia.Geology,1990,18:128~131
[11]张培震,邓起东,杨晓平等.天山的晚新生代构造变形及其地球动力学问题.中国地震,1996,12(2):127~138Zhang P Z,Deng Q D,Yang X P,et al.Late Cenozoic tectonicdeformation and mechanism along the Tianshan Mountain,Northwestern China.Earthquake Research in China(in Chinese),1996,20(3):127~138
[12]冯先岳.天山全新世活动断裂及古地震研究.内陆地震,1995,9(3):217~225Feng X Y.Holocene active faults and paleo-earthquakes of TianshanMountain.Inland Earthquake(in Chinese),1995,9(3):217~225
[13]沈军,汪一鹏,李莹甄等.中国新疆天山博阿断裂晚第四纪右旋走滑运动特征.地震地质,2003,25(2):184~192Shen J,Wang Y P,Li Y Z,et al.Late quaternary right-lateral strike-slip faulting along the Bolokenu-Aqikekuduke fault in ChineseTianshan.Seismology and Geology(in Chinese),2003,25(2):184~192
[14]杨晓平,邓起东,张培震等.北天山地区活动逆断裂-褶皱带构造与潜在震源区估计.地震地质,1998,20(3):193~198Yang X P,Deng Q D,Zhang P Z,et al.Active reverse fault-fold zoneand estimation of Potential earthquake sources in northern Tian-shan.Seismology and Geology(in Chinese),1998,20(3):193~198
[15]赵瑞斌,杨主恩,周伟新等.天山南北两侧山前坳陷带中新生代构造特征与地震.地震地质,2000,22(3):295~304Zhao R B,Yang Z E,Zhou W X,et al.Mesozoic-Cenozoic structuralcharacteristics and seismicty of the depressions on the southern andnorthern of the Tian-shan mountains.Seismology and Geology(inChinese),1998,22(3):295~304
[16]王椿镛,邹景文,史刚等.反射地震剖面解释的天山北缘地壳构造.见:中国地震局地质研究所编.活动断裂研究(8).北京:地震出版社,2001.1~8Wang C Y,Zou J W,Shi G,et al.Structure and tectonic of the crustin the northern Tianshan mountains revealed by seismic reflectionprofiles.In:Institute of Geology,CSB eds.Research on ActiveFaults(8)(in Chinese).Beijing:Seismological Press,2001.1~8
[17]杨晓平,顾梦林,孙振国等.1906年新疆玛纳斯大震区的多层次逆冲构造与深部结构.地震地质,2002,24(3):303~313Yang X P,Gu M L,Sun Z G,et al.Multilayered reverse faults anddeep structure of 1906 Manas earthquake area in Xinjiang.Seismology and Geology(in Chinese),2002,24(3):303~313
[18]渥伊尔马滋著.地震数据处理.黄绪德,袁明德译.北京:石油工业出版社.1994Yilmaz O.Seismic Data Processing(in Chinese).Huang X D,YuanM D translate.Beijing:Petroleum Industry Press,1994
[19]邵学钟,张家茹,范会吉等.天山造山带地壳结构和构造:乌鲁木齐-库尔勒地震转换波测深剖面.地球物理学报,1996,39(3):336~345Shao X Z,Zhang J R,Fan H J,et al.The crust structure and tectonicof Tianshan orogenic belt:a deep sounding work by converted wavesof seismic along Urumqi-Korla profile.Chinese J.Geophys.(inChinese),1996,39(3):336~345
[20]胥颐,刘福田,刘建华等.天山地震带的地壳结构与强震构造环境.地球物理学报,2000,43(2):184~193Xu Y,Liu F T,Liu J H,et al.Crustal structure and tectonicenvironment of strong earthquakes in the Tianshan earthquake belt.Chinese J.Geophys.(in Chinese),2000,43(2):184~193
[21]滕吉文,张中杰,白武明等.岩石圈物理学.北京:科学出版社.2004.142~144Teng J W,Zhang Z J,Bai W M,et al.Lithospheric Physical(inChinese).Beijing:Science Press,2004.142~144
[22]赵俊猛,刘国栋,卢造勋等.天山造山带与准噶尔盆地壳幔过渡带及其动力学含义.中国科学(D辑),2001,31(4):272~282Zhao J M,Liu G D,Lu Z X,et al.Crust-mantle transitional zone ofTianshan orogenic belt and Junggar Basin and its geodynamicimplication.Science in China(Series D)(in Chinese),2001,31(4):272~282
[23]王椿镛,楼海,魏修成等.天山北缘的地壳结构和1906年玛纳斯地震的地震构造.地震学报,2001,23(5):460~469Wang C Y,Lou H,Wei X C,et al.Crustal structure in northernmargin of Tianshan mountains and seismotectonics of 1906 Manasearthquake.Acta Seismologica Sinica(in Chinese),2001,23(5):460~469
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