琼北地区地壳速度结构与构造特征
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摘要
地震方法在获取地球深部结构特征方面有其独特的优势。该方法在大地构造深部环境研究、地震孕育深部动力学背景及国土资源勘查等领域有着广泛的应用前景，其中人工地震测深方法是获取地壳上地幔精细结构最为有效的方法。
琼北地区是一个地质构造复杂，地震活动比较活跃的地区。本文对穿过琼北地区的一条近200km的人工地震测深剖面资料进行了分析，针对不同的震相特征，分别采用基底折射波走时反演、反射波走时反演、一维走时反演及二维动力学射线追踪等多种分析处理方法，得到了琼北地区地壳上地幔的结构和构造特征。结果显示该地区地壳可分为上地壳、中地壳和下地壳三个结构层，其中上地壳厚度为11.5-14.5km，中地壳厚度为5.6-8.5km，下地壳厚度为6.0-8.2km。研究结果还表明：上地壳底界面的形态起伏较为明显，其深度为11.5-14.5km，中地壳底界面的深度为18.0-21.7km，莫霍面的深度为26.0-29.5km；上地幔顶部速度为8.00-8.15km/s，其速度随深度增加而加大，至40.0km深时速度为8.38-8.56km/s。
对琼北地区的壳幔结构研究结果发现，中下地壳存在走向北西的低速带，上地幔中的低速区北移，集中到了琼北火山区北端至琼州海峡地区，火山区的中下地壳还存在比较活跃的热运动，热物质可能来源于北部琼州海峡。因此，可以推断曾经作用于探测区下的岩浆应源自于地震测线北部地区的地幔。同时深入了解整个雷琼地区合理尺度的壳幔结构特征及深部地球动力学过程对整个雷琼地区(特别是海口及其邻近地区)的防震减灾工作意义重大。
Seismic method has its unique advantages to get the characteristics of the depthstructure, it has a wide range of applications on the research of deep tectonic setting,Seismogenic dynamics, territorial resources exploration, and so on,the artificial seismicsounding method is the most effective method for get the fine structure of the earth crustand mantle.
The northern Hainan has a complex geological structure and active seismicactivities.In this paper, the comparative analysis of artificial seismic sounding profilewhich is the length of200km in northern Hainan is made, in view of the differentcharacteristics of seismic phase, analyzes the datas with the method of basal refractionwave travel time inversion,the reflected wave inversion, one-dimensional travel timeinversion, two-dimensional dynamic ray tracing and so on, to get the structural feature ofthe earth crust and the upper mantle in the north of Hainan. The result shows that the earthcrust of this area is divided into the upper crust, the middle crust and the lower crust, thethickness of the upper crust is11.5-14.5km, the thickness of the middle crust is5.6-8.5km,the thickness of the lower crust is6.0-8.2km. The form fluctuation of C1interface arerelatively obvious, the range of variation of depth is11.5-14.5km, the depth of the C2interface is18.0-21.7km, the depth of Moho interface is26.0-29.5km, the velocity of thetop of upper mantle is8.00-8.15km/s, the velocity increases with the increase of the depth,it's8.38-8.56km/s when the depth is40.0km.
The results of crust-mantle structure show that the middle and lower crust have lowvelocity region which is north-west trend, it moves northward in the upper mantle,concentrated at the north of Qiongbei volcanic zone and Qiongzhou Strait, the middle andlower crust in volcanic zone still have comparatively active thermal motion, maybe thethermal materials come from the northern Qiongzhou strait. Therefore, it can infer that the magmas which once act on detection area should be derived from the mantle of northernseismic survey line. At the same time, understanding the crust-mantle structural feature andgeodynamic processes in the Leiqiong area is significant to the Leiqiong area (especially inHaikou and its neighboring region).
琼北地区是一个地质构造复杂，地震活动比较活跃的地区。本文对穿过琼北地区的一条近200km的人工地震测深剖面资料进行了分析，针对不同的震相特征，分别采用基底折射波走时反演、反射波走时反演、一维走时反演及二维动力学射线追踪等多种分析处理方法，得到了琼北地区地壳上地幔的结构和构造特征。结果显示该地区地壳可分为上地壳、中地壳和下地壳三个结构层，其中上地壳厚度为11.5-14.5km，中地壳厚度为5.6-8.5km，下地壳厚度为6.0-8.2km。研究结果还表明：上地壳底界面的形态起伏较为明显，其深度为11.5-14.5km，中地壳底界面的深度为18.0-21.7km，莫霍面的深度为26.0-29.5km；上地幔顶部速度为8.00-8.15km/s，其速度随深度增加而加大，至40.0km深时速度为8.38-8.56km/s。
对琼北地区的壳幔结构研究结果发现，中下地壳存在走向北西的低速带，上地幔中的低速区北移，集中到了琼北火山区北端至琼州海峡地区，火山区的中下地壳还存在比较活跃的热运动，热物质可能来源于北部琼州海峡。因此，可以推断曾经作用于探测区下的岩浆应源自于地震测线北部地区的地幔。同时深入了解整个雷琼地区合理尺度的壳幔结构特征及深部地球动力学过程对整个雷琼地区(特别是海口及其邻近地区)的防震减灾工作意义重大。
Seismic method has its unique advantages to get the characteristics of the depthstructure, it has a wide range of applications on the research of deep tectonic setting,Seismogenic dynamics, territorial resources exploration, and so on,the artificial seismicsounding method is the most effective method for get the fine structure of the earth crustand mantle.
The northern Hainan has a complex geological structure and active seismicactivities.In this paper, the comparative analysis of artificial seismic sounding profilewhich is the length of200km in northern Hainan is made, in view of the differentcharacteristics of seismic phase, analyzes the datas with the method of basal refractionwave travel time inversion,the reflected wave inversion, one-dimensional travel timeinversion, two-dimensional dynamic ray tracing and so on, to get the structural feature ofthe earth crust and the upper mantle in the north of Hainan. The result shows that the earthcrust of this area is divided into the upper crust, the middle crust and the lower crust, thethickness of the upper crust is11.5-14.5km, the thickness of the middle crust is5.6-8.5km,the thickness of the lower crust is6.0-8.2km. The form fluctuation of C1interface arerelatively obvious, the range of variation of depth is11.5-14.5km, the depth of the C2interface is18.0-21.7km, the depth of Moho interface is26.0-29.5km, the velocity of thetop of upper mantle is8.00-8.15km/s, the velocity increases with the increase of the depth,it's8.38-8.56km/s when the depth is40.0km.
The results of crust-mantle structure show that the middle and lower crust have lowvelocity region which is north-west trend, it moves northward in the upper mantle,concentrated at the north of Qiongbei volcanic zone and Qiongzhou Strait, the middle andlower crust in volcanic zone still have comparatively active thermal motion, maybe thethermal materials come from the northern Qiongzhou strait. Therefore, it can infer that the magmas which once act on detection area should be derived from the mantle of northernseismic survey line. At the same time, understanding the crust-mantle structural feature andgeodynamic processes in the Leiqiong area is significant to the Leiqiong area (especially inHaikou and its neighboring region).
引文
[1]张玮晶.法制建设与防震减灾事业发展的互为作用[J].华南地震,2007,27(1):98-102.
[2]王伟涛.基于人工震源的区域尺度介质波速探测研究[D].合肥:中国科学技术大学,2009.
[3]徐朝繁.伽师强震群区、西秦岭阿尼玛卿缝合带上部地壳精细结构[D].北京:中国地震局地球物理研究所,2005.
[4]周俊杰等.太行山断裂带南端的地震纵波速度结构分析[J].地震地质,2011,33(1):107-113.
[5]刘泰峰等.一种自由布置的地震勘探新方法[J].石油地球物理勘探,2003,38(1):5-12.
[6]张向林等.油气地球物理勘探技术进展[J].地球物理学进展,2006,21(1):143-151.
[7]刘怀山,尹燕欣.海洋地球物理勘探综述[C].中国海洋大学海底科学与探测技术教育部重点实验室,2009.
[8]阎全人等.北部湾大陆边缘地壳结构特征[J].广西地质,2000,13(3):13-17.
[9]王秀娟.编制区域地震波走时表方法探讨[J].东北地震研究,2005,21(3):52-55.
[10]袁惟正等.大别山地震波速度剖面的重力拟合及花岗岩带[J].中国地质,2003,30(3):235-239.
[11]刘惠英等.大同-阳高地震科技论文的统计与分析[J].山西地震,1999,20(3):67-69.
[12]郭宝东等.浅析可控源音频大地电磁（CSAMT）方法及应用[J].中国科技博览,2011,20(13):50-57.
[13]朱金芳.漳州盆地及其邻区地壳深部结构的探测与研究[J].中国地震,2006,22(4):405-417.
[14]闫成国等.琼北地区北西方向长流-仙沟断裂带晚第四纪活动及与火山活动关系的讨论[J].震灾防御技术,2007,2(3):230-242.
[15]任明甫.利用断层气（土气氡）探测琼北地区的断裂活动性[J].华南地震,2000,21(2):62-68.
[16]江林.惠民凹陷断裂构造与演化机制研究[D].中国石油大学(华东),2006.
[17]史兰斌等.琼北第四纪玄武岩中微型地幔岩捕虏体的发现及其意义[J].地震地质,2003,25(3):33-42.
[18]胡光明.中下扬子残留盆地演化特征与选区评价方法探析[D].同济大学海洋与地球科学学院,2007.
[19]谢明富等.1605年琼山大地震余震分布质疑[J].华南地震,2001,21(4):33-37.
[20]谢振福.海南岛及邻区地震活动特征研究[J].震灾防御技术,2006,1(4):326-336.
[21]毕宏基.海南有座火山“博物馆”[J].地球,2002,21(2):125-127.
[22]闫成国等.琼北地区北西方向长流-仙沟断裂带晚第四纪活动及与火山活动关系的讨论[J].震灾防御技术,2007,2(3):230-242.
[23]上官志冠等.琼北火山区流体地球化学特征及近期火山喷发危险性评估[J].地震地质,2003,25(5):42-50.
[24]嘉世旭等.雷琼拗陷地壳结构特征[J].地球物理学报,2006,49(5):1385-1394.
[25]方盛明等.城市活断层地震勘探的最佳组合方法与应用研究[J].地震地质,2006,28(4):646-654.
[26]宋玉龙全三维地震勘探采集技术研究[D].同济大学海洋地质与地球物理系,2001.
[27]赵金仁等.伽师—阿图什震区地壳深部结构特征的探测与研究[J].中国地震,2002,18(4):317-325.
[28]何洋等.垂向不均匀介质中射线追踪及等时线构造的VC实现[J].物探化探计算技术,2004,26(1):13-19.
[29]赵金仁等.利用宽角反射／折射和深反射探测剖面揭示三河—平谷大震区深部结构特征[J].地球物理学报,2004,47(4):646-653.
[30]郑文衡.地球动力学若干问题的计算仿真研究[D].华中科技大学,2009.
[31] Fuis G.S,Ryberg T,Lutter W.J. Seismic mapping of shallow fault zones in the San GrabrielMountains from the Los Angeles Region Seismic Experiment[J].southern California,J.G.R,2001,106(B4),6549—6568.
[32] Zhimei Yan, Robert W. Clayton, Jason Saleeby.Seismic refraction evidence for steep faults cuttinghighly attenuated continental basement in the central Transverse ranges[J]. Californa，Geophys. J.Int,2005,651—666.
[33]Zelt C.A.&Smith R.B. Seismic traveltime inversion for2-D crustal velocity structure[J]. Geophys.J. Int.,1992,108,16—34.
[34]Zelt C.A.Modelling strategies and model assessment for wide-angle seismic traveltimedata[J].Geophys. J. Int.,1999,139,183—204.
[2]王伟涛.基于人工震源的区域尺度介质波速探测研究[D].合肥:中国科学技术大学,2009.
[3]徐朝繁.伽师强震群区、西秦岭阿尼玛卿缝合带上部地壳精细结构[D].北京:中国地震局地球物理研究所,2005.
[4]周俊杰等.太行山断裂带南端的地震纵波速度结构分析[J].地震地质,2011,33(1):107-113.
[5]刘泰峰等.一种自由布置的地震勘探新方法[J].石油地球物理勘探,2003,38(1):5-12.
[6]张向林等.油气地球物理勘探技术进展[J].地球物理学进展,2006,21(1):143-151.
[7]刘怀山,尹燕欣.海洋地球物理勘探综述[C].中国海洋大学海底科学与探测技术教育部重点实验室,2009.
[8]阎全人等.北部湾大陆边缘地壳结构特征[J].广西地质,2000,13(3):13-17.
[9]王秀娟.编制区域地震波走时表方法探讨[J].东北地震研究,2005,21(3):52-55.
[10]袁惟正等.大别山地震波速度剖面的重力拟合及花岗岩带[J].中国地质,2003,30(3):235-239.
[11]刘惠英等.大同-阳高地震科技论文的统计与分析[J].山西地震,1999,20(3):67-69.
[12]郭宝东等.浅析可控源音频大地电磁（CSAMT）方法及应用[J].中国科技博览,2011,20(13):50-57.
[13]朱金芳.漳州盆地及其邻区地壳深部结构的探测与研究[J].中国地震,2006,22(4):405-417.
[14]闫成国等.琼北地区北西方向长流-仙沟断裂带晚第四纪活动及与火山活动关系的讨论[J].震灾防御技术,2007,2(3):230-242.
[15]任明甫.利用断层气（土气氡）探测琼北地区的断裂活动性[J].华南地震,2000,21(2):62-68.
[16]江林.惠民凹陷断裂构造与演化机制研究[D].中国石油大学(华东),2006.
[17]史兰斌等.琼北第四纪玄武岩中微型地幔岩捕虏体的发现及其意义[J].地震地质,2003,25(3):33-42.
[18]胡光明.中下扬子残留盆地演化特征与选区评价方法探析[D].同济大学海洋与地球科学学院,2007.
[19]谢明富等.1605年琼山大地震余震分布质疑[J].华南地震,2001,21(4):33-37.
[20]谢振福.海南岛及邻区地震活动特征研究[J].震灾防御技术,2006,1(4):326-336.
[21]毕宏基.海南有座火山“博物馆”[J].地球,2002,21(2):125-127.
[22]闫成国等.琼北地区北西方向长流-仙沟断裂带晚第四纪活动及与火山活动关系的讨论[J].震灾防御技术,2007,2(3):230-242.
[23]上官志冠等.琼北火山区流体地球化学特征及近期火山喷发危险性评估[J].地震地质,2003,25(5):42-50.
[24]嘉世旭等.雷琼拗陷地壳结构特征[J].地球物理学报,2006,49(5):1385-1394.
[25]方盛明等.城市活断层地震勘探的最佳组合方法与应用研究[J].地震地质,2006,28(4):646-654.
[26]宋玉龙全三维地震勘探采集技术研究[D].同济大学海洋地质与地球物理系,2001.
[27]赵金仁等.伽师—阿图什震区地壳深部结构特征的探测与研究[J].中国地震,2002,18(4):317-325.
[28]何洋等.垂向不均匀介质中射线追踪及等时线构造的VC实现[J].物探化探计算技术,2004,26(1):13-19.
[29]赵金仁等.利用宽角反射／折射和深反射探测剖面揭示三河—平谷大震区深部结构特征[J].地球物理学报,2004,47(4):646-653.
[30]郑文衡.地球动力学若干问题的计算仿真研究[D].华中科技大学,2009.
[31] Fuis G.S,Ryberg T,Lutter W.J. Seismic mapping of shallow fault zones in the San GrabrielMountains from the Los Angeles Region Seismic Experiment[J].southern California,J.G.R,2001,106(B4),6549—6568.
[32] Zhimei Yan, Robert W. Clayton, Jason Saleeby.Seismic refraction evidence for steep faults cuttinghighly attenuated continental basement in the central Transverse ranges[J]. Californa，Geophys. J.Int,2005,651—666.
[33]Zelt C.A.&Smith R.B. Seismic traveltime inversion for2-D crustal velocity structure[J]. Geophys.J. Int.,1992,108,16—34.
[34]Zelt C.A.Modelling strategies and model assessment for wide-angle seismic traveltimedata[J].Geophys. J. Int.,1999,139,183—204.
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