地震研究

巽他地块的构造演化与介质特性的动力学意义^*

张建国,皇甫岗,龙飞

(云南省地震局,云南昆明 650224)

关键词：巽他地块; 相对稳定地块; 古老陆核; 侧向挤出; 顺时针旋转

Geodynamic Significance of Tectonic Evolution & Medium Property of Sundaland

ZHANG Jian-guo,HUANGFU Gang,LONG Fei

(Earthquake Administration of Yunnan Province,Kunming 650224,Yunnan,China)

Keywords：Sundaland; relative stable block; ancient continental core; lateral extrusion; clockwise rotation

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参考文献

基于近年来国内外关于青藏高原及川、滇、缅、印支地区大地构造演化、现今地壳运动观测、地壳与上地幔结构反演等领域取得的大量观测与研究成果,结合对泰、越等国的野外地质考察与认识,以探索建立对该地区现今地壳运动与变形状态起控制作用的构造框架为目的 ,提出了相对于“活动地块”的“相对稳定地块”的概念。综合分析认为,巽他地块在构造演化、介质特性及现今运动与变形等方面类似于青藏高原周缘的塔里木、阿拉善、扬子等地块,具有“相对稳定地块”的特征,它们共同构成了调节青藏高原物质东向挤出后围绕东喜马拉雅构造结发生顺时针旋转的刚性约束边界。这同时意味着,青藏高原侧向挤出动力作用的势力范围可能覆盖了川、滇、缅及印度支那北部的广大地区,这有助于加深对该地区强震动力学环境的认识。

Based on the plentiful survey and study results about geodynamic evolution,contemporary crustal movement observation,inversion of crust and upper mantle structure in Tibet Plateau,Sichuan,Yunnan,Myanmar and Indochina areas,combined with our wild geological survey and knowledge in Thailand and Vietnam in recent years,and for the purpose to establish a geo-tectonic frame that controlling the regional crust movement and deformation,we propose the conceptions of “active block” and “relative stable block”. Our comprehensive analysis demonstrates that Sundaland may play a similar role to the Tarim block,Alashan block and Yangtze block that has the properties of “relative stable block” in the aspects of tectonic evolution,medium characteristics and the contemporary movement and deformation,and it is all these relative stable blocks that constitute the rigid constraint boundary regulating the clockwise rotation of the material extruded from Tibet Plateau laterally. Meanwhile,the point implies that the sphere of influence of lateral extrusion dynamic action by Tibet Plateau may cover the wide region including Sichuan,Yunnan,Myanmar and Northern Indochina,which will be helpful for furthering and improving our understanding about the geodynamic environment of strong earthquake.

引言
1 大地构造演化与壳幔介质特性
2 大地形变与地震活动
3 讨论与认识

图1 巽他地块的大地构造位置<br/>(据Simons et al.,2007)<br/>(大箭头代表国际地球参考框架2000下板块的绝对运动)<br/>Fig.1 The geotectonic position of Sundaland (from Simons et al.,2007)(large arrows represent the absolute motions of plates in International Terrestrial Reference Frame 2000)

图1 巽他地块的大地构造位置
(据Simons et al.,2007)
(大箭头代表国际地球参考框架2000下板块的绝对运动)
Fig.1 The geotectonic position of Sundaland (from Simons et al.,2007)(large arrows represent the absolute motions of plates in International Terrestrial Reference Frame 2000)

图2 巽他地块内的主要陆块与缝合带分布(据Metcalfe,2011)<br/>Fig.2 Major continental blocks and the distribution of sutures in Sundaland(from Metcalfe,2011)

图2 巽他地块内的主要陆块与缝合带分布(据Metcalfe,2011)
Fig.2 Major continental blocks and the distribution of sutures in Sundaland(from Metcalfe,2011)

图3 东亚现代板块及运动状态(据丁国瑜等,1991)<br/>Fig.3 Recent plates and their movement situation in East Asia(from Ding et al.,1991)

图3 东亚现代板块及运动状态(据丁国瑜等,1991)
Fig.3 Recent plates and their movement situation in East Asia(from Ding et al.,1991)

图4 巽他地块及邻区Moho面深度(据Sergei,Guust,2003(a)和Mooney,1998(b))<br/>Fig.4 The Moho depth of Sundaland and its adjacent area(from Sergei,Guust,2003(a)and Mooney et al.,1998(b))

图4 巽他地块及邻区Moho面深度(据Sergei,Guust,2003(a)和Mooney,1998(b))
Fig.4 The Moho depth of Sundaland and its adjacent area(from Sergei,Guust,2003(a)and Mooney et al.,1998(b))

图5 巽他地块及其邻近地区的上地幔速度结构(据Replumaz et al.,2004)<br/>(图中黑色虚线代表新生代不同时期下插于欧亚板块之下的印度—澳大利亚残留板片所刻画的板块边界位置及形态,重建的下插<br/>板片深度与时代关系:5 Ma,200 km; 10 Ma,400 km; 15 Ma,600 km; 30 Ma,900 km; 40 Ma,1 100 km)<br/>Fig.5 Horizontal sections of upper mantle velocity structure beneath Sundaland and its adjcent area from 100 to 1 200 km(from Replumaz et al.,2004)(the black dotted line represent the contours of plate position and shape of India-Australia residues plate inserted beneath the Eurasian plate in different period of Cenozonic Era,the relationship between the deep of reconstructed inserting plate and era:5 Ma,200 km; 10 Ma,400 km; 15 Ma,600 km; 30 Ma,900 km; 40 Ma,1100 km)

图5 巽他地块及其邻近地区的上地幔速度结构(据Replumaz et al.,2004)
(图中黑色虚线代表新生代不同时期下插于欧亚板块之下的印度—澳大利亚残留板片所刻画的板块边界位置及形态,重建的下插
板片深度与时代关系:5 Ma,200 km; 10 Ma,400 km; 15 Ma,600 km; 30 Ma,900 km; 40 Ma,1 100 km)
Fig.5 Horizontal sections of upper mantle velocity structure beneath Sundaland and its adjcent area from 100 to 1 200 km(from Replumaz et al.,2004)(the black dotted line represent the contours of plate position and shape of India-Australia residues plate inserted beneath the Eurasian plate in different period of Cenozonic Era,the relationship between the deep of reconstructed inserting plate and era:5 Ma,200 km; 10 Ma,400 km; 15 Ma,600 km; 30 Ma,900 km; 40 Ma,1100 km)

图6 相对巽他地块的区域GPS速度矢量(据Socquet et al.,2006)<br/>(黑色箭头属于印度板块,深灰色箭头属于华南地块,浅灰色箭头属于巽他地块。EHS:东喜马拉雅构造结; <br/>GSF:苏门答腊大断裂; MFT:主前冲断层; MCB:缅甸中央盆地; SF:实皆断裂带; <br/>RRF:红河断裂带; STD:藏南拆离席; XSH:鲜水河断裂带)<br/>Fig.6 Regional GPS velocity vectors with respect to Sundaland(from Socquet et al.,2006)(the black arrows belong to India plate,dark grey arrows belong to South China block,light grey arrows belong to Sundaland.EHS:Eastern Himalayan Syntaxis; GSF:Great Sumatran Fault; MFT:Main Frontal Thrust; MCB:Myanmar Central Basins; SF:Sagaing Fault; RRF:Red River Fault; STD:southern Tibet Detachment; XSH:Xianshuihe Fault)

图6 相对巽他地块的区域GPS速度矢量(据Socquet et al.,2006)
(黑色箭头属于印度板块,深灰色箭头属于华南地块,浅灰色箭头属于巽他地块。EHS:东喜马拉雅构造结;
GSF:苏门答腊大断裂; MFT:主前冲断层; MCB:缅甸中央盆地; SF:实皆断裂带;
RRF:红河断裂带; STD:藏南拆离席; XSH:鲜水河断裂带)
Fig.6 Regional GPS velocity vectors with respect to Sundaland(from Socquet et al.,2006)(the black arrows belong to India plate,dark grey arrows belong to South China block,light grey arrows belong to Sundaland.EHS:Eastern Himalayan Syntaxis; GSF:Great Sumatran Fault; MFT:Main Frontal Thrust; MCB:Myanmar Central Basins; SF:Sagaing Fault; RRF:Red River Fault; STD:southern Tibet Detachment; XSH:Xianshuihe Fault)

图7 相对巽他地块的东南亚GPS速度场(据Simons et al.,2007)<br/>Fig.7 GPS velocities field in SE Asia with respect to Sundaland(from Simons et al.,2007)

图7 相对巽他地块的东南亚GPS速度场(据Simons et al.,2007)
Fig.7 GPS velocities field in SE Asia with respect to Sundaland(from Simons et al.,2007)

图8 相对巽他地块的东南亚GPS速度场<br/>(据Iwakuni et al.,2004)<br/>Fig.8 GPS velocity field of SE Asia in the Sundablock fixed reference frame(from Iwakuni et al.,2004)

图8 相对巽他地块的东南亚GPS速度场
(据Iwakuni et al.,2004)
Fig.8 GPS velocity field of SE Asia in the Sundablock fixed reference frame(from Iwakuni et al.,2004)

图9 GPS观测基本无变形的巽他地块范围<br/>(据Simons et al.,2007)<br/>Fig.9 Undeformed area of Sundaland based on GPS Survey(from Simons et al.,2007)

图9 GPS观测基本无变形的巽他地块范围
(据Simons et al.,2007)
Fig.9 Undeformed area of Sundaland based on GPS Survey(from Simons et al.,2007)

图10 公元前2150年以来全球5级以上地震(据http://tsun.sscc.ru/nh/eq_descr.html)<br/>Fig.10 Distribution of global M≥5 earthquakes since 2150 BC(from http://tsun.sscc.ru/nh/eq_descr.html)

图10 公元前2150年以来全球5级以上地震(据http://tsun.sscc.ru/nh/eq_descr.html)
Fig.10 Distribution of global M≥5 earthquakes since 2150 BC(from http://tsun.sscc.ru/nh/eq_descr.html)

图11 1898年以来中国及邻区5级以上地震(据http://geophysics.eas.gatech.edu/anewman/classes/Geodynamics/misc/)<br/>Fig.11 Distribution of M≥5 earthquakes in Asia since 1898(from http://geophysics.eas.gatech.edu/anewman/classes/Geodynamics/misc/)

图11 1898年以来中国及邻区5级以上地震(据http://geophysics.eas.gatech.edu/anewman/classes/Geodynamics/misc/)
Fig.11 Distribution of M≥5 earthquakes in Asia since 1898(from http://geophysics.eas.gatech.edu/anewman/classes/Geodynamics/misc/)