全球GPS矢量场的分区描述及规律性分析  

Sub-regional Descriptions of Global GPS Vector Field and Its Geodynamic Significance

作　　者：马宗晋[1] 张进[1] 任金卫[2] 李智[3] 

机构地区：[1]中国地震局地质研究所,北京100029 [2]中国地震局地震预测研究所,北京100089 [3]装备指挥技术学院,北京101416

出　　处：《地质学报》2006年第8期1089-1100,共12页Acta Geologica Sinica

基　　金：国家重点自然科学基金项目(编号4983402)资助的成果。

摘　　要：以平均选择的GPS站点运动年速率编制了全球板块运动矢量场,从而揭示了以下几点规律:1从北大西洋洋脊东侧起,直至西北太平洋岛弧带,欧亚大板块总体呈现顺时针宽弧形运动;2从北大西洋洋脊西侧直至美洲大陆西边缘,北美大板块呈现反时针宽弧形运动;3从南大西洋洋脊东侧起,直至克马德克—新西兰一线,非洲板块和印—澳板块一并呈现从北东指向渐变为北北东指向的运动;4东南太平洋洋脊西侧太平洋板块总体向北西西方向运动;5东南太平洋脊东侧海底大小板块总体向北东东运动;6南美洲整体向北运动;7北极区总体向太平洋北缘运动;南极洲总体向大西洋区运动,并有分裂—对旋迹象。分析上述运动的分区展布,可推论以下几点运动动力学的认识:1拖动全球板块一级运动势态的地幔流可分解为由南极区向北的径向流与由大西洋洋脊和东南太平洋洋脊的东西两侧纬向流的二元动力联合作用,从而造成全球性指向北东和北西的斜向运动;2以重力大地水准面所展现的低阶双重非对称的地球,是引导表壳发育张裂洋脊带和汇聚俯冲带的力学条件;3沿赤道两侧不协调运动带呈现压扭、张扭的复杂变动除了南半球与北半球地幔流在运动指向和速度的差异而造成之外,还可能与地球质心的偏心和南、北半球自转速度的差异变化有关;4南极洲相对环南极洋脊的偏极分流运动还有待进一步研究。在以上认识的基础上,本文讨论了造成三大洋脊在全球表壳的分布、全球深俯冲带仅仅在环太平洋边缘带内发育、北半球和南半球的板块径向、纬向运动有整体性差异等问题的原因。造成上述现象是与地球整体的双重不对称性有关,即北、南半球和0°/180°半球的缩、胀和快、慢的双重非对称,而这种双重不对称性是地球内部物质的热状态、运动状态以及质量分布等原因造成的,我Based on the global vector field of plate movement shown by GPS stations chosen averagely, some characteristics of present plate tectonics can be distinguished as follows： （1） from the northern Atlantic ridge to the island arcs of the northwestern Pacific, the Eurasian Plate broadly shows a clockwise arc-shaped movement （2） the North American Plate rotated counter-clockwisely, showing arc-shaped movement （3） from the eastern part of the southern Atlantic ridge to the Kemadec-New Zealand Arc, the movement of the African Plate and Indian-Australian Plate change from NE to NNE gradually （4） the Pacific Plate to the west of the southeastern Pacific Rise broadly moves to the WNW; （5） several small plates to the east of the southeastern Pacific Rise move to the ENE; （6） the South American Plate moves to the north as a whole; （7） the Arctic region moves to the east as a whole; and the Antarctic region moves to the Atlantic Ocean region in general, which also shows the evidence of rifting and rotation. By analyzing the above characteristics of movements of plates globally, we can deduce the following understandings on the kinematics and dynamics of plate tectonics. （1） the mantle flows which result in the movement of plates at the global scale can be divided into sub-flows in the directions of the longitude and latitude, which lead to the oblique movement of many plates; （2） the outer shell of the Earth with characteristics of the double-asymmetry of the Earth shown by lower order geoid is the mechanical precondition to the developments of the oceanic ridges and subduction zones; （3） the complicated phenomena of transpression and transtention along the equatorial disharmony zone maybe result from the velocity difference of rotation between the Southern Hemisphere and the Northern Hemisphere and non-superposition of the centroid of the Earth with its geometrical center; （4） further study on the movement away from the pole of the Antarctic Plate related to the Peri-Antarctic oc

关 键 词：GPS矢量场 地球双重不对称性 地球低阶大地水准面 赤道不协调带 地幔经纬向流 自转差 质心 

分 类 号：P541[天文地球—构造地质学]