摘要
板块俯冲时海沟位置存在不变、前进和后撤 3种情况 ,后撤俯冲可能造成弧后扩张 .层析成像等资料显示 :太平洋板块低角度俯冲到欧亚板块之下后没有穿透 670km相变界面 ,而是平卧于该界面之上 .这种平卧过程可能始于 2 8Ma前 .地球动力学计算表明 :俯冲板片前缘触及上下地幔相变界面而受阻平卧时 ,有利于形成后撤俯冲和弧后扩张 .中国东北火山形成很可能属于这种后撤俯冲、远离海沟陆内弧后引张、地幔热物质上涌、减压熔融的情况 .
There are three cases of variation of trench location possible to occur during subduction: trench fixed, trench advancing, and trench retreating. Retreat of trench may lead to back-arc extension. The Pacific plate subducts at low angle beneath the Eurasia plate, tomographic results indicate that the subducted Pacific slab does not penetrate the 670 km discontinuity, instead, it is lying flat above the interface. The flattening occurred about 28 Ma ago. Geodynamic computation suggests: when the frontier of t...
出处
《地震学报》
CSCD
北大核心
2004年第S1期1-8,共8页
Acta Seismologica Sinica
基金
国家自然科学重点基金 (40 2 340 4 2 )
国家自然科学基金 (40 174 0 2 7)资助
