ON THE ORIGIN OF COMPRESSIONAL INTRAPLATE STRESSES IN SOUTH AMERICA
ON THE ORIGIN OF COMPRESSIONAL INTRAPLATE STRESSES IN SOUTH AMERICA
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南美洲板内压缩应力的起源
DOI：
10.5327/rbg.v8i2.136
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发表时间：
1978
影响因子：
1.4
通讯作者：
F. Richter
中科院分区：
文献类型：
--
作者：
J. A. Mendigurien;F. Richter
南美洲中部的板内应力不可忽略。我们报告了五次板内地震的逆冲断层机制，这表明主要的水平偏压应力方向为西北-东南方向。我们得出的结论是，这种应力状态是由于与大西洋中部海脊上的扩散有关的力以及加勒比板块向北和纳斯卡板块向西施加的阻力造成的。阻力的存在和性质是根据其他研究中提出的地震机制和地质证据推断出来的。纳斯卡和南美洲所有可用的板内应力数据表明，这两个板块都受到扩张中心产生的偏压缩作用。由于缺乏张力地震震源机制，特别是在海沟附近的纳斯卡板块，这表明与俯冲岩石圈重力下沉相关的力得到了局部补偿。我们对非俯冲板块进行了简单的数值计算，以展示如何使用南美洲中部的压缩偏应力来估计地幔粘度的上限（约 10 21 泊）。
Intraplate stresses in middle South America are not negligible. We report thrust faulting mechanisms for five intraplate earthquakes, which indicate a dominant horizontal deviatoric compressional stress oriented in a NW-SE direction. We conclude that this state of stress is due to forces connected with spreading on the mid Atlantic ridge and resistive forces exerted by the Caribbean plate to the north and the Nazca plate to the west. The existence and nature of the resistive forces is inferred from earthquake mechanisms and geological evidence presented in other studies. All the available intraplate stress data for Nazca and South America indicate that both plates are under deviatoric compression generated at spreading centers. The absence of tensional earthquake focal mechanisms, particularly in the Nazca plate near the trench, suggests that the forces associated with the gravitational sinking of subducted lithosphere are locally compensated. We present a simple numerical calculation of a non-subducting plate to show how the compressional deviatoric stresses in middle South America can be used to estimate an upper bound of about 10 21 poise for theviscosity of the mantle.