Stress release in exhumed intermediate and deep earthquakes determined from ultramafic pseudotachylyte
Stress release in exhumed intermediate and deep earthquakes determined from ultramafic pseudotachylyte
复制标题
DOI：
10.1130/g25230a.1
复制
发表时间：
2008-12-01
期刊：
影响因子：
5.8
通讯作者：
Vrijmoed, Johannes C.
中科院分区：
文献类型：
--
作者：
Andersen, Torgeir B.;Mair, Karen;Vrijmoed, Johannes C.
在科西嘉岛阿尔卑斯山俯冲杂岩中，同震断层向劳钠铝石-榴辉岩相俯冲时释放的应力可以根据形成剪切应变的假玄武岩断裂脉所需的能量来估计。在1.5 Gpa和470摄氏度的环境条件下，全组分橄榄岩熔融需要1280摄氏度到1750摄氏度的温度上升。我们假设在断裂过程中95%以上的功被转化为热，因此应力降几乎与熔融量成正比，与剪切应变成反比。最小估计应力或释放的应力通常大于220兆帕，最高可达580兆帕。在所研究的橄榄岩中，小断层上的假玄武岩的丰度表明，熔融在中深部地震中是非常常见的，剪切敲击对深部的地震断层作用是重要的。
Stresses released by coseismic faults during subduction toward lawsonite-eclogite facies conditions in the Alpine subduction complex of Corsica can be estimated based on the energy required to form pseudotachylyte fault veins where shear strain can be measured. Congruent peridotite melting at ambient conditions of 1.5 GPa and 470 degrees C requires a temperature increase of 1280 degrees C to 1750 degrees C. We assume that more than 95% of the work is converted to heat during faulting, hence that the stress drop is nearly proportional to the amount of melting and inversely proportional to shear strain. Minimum estimates or released stress are typically greater than 220 MPa and as high as 580 MPa. The abundance of pseudotachylyte on small faults in the studied peridotite suggests that melting is very common on intermediate and deep earthquakes and that shear beating is important for seismic faulting at depth.