Nanoscale evidence for temperature-induced transient rheology and postseismic fault healing
Nanoscale evidence for temperature-induced transient rheology and postseismic fault healing
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DOI：
10.1130/g46317.1
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发表时间：
2019-12-01
期刊：
影响因子：
5.8
通讯作者：
Van Devener, B. R.
中科院分区：
文献类型：
--
作者：
Ault, A. K.;Jensen, J. L.;Van Devener, B. R.
摩擦产生的热量和随后的热演化控制断层材料的特性，从而控制地震周期期间的强度。我们在高光泽、反光赤铁矿断层镜 (FM) 上记录了瞬态、纳米级断层流变学的证据。 FM 切割了智利北部更新世 El Laco 铁矿床中含有少量石英的镜面岩。扫描和透射电子显微镜数据表明，FM 体积包含在 1000 摄氏度下产生的瞬时无定形、混合但不混溶、流变性弱的氧化铁和二氧化硅。赤铁矿在垂直于断层的热梯度中重新生长、烧结、孪生，以及来自穿过 FM 表面互锁的晶体的纳米级脊的地形网络，共同重新强化了断层材料。结果揭示了温度引起的弱化如何为断层愈合提供先决条件。纳米级转化可能会促进随后的应变离域和断层损伤的发展。
Friction-generated heat and the subsequent thermal evolution control fault material properties and thus strength during the earthquake cycle. We document evidence for transient, nanoscale fault rheology on a high-gloss, light-reflective hematite fault mirror (FM). The FM cuts specularite with minor quartz from the Pleistocene El Laco Fe-ore deposit, northern Chile. Scanning and transmission electron microscopy data reveal that the FM volume comprises a 1000 degrees C) generated transiently amorphous, intermixed but immiscible, and rheologically weak Fe-oxide and silica. Hematite regrowth in a fault-perpendicular thermal gradient, sintering, twinning, and a topographic network of nanometer-scale ridges from crystals interlocking across the FM surface collectively restrengthened fault material. Results reveal how temperature-induced weakening preconditions fault healing. Nanoscale transformations may promote subsequent strain delocalization and development of off-fault damage.