Shallow Rupture Propagation of Pleistocene Earthquakes Along the Hurricane Fault, UT, Revealed by Hematite (U‐Th)/He Thermochronometry and Textures
Shallow Rupture Propagation of Pleistocene Earthquakes Along the Hurricane Fault, UT, Revealed by Hematite (U‐Th)/He Thermochronometry and Textures
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DOI：
10.1029/2021gl094379
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发表时间：
2021-08
影响因子：
5.2
通讯作者：
Madison P. Taylor;A. Ault;M. Odlum;D. Newell
中科院分区：
文献类型：
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作者：
Madison P. Taylor;A. Ault;M. Odlum;D. Newell
孕震带上方断裂的物质性质和分布对地震破裂传播具有促进或抑制作用。我们用扫描和透射电子显微镜和赤铁矿(U-Th)/He热计时技术记录了沿地震活跃的飓风断层UT的断层滑动的深度和机制。赤铁矿以毫米尺度的条纹状斑块出现在10平方米薄的镜状二氧化硅断层表面。赤铁矿结构包括球状集合体和碎裂岩，被晶态氧化铁纳米棒覆盖，在滑移界面处有无定形二氧化硅层。结构反映了赤铁矿和富硅主岩的机械、流体和热辅助的非晶化作用，这些岩石削弱了断层并促进了破裂的传播。赤铁矿(U-Th)/He测年记录了∼300m深处0.65 Ma至0.36 Ma之间的矿化和断层滑动事件。资料表明，一些地震破裂沿着地壳浅层局部滑动面反复传播，为断层滑动模型提供了结构和材料性质的约束。
The material properties and distribution of faults above the seismogenic zone promote or inhibit earthquake rupture propagation. We document the depths and mechanics of fault slip along the seismically active Hurricane fault, UT, with scanning and transmission electron microscopy and hematite (U‐Th)/He thermochronometry. Hematite occurs as mm‐scale, striated patches on a >10 m2 thin, mirror‐like silica fault surface. Hematite textures include bulbous aggregates and cataclasite, overlain by crystalline Fe‐oxide nanorods and an amorphous silica layer at the slip interface. Textures reflect mechanical, fluid, and heat‐assisted amorphization of hematite and silica‐rich host rock that weaken the fault and promote rupture propagation. Hematite (U‐Th)/He dates document episodes of mineralization and fault slip between 0.65 and 0.36 Ma at ∼300 m depth. Data illustrate that some earthquake ruptures repeatedly propagate along localized slip surfaces in the shallow crust and provide structural and material property constraints for in models of fault slip.