Redox Conditions During Coseismic Rupture - A Mossbauer Study of Frictional Melts

[98148510]人们对水在地震破裂过程中的作用有相当大的兴趣，但是现代的例子很难研究。摩擦熔体（pseudoachylytes）是岩石记录中为数不多的古地震指标之一，它可以记录水在导致部分熔体的破裂事件中所起的作用。本研究将使用穆斯堡尔光谱来评估在几种特征良好的伪水解液中发现的不透明矿物中铁的氧化态，这些矿物可作为相应古地震带氧逸度的代理。预计各个地方的Fe +2/ Fe +3比值将揭示局部氧分压的变化，并允许评估活动断裂带中流体分区化的作用。

9814851O'Hara There is considerable interest in the role of water in the earthquake rupture process, but modern example are very difficult to study. Pseudotachylytes (friction melts) represent one of the few paleoseismic indicators in the rock record that may record aspects of the role of water during the rupture event that caused the partial melt. This study will use Mossbauer spectroscopy to assess the oxidation state of iron in opaque minerals found in several well characterized pseudotachylytes which serves as a proxy for oxygen fugacity in the corresponding paleoseismic zones. If is anticipated that Fe +2/ Fe +3 ratios at individual localities will reveal local variations of oxygen partial pressure and permit the role of fluid compartmentalization in active fault zones to be evaluated.