Fluid Pressure Changes Recorded by Trace Elements in Quartz
Fluid Pressure Changes Recorded by Trace Elements in Quartz
复制标题
石英中微量元素记录的流体压力变化
DOI：
10.1029/2022gc010346
复制
发表时间：
2022
期刊：
影响因子：
3.7
通讯作者：
E. Le Trong
中科院分区：
文献类型：
--
作者：
H. Raimbourg;V. Famin;A. Canizarès;E. Le Trong
流体压力是地震力学中的关键参数，控制聚合区的地震破坏和板块耦合。然而，在地震发生深度，流体压力也极难量化，这限制了我们对增生棱柱应力状态的了解。在这里，我们表明，挖出的热液石英脉的地球化学记录可用于对俯冲带流体压力变化进行定量限制。研究的矿脉来自日本西南部板块汇聚所积聚和挖出的沉积物。脉中的石英显示出对比亮蓝色/深棕色阴极发光 (CL) 颜色的生长边缘、高/低铝浓度以及低/高流体包裹体丰度。由于 Si-Al 取代（以及 Li 的电荷补偿）很大程度上取决于石英沉淀速率和 Si 溶解度，因此 Al-Li 浓度必须对流体压力敏感。流体包裹体证实了这一点，流体包裹体的密度转化为捕获压力，记录流体压力从 CL-棕色、贫铝锂边缘到 CL-蓝色、富铝锂石英边缘下降了约 70 MPa。 CL-蓝色边缘生长速度快、硅过饱和度高、流体压力低，而CL-棕色边缘生长速度慢、硅过饱和度低、流体压力高。因此，石英微量元素化学提供了一种有前途的工具来量化深层流体压力变化及其与地震的关系。
Fluid pressure is a key parameter in earthquake mechanics, controlling seismic failure and plate coupling in convergent zones. Yet fluid pressure is also extremely difficult to quantify at seismogenic depth, which limits our knowledge of the stress state in accretionary prisms. Here, we show that the geochemical record of exhumed hydrothermal quartz veins may be used to place quantitative bounds on fluid pressure variations in subduction zones. The studied veins come from sediments accreted and exhumed by plate convergence in southwestern Japan. Quartz in veins displays growth rims of contrasted bright blue/dark brown cathodoluminescence (CL) colors, high/low Al concentrations, and low/high fluid inclusion abundance. Because Si‐Al substitution (and charge compensation by Li) strongly depends on the rate of quartz precipitation and Si solubility, Al‐Li concentrations must be sensitive to fluid pressure. This is confirmed by fluid inclusions, the density of which, converted into trapping pressures, record fluid pressure drops by up to ∼70 MPa from CL‐brown, Al‐Li‐poor rims to CL‐blue, Al‐Li‐rich quartz rims. CL‐blue rims grow at a fast rate, high Si supersaturation and low fluid pressure whereas CL‐brown rims grow at a slower pace, lower Si supersaturation, and higher fluid pressure. Quartz trace element chemistry thus offers a promising tool to quantify deep fluid pressure variations and their relationships to earthquakes.
影响因子：
18.3
作者：
M. Moreno;C. Haberland;O. Oncken;A. Rietbrock;S. Angiboust;O. Heidbach
通讯作者：
M. Moreno;C. Haberland;O. Oncken;A. Rietbrock;S. Angiboust;O. Heidbach