Deep MT Sounding Across the Yellowstone-Snake River Hotspot Track

EAR-0229814 DeGroot-Hedlin研究人员建议使用大地电磁测深(MT)来约束黄石-蛇河地区羽流物质的温度和熔体比例，并对黄石羽流的动力学及其与大陆的相互作用的模型提供约束。之前的几项研究表明，爱达荷州东部蛇河平原下方存在一个狭窄的低P波速度，与黄石热点的运动方向一致。较低的地震速度可归因于温差、部分熔融和熔体分离导致的成分差异的综合影响。研究人员建议沿两条垂直线部署长周期大地电磁测深仪器：第一条是西北向东南的断面，以前通过层析反演法获得了P波速度模型；第二条是以蛇河平原为中心。考虑到富含橄榄石的岩石的电导率强烈地依赖于熔体分数和温度，对大地电磁测深数据的解释可以用来确定地幔温度和熔体分数，从而产生对烟柱粘度的估计。

EAR-0229814DeGroot-HedlinThe investigators propose to use magnetotelluric (MT) sounding to constrain the temperature and melt fraction of plume material in the Yellowstone-Snake River region, and provide constraints on models of the dynamics of the Yellowstone plume flow and its interaction with a continent. Several previous studies have indicated the presence of a narrow, low P-wave velocity beneath the eastern Snake River Plain in Idaho, aligned in the direction of motion of the Yellowstone hotspot. The lower seismic velocities can be attributed to the combined effects of temperature differences, partial melt, and compositional differences resulting from melt segregation. The investigators propose to deploy long period MT sounding instruments along two perpendicular lines: the first a northwest to southeast transect for which a P-wave velocity model was previously obtained from tomographic inversion, the second centered along the Snake River Plain. Given that the conductivity of olivine-rich rocks is strongly dependent upon both melt fraction and temperature, interpretation of MT sounding data can be used to determine mantle temperatures and melt fraction, hence yielding an estimate of plume viscosity.