Localization of Melt Transport at Mid-Ocean Ridges

地震实验和海底形态表明，熔体到达地壳底部的地壳吸积区宽度约为2 km，而减压熔融产生熔体的区域要宽得多。不知何故，熔体在上升过程中以约50倍的倍数聚焦，但目前还没有提出一种机制来充分解释这种聚焦。根据这项授权，调查团将进行以下几方面的调查：1)改进稳态一维柱中结晶和熔岩反应的处理，以更好地了解热边界层底部的渗透率结构；2)探索岩石圈底部热结构对结晶功能和粘度场的横向变化的影响；3)重新建立大尺度流动模型，包括非牛顿流变学和孔隙度变化对粘度的影响。

Seismic experiments and seafloor morphology indicate that the region of crustal accretion, where melts reaches the base of the crust, has a half width of ~ 2 km, whereas the zone of melt production by decompression melting is much broader. Somehow, melt becomes focused by a factor of ~ 50 as it ascends, yet no single mechanism that has been proposed fully explains this focusing. Under this award, the PI will follow several lines of investigation, to: 1) Improve the treatment of crystallization and melt-rock reactions in steady-state one-dimensional columns to better understand the permeability structure at the base of the thermal boundary layer 2) Explore the effects of lateral variations in the crystallization function and the viscosity field, due to the thermal structure at the base of the lithosphere 3) Revisit the large-scale flow models to include non-Newtonian rheology and the effect of porosity variations on viscosity.