报告地点：教学行政楼706会议室
报告时间：2024-01-18从15:00到16:30
报告人：鲍习源（加州大学洛杉矶分校）
报告人简介：
鲍习源，2018年于中国科学技术大学获得地球物理学士学位， 2024年1月于加州大学洛杉矶分校得到地球物理博士学位，目前继续在同一实验室从事博士后研究。研究方向是通过实验，数值计算和机器学习的手段研究地幔动力学。博士期间主要研究内容包括通过糖浆实验来模拟地幔的粘性流动，研究火山热点与深部地幔的关系。曾在Science, Nature Geoscience, JGR Solid Earth 等刊物发表多篇文章。曾获得2022 Computers and Geosciences Research Scholarship，2023 AGU Study of the Earth's Deep Interior Section Award for Graduate Research。
报告题目：Hotspots from Top to Bottom
报告内容简介
Hotspots have geochemical fingerprints distinct from mid-ocean ridges. Approximately half of catalogued hotspots are obviously hotter than the ambient mantle. This is compatible with buoyant plumes rising from the lowermost mantle, entraining a distinct geochemical reservoir, perhaps housed in the Low Shear Velocity Provinces (LLSVPs). However, the nature of LLSVPs themselves and the dynamical relationship between plumes and LLSVPs remain hotly debated. In the spectrum of LLSVPs, two end-members exist: purely thermal plume clusters and fixed, rigid, thermochemical piles.
We address the link between hotspots and LLSVPs from a new perspective, using state-of-the-art 3-D optical visualization in very viscous fluids, which serve as analogs for the two end-member cases. We perform a series of experiments in a 40.5cm x 40.5 cm x 27.5 cm plexiglass tank, with corn syrup heated from below. With the reconstruction of the full 4-D velocity and temperature field, as well as Lagrangian analysis, we can track the plumes with unprecedented detail. I will show how rigid thermochemical piles are a better explanation for LLSVPs as they can explain the buoyancy flux of global hotspots to the first order. I further discuss the entrainment of LLSVP material and the implications for the source of the distinct geochemical signatures.