报告题目：Ocean bottom geophysical array studies may reveal the cause of seafloor flattening
报告人：Prof. Hisashi Utada
Earthquake Research Institute (ERI), University of Tokyo, Japan.
Prof. Utada has 43-years experience working in geo-electromagnetism, including electrical conductivity distribution, observation of the geomagnetic and geo-electric field, and dynamics in the core and the core-mantle interaction. Prof. Utada’s work has been published in more than 119 academic papers on SCI journals including Science, EPSL, GRL, GJI, JGR, G-Cubed and Tectonophysics.
Flattening of old seafloor has been studied for several decades and remains one of the unresolved fundamental problems of geodynamics. The phenomenon of seafloor flattening at ages greater than 70-80 Ma can be explained by a simple model of a cooling plate with a fixed thickness, but the physical cause of flattening is not fully understood. Here, a simple model of lithosphere rejuvenation is considered as an alternative mechanism and is also shown to represent features of similar seafloor flattening. We suggest that constraints on mantle structure from use of data such as variations of seafloor depth and heat flow are weak, but that first order differences in mantle thermal structure are introduced by rejuvenation and plate cooling models. This suggests that probing of the mantle by geophysical seafloor arrays, particularly those sensitive to mantle temperature, should be able to identify regions of the seafloor that deviate from a simple cooling history, if such exist. This presentation shows possible approach to solve this problem by seafloor electromagnetic array observation.