Electrical Conductivity Evidence for the Existence of a Mantle Plume Beneath Tarim Basin

Abstract

This paper proposes using a simulated annealing (SA) calculation to perform one-dimensional inversion of Geomagnetic Depth Sounding (GDS) to obtain the conductivity information of the lower mantle beneath the Tarim area, to calculate the temperature of the lower mantle according to the relevant formula of the petrophysical experiment, and to provide evidence of the existence of the Tarim mantle plume. The data used for inversion originate from the China Geomagnetic Network Center. This article uses theoretical data to prove that the simulated annealing algorithm can invert the true conductivity model when the data do not contain noise. However, when the data contain noise, it is more accurate to use the statistical expected value of the high-quality conductivity model during the simulated annealing inversion process as the optimal conductivity model rather than the classic simulated annealing algorithm. The simulated annealing inversion results of only four stations in Tarim area show that the conductivity of the top of the lower mantle and the upper part of the mantle transition zone in Tarim area is higher than the global average, and it is speculated that the temperature is 150k–450k higher than the global average. This is important evidence for the existence of the mantle plume beneath the Tarim Basin.