Thermal modelling for Hole 735B

Abstract

Two temperature logs subsequent to the drilling of the 500m-deep Hole 735B on the flank of the Atlantis-II Fracture Zone in the southwest Indian Ocean are used to determine the equilibrium temperature profile beneath the seafloor. The overall equilibrium temperature gradient with depth is negative at the surface, then changes to a positive gradient at about 300m, and gradually increases to the bottom of the hole. Positive excursions of the temperature profile are centered at depths of about 30, 190, and 260m below the seafloor (mbsf). The data are interpreted using two different models: 1) advection of seawater into permeable zones in the upper 400m beneath the seafloor, and 2) warming by conduction from the surface since the last glacial maximum. -from Authors