REGIONAL VARIATIONS IN SUBSIDENCE RATE OF LITHOSPHERIC PLATES - IMPLICATION FOR THERMAL COOLING MODELS

Although simple thermal models of lithospheric cooling predict to first order the general behaviour of observed seafloor depth with increasing age, important regional variations in seafloor subsidence, in the range 250-400 m Ma 1 2, are reported for several lithospheric plates. Such variations cannot be accounted for by classical cooling models unless implausible variations in asthenospheric temperature of ∼550°C are assumed. Here we present an alternative cooling model, which assumes that at the ridge axis the temperature may deviate from the mean asthenospheric temperature. Such a model satisfactorily explains the data provided that the temperature deviation is ±100°C only. © 1990.