Abstract

Thermal evolution of the continental lithosphere at a continent-ocean transform margin is examined using a two-dimensional heat conduction model. All heating is assumed to result from the emplacement of new oceanic ridge against the continent. The assumed initial continental temperature gradient is probably best applied to regions having experienced finite-duration periods of rifting lasting tens of millions of years. A deep seismic reflection profile across the southern paleo-transform margin of the Exmouth Plateau (northwest Australia) tests the predictions of the model. Using this reflection profile, it is estimated that up to 3.5 km of sediments have been eroded from the continental rim, diminishing to almost no erosion at 60 km from the continent-ocean transform boundary. This trend and these values for erosion can be matched approximately using the model under the condition of local isostasy. A finite-difference scheme is employed, where the surface elevation is the result of the competing (1) thermal uplift (up), (2) surficial erosion (down), and (3) local isostatic rebound (up) in response to the erosion. The model predicts that most of the erosion ceases by 40 Ma after ridge emplacement and that of the order of 1000 km3 eroded sediments are shed for every 10 km of transform length.