This document summarizes several hypotheses for subsidence at passive continental margins: 1) The gravity loading hypothesis attributes subsidence to sediment loading replacing lower density seawater. 2) The thermal hypothesis proposes that lithospheric cooling after rifting and crustal thinning causes thermal contraction and subsidence. 3) The crustal thinning hypothesis suggests the lower continental crust flows plastically towards the upper mantle during rifting, contributing to subsidence.

1. SUBSIDENCE July 2008 Sedimentary Basin Analysis

3. Subsidence Passive continental margins are those associated with continental rifting and the subsequent formation of ocean basins. They differ from active continental margins which are associated with subduction. Arapahoe Basin, Colorado, USA Subsidence is a cooling of the surface of the earth. Causes include sediment loading, tectonic activity, and thermal contraction during cooling of the crust.

7. Thermal Hypothesis Thermal Hypothesis of Sleep 1971 (After Bott, 1978) Thermal hypothesis of Sleep. This was the first to recognise that heating up the mantle (by a plume or whatever) could produce substantial crustal uplift (and erosion), followed by thermal subsidence. 1. 2. 3.

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