The Nature and Origin of Compression in Passive Margins

Increasingly, researchers have reported that passive margins do not show a simple uninterrupted thermal sag pattern of post-rift subsidence following continental separation. Rather, the structural and stratigraphic development of such margins may record evidence of complex phases of differential subsidence, exhumation and fold development. Some of the fold structures observed on passive continental margins appear to be related to regional stresses transmitted through basement rocks, whereas others are related to gravitational sliding and toe-thrusting. This special publication concentrates on the first of these categories. The morphology and distribution of such folds, together with potential mechanisms for generation of regional stress, are described in a series of papers by authorities in the field. As well as being an enigmatic feature of passive margin geology, the compressive folds have significance in the exploration for petroleum.