Uplift, compression and the Cenozoic Faroe–Shetland sediment budget
Published:January 01, 2008
John R. Smallwood, 2008. "Uplift, compression and the Cenozoic Faroe–Shetland sediment budget", The Nature and Origin of Compression in Passive Margins, Howard Johnson, Tony G. Doré, Robert W. Gatliff, Robert W. Holdsworth, Erik R. Lundin, J. Derek Ritchie
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Throughout the Cenozoic, the dominant sediment supply to the Faroe–Shetland Basin has been from the SE. However, the volume of sediment in the basin is greater than that supplied from the British Isles’ provenance area alone. The British Isles and Faroes Platform experienced both epeirogenic and local uplift, caused by igneous underplating, mantle thermal variations and compression. A Cenozoic topographic model is presented for the British Isles’ and Faroe Islands’ provenance areas, from which sediment supply rates are calculated. The model includes permanent uplift from igneous underplating, which is estimated from gravity anomaly data, transient regional uplift and a simple elevation-dependent erosion term, under isostatic balance. Even using upside estimates of the British Isles’ Cenozoic denudation and the documented post-Eocene contribution from the Faroe Islands, there is an apparent undersupply of sediment to the basin. The sediment volume balance suggests that around 30% of the Paleocene sediments currently in the basin were sourced from a westerly provenance area, the pre-basalt Faroes Platform terrane or East Greenland.
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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.