Palaeogene evolution of the Ymir and Wyville Thomson ridges, European North Atlantic margin
Published:January 01, 2008
H. Ziska, T. Varming, 2008. "Palaeogene evolution of the Ymir and Wyville Thomson ridges, European North Atlantic margin", 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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The region to the SW of the Faroe Islands is an enigmatic area where the structural trends of the Faroe–Shetland and North Rockall basins meet. The Munkagrunnur, Wyville Thomson and Ymir ridges are major tectonic features within the area and arc approximately perpendicular to the primary Caledonian structural trend. Previous studies have suggested that these ridges formed as a result of compressive forces during the Eocene, Oligocene and Miocene. However, this study suggests that these ridges were initiated by a transient rifting event in the early Paleocene. This rifting event was accompanied by an igneous phase which emplaced large volumes of intrusive and extrusive igneous rocks. The igneous centres within the study area are located on older structural features, indicating exploitation of pre-existing structural weaknesses. The same structural weaknesses were later exploited by compressive events, which resulted in the generation of Ymir Ridge South, and also influenced the orientation and shape of the other segments of Ymir Ridge and the Wyville Thomson Ridge.
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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.