Extensive occurrences of Permo‐Triassic strata are preserved along the Northwest European Atlantic margin. Seismic reflection and well data are used to describe large‐scale Permo‐Triassic basin geometries along a swath of the continental shelf more than 2000 km long extending from the Irish to the mid‐Norwegian sectors. Successions in the Celtic Sea, the flanks of the Irish Rockall Basin, basins west and north of Scotland, and the Trøndelag and Horda platforms west of Norway are described. The large‐scale Permo‐Triassic depositional geometries commonly represent erosional remnants of larger basins modified by later rifting episodes, uplift, inversion and continental breakup. However, the interpreted geometries reveal spatial and temporal differences in rifting style. The basins developed above a complex mosaic of petrologically heterogeneous crustal terranes with inherited crustal fabrics, which had a significant impact on the depositional basin geometries. Small Permian basins with growth faulting developed in the southern Celtic Sea region. Extensive, uniformly thick Triassic strata are characteristic of the wide rift basins in the southeastern Rockall Basin and northwest of the Solan Bank High. Thick, fault‐controlled basins developed in the Horda and Trøndelag platform regions. The main controls on Permo‐Triassic basin architecture are (a) crustal thickness and composition, which determined the development of narrow or wide rift basin geometries, (b) inherited Variscan, Caledonian and Precambrian basement structures and (c) pre‐rift palaeotopography. Copyright © 2009 John Wiley & Sons, Ltd.
Permo-Triassic rift basins offer important hydrocarbon targets along the Atlantic margins. Their fill is dominated by continental red beds, comprising braided fluvial, alluvial fan, aeolian, floodplain and lacustrine facies. These relatively lightly explored basins span both the Atlantic and Tethyan domains and developed above a complex basement with inherited structural fabrics. Sparse data in offshore regions constrain understanding of depositional geometries and sedimentary architecture, further impeded by their deep burial beneath younger strata, combined with the effects of later deformation during continental breakup. This paper provides results from a multidisciplinary analysis of basins along the Atlantic margin. Regional seismic and well data, combined with geochemical provenance analysis from the European North Atlantic margins, are integrated with detailed outcrop studies in Morocco and Nova Scotia. The research provides new insights into regional basin tectonostratigraphic evolution, sediment fill, and reservoir distribution, architecture and quality at a range of scales. Regional seismic profiles, supported by key well data, indicate the presence of post-orogenic collapse basins, focused narrow rifts and low-magnitude multiple extensional depocentres. Significantly, Permo-Triassic basin geometries are different and more varied than the overlying Jurassic and younger basins. Provenance analysis using Pb isotopic composition of detrital K-feldspar yields new and robust controls on the sediment dispersal patterns of Triassic sandstones in the NE Atlantic margin. The evolving sedimentary architecture is characterized by detailed sedi-mentological studies of key outcrops of age equivalent Permian-Triassic rifts in Morocco and Nova Scotia. The interplay of tectonics and climate is observed to influence sedimentation, which has significant implications for reservoir distribution in analogue basins. New digital outcrop techniques are providing improved reservoir models, and identification of key marker horizons and sequence boundaries offers a potential subsurface correlation tool. Future work will address source and seal distribution within the potentially petroliferous basins.
This study focuses on identifying major source areas in several stratigraphic intervals in the Permian sediments of the Krkonoše Piedmont Basin and integrates it with existing sedimentological data. Pebbles in Cisuralian-Guadalupian conglomerates of alluvial fans, nearshore lacustrine and lacustrine fan-delta deposits that were deposited close to the northwestern and southeastern basin margin, respectively, correspond almost exclusively to local material from adjacent crystalline complexes. The heavy mineral associations of the sandstone matrix of these conglomerates support this interpretation. Crystalline units of the south-western part of the Krkonoše-Jizera Crystalline Complex and Orlice-Sněžník Crystalline Complex, respectively, are considered as the most favourable sources. Heavy mineral associations of fluvial sandstone facies are of complex composition pointing to repeated recycling of clastic material. However, heavy mineral indices reveal distinct source areas for the main lithostratigraphic units. Two main possible source areas for the fluvial Asselian deposits (Vrchlabí Formation) of the south-western part of the basin were found. Pebbles of late Devonian- early Carboniferous marine limestones probably came from the central part of the hypothetical Jítrava-Hradec Basin. The garnet compositions in sand detrital material point to leucogranites and pegmatites of the north-eastern Moldanubian Zone, Přibyslavice area, as the possible source rocks. Guadalupian fluvial deposits reveal a wide range of sources that can be attributed to the recycling of detrital material from Cisuralian and Carboniferous deposits. Garnet compositions indicate Moldanubian granulites, garnet clinopyroxenites, leucogranites and pegmatites as a possible sources. We infer that Moldanubian granulites and garnet clinopyroxenites were exposed to an erosion level in the Early Permian at the latest
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