ALBERT

Description: The papers in this volume represent a step forward in our knowledge of the geological evolution of the North Atlantic from the Cretaceous-Palaeogene boundary through to the early Eocene. With the increase in hydrocarbon exploration activities in the Faroe-Shetland Basin (Fig. 1), new interpretations of the regional geology have become increasingly important, and the accuracy of the time frame for this work is vital to our understanding of the sequence of volcanic and sedimentary events. The synthesis of data relating to Palaeogene volcanism and sedimentation along the Norwegian Margin by Eldholm et al. emphasizes the importance of transfer zones, possibly inherited from the Proterozoic basement, in the distribution of sediments and volcanic products during rifting (Fig. 2). Furthermore, subsequent uplift and the development of marginal highs are invoked as factors which affected water circulation within the basins, leading to a deterioration in the Eocene climate. This work identifies the relevance of the North Atlantic Igneous Province (NAIP) as an influence on environmental systems on a global scale. Ar-Ar and Pb-U isotopic age data show that the main period of continental flood basalt volcanism in the NAIP extended from c. 60.5 Ma through to c. 54.5 Ma (Table 1). Biostratigraphical analysis of these volcanic-sedimentary sections (Jolley et al. 2002) shows that the onset of this interval equates to the Late Paleocene Thermal Maximum (LPTM). New isotopic dating of the oldest part of the volcanic sequence on the Faroe Islands, the Lower Formation, by Waagstein et al. has further confirmed the age ... This 250-word extract was created in the absence of an abstract.

Description: Palaeogene volcanism on the NW margin of the Faroe-Shetland Basin is represented by the Faroes Lava Group, within an age range of 57.5-60.56 Ma. The volcanic sequence comprises 〉1000 m of basaltic volcaniclastic rocks deposited in estuarine or marginal lagoons, overlain by three laterally-extensive formations of subaerial facies basaltic lavas: Lower, c. 3250 m; Middle, c. 1400 m; Upper, at least 900 m (top not preserved). The Lower and Upper formations comprise high-volume sheet flows, commonly with ferrallitized tops, interbedded with reddened, thin, fluvial claystone and basaltic siltstone deposits. Laterally-impersistent coals occur within the Lower Lava Formation. The Coal-bearing Formation (c. 20 m) was deposited in an overbank floodplain environment during an hiatus in the volcanism between the Lower and Middle formations. The Volcaniclastic Sandstone Sequence comprises hydroclastic and pyroclastic deposits which post-date the Coal-bearing Formation and represent a return to volcanism, prior to the eruption of the Middle Lava Formation which is mainly characterized by inflated pahoehoe flows. The onshore sequence of the Faroes Lava Group can be correlated with basaltic flows within the Faroe-Shetland Basin, where lavas in Well 205/9-1 are interpreted to be of Lower Lava Formation affinity, possibly erupted from a local vent system. Seismic and gravity mapping and modelling suggest that the offshore extension of the Lower Lava Formation, together with the oldest part of the Middle Lava Formation, comprise subaqueous hyaloclastites deposited in a prograding Gilbert-type lava delta system. The youngest part of the Middle Lava Formation and all of the Upper Lava Formation occur as subaerial facies lavas within the basin.

Description: The North Faroe-Shetland Basin (NFSB) Sill Complex is of late Paleocene/earliest Eocene age and was emplaced within Cretaceous and Paleocene sedimentary rocks, in places to depths as shallow as a few hundred metres below the contemporaneous basin floor. Intersections of the Complex occur in exploration wells drilled by the oil industry and indicate tholeiitic basaltic compositions. High quality 3D seismic data, obtained during hydrocarbon exploration along the NE Atlantic Margin, provide a unique view of an uneroded suite of these sheet-like intrusions in UK Quadrants 218 and 219 and indicate the multi-centred nature of the NFSB Sill Complex, with upward-fingering terminations from broad bowlshaped foci of intrusion. Where the intrusion depth is very shallow, depending upon the host lithology, sill emplacement has lead to the development of structures on the contemporaneous basin floor interpreted as submarine hyaloclastite-dominated vents, up to c. 2 km across and with heights of up to c. 100 m. Where intrusion depth is greater, seismic chimney' structures are interpreted as the fluidescape feeders of sedimentary-hydrothermal mounds. Subsequent differential compaction of sedimentary sections, with and without shallow-emplaced sills, has given rise to distinctive eye' structures, as seen in seismic sections.

Description: The Palaeogene Erlend Volcano subcrops in the Faroe-Shetland Basin on the NE Atlantic Margin and was first recognized on the basis of its pronounced positive gravity and magnetic anomalies. Three hydrocarbon exploration wells (209/3-1; 209/4-1A; 209/9-1) have penetrated thick sequences of subaerial facies basaltic lavas and subaqueous volcanic breccias (the Basaltic Suite'), overlying Palaeogene (Thanetian) and Cretaceous (Maastrichtian and Campanian) sedimentary rocks interbedded with medium to fine-grained silicic igneous rocks (the Acidic Suite'). Detailed palynological and petrological analysis indicates that the basaltic rocks were contemporaneous with the Faroes Lower Lava Formation at c. 56.6-55 Ma, and were erupted into environments ranging between dry land and brackish to freshwater lagoons at the margin of a marine channel separating the Erlend Volcano from the Brendan's Volcano to the north. The subjacent Acidic Suite is interpreted as a series of sills emplaced approximately contemporaneously with the volcanic rocks on the basis of their diachronous relationship with interbedded sedimentary rocks, together with high Thermal Alteration Index values of in situ fossils.

Description: The North Atlantic Igneous Province has been the subject of extensive scientific investigation over the past thirty years, with a wide field of knowledge being accumulated. Recently, recognition of the potential role of Large Igneous Provinces in affecting ocean and atmosphere systems and biotic evolutionary pathways has lead to increased interest in this province. This has been further stimulated by the expansion in the search for oil and gas in Mesozoic and Tertiary sediments along the NE Atlantic Margin. An improved understanding of the interaction between igneous and sedimentary processes is vital for the identification of potential hydrocarbon resources. The regions covered include continental margin Norway, east and west Greenland, the Faroe-Shetland Basin and the Faroe Islands themselves. The papers in this book contain new data and interpretations of North Atlantic Igneous Province magmatic processes, rift evolution, tectonics, stratigraphy (chemostratigraphy, biostratigraphy, seismic and isotope stratigraphy) and sediment dispersal. Many of the papers adopt a multidisciplinary approach to tha analysis and interpretation of complex volcanic and sedimentary sequences. These new data, and the reviews and compilations of existing data provide the reader with access to current research directions in North Atlantic Igneous Province geology.

Description: The West Antarctic Ice Sheet (WAIS) flows through the volcanically active, late Cenozoic West Antarctic rift system. Active subglacial volcanism and a vast (〉 106 km3) extent of subglacial volcanic structures have been interpreted from aerogeophysical surveys over central West Antarctica in the past decade, combined with results from 1960s and 1970s aeromagnetic profiles over the WAIS. Modelling of magnetic anomalies constrained by radar ice sounding shows volcanic sources at the base of the ice throughout large areas, whose subglacially erupted hyaloclastite edifices have been eroded by moving ice, as in Iceland. The 1800 m-high divide of the WAIS is underlain by the 400 km-long volcanic Sinuous Ridge, which rises above sea level; most hyaloclastite edifices there have also been glacially removed, indicating migration of the ice divide through time. Northeast of the divide of the WAIS there is a 400-nT positive magnetic anomaly over the shallowest, most rugged bedrock topography (elevation +380m above sea level), probably comprising subaerially erupted flows erupted when the Sinuous Ridge area was deglaciated. Uplift of the Sinuous Ridge may have forced the advance of the WAIS. Other aspects of the subglacial volcanism in Antarctica can be observed in Iceland and have a direct bearing on our understanding of the subglacial conditions of the WAIS and its dynamics.