North Atlantic climatic events recorded in Aptian Naskapi Member cores,Scotian Basin |
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| Affiliation: | 1. Department of Geology, Saint Mary''s University, Halifax, Nova Scotia, B3H 3C3, Canada;2. Natural Resources Canada, Geological Survey of Canada (Atlantic), Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, Nova Scotia, B2Y 4A2, Canada;1. Departamento de Petrología y Geoquímica, UCM, IGEO (UCM-CSIC), Madrid, Spain;2. Instituto Nacional del Carbón, INCAR-CSIC, Oviedo, Spain;3. Departamento de Estratigrafía, UCM, IGEO (UCM-CSIC), Madrid, Spain;4. EOST, Université de Strasbourg, Strasbourg, France;1. Department of Earth Sciences, Montana State University, Bozeman, MT, USA;2. Museum of the Rockies, Montana State University, Bozeman, MT, USA;3. BHP Billiton Petroleum, Houston, TX, USA;4. Research Casting International, Trenton, ON, Canada;1. Institute of Geoscience, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves, 9500, Porto Alegre, RS 91.501-970, Brazil;2. Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow 226 007, India |
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| Abstract: | Early Aptian black laminated organic mudstones, including the Selli Level, are recognized over large areas of Tethys and western European basins. This interval was investigated in a 75 m-thick continuously cored section of varicoloured shale in the lower Naskapi Member from the Panuke B-90 well in the Scotian Basin, offshore eastern Canada. This study complements the palaeogeographic range of correlatable Selli black shales and provides information on their relationship to sea-level change and palaeoclimate. Total organic carbon (TOC) was measured on 127 discrete samples, chemical environmental proxies (Th/K, Mn/Ti, K/Ti, Th/Ti, V/Ti) were measured with a portable X-ray fluorescence (pXRF) spectrometer, and colour parameters L*a*b* were measured by spectrophotometer. Several black shale levels are recognized and correlated with similar shales in Europe between the Barremian–Aptian boundary and the Selli Level. The Th/K ratio proxy for hinterland humid or arid climate conditions shows no systematic variation with black shale levels. Several sea-level lowstands are inferred from condensed sandy intervals with some brackish water biota and tidal sedimentary structures. Black shale intervals are found in highstand intervals, with no systematic relationship to inferred transgressions. The formation of black shales is related to palaeoceanographic changes that may be driven by conditions remote from the Scotian Basin. |
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| Keywords: | Portable XRF Selli Level Black shales Sea level Palaeoclimate Cretaceous |
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