Paleoenvironmental reconstruction of Challenger Mound initiation in the Porcupine Seabight, NE Atlantic

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doi: 10.1016/j.margeo.2010.10.019
Author(s): Raddatz, Jacek; Rüggeberg, Andres; Margreth, Stephan; Dullo, Wolf-Christian
Integrated Ocean Drilling Program, Expedition 307 Scientists
Author Affiliation(s): Primary:
Kiel University, Leibniz-Institute of Marine Sciences, Kiel, Germany
Ghent University, Belgium
Leibniz-Institute of Marine Sciences, Germany
University of Geneva, Switzerland
University of Fribourg, Switzerland
Volume Title: COld-water CArbonate Reservoir systems in Deep Environments; COCARDE
Volume Author(s): Spezzaferri, Silvia, editor; van Rooij, David; Rüggeberg, Andres; Samankassou, Elias; Henriet, Jean-Pierre
Source: COld-water CArbonate Reservoir systems in Deep Environments; COCARDE, edited by Silvia Spezzaferri, David van Rooij, Andres Rüggeberg, Elias Samankassou and Jean-Pierre Henriet. Marine Geology, 282(1-2), p.79-90. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0025-3227 CODEN: MAGEA6
Note: In English. 83 refs.; illus., incl. 1 plate, sketch map
Summary: The understanding of the paleoenvironment during initiation and early development of deep cold-water coral carbonate mounds in the NE Atlantic is currently a focus of international research. The Integrated Ocean Drilling Program (IODP) Expedition 307 drilled the 155 m high Challenger Mound in the Porcupine Seabight (SW off Ireland) in order to investigate for the first time sediments from the base of a giant carbonate mound. In this study we focus in high resolution on 12 m of sediments from Site 1317 encompassing the mound base. The mound initiation and start-up phase coincide with the intensification of the Northern Hemisphere Glaciation (INHG) at around 2.7 Ma. Further carbonate mound development seems to be strongly dependent on rapid changes in paleoceanographic and climatic conditions at the Pliocene-Pleistocene boundary, especially characterized and caused by the interaction of intermediate water masses, the Mediterranean Outflow Water (MOW), the Eastern North Atlantic Water (ENAW) and the influence of Southern Component Water (SCW). This study is based on well-established proxies such as δ18O and δ13C of planktonic (Globigerina bulloides) and benthic foraminifera (Fontbotia wuellerstorfi, Discanomalina coronata, Lobatula lobatula, Lobatula antarctica, and Planulina ariminensis) as well as grain size parameters to identify the paleoenvironmental and paleoecological setting favourable for the initial coral colonization on the mound. Stable oxygen and carbon isotope records of benthic foraminiferal species indicate that L. lobatula provides a reliable isotopic signature for paleoenvironmental reconstructions. In particular, δ18O values of L. lobatula indicate that initial mound growth started in a glacial mode with moderate excursions in δ18O values. Carbon isotope values of D. coronata are significantly offset compared to other epibenthic species. This offset may be related to vital effects. Bottom water temperatures, calculated using standard equations based on δ18O of foraminiferal tests, range between 7 and 11°C, consistent with the known temperature range conducive for cold-water coral growth and development. Bottom currents transporting intermediate water masses of southern origin (Mediterranean and Bay of Biscay) enhanced at 2.6 Ma supporting first coral settlements with the INHG. The benthic δ13C and the sortable silt records indicate that the early Pleistocene hydrodynamic regime was characterized by weaker current intensities associated with vertical movements of MOW or its replacement by SCW at intermediate depth. After these sluggish phases enhanced MOW flow dominated again and led to stronger current intensities and most probably sediment erosion on Challenger Mound. Erosion in combination with early diagenetic (oxidation) processes overprinted the sediment layers as indicated by dissolved coral skeletons, the increase in Ca-content and sediment density, minimum δ13Cplanktonic values, as well as the occurrence of gypsum and pyrite, implying a careful evaluation of original and overprinted geochemical signals. We conclude that the Challenger Mound development was already influenced by short-term variability of water masses from southern origin and possible erosional events comparable to the late Pleistocene setting. Abstract Copyright (2011) Elsevier, B.V.
Year of Publication: 2011
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Anthozoa; Atlantic Ocean; Belgica Mounds; Benthic taxa; Biochemistry; Biogenic structures; Bioherms; Bottom currents; C-13/C-12; Carbon; Carbonate sediments; Cenozoic; Challenger Mound; Cnidaria; Cold-water environment; Currents; Deep-water environment; Diagenesis; Early diagenesis; Expedition 307; Foraminifera; Geochemistry; Globigerina; Globigerina bulloides; Globigerinacea; Globigerinidae; IODP Site U1317; Integrated Ocean Drilling Program; Invertebrata; Isotope ratios; Isotopes; Lobatula; Lower Pleistocene; Marine environment; Mediterranean Outflow Water; Microfossils; Neogene; North Atlantic; Northeast Atlantic; O-18/O-16; Oxygen; Paleo-oceanography; Paleocirculation; Paleoclimatology; Paleocurrents; Paleoecology; Paleoenvironment; Paleotemperature; Planktonic taxa; Planulina; Pleistocene; Pliocene; Porcupine Seabight; Protista; Quaternary; Reconstruction; Rotaliina; Sedimentary structures; Sediments; Southern Component Water; Stable isotopes; Tertiary; Upper Pliocene
Coordinates: N512300 N512300 W0114300 W0114300
Record ID: 2011053840
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands