A regional perspective on the timing of ventilation of the Arctic Ocean; did it occur in the late Eocene or early Miocene?

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Author(s): O'Regan, M. A.; Jakobsson, Martin; Ahnfelt, P.
Author Affiliation(s): Primary:
Cardiff University, School of Earth and Ocean Sciences, Cardiff, United Kingdom
Stockholm University, Sweden
Volume Title: AGU 2011 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2011; American Geophysical Union 2011 fall meeting, San Francisco, CA, Dec. 5-9, 2011. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The marine sedimentary sequence recovered from the Lomonosov Ridge during the Arctic Coring Expedition (IODP 302) provides our only template of the Cenozoic paleoceanographic history of the Arctic Ocean. One of the most dramatic changes in this ∼400 meter cored record is a relatively abrupt shift from freshwater influenced biosiliceous and organic rich sediments to fossil-poor glaciomarine silty clays. This transition is interpreted as representing the 'ventilation' of the intermediate and deep-waters of the Arctic Ocean, which were strongly stratified and oxygen-deficient at subsurface levels for much of the early Paleogene and possibly the Late Cretaceous. This potentially basin-wide change in water mass chemistry and the nature of sediment deposition is attributed to the establishment of a critical two-way oceanic exchange between the Arctic Ocean and Norwegian Greenland Sea through the proto-Fram Strait. However the timing of these events is highly controversial. In the original ACEX age model (Backman et al., 2008), Arctic ventilation occurred above a 26 Myr hiatus that separated middle Eocene (44.4 Ma) from late early Miocene (18.2 Ma) sediments. In contrast, recently published radiometric ages, derived from osmium isotopes (Poirier and Hillaire-Marcel, 2011), date the ventilation of the Arctic almost 20 million years earlier in the late Eocene (∼36 Ma). This latter model involves an entirely different interpretation of the paleogeography and depositional setting for the Arctic Ocean during the late Paleogene and early Neogene, and argues against a pronounced hiatus in the ACEX record. Here we provide a brief outline of the pros and cons of these competing age models, discussing them in the context of regional published seismic stratigraphic interpretations and paleogeographic reconstructions for the Arctic Ocean.
Year of Publication: 2011
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Absolute age; Arctic Coring EXpedition; Arctic Ocean; Cenozoic; Cretaceous; Dates; Eocene; Expedition 302; Glacial sedimentation; Glaciomarine sedimentation; Integrated Ocean Drilling Program; Lomonosov Ridge; Lower Miocene; Lower Paleogene; Marine geology; Marine sedimentation; Marine sediments; Mesozoic; Miocene; Neogene; Paleo-oceanography; Paleogene; Reconstruction; Sedimentation; Sediments; Tertiary; Upper Cretaceous; Upper Eocene
Coordinates: N875100 N875600 E1393300 E1361000
Record ID: 2018032661
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