Unraveling the onset of Cretaceous Oceanic Anoxic Event 2 in an extended sediment archive from the Tarfaya-Laayoune Basin, Morocco

Kuhnt, Wolfgang, Holbourn, Ann, Beil, Sebastian, Aquit, Mohamed, Krawczyk, Tim, Flögel, Sascha, Chellai, El Hassane and Jabour, Haddou (2017) Unraveling the onset of Cretaceous Oceanic Anoxic Event 2 in an extended sediment archive from the Tarfaya-Laayoune Basin, Morocco Paleoceanography, 32 (8). pp. 923-946. DOI 10.1002/2017PA003146.

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Abstract

We investigated the onset and development of Cretaceous Oceanic Anoxic Event 2 (OAE2) in a newly drilled core (SN degrees 4) from the Tarfaya Basin (southern Morocco), where this interval is unusually expanded. High-resolution (centimeter-scale equivalent to centennial) analysis of bulk organic and carbonate stable isotopes and of carbonate and organic carbon content in combination with XRF scanner derived elemental distribution reveal that the ocean-climate system behaved in a highly dynamic manner prior to and during the onset of OAE2. Correlation with the latest orbital solution indicates that the main carbon isotope shift occurred during an extended minimum in orbital eccentricity (similar to 400 kyr cycle). Shorter-term fluctuations in carbonate and organic carbon accumulation and in sea level related terrigenous discharge were predominantly driven by variations in orbital obliquity. Negative excursions in organic and carbonate delta C-13 preceded the global positive delta C-13 shift marking the onset of OAE2, suggesting injection of isotopically depleted carbon into the atmosphere. The main delta C-13 increase during the early phase of OAE2 in the late Cenomanian was punctuated by a transient plateau. Maximum organic carbon accumulation occurred during the later part of the main delta C-13 increase and was associated with climate cooling events, expressed as three consecutive maxima in bulk carbonate delta O-18. The extinctions of the thermocline dwelling keeled planktonic foraminifers Rotalipora greenhornensis and Rotalipora cushmani occurred during the first and last of these cooling events and were likely associated with obliquity paced, ocean-wide expansions, and intensifications of the oxygen minimum zone, affecting their habitat space on a global scale.

Document Type: Article
Additional Information: Data will be archived at PANGAEA, data publisher for Earth and Environmental Science, doi:10.1594/PANGAEA.
Keywords: Paleoclimate; Cretaceous; Oceanic Anoxic Event; CENOMANIAN-TURONIAN BOUNDARY; CARBON-ISOTOPE STRATIGRAPHY; WESTERN INTERIOR BASIN; MARINE ORGANIC-MATTER; EOCENE THERMAL MAXIMUM; ORBITAL TIME-SCALE; SEA-LEVEL; BLACK SHALES; PALEOENVIRONMENTAL CHANGES; MIDCRETACEOUS GREENHOUSE
Research affiliation: OceanRep > SFB 754 > A7
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
Kiel University
Kiel University > Kiel Marine Science
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > SFB 754
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: Yes
DOI etc.: 10.1002/2017PA003146
ISSN: 0883-8305
Projects: SFB754
Date Deposited: 21 Sep 2017 08:37
Last Modified: 01 Mar 2018 00:38
URI: http://eprints.uni-kiel.de/id/eprint/39496

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