Universität zu Köln

Dummann, Wolf ORCID: 0000-0001-6054-2440, Steinig, Sebastian ORCID: 0000-0003-3700-1106, Hofmann, Peter ORCID: 0000-0002-9796-0352, Lenz, Matthias, Kusch, Stephanie ORCID: 0000-0002-2708-4975, Floege, Sascha, Herrle, Jens Olaf, Hallmann, Christian ORCID: 0000-0003-3696-7371, Rethemeyer, Janet ORCID: 0000-0001-6698-4186, Kasper, Haino Uwe and Wagner, Thomas ORCID: 0000-0001-5006-625X (2021). Driving mechanisms of organic carbon burial in the Early Cretaceous South Atlantic Cape Basin (DSDP Site 361). Clim. Past., 17 (1). S. 469 - 491. GOTTINGEN: COPERNICUS GESELLSCHAFT MBH. ISSN 1814-9332

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Abstract

Extensive black shale deposits formed in the Early Cretaceous South Atlantic, supporting the notion that this emerging ocean basin was a globally important site of organic carbon burial. The magnitude of organic carbon burial in marine basins is known to be controlled by various tectonic, oceanographic, hydrological, and climatic processes acting on different temporal and spatial scales, the nature and relative importance of which are poorly understood for the young South Atlantic. Here we present new bulk and molecular geochemical data from an Aptian-Albian sediment record recovered from the deep Cape Basin at Deep Sea Drilling Project (DSDP) Site 361, which we combine with general circulation model results to identify driving mechanisms of organic carbon burial. A multimillion-year decrease (i.e., Early Aptian-Albian) in organic carbon burial, reflected in a lithological succession of black shale, gray shale, and red beds, was caused by increasing bottom water oxygenation due to abating hydrographic restriction via South Atlantic-Southern Ocean gateways. These results emphasize basin evolution and ocean gateway development as a decisive primary control on enhanced organic carbon preservation in the Cape Basin at geological timescales (> 1 Myr). The Early Aptian black shale sequence comprises alternations of shales with high (> 6 %) and relatively low (similar to 3.5 %) organic carbon content of marine sources, the former being deposited during the global Oceanic Anoxic Event (OAE) la, as well as during repetitive intervals before and after OAE la. In all cases, these short-term intervals of enhanced organic carbon burial coincided with strong influxes of sediments derived from the proximal African continent, indicating closely coupled climate-land-ocean interactions. Supported by our model results, we show that fluctuations in weathering-derived nutrient input from the southern African continent, linked to changes in orbitally driven humidity and aridity, were the underlying drivers of repetitive episodes of enhanced organic carbon burial in the deep Cape Basin. These results suggest that deep marine environments of emerging ocean basins responded sensitively and directly to short-term fluctuations in riverine nutrient fluxes. We explain this relationship using the lack of wide and mature continental shelf seas that could have acted as a barrier or filter for nutrient transfer from the continent into the deep ocean.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Dummann, Wolf UNSPECIFIED orcid.org/0000-0001-6054-2440 UNSPECIFIED Steinig, Sebastian UNSPECIFIED orcid.org/0000-0003-3700-1106 UNSPECIFIED Hofmann, Peter UNSPECIFIED orcid.org/0000-0002-9796-0352 UNSPECIFIED Lenz, Matthias UNSPECIFIED UNSPECIFIED UNSPECIFIED Kusch, Stephanie UNSPECIFIED orcid.org/0000-0002-2708-4975 UNSPECIFIED Floege, Sascha UNSPECIFIED UNSPECIFIED UNSPECIFIED Herrle, Jens Olaf UNSPECIFIED UNSPECIFIED UNSPECIFIED Hallmann, Christian UNSPECIFIED orcid.org/0000-0003-3696-7371 UNSPECIFIED Rethemeyer, Janet UNSPECIFIED orcid.org/0000-0001-6698-4186 UNSPECIFIED Kasper, Haino Uwe UNSPECIFIED UNSPECIFIED UNSPECIFIED Wagner, Thomas UNSPECIFIED orcid.org/0000-0001-5006-625X UNSPECIFIED
URN:	urn:nbn:de:hbz:38-596936
DOI:	10.5194/cp-17-469-2021
Journal or Publication Title:	Clim. Past.
Volume:	17
Number:	1
Page Range:	S. 469 - 491
Date:	2021
Publisher:	COPERNICUS GESELLSCHAFT MBH
Place of Publication:	GOTTINGEN
ISSN:	1814-9332
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language BLACK SHALE DEPOSITION; OCEANIC ANOXIC EVENT; RICH SEDIMENTS; ENVIRONMENTS; PRODUCTIVITY; HISTORY; SULFUR; TIME; ACCUMULATION; STRATIGRAPHY Multiple languages Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/59693