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Warm saline intermediate waters in the Cretaceous tropical Atlantic Ocean

Warm saline intermediate waters in the Cretaceous tropical Atlantic Ocean
Warm saline intermediate waters in the Cretaceous tropical Atlantic Ocean
During the mid-Cretaceous period, the global subsurface oceans were relatively warm, but the origins of the high temperatures are debated. One hypothesis suggests that high sea levels and the continental configuration allowed high-salinity waters in low-latitude epicontinental shelf seas to sink and form deep-water masses1, 2, 3. In another scenario, surface waters in high-latitude regions, the modern area of deep-water formation, were warmed through greenhouse forcing4, which then propagated through deep-water circulation. Here, we use oxygen isotopes and Mg/Ca ratios from benthic foraminifera to reconstruct intermediate-water conditions in the tropical proto-Atlantic Ocean from 97 to 92 Myr ago. According to our reconstruction, intermediate-water temperatures ranged between 20 and 25 °C, the warmest ever documented for depths of 500–1,000 m. Our record also reveals intervals of high-salinity conditions, which we suggest reflect an influx of saline water derived from epicontinental seas around the tropical proto-North Atlantic Ocean. Although derived from only one site, our data indicate the existence of warm, saline intermediate waters in this silled basin. This combination of warm saline intermediate waters and restricted palaeogeography probably acted as preconditioning factors for the prolonged period of anoxia and black-shale formation in the equatorial proto-North Atlantic Ocean during the Cretaceous period.
1752-0894
453-457
Friedrich, Oliver
680f066c-a4b1-4647-beb3-281addc1ee17
Erbacher, Jochen
77fb7ba3-7411-4331-aa09-c467cd9c43ba
Moriya, Kazuyoshi
d6b84bd5-a826-4cf9-8db3-5c65c4f1e93b
Wilson, Paul A.
f940a9f0-fa5a-4a64-9061-f0794bfbf7c6
Kuhnert, Henning
51bfece3-dab4-413a-b4f1-bd4ccc9c9b43
Friedrich, Oliver
680f066c-a4b1-4647-beb3-281addc1ee17
Erbacher, Jochen
77fb7ba3-7411-4331-aa09-c467cd9c43ba
Moriya, Kazuyoshi
d6b84bd5-a826-4cf9-8db3-5c65c4f1e93b
Wilson, Paul A.
f940a9f0-fa5a-4a64-9061-f0794bfbf7c6
Kuhnert, Henning
51bfece3-dab4-413a-b4f1-bd4ccc9c9b43

Friedrich, Oliver, Erbacher, Jochen, Moriya, Kazuyoshi, Wilson, Paul A. and Kuhnert, Henning (2008) Warm saline intermediate waters in the Cretaceous tropical Atlantic Ocean. Nature Geoscience, 1, 453-457. (doi:10.1038/ngeo217).

Record type: Article

Abstract

During the mid-Cretaceous period, the global subsurface oceans were relatively warm, but the origins of the high temperatures are debated. One hypothesis suggests that high sea levels and the continental configuration allowed high-salinity waters in low-latitude epicontinental shelf seas to sink and form deep-water masses1, 2, 3. In another scenario, surface waters in high-latitude regions, the modern area of deep-water formation, were warmed through greenhouse forcing4, which then propagated through deep-water circulation. Here, we use oxygen isotopes and Mg/Ca ratios from benthic foraminifera to reconstruct intermediate-water conditions in the tropical proto-Atlantic Ocean from 97 to 92 Myr ago. According to our reconstruction, intermediate-water temperatures ranged between 20 and 25 °C, the warmest ever documented for depths of 500–1,000 m. Our record also reveals intervals of high-salinity conditions, which we suggest reflect an influx of saline water derived from epicontinental seas around the tropical proto-North Atlantic Ocean. Although derived from only one site, our data indicate the existence of warm, saline intermediate waters in this silled basin. This combination of warm saline intermediate waters and restricted palaeogeography probably acted as preconditioning factors for the prolonged period of anoxia and black-shale formation in the equatorial proto-North Atlantic Ocean during the Cretaceous period.

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Published date: 2008
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 52489
URI: http://eprints.soton.ac.uk/id/eprint/52489
ISSN: 1752-0894
PURE UUID: 99db40e2-9201-4ae4-9e29-e6a191e4efac
ORCID for Paul A. Wilson: ORCID iD orcid.org/0000-0001-6425-8906

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Date deposited: 02 Jul 2008
Last modified: 16 Mar 2024 03:13

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Contributors

Author: Oliver Friedrich
Author: Jochen Erbacher
Author: Kazuyoshi Moriya
Author: Paul A. Wilson ORCID iD
Author: Henning Kuhnert

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