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What happens when the ocean is overheated? The foraminiferal response across the Paleocene-Eocene Thermal Maximum at the Alamedilla section (Spain)

Laia Alegret, Silvia Ortiz, Ignacio Arenillas and Eustoquio Molina
What happens when the ocean is overheated? The foraminiferal response across the Paleocene-Eocene Thermal Maximum at the Alamedilla section (Spain)
Geological Society of America Bulletin (September 2010) 122 (9-10): 1616-1624

Abstract

The global warming and major perturbation of the global carbon cycle that occurred during the Paleocene-Eocene Thermal Maximum (PETM) have been investigated in the lower bathyal-upper abyssal Alamedilla section (Spain). Geochemical anomalies and dramatic faunal changes (including the globally recognized extinction event of deep-sea benthic foraminifera and the rapid evolutionary turnover of planktic foraminifera and calcareous nannofossils) are associated with the PETM at Alamedilla. Biotic changes in the plankton and benthos indicate environmental instability approximately 11-14 k.y. before the onset of carbon isotope excursion that marks the Paleocene/Eocene boundary. The reorganization of the planktic ecosystem points to warm and oligotrophic conditions in surface waters during the earliest Eocene, whereas faunal and geochemical data indicate that the extinctions of benthic foraminifera occurred over an interval with a high CaCO (sub 3) content and oxic conditions at the seafloor. The proliferation of disaster taxa (Glomospira spp.) after the extinctions has been related to a potential source of isotopically light carbon in the western Tethys and North Atlantic. Significant changes in foraminiferal test size are documented across the PETM. We suggest that increased temperatures played an important role in benthic foraminiferal test size, increasing their metabolic rates and, consequently, their food requirements. Decreased planktic foraminiferal test size may be related to decreased nutrient availability or surface-water density. However, the differences in test size evolution among different species of both benthic and planktic foraminifera may be related to interspecific competition and ecological adaptations to direct or indirect consequences of the carbon addition during the PETM.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 122
Serial Issue: 9-10
Title: What happens when the ocean is overheated? The foraminiferal response across the Paleocene-Eocene Thermal Maximum at the Alamedilla section (Spain)
Affiliation: Universidad de Zaragoza, Departamento de Ciencias de la Tierra, Saragossa, Spain
Pages: 1616-1624
Published: 201009
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 77
Accession Number: 2010-068244
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2010098
Illustration Description: illus. incl. sects., sketch map
N37°34'60" - N37°36'00", W03°13'60" - W03°13'00"
Secondary Affiliation: University College London, GBR, United Kingdom
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201037
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