The biotic crisis across the Oceanic Anoxic Event 2: Palaeoenvironmental inferences based on foraminifera and geochemical proxies from the South Iberian Paleomargin

Open marine sediments deposited during the CenomanianeTuronian transition are well exposed in the Spanish Ba~nos de la Hedionda section (Betic Cordillera, South Iberian Palaeomargin). Analysis of foraminiferal assemblages and geochemical proxies allow inferences on the impact of the Oceanic Anoxic E...

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Autores: Reolid, Matias, Sánchez-Quiñónez, Carlos A., Alegret, Laia, Molina, Eustoquio
Tipo de documento: artigo
Estado:Versión aceptada para publicación
Data de publicação:2016
País:España
Recursos:Universidad de Zaragoza
Repositório:Zaguán. Repositorio Digital de la Universidad de Zaragoza
OAI Identifier:oai:zaguan.unizar.es:61854
Acesso em linha:http://zaguan.unizar.es/record/61854
Access Level:Acceso aberto
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spelling The biotic crisis across the Oceanic Anoxic Event 2: Palaeoenvironmental inferences based on foraminifera and geochemical proxies from the South Iberian PaleomarginReolid, MatiasSánchez-Quiñónez, Carlos A.Alegret, LaiaMolina, EustoquioOpen marine sediments deposited during the CenomanianeTuronian transition are well exposed in the Spanish Ba~nos de la Hedionda section (Betic Cordillera, South Iberian Palaeomargin). Analysis of foraminiferal assemblages and geochemical proxies allow inferences on the impact of the Oceanic Anoxic Event 2 (OAE2) in this area of the western Tethys. Three main intervals have been identified corresponding to different lithological units and biozones. (1) The top of the Capas Blancas Member (Rotalipora cushmani Biozone) represents the pre-extinction phase with diverse foraminiferal assemblages and well developed water-column tiering, well-oxygenated, oligotrophic deep-waters and oxygenated to poorly oxygenated, mesotrophic surface-waters. Foraminiferal opportunist species point to a minor event with dysoxic conditions preceding the OAE2. (2) The black radiolaritic shales (Whiteinella archaeocretacea Biozone) consist of a foraminiferal-barren interval, except for the lowermost centimetres where planktic surface-dweller opportunists are common. Redox sensitive elements (Cr/Al, V/Al, U/Th, MoEF, Moaut, UEF and Uaut) and increased TOC values reflect oxygen depleted conditions related to the OAE2. The increase in P/Ti values at the base of this stratigraphic interval indicates an abrupt increase in productivity. High concentrations of radiolarians are congruent with high surface productivity probably related to changes in oceanic circulation and enhanced upwelling currents, as well as subsequent shallowing of the oxygenminimum zone. The increase in MoEF and Moaut towards the top of the black radiolaritic shales indicates temporal euxinic conditions. (3) A slow, bottom-up recovery of foraminiferal assemblages is inferred at the base of the Boqueron Member (Helvetoglobotruncana helvetica Biozone), with seafloor recolonization by benthic foraminifera being recorded previous to the water column colonization by planktic forms, mainly by intermediate-dwellers typical of mesotrophic waters. The subsequent proliferation of surfacedweller opportunists and deep-dweller opportunists adapted to mesotrophic to eutrophic conditions, and the decrease in planktic foraminiferal diversity, may indicate the persistence of poorly oxygenated conditions in the water column towards the lower-middle part of the H. helvetica Biozone.2016info:eu-repo/semantics/articleinfo:eu-repo/semantics/acceptedVersionapplication/pdfhttp://zaguan.unizar.es/record/61854reponame:Zaguán. Repositorio Digital de la Universidad de Zaragozainstname:Universidad de ZaragozaInglésinfo:eu-repo/grantAgreement/ES/DGA/E05info:eu-repo/grantAgreement/ES/MICINN/RYC-2009-04316info:eu-repo/grantAgreement/ES/MINECO/CGL2011-229121info:eu-repo/grantAgreement/ES/MINECO/CGL2011-23077info:eu-repo/grantAgreement/ES/MINECO/CGL2012-33281info:eu-repo/grantAgreement/ES/MINECO-FEDER/CGL2014-58794-Pinfo:eu-repo/semantics/openAccessoai:zaguan.unizar.es:618542026-05-29T13:59:51Z
dc.title.none.fl_str_mv The biotic crisis across the Oceanic Anoxic Event 2: Palaeoenvironmental inferences based on foraminifera and geochemical proxies from the South Iberian Paleomargin
title The biotic crisis across the Oceanic Anoxic Event 2: Palaeoenvironmental inferences based on foraminifera and geochemical proxies from the South Iberian Paleomargin
spellingShingle The biotic crisis across the Oceanic Anoxic Event 2: Palaeoenvironmental inferences based on foraminifera and geochemical proxies from the South Iberian Paleomargin
Reolid, Matias
title_short The biotic crisis across the Oceanic Anoxic Event 2: Palaeoenvironmental inferences based on foraminifera and geochemical proxies from the South Iberian Paleomargin
title_full The biotic crisis across the Oceanic Anoxic Event 2: Palaeoenvironmental inferences based on foraminifera and geochemical proxies from the South Iberian Paleomargin
title_fullStr The biotic crisis across the Oceanic Anoxic Event 2: Palaeoenvironmental inferences based on foraminifera and geochemical proxies from the South Iberian Paleomargin
title_full_unstemmed The biotic crisis across the Oceanic Anoxic Event 2: Palaeoenvironmental inferences based on foraminifera and geochemical proxies from the South Iberian Paleomargin
title_sort The biotic crisis across the Oceanic Anoxic Event 2: Palaeoenvironmental inferences based on foraminifera and geochemical proxies from the South Iberian Paleomargin
dc.creator.none.fl_str_mv Reolid, Matias
Sánchez-Quiñónez, Carlos A.
Alegret, Laia
Molina, Eustoquio
author Reolid, Matias
author_facet Reolid, Matias
Sánchez-Quiñónez, Carlos A.
Alegret, Laia
Molina, Eustoquio
author_role author
author2 Sánchez-Quiñónez, Carlos A.
Alegret, Laia
Molina, Eustoquio
author2_role author
author
author
description Open marine sediments deposited during the CenomanianeTuronian transition are well exposed in the Spanish Ba~nos de la Hedionda section (Betic Cordillera, South Iberian Palaeomargin). Analysis of foraminiferal assemblages and geochemical proxies allow inferences on the impact of the Oceanic Anoxic Event 2 (OAE2) in this area of the western Tethys. Three main intervals have been identified corresponding to different lithological units and biozones. (1) The top of the Capas Blancas Member (Rotalipora cushmani Biozone) represents the pre-extinction phase with diverse foraminiferal assemblages and well developed water-column tiering, well-oxygenated, oligotrophic deep-waters and oxygenated to poorly oxygenated, mesotrophic surface-waters. Foraminiferal opportunist species point to a minor event with dysoxic conditions preceding the OAE2. (2) The black radiolaritic shales (Whiteinella archaeocretacea Biozone) consist of a foraminiferal-barren interval, except for the lowermost centimetres where planktic surface-dweller opportunists are common. Redox sensitive elements (Cr/Al, V/Al, U/Th, MoEF, Moaut, UEF and Uaut) and increased TOC values reflect oxygen depleted conditions related to the OAE2. The increase in P/Ti values at the base of this stratigraphic interval indicates an abrupt increase in productivity. High concentrations of radiolarians are congruent with high surface productivity probably related to changes in oceanic circulation and enhanced upwelling currents, as well as subsequent shallowing of the oxygenminimum zone. The increase in MoEF and Moaut towards the top of the black radiolaritic shales indicates temporal euxinic conditions. (3) A slow, bottom-up recovery of foraminiferal assemblages is inferred at the base of the Boqueron Member (Helvetoglobotruncana helvetica Biozone), with seafloor recolonization by benthic foraminifera being recorded previous to the water column colonization by planktic forms, mainly by intermediate-dwellers typical of mesotrophic waters. The subsequent proliferation of surfacedweller opportunists and deep-dweller opportunists adapted to mesotrophic to eutrophic conditions, and the decrease in planktic foraminiferal diversity, may indicate the persistence of poorly oxygenated conditions in the water column towards the lower-middle part of the H. helvetica Biozone.
publishDate 2016
dc.date.none.fl_str_mv 2016
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
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dc.identifier.none.fl_str_mv http://zaguan.unizar.es/record/61854
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dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv info:eu-repo/grantAgreement/ES/DGA/E05
info:eu-repo/grantAgreement/ES/MICINN/RYC-2009-04316
info:eu-repo/grantAgreement/ES/MINECO/CGL2011-229121
info:eu-repo/grantAgreement/ES/MINECO/CGL2011-23077
info:eu-repo/grantAgreement/ES/MINECO/CGL2012-33281
info:eu-repo/grantAgreement/ES/MINECO-FEDER/CGL2014-58794-P
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
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publisher.none.fl_str_mv
dc.source.none.fl_str_mv reponame:Zaguán. Repositorio Digital de la Universidad de Zaragoza
instname:Universidad de Zaragoza
instname_str Universidad de Zaragoza
reponame_str Zaguán. Repositorio Digital de la Universidad de Zaragoza
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