Evaluation of two genera of benthic foraminifera for down-core paleotemperature studies in the western south atlantic
In this study we have compared the oxygen isotopic composition of two genera of benthic foraminifera (Uvigerinaand Cibicidoides) from core-top samples with modern oxygen isotopic composition of seawater (d18O). Based on a new relationship between d18O and salinity for the mid-latitude western South...
| Autor principal: | COSTA, Karen Badaraco |
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| Outros Autores: | TOLEDO, Felipe Antonio de Lima, PIVEL, María Alejandra Gómez, MOURA, Candido Augusto Veloso, CHEMALE JUNIOR, Farid |
| Grau: | Artigo |
| Idioma: | eng |
| Publicado em: |
2011
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| Acesso em linha: |
http://www.repositorio.ufpa.br:8080/jspui/handle/2011/2383 |
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ir-2011-2383 |
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ir-2011-23832018-01-02T17:05:33Z Evaluation of two genera of benthic foraminifera for down-core paleotemperature studies in the western south atlantic COSTA, Karen Badaraco TOLEDO, Felipe Antonio de Lima PIVEL, María Alejandra Gómez MOURA, Candido Augusto Veloso CHEMALE JUNIOR, Farid Geoquímica Geologia isotópica Isótopos de oxigênio Paleoceanografia Paleotermometria In this study we have compared the oxygen isotopic composition of two genera of benthic foraminifera (Uvigerinaand Cibicidoides) from core-top samples with modern oxygen isotopic composition of seawater (d18O). Based on a new relationship between d18O and salinity for the mid-latitude western South Atlantic, we estimated the isotopic composition of equilibrium calcite (d18Oeq) using two different equations: (1) O'Neil et al. (1969), modified by McCorkle et al. (1997) and (2) Kim & O'Neil (1997). When using (1), the small difference between d18Oeq and d18O of Uvigerina suggests that this genus precipitates its shell close to equilibrium with ambient seawater. The d18OCibicidoides data are 0.82 ‰ lower than the predicted (equilibrium) oxygen isotopic composition. Conversely, using (2) the Cibicidoides d18O data show excellent agreement with the oxygen isotopic composition predicted from d18O and water temperature while Uvigerina d18O data are 0.69 ‰ higher than predicted oxygen isotope equilibrium values. Based on the evidences presented here and on the results from previous studies we suggest using the genus Cibicidoides and applying Kim & O'Neil's (1997) equation for down-core paleotemperature investigations. In the absence of enough Cibicidoides specimens we suggest using Uvigerina d18O data and applying a correction factor of -0.69 ‰. Neste estudo, compara-se a composição de isótopos de oxigênio de dois gêneros de foraminíferos bentônicos (Uvigerina e Cibicidoides) de amostras de topo de testemunho com a composição isotópica moderna da água do mar (d18O). Baseados em uma nova relação entre d18O e salinidade para a latitude média do Atlântico Sul ocidental, estimou-se a composição isotópica da calcita em equilíbrio (d18Oeq) a partir de duas equações diferentes: (1) O'Neil et al. (1969), modificada por McCorkle et al. (1997) e (2) Kim & O'Neil (1997). Utilizando (1), a pequena diferença entre d18Oeq e d18O de Uvigerina sugere que este gênero precipita as suas testas próximo ao equilíbrio com a água. Já os dados de d18O de Cibicidoides são 0,82 ‰ menores que a composição isotópica prevista. Ao contrário, utilizando (2) os dados de d18O de Cibicidoides mostram uma concordância excelente com a composição isotópica esperada, enquanto que os dados de d18O de Uvigerina são 0,69 ‰ maiores que os valores de equilíbrio previstos. A partir das evidências apresentadas neste trabalho e em estudos prévios sugerimos a utilização do gênero Cibicidoides e a aplicação da equação de Kim & O'Neil (1997) para pesquisas de paleotemperatura. Na ausência de suficientes espécimens de Cibicidoides sugerimos a utilização de d18O deUvigerina aplicando um fator de correção de -0,69 ‰. 2011-11-29T21:07:27Z 2011-11-29T21:07:27Z 2006 Artigo de Periódico COSTA, Karen B. et al. Evaluation of two genera of benthic foraminifera for down-core paleotemperature studies in the western south atlantic. Brazilian Journal of Oceanography, São Paulo, v. 54, n. 1, p. 75-84, 2006. Disponível em: <http://www.scielo.br/pdf/bjoce/v54n1/v54n1a07.pdf>. Acesso em: 29 nov. 2011. <http://dx.doi.org/10.1590/S1679-87592006000100007>. 1982-436X http://www.repositorio.ufpa.br:8080/jspui/handle/2011/2383 eng Acesso Aberto application/pdf |
| institution |
Repositório Institucional - Universidade Federal do Pará |
| collection |
RI-UFPA |
| language |
eng |
| topic |
Geoquímica Geologia isotópica Isótopos de oxigênio Paleoceanografia Paleotermometria |
| spellingShingle |
Geoquímica Geologia isotópica Isótopos de oxigênio Paleoceanografia Paleotermometria COSTA, Karen Badaraco Evaluation of two genera of benthic foraminifera for down-core paleotemperature studies in the western south atlantic |
| topic_facet |
Geoquímica Geologia isotópica Isótopos de oxigênio Paleoceanografia Paleotermometria |
| description |
In this study we have compared the oxygen isotopic composition of two genera of benthic foraminifera (Uvigerinaand Cibicidoides) from core-top samples with modern oxygen isotopic composition of seawater (d18O). Based on a new relationship between d18O and salinity for the mid-latitude western South Atlantic, we estimated the isotopic composition of equilibrium calcite (d18Oeq) using two different equations: (1) O'Neil et al. (1969), modified by McCorkle et al. (1997) and (2) Kim & O'Neil (1997). When using (1), the small difference between d18Oeq and d18O of Uvigerina suggests that this genus precipitates its shell close to equilibrium with ambient seawater. The d18OCibicidoides data are 0.82 ‰ lower than the predicted (equilibrium) oxygen isotopic composition. Conversely, using (2) the Cibicidoides d18O data show excellent agreement with the oxygen isotopic composition predicted from d18O and water temperature while Uvigerina d18O data are 0.69 ‰ higher than predicted oxygen isotope equilibrium values. Based on the evidences presented here and on the results from previous studies we suggest using the genus Cibicidoides and applying Kim & O'Neil's (1997) equation for down-core paleotemperature investigations. In the absence of enough Cibicidoides specimens we suggest using Uvigerina d18O data and applying a correction factor of -0.69 ‰. |
| format |
Artigo |
| author |
COSTA, Karen Badaraco |
| author2 |
TOLEDO, Felipe Antonio de Lima PIVEL, María Alejandra Gómez MOURA, Candido Augusto Veloso CHEMALE JUNIOR, Farid |
| author2Str |
TOLEDO, Felipe Antonio de Lima PIVEL, María Alejandra Gómez MOURA, Candido Augusto Veloso CHEMALE JUNIOR, Farid |
| title |
Evaluation of two genera of benthic foraminifera for down-core paleotemperature studies in the western south atlantic |
| title_short |
Evaluation of two genera of benthic foraminifera for down-core paleotemperature studies in the western south atlantic |
| title_full |
Evaluation of two genera of benthic foraminifera for down-core paleotemperature studies in the western south atlantic |
| title_fullStr |
Evaluation of two genera of benthic foraminifera for down-core paleotemperature studies in the western south atlantic |
| title_full_unstemmed |
Evaluation of two genera of benthic foraminifera for down-core paleotemperature studies in the western south atlantic |
| title_sort |
evaluation of two genera of benthic foraminifera for down-core paleotemperature studies in the western south atlantic |
| publishDate |
2011 |
| url |
http://www.repositorio.ufpa.br:8080/jspui/handle/2011/2383 |
| _version_ |
1832605149414031360 |
| score |
11.755432 |