Late Oligocene Larger Foraminifera From Nosara (Nicoya Península, Costa Rica) and Indward (Carriacou, Lesser Antilles), Calibrated by 87sr/ 86sr Isotope Stratigraphy

Late Oligocene Larger Foraminifera From Nosara (Nicoya Península, Costa Rica) and Indward (Carriacou, Lesser Antilles), Calibrated by 87sr/ 86sr Isotope Stratigraphy

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Detalles Bibliográficos
Autores principales: Baumgartner-Mora, Claudia, O. Baumgartner, Peter, Tschudin, Pascal
Formato: Online
Idioma:eng
Publicado: Universidad de Costa Rica 2007
Acceso en línea:https://revistas.ucr.ac.cr/index.php/geologica/article/view/4215
id RGAC4215
record_format ojs
spelling RGAC42152023-04-26T01:46:48Z Late Oligocene Larger Foraminifera From Nosara (Nicoya Península, Costa Rica) and Indward (Carriacou, Lesser Antilles), Calibrated by 87sr/ 86sr Isotope Stratigraphy Late Oligocene Larger Foraminifera From Nosara (Nicoya Península, Costa Rica) and Indward (Carriacou, Lesser Antilles), Calibrated by 87sr/ 86sr Isotope Stratigraphy Baumgartner-Mora, Claudia O. Baumgartner, Peter Tschudin, Pascal Macroforaminíferos Miogypsina Oligoceno Costa Rica Carriacou razón de isótopos de estroncio Larger foraminifera Oligocene strontium isotope ratios The Late Oligocene first occurrence of Miogypsina gunteri Cole and Miogypsina tani Drooger is verified in the light of larger foraminiferal assemblages from Nosara (Nicoya Peninsula, Costa Rica) and Windward (Carriacou, Grenada, Lesser Antilles). At Windward, they co-occur with planktonic foraminifera and nannofossils studied by earlier workers. 87Sr/86Sr isotope ratios were measured in calcite of larger foraminifera at both sites to determine independent absolute ages of the two outcrops. Late Oligocene shallow water formations unconformably overlie Paleocene-Eocene distal turbidites and siliceous shales in the outcrops in Costa Rica. The shallow-water lithostratigraphy includes near shore volcanic sandstones that alternate with sandy bioclastic limestones. The latter have yielded rich assemblages of larger foraminifera that have been studied in oriented sections, SEM for split material and polished rock thin sections for transmitted light and cathodoluminescence (CL) observation. The association of larger foraminifera includes Heterostegina antillea Cushman, Miogypsina tani Drooger, Miogypsina gunteri Cole, Miogypsina c.f (Miolepidocyclina) panamensis (Cushman), Miogypsina sp., Lepidocyclina (nephrolepidina) vaughani Cushman, Lepidocyclina yurnagurensis Cushman, Lepidocyclina undosa Cushman. At Windward, scattered outcrops of the Belvedere Formation expose mass flow deposits rich in larger foraminifera associated with an early late Oligocene (NP24) planktonic foraminifa assemblage. Planktonic foraminifera and nannofossils recovered in rocks slightly downsection indicate an upper Middle Oligocene age. Larger foraminifera species collected just north of Windward include Lepidocyclina undosa Cushman and Miogypsina gunteri Cole. The 87Sr/86Sr ratio was measured in 11 specimens of megalosphaeric Lepidocyclina spp., mechanically extracted from 2 rock samples collected at Punta Peladas (Costa Rica) Ratios range from 0.709088 to 0.708196, which correspond to a model age of 27.4 to 24.94 Ma. Very similar ratios, ranging from 0.708150 to 0.708167 were obtained from Windward Village (Carriacou). All measured 87Sr/86Sr ratios fall within a Chattian (Late Oligocene) age. Nannofossils, planktonic foraminifera and identical 87Sr/86Sr ratios from Punta Peladas and Windward clearly indicate a Chattian (Upper Oligocene) first occurrence of Miogypsina gunteri and Miogypsina tani and confirm this age range for the other larger foraminifera cited above. The first occurrence of Miogypsina gunteri in the lower Aquitanian and Miogypsina tani in the upper Aquitanian as proposed by European workers cannot be confirmed. . Universidad de Costa Rica 2007-03-24 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Text Article application/pdf https://revistas.ucr.ac.cr/index.php/geologica/article/view/4215 10.15517/rgac.v0i38.4215 Revista geológica de América central; Vol. 38 (2008) Revista geológica de América central; Vol. 38 (2008) 2215-261X 0256-7024 eng https://revistas.ucr.ac.cr/index.php/geologica/article/view/4215/4039 Derechos de autor 2014 Revista Geológica de América Central
institution Universidad de Costa Rica
collection Revista Geológica de América Central
language eng
format Online
author Baumgartner-Mora, Claudia
O. Baumgartner, Peter
Tschudin, Pascal
spellingShingle Baumgartner-Mora, Claudia
O. Baumgartner, Peter
Tschudin, Pascal
Late Oligocene Larger Foraminifera From Nosara (Nicoya Península, Costa Rica) and Indward (Carriacou, Lesser Antilles), Calibrated by 87sr/ 86sr Isotope Stratigraphy
author_facet Baumgartner-Mora, Claudia
O. Baumgartner, Peter
Tschudin, Pascal
author_sort Baumgartner-Mora, Claudia
description .
title Late Oligocene Larger Foraminifera From Nosara (Nicoya Península, Costa Rica) and Indward (Carriacou, Lesser Antilles), Calibrated by 87sr/ 86sr Isotope Stratigraphy
title_short Late Oligocene Larger Foraminifera From Nosara (Nicoya Península, Costa Rica) and Indward (Carriacou, Lesser Antilles), Calibrated by 87sr/ 86sr Isotope Stratigraphy
title_full Late Oligocene Larger Foraminifera From Nosara (Nicoya Península, Costa Rica) and Indward (Carriacou, Lesser Antilles), Calibrated by 87sr/ 86sr Isotope Stratigraphy
title_fullStr Late Oligocene Larger Foraminifera From Nosara (Nicoya Península, Costa Rica) and Indward (Carriacou, Lesser Antilles), Calibrated by 87sr/ 86sr Isotope Stratigraphy
title_full_unstemmed Late Oligocene Larger Foraminifera From Nosara (Nicoya Península, Costa Rica) and Indward (Carriacou, Lesser Antilles), Calibrated by 87sr/ 86sr Isotope Stratigraphy
title_sort late oligocene larger foraminifera from nosara (nicoya península, costa rica) and indward (carriacou, lesser antilles), calibrated by 87sr/ 86sr isotope stratigraphy
title_alt Late Oligocene Larger Foraminifera From Nosara (Nicoya Península, Costa Rica) and Indward (Carriacou, Lesser Antilles), Calibrated by 87sr/ 86sr Isotope Stratigraphy
publisher Universidad de Costa Rica
publishDate 2007
url https://revistas.ucr.ac.cr/index.php/geologica/article/view/4215
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