Cryptic Diagenetic Changes in Quaternary Aragonitic Shells: A Textural, Crystallographic, and Trace-Element Study on Amiantis Purpurata (Bivalvia) From Patagonia, Argentina

Autores
Bayer, María Sol; Colombo, Fernando; de Vincentis, Natalia Soledad; Duarte, Gonzalo; Bolmaro, Raul Eduardo; Gordillo, Sandra
Año de publicación
2013
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
Modern to Pleistocene Amiantis purpurata shells collected in Bahı´a San Antonio (Patagonia, Argentina) were studied by X-ray diffraction (XRD), optical and electron microscopy, electron microprobe analyses, and microindentation, in order to characterize early diagenetic changes and mechanical resistance. The sole crystalline phase is twinned aragonite showing pseudohexagonal symmetry. The regularity of the crystallographic texture decreases in older samples, but average crystallite size does not increase. The microstructure, which is dominantly crossed lamellar, is progressively replaced by a more randomly oriented grain aggregate. Compositional profiles across the shell show gradients in Sr, Na, S, and Cl, whereas Mg and P are more evenly distributed. Each shell layer has a distinct chemical signature. A marked decrease in the concentration of all of these elements, along with flattening of profiles, is evident as age increases. Vickers microhardness is lowest in modern specimens, showing at the same time the least chipped regions; older shells become harder and more fragile. All of these changes are attributed to postdepositional modifications by dissolution-recrystallization processes mediated by a thin film of water in a vadose environment. Microstructural adjustments are more sluggish than chemical modifications produced by diagenetic processes, whereas microhardness rapidly reaches high values,probably due to the early degradation of organic compounds from the shell. Our study shows that aragonitic shells that retain their primary mineralogical composition have undergone subtle chemical and microstructural changes. A very small amount of calcite was produced during grinding for XRD. Care should therefore be taken when seeking calcite as evidence of diagenetic changes.
Fil: Bayer, María Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones En Ciencias de la Tierra; Argentina
Fil: Colombo, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones En Ciencias de la Tierra; Argentina
Fil: de Vincentis, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentina
Fil: Duarte, Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentina
Fil: Bolmaro, Raul Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentina
Fil: Gordillo, Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones En Ciencias de la Tierra; Argentina
Materia
Mollusca
Quaternary
Amiantis Purpurata
Diagenesis
Nivel de accesibilidad
acceso abierto
Condiciones de uso
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repositorio
CONICET Digital (CONICET)
Institución
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identificador
oai:ri.conicet.gov.ar:11336/7586
Acceder
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oai_identifier_str oai:ri.conicet.gov.ar:11336/7586
network_acronym_str CONICETDig
repository_id_str 3498
network_name_str CONICET Digital (CONICET)
spelling Cryptic Diagenetic Changes in Quaternary Aragonitic Shells: A Textural, Crystallographic, and Trace-Element Study on Amiantis Purpurata (Bivalvia) From Patagonia, ArgentinaBayer, María SolColombo, Fernandode Vincentis, Natalia SoledadDuarte, GonzaloBolmaro, Raul EduardoGordillo, SandraMolluscaQuaternaryAmiantis PurpurataDiagenesishttps://purl.org/becyt/ford/2.5https://purl.org/becyt/ford/2https://purl.org/becyt/ford/1.5https://purl.org/becyt/ford/1https://purl.org/becyt/ford/1.7https://purl.org/becyt/ford/1Modern to Pleistocene Amiantis purpurata shells collected in Bahı´a San Antonio (Patagonia, Argentina) were studied by X-ray diffraction (XRD), optical and electron microscopy, electron microprobe analyses, and microindentation, in order to characterize early diagenetic changes and mechanical resistance. The sole crystalline phase is twinned aragonite showing pseudohexagonal symmetry. The regularity of the crystallographic texture decreases in older samples, but average crystallite size does not increase. The microstructure, which is dominantly crossed lamellar, is progressively replaced by a more randomly oriented grain aggregate. Compositional profiles across the shell show gradients in Sr, Na, S, and Cl, whereas Mg and P are more evenly distributed. Each shell layer has a distinct chemical signature. A marked decrease in the concentration of all of these elements, along with flattening of profiles, is evident as age increases. Vickers microhardness is lowest in modern specimens, showing at the same time the least chipped regions; older shells become harder and more fragile. All of these changes are attributed to postdepositional modifications by dissolution-recrystallization processes mediated by a thin film of water in a vadose environment. Microstructural adjustments are more sluggish than chemical modifications produced by diagenetic processes, whereas microhardness rapidly reaches high values,probably due to the early degradation of organic compounds from the shell. Our study shows that aragonitic shells that retain their primary mineralogical composition have undergone subtle chemical and microstructural changes. A very small amount of calcite was produced during grinding for XRD. Care should therefore be taken when seeking calcite as evidence of diagenetic changes.Fil: Bayer, María Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones En Ciencias de la Tierra; ArgentinaFil: Colombo, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones En Ciencias de la Tierra; ArgentinaFil: de Vincentis, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); ArgentinaFil: Duarte, Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); ArgentinaFil: Bolmaro, Raul Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); ArgentinaFil: Gordillo, Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones En Ciencias de la Tierra; ArgentinaGeo Science World2013-08info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfapplication/pdfapplication/pdfapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/7586Bayer, María Sol; Colombo, Fernando; de Vincentis, Natalia Soledad; Duarte, Gonzalo; Bolmaro, Raul Eduardo; et al.; Cryptic Diagenetic Changes in Quaternary Aragonitic Shells: A Textural, Crystallographic, and Trace-Element Study on Amiantis Purpurata (Bivalvia) From Patagonia, Argentina; Geo Science World; Palaios; 28; 7; 8-2013; 438-4510883-1351enginfo:eu-repo/semantics/altIdentifier/url/http://palaios.geoscienceworld.org/content/28/7/438.article-infoinfo:eu-repo/semantics/altIdentifier/doi/10.2110/palo.2012.p12-111rinfo:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-10-15T14:31:01Zoai:ri.conicet.gov.ar:11336/7586instacron:CONICETInstitucionalhttp://ri.conicet.gov.ar/Organismo científico-tecnológicoNo correspondehttp://ri.conicet.gov.ar/oai/requestdasensio@conicet.gov.ar; lcarlino@conicet.gov.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:34982025-10-15 14:31:02.082CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv Cryptic Diagenetic Changes in Quaternary Aragonitic Shells: A Textural, Crystallographic, and Trace-Element Study on Amiantis Purpurata (Bivalvia) From Patagonia, Argentina
title Cryptic Diagenetic Changes in Quaternary Aragonitic Shells: A Textural, Crystallographic, and Trace-Element Study on Amiantis Purpurata (Bivalvia) From Patagonia, Argentina
spellingShingle Cryptic Diagenetic Changes in Quaternary Aragonitic Shells: A Textural, Crystallographic, and Trace-Element Study on Amiantis Purpurata (Bivalvia) From Patagonia, Argentina
Bayer, María Sol
Mollusca
Quaternary
Amiantis Purpurata
Diagenesis
title_short Cryptic Diagenetic Changes in Quaternary Aragonitic Shells: A Textural, Crystallographic, and Trace-Element Study on Amiantis Purpurata (Bivalvia) From Patagonia, Argentina
title_full Cryptic Diagenetic Changes in Quaternary Aragonitic Shells: A Textural, Crystallographic, and Trace-Element Study on Amiantis Purpurata (Bivalvia) From Patagonia, Argentina
title_fullStr Cryptic Diagenetic Changes in Quaternary Aragonitic Shells: A Textural, Crystallographic, and Trace-Element Study on Amiantis Purpurata (Bivalvia) From Patagonia, Argentina
title_full_unstemmed Cryptic Diagenetic Changes in Quaternary Aragonitic Shells: A Textural, Crystallographic, and Trace-Element Study on Amiantis Purpurata (Bivalvia) From Patagonia, Argentina
title_sort Cryptic Diagenetic Changes in Quaternary Aragonitic Shells: A Textural, Crystallographic, and Trace-Element Study on Amiantis Purpurata (Bivalvia) From Patagonia, Argentina
dc.creator.none.fl_str_mv Bayer, María Sol
Colombo, Fernando
de Vincentis, Natalia Soledad
Duarte, Gonzalo
Bolmaro, Raul Eduardo
Gordillo, Sandra
author Bayer, María Sol
author_facet Bayer, María Sol
Colombo, Fernando
de Vincentis, Natalia Soledad
Duarte, Gonzalo
Bolmaro, Raul Eduardo
Gordillo, Sandra
author_role author
author2 Colombo, Fernando
de Vincentis, Natalia Soledad
Duarte, Gonzalo
Bolmaro, Raul Eduardo
Gordillo, Sandra
author2_role author
author
author
author
author
dc.subject.none.fl_str_mv Mollusca
Quaternary
Amiantis Purpurata
Diagenesis
topic Mollusca
Quaternary
Amiantis Purpurata
Diagenesis
purl_subject.fl_str_mv https://purl.org/becyt/ford/2.5
https://purl.org/becyt/ford/2
https://purl.org/becyt/ford/1.5
https://purl.org/becyt/ford/1
https://purl.org/becyt/ford/1.7
https://purl.org/becyt/ford/1
dc.description.none.fl_txt_mv Modern to Pleistocene Amiantis purpurata shells collected in Bahı´a San Antonio (Patagonia, Argentina) were studied by X-ray diffraction (XRD), optical and electron microscopy, electron microprobe analyses, and microindentation, in order to characterize early diagenetic changes and mechanical resistance. The sole crystalline phase is twinned aragonite showing pseudohexagonal symmetry. The regularity of the crystallographic texture decreases in older samples, but average crystallite size does not increase. The microstructure, which is dominantly crossed lamellar, is progressively replaced by a more randomly oriented grain aggregate. Compositional profiles across the shell show gradients in Sr, Na, S, and Cl, whereas Mg and P are more evenly distributed. Each shell layer has a distinct chemical signature. A marked decrease in the concentration of all of these elements, along with flattening of profiles, is evident as age increases. Vickers microhardness is lowest in modern specimens, showing at the same time the least chipped regions; older shells become harder and more fragile. All of these changes are attributed to postdepositional modifications by dissolution-recrystallization processes mediated by a thin film of water in a vadose environment. Microstructural adjustments are more sluggish than chemical modifications produced by diagenetic processes, whereas microhardness rapidly reaches high values,probably due to the early degradation of organic compounds from the shell. Our study shows that aragonitic shells that retain their primary mineralogical composition have undergone subtle chemical and microstructural changes. A very small amount of calcite was produced during grinding for XRD. Care should therefore be taken when seeking calcite as evidence of diagenetic changes.
Fil: Bayer, María Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones En Ciencias de la Tierra; Argentina
Fil: Colombo, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones En Ciencias de la Tierra; Argentina
Fil: de Vincentis, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentina
Fil: Duarte, Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentina
Fil: Bolmaro, Raul Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentina
Fil: Gordillo, Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones En Ciencias de la Tierra; Argentina
description Modern to Pleistocene Amiantis purpurata shells collected in Bahı´a San Antonio (Patagonia, Argentina) were studied by X-ray diffraction (XRD), optical and electron microscopy, electron microprobe analyses, and microindentation, in order to characterize early diagenetic changes and mechanical resistance. The sole crystalline phase is twinned aragonite showing pseudohexagonal symmetry. The regularity of the crystallographic texture decreases in older samples, but average crystallite size does not increase. The microstructure, which is dominantly crossed lamellar, is progressively replaced by a more randomly oriented grain aggregate. Compositional profiles across the shell show gradients in Sr, Na, S, and Cl, whereas Mg and P are more evenly distributed. Each shell layer has a distinct chemical signature. A marked decrease in the concentration of all of these elements, along with flattening of profiles, is evident as age increases. Vickers microhardness is lowest in modern specimens, showing at the same time the least chipped regions; older shells become harder and more fragile. All of these changes are attributed to postdepositional modifications by dissolution-recrystallization processes mediated by a thin film of water in a vadose environment. Microstructural adjustments are more sluggish than chemical modifications produced by diagenetic processes, whereas microhardness rapidly reaches high values,probably due to the early degradation of organic compounds from the shell. Our study shows that aragonitic shells that retain their primary mineralogical composition have undergone subtle chemical and microstructural changes. A very small amount of calcite was produced during grinding for XRD. Care should therefore be taken when seeking calcite as evidence of diagenetic changes.
publishDate 2013
dc.date.none.fl_str_mv 2013-08
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/11336/7586
Bayer, María Sol; Colombo, Fernando; de Vincentis, Natalia Soledad; Duarte, Gonzalo; Bolmaro, Raul Eduardo; et al.; Cryptic Diagenetic Changes in Quaternary Aragonitic Shells: A Textural, Crystallographic, and Trace-Element Study on Amiantis Purpurata (Bivalvia) From Patagonia, Argentina; Geo Science World; Palaios; 28; 7; 8-2013; 438-451
0883-1351
url http://hdl.handle.net/11336/7586
identifier_str_mv Bayer, María Sol; Colombo, Fernando; de Vincentis, Natalia Soledad; Duarte, Gonzalo; Bolmaro, Raul Eduardo; et al.; Cryptic Diagenetic Changes in Quaternary Aragonitic Shells: A Textural, Crystallographic, and Trace-Element Study on Amiantis Purpurata (Bivalvia) From Patagonia, Argentina; Geo Science World; Palaios; 28; 7; 8-2013; 438-451
0883-1351
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/url/http://palaios.geoscienceworld.org/content/28/7/438.article-info
info:eu-repo/semantics/altIdentifier/doi/10.2110/palo.2012.p12-111r
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
eu_rights_str_mv openAccess
rights_invalid_str_mv https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.format.none.fl_str_mv application/pdf
application/pdf
application/pdf
application/pdf
application/pdf
application/pdf
dc.publisher.none.fl_str_mv Geo Science World
publisher.none.fl_str_mv Geo Science World
dc.source.none.fl_str_mv reponame:CONICET Digital (CONICET)
instname:Consejo Nacional de Investigaciones Científicas y Técnicas
reponame_str CONICET Digital (CONICET)
collection CONICET Digital (CONICET)
instname_str Consejo Nacional de Investigaciones Científicas y Técnicas
repository.name.fl_str_mv CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicas
repository.mail.fl_str_mv dasensio@conicet.gov.ar; lcarlino@conicet.gov.ar
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score 13.22299

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