Graptolitos con preservación tridimensional en el Silúrico centroibérico (España y Portugal)

Silurian graptolites form the Central-Iberian Zone are often preserved as flattened moulds in black shales, but in some cases rhabdosomes can maintain a part of its original relief, and even can appear three-dimensionally preserved. The majority of these cases can be related to an early pyritisation...

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Detalhes bibliográficos
Autores: Gutiérrez Marco, Juan Carlos, Lorenzo Álvarez, Saturnino, Piçarra, José Manuel
Formato: artículo
Fecha de publicación:2014
País:España
Recursos:Universidad de Castilla-La Mancha
Repositorio:RUIdeRA. Repositorio Institucional de la UCLM
OAI Identifier:oai:ruidera.uclm.es:10578/47767
Acesso em linha:https://hdl.handle.net/10578/47767
https://www.rsehn.es/publicaciones-memorias/art255
Access Level:acceso abierto
Palavra-chave:black shales
Central Iberian Zone
conservación en relieve
España
Graptolites
Graptolitos
nodules
nódulos
pizarras negras
Portugal
relief preservation
Silurian
Silúrico
Spain
Zone Centroibérica
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oai_identifier_str oai:ruidera.uclm.es:10578/47767
network_acronym_str ES
network_name_str España
repository_id_str
spelling Graptolitos con preservación tridimensional en el Silúrico centroibérico (España y Portugal)Three-dimensionally preserved graptolites from the Silurian of the Central Iberian Zone (Spain and Portugal)Gutiérrez Marco, Juan CarlosLorenzo Álvarez, SaturninoPiçarra, José Manuelblack shalesCentral Iberian Zoneconservación en relieveEspañaGraptolitesGraptolitosnodulesnódulospizarras negrasPortugalrelief preservationSilurianSilúricoSpainZone CentroibéricaSilurian graptolites form the Central-Iberian Zone are often preserved as flattened moulds in black shales, but in some cases rhabdosomes can maintain a part of its original relief, and even can appear three-dimensionally preserved. The majority of these cases can be related to an early pyritisation of the periderm favoured by bacterial activity under anoxic conditions, which also led to the genesis of nodules on the same beds. Further oxidation and dissapearance of iron minerals limited the preservation of graptolites to external moulds, that can be studied through latex casts. A different way of preservation of 3-D graptolites occurs in coarse sandstone that enhanced multiphase pyritisation fenomena, where ferruginous nodules enclosing rhabdosomes reveal that the framboidal pyrite that mineralized the periderm during very early diagenesis was remarkably resilient not only to subsequent deformation, but also to the differential weathering of the massive overpyrite that constitute the nodules. The pyritised graptolite periderm was finally replicated by iron-oxides with a minor proportion of phyllosilicates. The occurrence of “hollow” graptolites is also known from silico-phosphatic nodules, where the organic periderm was finely replicated by phosphatic overgrowths that coated the inner and outer surfaces of the rhabdosome. Occasional pseudostalactites of phosphatic minerals and colloidal silica partially occupied the empty spaces. Graptolite internal moulds occurring in limestone are very rare and are restricted to a single locality within the studied region.Los graptolitos silúricos de la Zona Centroibérica suelen conservarse aplastados en pizarras negras, pero en algunos yacimientos los rabdosomas pueden retener parte de su relieve original o conservarse incluso en tres dimensiones. La mayoría de las veces existe una piritización temprana de los rabdosomas por la acción de bacterias sulforreductoras en ambiente anóxico, a la que se suma la génesis de nódulos. La alteración posterior de la pirita deja los graptolitos en forma de moldes, que pueden ser estudiados mediante vaciados en látex. Otros fenómenos de piritización multifásica en sedimentos gruesos conducen a la formación de nódulos de pirita que incluyen en su interior graptolitos huecos y en tres dimensiones, con el peridermo replicado delicadamente en óxidos de hierro. En otras ocasiones, los graptolitos preservados en nódulos generados en sedimentos pelágicos incluyen el recrecimiento de fosfatos sobre el peridermo de los graptolitos, que llegan a conservarse huecos y con estructuras de rellenos geopetales. Finalmente, se presenta el único caso de calizas con graptolitos conocido en el Silúrico centroibérico.Real Sociedad Española de Historia Natural202620262014info:eu-repo/semantics/articleapplication/pdfapplication/pdfhttps://hdl.handle.net/10578/47767https://www.rsehn.es/publicaciones-memorias/art255reponame:RUIdeRA. Repositorio Institucional de la UCLMinstname:Universidad de Castilla-La ManchaEspañolinfo:eu-repo/semantics/openAccessoai:ruidera.uclm.es:10578/477672026-05-27T07:36:41Z
dc.title.none.fl_str_mv Graptolitos con preservación tridimensional en el Silúrico centroibérico (España y Portugal)
Three-dimensionally preserved graptolites from the Silurian of the Central Iberian Zone (Spain and Portugal)
title Graptolitos con preservación tridimensional en el Silúrico centroibérico (España y Portugal)
spellingShingle Graptolitos con preservación tridimensional en el Silúrico centroibérico (España y Portugal)
Gutiérrez Marco, Juan Carlos
black shales
Central Iberian Zone
conservación en relieve
España
Graptolites
Graptolitos
nodules
nódulos
pizarras negras
Portugal
relief preservation
Silurian
Silúrico
Spain
Zone Centroibérica
title_short Graptolitos con preservación tridimensional en el Silúrico centroibérico (España y Portugal)
title_full Graptolitos con preservación tridimensional en el Silúrico centroibérico (España y Portugal)
title_fullStr Graptolitos con preservación tridimensional en el Silúrico centroibérico (España y Portugal)
title_full_unstemmed Graptolitos con preservación tridimensional en el Silúrico centroibérico (España y Portugal)
title_sort Graptolitos con preservación tridimensional en el Silúrico centroibérico (España y Portugal)
dc.creator.none.fl_str_mv Gutiérrez Marco, Juan Carlos
Lorenzo Álvarez, Saturnino
Piçarra, José Manuel
author Gutiérrez Marco, Juan Carlos
author_facet Gutiérrez Marco, Juan Carlos
Lorenzo Álvarez, Saturnino
Piçarra, José Manuel
author_role author
author2 Lorenzo Álvarez, Saturnino
Piçarra, José Manuel
author2_role author
author
dc.subject.none.fl_str_mv black shales
Central Iberian Zone
conservación en relieve
España
Graptolites
Graptolitos
nodules
nódulos
pizarras negras
Portugal
relief preservation
Silurian
Silúrico
Spain
Zone Centroibérica
topic black shales
Central Iberian Zone
conservación en relieve
España
Graptolites
Graptolitos
nodules
nódulos
pizarras negras
Portugal
relief preservation
Silurian
Silúrico
Spain
Zone Centroibérica
description Silurian graptolites form the Central-Iberian Zone are often preserved as flattened moulds in black shales, but in some cases rhabdosomes can maintain a part of its original relief, and even can appear three-dimensionally preserved. The majority of these cases can be related to an early pyritisation of the periderm favoured by bacterial activity under anoxic conditions, which also led to the genesis of nodules on the same beds. Further oxidation and dissapearance of iron minerals limited the preservation of graptolites to external moulds, that can be studied through latex casts. A different way of preservation of 3-D graptolites occurs in coarse sandstone that enhanced multiphase pyritisation fenomena, where ferruginous nodules enclosing rhabdosomes reveal that the framboidal pyrite that mineralized the periderm during very early diagenesis was remarkably resilient not only to subsequent deformation, but also to the differential weathering of the massive overpyrite that constitute the nodules. The pyritised graptolite periderm was finally replicated by iron-oxides with a minor proportion of phyllosilicates. The occurrence of “hollow” graptolites is also known from silico-phosphatic nodules, where the organic periderm was finely replicated by phosphatic overgrowths that coated the inner and outer surfaces of the rhabdosome. Occasional pseudostalactites of phosphatic minerals and colloidal silica partially occupied the empty spaces. Graptolite internal moulds occurring in limestone are very rare and are restricted to a single locality within the studied region.
publishDate 2014
dc.date.none.fl_str_mv 2014
2026
2026
dc.type.none.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://hdl.handle.net/10578/47767
https://www.rsehn.es/publicaciones-memorias/art255
url https://hdl.handle.net/10578/47767
https://www.rsehn.es/publicaciones-memorias/art255
dc.language.none.fl_str_mv Español
language_invalid_str_mv Español
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
application/pdf
dc.publisher.none.fl_str_mv Real Sociedad Española de Historia Natural
publisher.none.fl_str_mv Real Sociedad Española de Historia Natural
dc.source.none.fl_str_mv reponame:RUIdeRA. Repositorio Institucional de la UCLM
instname:Universidad de Castilla-La Mancha
instname_str Universidad de Castilla-La Mancha
reponame_str RUIdeRA. Repositorio Institucional de la UCLM
collection RUIdeRA. Repositorio Institucional de la UCLM
repository.name.fl_str_mv
repository.mail.fl_str_mv
_version_ 1869408105164439552
score 15,81155

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