Early Middle Cambrian Trilobites from La Laja Formation, Cerro El Molle, Precordillera of Western Argentina

Autores
Pratt, Brian R.; Bordonaro, Osvaldo Luis
Año de publicación
2015
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
A tectonically undeformed portion of the lower part of La Laja Formation is exposed at Cerro El Molle near San Juan, Precordillera of western Argentina. It consists of shallow-water, variably argillaceous lime mudstone and sporadically interbedded bioclastic grainstone deposited in an inner shelf setting. The El Estero Member and the basal 0.2 m of the Soldano Member contain a trilobite fauna of olenelloids and ‘simple’ ptychoparioids indicative of the early Cambrian (series 2, stage 4; Dyeran stage of Laurentia). The succeeding 50 m of the lower Soldano Member yield trilobites characteristic of the early middle Cambrian (series 3, stage 5; Delamaran stage of Laurentia). In ascending order of occurrence, Amecephalus arrojosensis, Kochiella maxeyi and Eokochaspis nodosa, along with several other taxa, including Ptychobaba n. gen. (type species Ptychoparella buttsi), belong to the traditional lower Plagiura–Poliella Biozone. However, while this fauna is similar to that of the Great Basin, the nominative species of the Eokochaspsis nodosa and overlying Amecephalus arrojosensis biozones recognized in southern Nevada occur in reverse order in the Soldano Member. This suggests that the ranges of these species overlap, thereby reducing the temporal resolution in the Precordillera into a combined Amecephalus arrojosensis–Eokochaspis nodosa Biozone. Argillaceous lime mudstones at the top yield Mexicella mexicana, indicative of the Mexicella mexicana Biozone recognized in the Great Basin, which is equivalent to the traditional Albertella Biozone of Laurentia. Because corynexochids are almost absent, the low-diversity ‘kochaspid’-dominated biofacies appears to typify the platform interior. The fauna is entirely Laurentian in composition, reinforcing notions of a close proximity of Cuyania to Laurentia during the Cambrian that enabled faunal migration and interchange. The absence of a late early Cambrian to early middle Cambrian hiatus correlative with the Hawke Bay Event, however, suggests no close affinity to the Iapetus-facing margin of eastern Laurentia.
Fil: Pratt, Brian R.. University of Saskatchewan; Canadá
Fil: Bordonaro, Osvaldo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina
Materia
TRILOBITES
MIDDLE CAMBRIAN
LA LAJA FORMATION
ARGENTINA
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:11336/182838

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network_name_str CONICET Digital (CONICET)
spelling Early Middle Cambrian Trilobites from La Laja Formation, Cerro El Molle, Precordillera of Western ArgentinaPratt, Brian R.Bordonaro, Osvaldo LuisTRILOBITESMIDDLE CAMBRIANLA LAJA FORMATIONARGENTINAhttps://purl.org/becyt/ford/1.7https://purl.org/becyt/ford/1A tectonically undeformed portion of the lower part of La Laja Formation is exposed at Cerro El Molle near San Juan, Precordillera of western Argentina. It consists of shallow-water, variably argillaceous lime mudstone and sporadically interbedded bioclastic grainstone deposited in an inner shelf setting. The El Estero Member and the basal 0.2 m of the Soldano Member contain a trilobite fauna of olenelloids and ‘simple’ ptychoparioids indicative of the early Cambrian (series 2, stage 4; Dyeran stage of Laurentia). The succeeding 50 m of the lower Soldano Member yield trilobites characteristic of the early middle Cambrian (series 3, stage 5; Delamaran stage of Laurentia). In ascending order of occurrence, Amecephalus arrojosensis, Kochiella maxeyi and Eokochaspis nodosa, along with several other taxa, including Ptychobaba n. gen. (type species Ptychoparella buttsi), belong to the traditional lower Plagiura–Poliella Biozone. However, while this fauna is similar to that of the Great Basin, the nominative species of the Eokochaspsis nodosa and overlying Amecephalus arrojosensis biozones recognized in southern Nevada occur in reverse order in the Soldano Member. This suggests that the ranges of these species overlap, thereby reducing the temporal resolution in the Precordillera into a combined Amecephalus arrojosensis–Eokochaspis nodosa Biozone. Argillaceous lime mudstones at the top yield Mexicella mexicana, indicative of the Mexicella mexicana Biozone recognized in the Great Basin, which is equivalent to the traditional Albertella Biozone of Laurentia. Because corynexochids are almost absent, the low-diversity ‘kochaspid’-dominated biofacies appears to typify the platform interior. The fauna is entirely Laurentian in composition, reinforcing notions of a close proximity of Cuyania to Laurentia during the Cambrian that enabled faunal migration and interchange. The absence of a late early Cambrian to early middle Cambrian hiatus correlative with the Hawke Bay Event, however, suggests no close affinity to the Iapetus-facing margin of eastern Laurentia.Fil: Pratt, Brian R.. University of Saskatchewan; CanadáFil: Bordonaro, Osvaldo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaCambridge University Press2015-10info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/182838Pratt, Brian R.; Bordonaro, Osvaldo Luis; Early Middle Cambrian Trilobites from La Laja Formation, Cerro El Molle, Precordillera of Western Argentina; Cambridge University Press; Journal of Paleontology; 88; 5; 10-2015; 906-9240022-33601937-2337CONICET DigitalCONICETenginfo:eu-repo/semantics/altIdentifier/url/https://www.cambridge.org/core/journals/journal-of-paleontology/article/abs/early-middle-cambrian-trilobites-from-la-laja-formation-cerro-el-molle-precordillera-of-western-argentina/145E2870BF87451B3F597E2E52C797B5info:eu-repo/semantics/altIdentifier/doi/10.1017/S0022336000057577info:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-09-03T09:53:01Zoai:ri.conicet.gov.ar:11336/182838instacron: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:34982025-09-03 09:53:01.713CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv Early Middle Cambrian Trilobites from La Laja Formation, Cerro El Molle, Precordillera of Western Argentina
title Early Middle Cambrian Trilobites from La Laja Formation, Cerro El Molle, Precordillera of Western Argentina
spellingShingle Early Middle Cambrian Trilobites from La Laja Formation, Cerro El Molle, Precordillera of Western Argentina
Pratt, Brian R.
TRILOBITES
MIDDLE CAMBRIAN
LA LAJA FORMATION
ARGENTINA
title_short Early Middle Cambrian Trilobites from La Laja Formation, Cerro El Molle, Precordillera of Western Argentina
title_full Early Middle Cambrian Trilobites from La Laja Formation, Cerro El Molle, Precordillera of Western Argentina
title_fullStr Early Middle Cambrian Trilobites from La Laja Formation, Cerro El Molle, Precordillera of Western Argentina
title_full_unstemmed Early Middle Cambrian Trilobites from La Laja Formation, Cerro El Molle, Precordillera of Western Argentina
title_sort Early Middle Cambrian Trilobites from La Laja Formation, Cerro El Molle, Precordillera of Western Argentina
dc.creator.none.fl_str_mv Pratt, Brian R.
Bordonaro, Osvaldo Luis
author Pratt, Brian R.
author_facet Pratt, Brian R.
Bordonaro, Osvaldo Luis
author_role author
author2 Bordonaro, Osvaldo Luis
author2_role author
dc.subject.none.fl_str_mv TRILOBITES
MIDDLE CAMBRIAN
LA LAJA FORMATION
ARGENTINA
topic TRILOBITES
MIDDLE CAMBRIAN
LA LAJA FORMATION
ARGENTINA
purl_subject.fl_str_mv https://purl.org/becyt/ford/1.7
https://purl.org/becyt/ford/1
dc.description.none.fl_txt_mv A tectonically undeformed portion of the lower part of La Laja Formation is exposed at Cerro El Molle near San Juan, Precordillera of western Argentina. It consists of shallow-water, variably argillaceous lime mudstone and sporadically interbedded bioclastic grainstone deposited in an inner shelf setting. The El Estero Member and the basal 0.2 m of the Soldano Member contain a trilobite fauna of olenelloids and ‘simple’ ptychoparioids indicative of the early Cambrian (series 2, stage 4; Dyeran stage of Laurentia). The succeeding 50 m of the lower Soldano Member yield trilobites characteristic of the early middle Cambrian (series 3, stage 5; Delamaran stage of Laurentia). In ascending order of occurrence, Amecephalus arrojosensis, Kochiella maxeyi and Eokochaspis nodosa, along with several other taxa, including Ptychobaba n. gen. (type species Ptychoparella buttsi), belong to the traditional lower Plagiura–Poliella Biozone. However, while this fauna is similar to that of the Great Basin, the nominative species of the Eokochaspsis nodosa and overlying Amecephalus arrojosensis biozones recognized in southern Nevada occur in reverse order in the Soldano Member. This suggests that the ranges of these species overlap, thereby reducing the temporal resolution in the Precordillera into a combined Amecephalus arrojosensis–Eokochaspis nodosa Biozone. Argillaceous lime mudstones at the top yield Mexicella mexicana, indicative of the Mexicella mexicana Biozone recognized in the Great Basin, which is equivalent to the traditional Albertella Biozone of Laurentia. Because corynexochids are almost absent, the low-diversity ‘kochaspid’-dominated biofacies appears to typify the platform interior. The fauna is entirely Laurentian in composition, reinforcing notions of a close proximity of Cuyania to Laurentia during the Cambrian that enabled faunal migration and interchange. The absence of a late early Cambrian to early middle Cambrian hiatus correlative with the Hawke Bay Event, however, suggests no close affinity to the Iapetus-facing margin of eastern Laurentia.
Fil: Pratt, Brian R.. University of Saskatchewan; Canadá
Fil: Bordonaro, Osvaldo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina
description A tectonically undeformed portion of the lower part of La Laja Formation is exposed at Cerro El Molle near San Juan, Precordillera of western Argentina. It consists of shallow-water, variably argillaceous lime mudstone and sporadically interbedded bioclastic grainstone deposited in an inner shelf setting. The El Estero Member and the basal 0.2 m of the Soldano Member contain a trilobite fauna of olenelloids and ‘simple’ ptychoparioids indicative of the early Cambrian (series 2, stage 4; Dyeran stage of Laurentia). The succeeding 50 m of the lower Soldano Member yield trilobites characteristic of the early middle Cambrian (series 3, stage 5; Delamaran stage of Laurentia). In ascending order of occurrence, Amecephalus arrojosensis, Kochiella maxeyi and Eokochaspis nodosa, along with several other taxa, including Ptychobaba n. gen. (type species Ptychoparella buttsi), belong to the traditional lower Plagiura–Poliella Biozone. However, while this fauna is similar to that of the Great Basin, the nominative species of the Eokochaspsis nodosa and overlying Amecephalus arrojosensis biozones recognized in southern Nevada occur in reverse order in the Soldano Member. This suggests that the ranges of these species overlap, thereby reducing the temporal resolution in the Precordillera into a combined Amecephalus arrojosensis–Eokochaspis nodosa Biozone. Argillaceous lime mudstones at the top yield Mexicella mexicana, indicative of the Mexicella mexicana Biozone recognized in the Great Basin, which is equivalent to the traditional Albertella Biozone of Laurentia. Because corynexochids are almost absent, the low-diversity ‘kochaspid’-dominated biofacies appears to typify the platform interior. The fauna is entirely Laurentian in composition, reinforcing notions of a close proximity of Cuyania to Laurentia during the Cambrian that enabled faunal migration and interchange. The absence of a late early Cambrian to early middle Cambrian hiatus correlative with the Hawke Bay Event, however, suggests no close affinity to the Iapetus-facing margin of eastern Laurentia.
publishDate 2015
dc.date.none.fl_str_mv 2015-10
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/11336/182838
Pratt, Brian R.; Bordonaro, Osvaldo Luis; Early Middle Cambrian Trilobites from La Laja Formation, Cerro El Molle, Precordillera of Western Argentina; Cambridge University Press; Journal of Paleontology; 88; 5; 10-2015; 906-924
0022-3360
1937-2337
CONICET Digital
CONICET
url http://hdl.handle.net/11336/182838
identifier_str_mv Pratt, Brian R.; Bordonaro, Osvaldo Luis; Early Middle Cambrian Trilobites from La Laja Formation, Cerro El Molle, Precordillera of Western Argentina; Cambridge University Press; Journal of Paleontology; 88; 5; 10-2015; 906-924
0022-3360
1937-2337
CONICET Digital
CONICET
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/url/https://www.cambridge.org/core/journals/journal-of-paleontology/article/abs/early-middle-cambrian-trilobites-from-la-laja-formation-cerro-el-molle-precordillera-of-western-argentina/145E2870BF87451B3F597E2E52C797B5
info:eu-repo/semantics/altIdentifier/doi/10.1017/S0022336000057577
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
dc.publisher.none.fl_str_mv Cambridge University Press
publisher.none.fl_str_mv Cambridge University Press
dc.source.none.fl_str_mv reponame:CONICET Digital (CONICET)
instname:Consejo Nacional de Investigaciones Científicas y Técnicas
reponame_str CONICET Digital (CONICET)
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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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