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
- Institución
- Consejo Nacional de Investigaciones Científicas y Técnicas
- OAI Identificador
- oai:ri.conicet.gov.ar:11336/182838
Ver los metadatos del registro completo
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CONICET Digital (CONICET) |
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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 |
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https://creativecommons.org/licenses/by-nc-sa/2.5/ar/ |
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application/pdf application/pdf |
dc.publisher.none.fl_str_mv |
Cambridge University Press |
publisher.none.fl_str_mv |
Cambridge University Press |
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CONICET Digital (CONICET) |
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CONICET Digital (CONICET) |
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Consejo Nacional de Investigaciones Científicas y Técnicas |
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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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