The late Neoproterozoic Sierra de las Ánimas Magmatic Complex and Playa Hermosa Formation, southern Uruguay, revisited: Paleogeographic implications of new paleomagnetic and precise geochronologic data

A new paleomagnetic study was carried out on 15 sites of the Sierra de las Ánimas complex, exposed in SE Uruguay. A paleomagnetic remanence was isolated at six sites, and this direction is likely to be pre-tectonic and primary. Mean directions from five of these sites are consistent with the SA2 pal...

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Detalles Bibliográficos
Publicado: 2015
Materias:
Gondwana
Paleomagnetism
Río de la Plata craton
South America
Uruguay
apparent polar wander path
craton
geochronology
magmatism
paleogeography
paleomagnetism
Proterozoic
remanent magnetization
Amazonia
Brazil
Congo Craton
Rio de la Plata
Sao Francisco Craton
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03019268_v259_n_p143_Rapalini
http://hdl.handle.net/20.500.12110/paper_03019268_v259_n_p143_Rapalini
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling paper:paper_03019268_v259_n_p143_Rapalini2023-06-08T15:28:07Z The late Neoproterozoic Sierra de las Ánimas Magmatic Complex and Playa Hermosa Formation, southern Uruguay, revisited: Paleogeographic implications of new paleomagnetic and precise geochronologic data Gondwana Paleomagnetism Río de la Plata craton South America Uruguay apparent polar wander path craton geochronology Gondwana magmatism paleogeography paleomagnetism Proterozoic remanent magnetization Amazonia Brazil Congo Craton Rio de la Plata Sao Francisco Craton Uruguay A new paleomagnetic study was carried out on 15 sites of the Sierra de las Ánimas complex, exposed in SE Uruguay. A paleomagnetic remanence was isolated at six sites, and this direction is likely to be pre-tectonic and primary. Mean directions from five of these sites are consistent with the SA2 paleomagnetic pole, which is based on a previous paleomagnetic study of the complex. A new paleomagnetic pole was computed for compiled results from the Sierra de las Ánimas complex (SAn, 12.2°. S, 258.9°. E, A95: 14.9°). A geochronological study based on U/Pb (SHRIMP) dating of magmatic zircons was also carried out on three samples of the Sierra de las Animas Complex, yielding a grand mean age of 578 ± 4. Ma. The new SAn paleomagnetic pole anchors the Early Ediacaran segment of the Apparent Polar Wander Path for the Río de la Plata craton. Consistency of the new pole with other Ediacaran poles from the Congo-São Francisco craton suggests a coherent Central Gondwana by this time. These data also support a wide Clymene Ocean between the conjoined Río de la Plata-Congo-São Francisco blocks and Western Gondwana, i.e., Amazonia-West Africa. Additional sampling (sixteen samples) was carried out on the basal levels of the glaciogenic Playa Hermosa Formation, exposed in the same area. These samples retain a paleomagnetic component consistent with the previously reported data, confirming the original pole position. U-Pb (SHRIMP) dating of detrital zircons reveal a bimodal distribution of Paleoproterozoic (around 2.1. Ga) and late Neoproterozoic ages. The youngest zircons are interpreted as pre-dating to penecontemporaneous with deposition and points to a ≤594. Ma age for deposition of the older levels of the Playa Hermosa Formation. A minimum age of deposition is set by the 578 ± 4. Ma age of the Sierra de las Ánimas magmatism. The low inclination of magnetization indicates that low-latitude (13.0°. +. 9.5°/-5.5°), Gaskiers-aged glacial deposits are preserved atop the Rio de la Plata craton. © 2014 Elsevier B.V. 2015 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03019268_v259_n_p143_Rapalini http://hdl.handle.net/20.500.12110/paper_03019268_v259_n_p143_Rapalini
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Gondwana
Paleomagnetism
Río de la Plata craton
South America
Uruguay
apparent polar wander path
craton
geochronology
Gondwana
magmatism
paleogeography
paleomagnetism
Proterozoic
remanent magnetization
Amazonia
Brazil
Congo Craton
Rio de la Plata
Sao Francisco Craton
Uruguay
spellingShingle Gondwana
Paleomagnetism
Río de la Plata craton
South America
Uruguay
apparent polar wander path
craton
geochronology
Gondwana
magmatism
paleogeography
paleomagnetism
Proterozoic
remanent magnetization
Amazonia
Brazil
Congo Craton
Rio de la Plata
Sao Francisco Craton
Uruguay
The late Neoproterozoic Sierra de las Ánimas Magmatic Complex and Playa Hermosa Formation, southern Uruguay, revisited: Paleogeographic implications of new paleomagnetic and precise geochronologic data
topic_facet Gondwana
Paleomagnetism
Río de la Plata craton
South America
Uruguay
apparent polar wander path
craton
geochronology
Gondwana
magmatism
paleogeography
paleomagnetism
Proterozoic
remanent magnetization
Amazonia
Brazil
Congo Craton
Rio de la Plata
Sao Francisco Craton
Uruguay
description A new paleomagnetic study was carried out on 15 sites of the Sierra de las Ánimas complex, exposed in SE Uruguay. A paleomagnetic remanence was isolated at six sites, and this direction is likely to be pre-tectonic and primary. Mean directions from five of these sites are consistent with the SA2 paleomagnetic pole, which is based on a previous paleomagnetic study of the complex. A new paleomagnetic pole was computed for compiled results from the Sierra de las Ánimas complex (SAn, 12.2°. S, 258.9°. E, A95: 14.9°). A geochronological study based on U/Pb (SHRIMP) dating of magmatic zircons was also carried out on three samples of the Sierra de las Animas Complex, yielding a grand mean age of 578 ± 4. Ma. The new SAn paleomagnetic pole anchors the Early Ediacaran segment of the Apparent Polar Wander Path for the Río de la Plata craton. Consistency of the new pole with other Ediacaran poles from the Congo-São Francisco craton suggests a coherent Central Gondwana by this time. These data also support a wide Clymene Ocean between the conjoined Río de la Plata-Congo-São Francisco blocks and Western Gondwana, i.e., Amazonia-West Africa. Additional sampling (sixteen samples) was carried out on the basal levels of the glaciogenic Playa Hermosa Formation, exposed in the same area. These samples retain a paleomagnetic component consistent with the previously reported data, confirming the original pole position. U-Pb (SHRIMP) dating of detrital zircons reveal a bimodal distribution of Paleoproterozoic (around 2.1. Ga) and late Neoproterozoic ages. The youngest zircons are interpreted as pre-dating to penecontemporaneous with deposition and points to a ≤594. Ma age for deposition of the older levels of the Playa Hermosa Formation. A minimum age of deposition is set by the 578 ± 4. Ma age of the Sierra de las Ánimas magmatism. The low inclination of magnetization indicates that low-latitude (13.0°. +. 9.5°/-5.5°), Gaskiers-aged glacial deposits are preserved atop the Rio de la Plata craton. © 2014 Elsevier B.V.
title The late Neoproterozoic Sierra de las Ánimas Magmatic Complex and Playa Hermosa Formation, southern Uruguay, revisited: Paleogeographic implications of new paleomagnetic and precise geochronologic data
title_short The late Neoproterozoic Sierra de las Ánimas Magmatic Complex and Playa Hermosa Formation, southern Uruguay, revisited: Paleogeographic implications of new paleomagnetic and precise geochronologic data
title_full The late Neoproterozoic Sierra de las Ánimas Magmatic Complex and Playa Hermosa Formation, southern Uruguay, revisited: Paleogeographic implications of new paleomagnetic and precise geochronologic data
title_fullStr The late Neoproterozoic Sierra de las Ánimas Magmatic Complex and Playa Hermosa Formation, southern Uruguay, revisited: Paleogeographic implications of new paleomagnetic and precise geochronologic data
title_full_unstemmed The late Neoproterozoic Sierra de las Ánimas Magmatic Complex and Playa Hermosa Formation, southern Uruguay, revisited: Paleogeographic implications of new paleomagnetic and precise geochronologic data
title_sort late neoproterozoic sierra de las ánimas magmatic complex and playa hermosa formation, southern uruguay, revisited: paleogeographic implications of new paleomagnetic and precise geochronologic data
publishDate 2015
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03019268_v259_n_p143_Rapalini
http://hdl.handle.net/20.500.12110/paper_03019268_v259_n_p143_Rapalini
_version_ 1768545646765146112

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