Paleomagnetic evidence for a very large counterclockwise rotation of the Madre de Dios Archipelago, Southern Chile

A paleomagnetic study of Late Paleozoic exotic units exposed in the Madre de Dios Archipelago and Diego de Almagro island, southern Chile, is reported. These units correspond to the Tarlton Limestone and the metabasaltic pillow lavas of the Denaro Complex. Nineteen sites were drilled (14 in limeston...

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Autores principales: Rapalini, Augusto Ernesto, Ramos, Victor Alberto, Singer, Silvia
Publicado: 2001
Materias:
Paleomagnetism
Plate rotation
South America
Southern Andes
Tectonics
Terranes
paleomagnetism
Paleozoic
plate motion
tectonic rotation
Chile
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0012821X_v184_n2_p471_Rapalini
http://hdl.handle.net/20.500.12110/paper_0012821X_v184_n2_p471_Rapalini
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_0012821X_v184_n2_p471_Rapalini
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spelling paper:paper_0012821X_v184_n2_p471_Rapalini2023-06-08T14:35:29Z Paleomagnetic evidence for a very large counterclockwise rotation of the Madre de Dios Archipelago, Southern Chile Rapalini, Augusto Ernesto Ramos, Victor Alberto Singer, Silvia Paleomagnetism Plate rotation South America Southern Andes Tectonics Terranes paleomagnetism Paleozoic plate motion tectonic rotation Chile A paleomagnetic study of Late Paleozoic exotic units exposed in the Madre de Dios Archipelago and Diego de Almagro island, southern Chile, is reported. These units correspond to the Tarlton Limestone and the metabasaltic pillow lavas of the Denaro Complex. Nineteen sites were drilled (14 in limestone and five in lavas). Standard demagnetization procedures show that the primary remanence is not present in the investigated rocks, preventing the determination of the original latitudinal position of these rocks. However, a post-tectonic secondary magnetic component was isolated in eight sites at the Madre de Dios Archipelago, in both limestone and basaltic pillow lavas. Rock magnetic experiments and microscopic observations indicated that the carrier of this remanence is secondary titanomagnetite in the limestone and titanomagnetite-titanomaghemite in the lavas. The most likely event to produce this secondary magnetization is the nearby intrusion of the south Patagonian batholith in the Early Cretaceous. Mean direction from eight sites shows a very large (117.7 ± 29.9°) counterclockwise rotation of the study area with negligible paleolatitude anomaly. This rotation is only constrained as post-Early Cretaceous. Restoration of the structures to their pre-rotation position indicates that accretion of the exotic block took place from the northwest and not from the south as previously proposed. This is more consistent with a low latitude origin for the limestone and the general paleogeographic framework. Different tectonic mechanisms and ages for this large rotation are possible. © 2001 Elsevier Science B.V. All rights reserved. Fil:Rapalini, A.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Ramos, V.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Singer, S.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2001 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0012821X_v184_n2_p471_Rapalini http://hdl.handle.net/20.500.12110/paper_0012821X_v184_n2_p471_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 Paleomagnetism
Plate rotation
South America
Southern Andes
Tectonics
Terranes
paleomagnetism
Paleozoic
plate motion
tectonic rotation
Chile
spellingShingle Paleomagnetism
Plate rotation
South America
Southern Andes
Tectonics
Terranes
paleomagnetism
Paleozoic
plate motion
tectonic rotation
Chile
Rapalini, Augusto Ernesto
Ramos, Victor Alberto
Singer, Silvia
Paleomagnetic evidence for a very large counterclockwise rotation of the Madre de Dios Archipelago, Southern Chile
topic_facet Paleomagnetism
Plate rotation
South America
Southern Andes
Tectonics
Terranes
paleomagnetism
Paleozoic
plate motion
tectonic rotation
Chile
description A paleomagnetic study of Late Paleozoic exotic units exposed in the Madre de Dios Archipelago and Diego de Almagro island, southern Chile, is reported. These units correspond to the Tarlton Limestone and the metabasaltic pillow lavas of the Denaro Complex. Nineteen sites were drilled (14 in limestone and five in lavas). Standard demagnetization procedures show that the primary remanence is not present in the investigated rocks, preventing the determination of the original latitudinal position of these rocks. However, a post-tectonic secondary magnetic component was isolated in eight sites at the Madre de Dios Archipelago, in both limestone and basaltic pillow lavas. Rock magnetic experiments and microscopic observations indicated that the carrier of this remanence is secondary titanomagnetite in the limestone and titanomagnetite-titanomaghemite in the lavas. The most likely event to produce this secondary magnetization is the nearby intrusion of the south Patagonian batholith in the Early Cretaceous. Mean direction from eight sites shows a very large (117.7 ± 29.9°) counterclockwise rotation of the study area with negligible paleolatitude anomaly. This rotation is only constrained as post-Early Cretaceous. Restoration of the structures to their pre-rotation position indicates that accretion of the exotic block took place from the northwest and not from the south as previously proposed. This is more consistent with a low latitude origin for the limestone and the general paleogeographic framework. Different tectonic mechanisms and ages for this large rotation are possible. © 2001 Elsevier Science B.V. All rights reserved.
author Rapalini, Augusto Ernesto
Ramos, Victor Alberto
Singer, Silvia
author_facet Rapalini, Augusto Ernesto
Ramos, Victor Alberto
Singer, Silvia
author_sort Rapalini, Augusto Ernesto
title Paleomagnetic evidence for a very large counterclockwise rotation of the Madre de Dios Archipelago, Southern Chile
title_short Paleomagnetic evidence for a very large counterclockwise rotation of the Madre de Dios Archipelago, Southern Chile
title_full Paleomagnetic evidence for a very large counterclockwise rotation of the Madre de Dios Archipelago, Southern Chile
title_fullStr Paleomagnetic evidence for a very large counterclockwise rotation of the Madre de Dios Archipelago, Southern Chile
title_full_unstemmed Paleomagnetic evidence for a very large counterclockwise rotation of the Madre de Dios Archipelago, Southern Chile
title_sort paleomagnetic evidence for a very large counterclockwise rotation of the madre de dios archipelago, southern chile
publishDate 2001
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0012821X_v184_n2_p471_Rapalini
http://hdl.handle.net/20.500.12110/paper_0012821X_v184_n2_p471_Rapalini
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AT ramosvictoralberto paleomagneticevidenceforaverylargecounterclockwiserotationofthemadredediosarchipelagosouthernchile
AT singersilvia paleomagneticevidenceforaverylargecounterclockwiserotationofthemadredediosarchipelagosouthernchile
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