Late Cretaceous Ridge Reorganization, Microplate Formation, and the Evolution of the Rio Grande Rise – Walvis Ridge Hot Spot Twins, South Atlantic Ocean
Abstract Rio Grande Rise (RGR) and Walvis Ridge (WR) are South Atlantic large igneous provinces (LIPs), formed on the South American and African plates, respectively, mainly by volcanism from a hot spot erupting at the Mid‐Atlantic Ridge (MAR) during the Late Cretaceous. Both display morphologic com...
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ftdoajarticles:oai:doaj.org/article:9d5f35365eb748988b6f7a936b0c87ca 2023-12-03T10:30:20+01:00 Late Cretaceous Ridge Reorganization, Microplate Formation, and the Evolution of the Rio Grande Rise – Walvis Ridge Hot Spot Twins, South Atlantic Ocean William W. Sager Sriharsha Thoram Daniel W. Engfer Anthony A. P. Koppers Cornelia Class 2021-03-01T00:00:00Z https://doi.org/10.1029/2020GC009390 https://doaj.org/article/9d5f35365eb748988b6f7a936b0c87ca EN eng Wiley https://doi.org/10.1029/2020GC009390 https://doaj.org/toc/1525-2027 1525-2027 doi:10.1029/2020GC009390 https://doaj.org/article/9d5f35365eb748988b6f7a936b0c87ca Geochemistry, Geophysics, Geosystems, Vol 22, Iss 3, Pp n/a-n/a (2021) abyssal hills gravity plate motion Rio Grande Rise South Atlantic Walvis Ridge Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.1029/2020GC009390 2023-11-05T01:35:57Z Abstract Rio Grande Rise (RGR) and Walvis Ridge (WR) are South Atlantic large igneous provinces (LIPs), formed on the South American and African plates, respectively, mainly by volcanism from a hot spot erupting at the Mid‐Atlantic Ridge (MAR) during the Late Cretaceous. Both display morphologic complexities that imply their tectonic evolution is incompletely understood. We studied bathymetry, gravity, and vertical gravity gradient maps derived from satellite altimetry to trace faults providing indications of seafloor spreading directions and changes. We also examined magnetic anomalies for time constraint and reflection seismic data for structural information. Abyssal hill fabric and magnetic anomaly data indicate that the area between RGR and WR was anomalous between anomalies C34 (83.6 Ma) and C30 (66.4 Ma) owing to reorganization of a right‐lateral transform on the MAR. This event began ∼92 Ma as the transform shifted south to form multiple, short‐offset right‐lateral transforms, with the reorganization extending through anomaly C34 and ending before anomaly C30. Anomalous spacing of magnetic anomalies and discordant fault fabric indicate that a microplate formed with a core of Cretaceous Quiet Zone seafloor. As the MAR jumped eastward, this microplate was captured by the South American plate and now resides mostly in a basin between the main RGR plateau and a related ridge to the east (East Rio Grande Rise). The microplate is ringed by igneous massifs, implying a link with volcanism. The results presented here indicate that these two LIPs had a complex Late Cretaceous history that belies simple hot spot models. Article in Journal/Newspaper South Atlantic Ocean Directory of Open Access Journals: DOAJ Articles Mid-Atlantic Ridge Geochemistry, Geophysics, Geosystems 22 3 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
abyssal hills gravity plate motion Rio Grande Rise South Atlantic Walvis Ridge Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 |
spellingShingle |
abyssal hills gravity plate motion Rio Grande Rise South Atlantic Walvis Ridge Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 William W. Sager Sriharsha Thoram Daniel W. Engfer Anthony A. P. Koppers Cornelia Class Late Cretaceous Ridge Reorganization, Microplate Formation, and the Evolution of the Rio Grande Rise – Walvis Ridge Hot Spot Twins, South Atlantic Ocean |
topic_facet |
abyssal hills gravity plate motion Rio Grande Rise South Atlantic Walvis Ridge Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 |
description |
Abstract Rio Grande Rise (RGR) and Walvis Ridge (WR) are South Atlantic large igneous provinces (LIPs), formed on the South American and African plates, respectively, mainly by volcanism from a hot spot erupting at the Mid‐Atlantic Ridge (MAR) during the Late Cretaceous. Both display morphologic complexities that imply their tectonic evolution is incompletely understood. We studied bathymetry, gravity, and vertical gravity gradient maps derived from satellite altimetry to trace faults providing indications of seafloor spreading directions and changes. We also examined magnetic anomalies for time constraint and reflection seismic data for structural information. Abyssal hill fabric and magnetic anomaly data indicate that the area between RGR and WR was anomalous between anomalies C34 (83.6 Ma) and C30 (66.4 Ma) owing to reorganization of a right‐lateral transform on the MAR. This event began ∼92 Ma as the transform shifted south to form multiple, short‐offset right‐lateral transforms, with the reorganization extending through anomaly C34 and ending before anomaly C30. Anomalous spacing of magnetic anomalies and discordant fault fabric indicate that a microplate formed with a core of Cretaceous Quiet Zone seafloor. As the MAR jumped eastward, this microplate was captured by the South American plate and now resides mostly in a basin between the main RGR plateau and a related ridge to the east (East Rio Grande Rise). The microplate is ringed by igneous massifs, implying a link with volcanism. The results presented here indicate that these two LIPs had a complex Late Cretaceous history that belies simple hot spot models. |
format |
Article in Journal/Newspaper |
author |
William W. Sager Sriharsha Thoram Daniel W. Engfer Anthony A. P. Koppers Cornelia Class |
author_facet |
William W. Sager Sriharsha Thoram Daniel W. Engfer Anthony A. P. Koppers Cornelia Class |
author_sort |
William W. Sager |
title |
Late Cretaceous Ridge Reorganization, Microplate Formation, and the Evolution of the Rio Grande Rise – Walvis Ridge Hot Spot Twins, South Atlantic Ocean |
title_short |
Late Cretaceous Ridge Reorganization, Microplate Formation, and the Evolution of the Rio Grande Rise – Walvis Ridge Hot Spot Twins, South Atlantic Ocean |
title_full |
Late Cretaceous Ridge Reorganization, Microplate Formation, and the Evolution of the Rio Grande Rise – Walvis Ridge Hot Spot Twins, South Atlantic Ocean |
title_fullStr |
Late Cretaceous Ridge Reorganization, Microplate Formation, and the Evolution of the Rio Grande Rise – Walvis Ridge Hot Spot Twins, South Atlantic Ocean |
title_full_unstemmed |
Late Cretaceous Ridge Reorganization, Microplate Formation, and the Evolution of the Rio Grande Rise – Walvis Ridge Hot Spot Twins, South Atlantic Ocean |
title_sort |
late cretaceous ridge reorganization, microplate formation, and the evolution of the rio grande rise – walvis ridge hot spot twins, south atlantic ocean |
publisher |
Wiley |
publishDate |
2021 |
url |
https://doi.org/10.1029/2020GC009390 https://doaj.org/article/9d5f35365eb748988b6f7a936b0c87ca |
geographic |
Mid-Atlantic Ridge |
geographic_facet |
Mid-Atlantic Ridge |
genre |
South Atlantic Ocean |
genre_facet |
South Atlantic Ocean |
op_source |
Geochemistry, Geophysics, Geosystems, Vol 22, Iss 3, Pp n/a-n/a (2021) |
op_relation |
https://doi.org/10.1029/2020GC009390 https://doaj.org/toc/1525-2027 1525-2027 doi:10.1029/2020GC009390 https://doaj.org/article/9d5f35365eb748988b6f7a936b0c87ca |
op_doi |
https://doi.org/10.1029/2020GC009390 |
container_title |
Geochemistry, Geophysics, Geosystems |
container_volume |
22 |
container_issue |
3 |
_version_ |
1784256113942724608 |