The denudation history of the onshore continental margin of SE Brazil inferred from apatite fission track data
A suite of 68 new apatite fission track analysis results from the onshore rift margin in southeast Brazil are presented. Some of the results reflect resetting related to the eruption of the Parana continental flood basalt (similar to 130 Ma), and four others are directly related to Late Cretaceous m...
Published in: | Journal of Geophysical Research: Solid Earth |
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Format: | Article in Journal/Newspaper |
Language: | English |
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1994
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Online Access: | https://risweb.st-andrews.ac.uk/portal/en/researchoutput/the-denudation-history-of-the-onshore-continental-margin-of-se-brazil-inferred-from-apatite-fission-track-data(39ea13ea-4b8d-4e54-b923-e4755ab81f07).html https://doi.org/10.1029/94JB00661 |
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ftunstandrewcris:oai:risweb.st-andrews.ac.uk:publications/39ea13ea-4b8d-4e54-b923-e4755ab81f07 2023-05-15T18:42:53+02:00 The denudation history of the onshore continental margin of SE Brazil inferred from apatite fission track data GALLAGHER, K Hawkesworth, Chris MANTOVANI, M S M 1994-09-10 https://risweb.st-andrews.ac.uk/portal/en/researchoutput/the-denudation-history-of-the-onshore-continental-margin-of-se-brazil-inferred-from-apatite-fission-track-data(39ea13ea-4b8d-4e54-b923-e4755ab81f07).html https://doi.org/10.1029/94JB00661 eng eng info:eu-repo/semantics/restrictedAccess GALLAGHER , K , Hawkesworth , C & MANTOVANI , M S M 1994 , ' The denudation history of the onshore continental margin of SE Brazil inferred from apatite fission track data ' , Journal of Geophysical Research , vol. 99 , no. B9 , pp. 18117-18145 . https://doi.org/10.1029/94JB00661 SOUTHERN VICTORIA LAND TRANSANTARCTIC MOUNTAINS SOUTHEASTERN AUSTRALIA TECTONIC EVOLUTION SEDIMENTARY BASINS GENETIC ALGORITHMS BASEMENT APATITES THERMAL EVOLUTION FLANK UPLIFTS MANTLE PLUMES article 1994 ftunstandrewcris https://doi.org/10.1029/94JB00661 2021-12-26T14:18:05Z A suite of 68 new apatite fission track analysis results from the onshore rift margin in southeast Brazil are presented. Some of the results reflect resetting related to the eruption of the Parana continental flood basalt (similar to 130 Ma), and four others are directly related to Late Cretaceous magmatism (similar to 80 Ma). The majority of the results were obtained from Precambrian basement rocks and sediments from the Parana Basin. The fission track ages broadly increase inland from 60-90 Ma on the coastal plain to > 300 Ma in the continental hinterland. The track length distributions show a characteristic trend, being negatively skewed at the coast and showing increasing bimodality inland, except for the oldest samples which are more unimodal. These trends do not reflect rift-related heating and resetting but are the result of protracted denudation since the opening of the South Atlantic. The results are consistent with more than 3 km of exhumation on the coastal plain but little more than 1 km in the hinterland. The topographic morphology in the northern region of the study area is complex and is clearly influenced by structure and bedrock lithology. For the region further south, model calculations of the isostatic response to the denudation suggest that isostatic rebound makes a minor contribution to the long-wavelength topography, unless the flexural rigidity is more than 10(25) N m. In this case the initial elevation of the rift margin would need to be >2.5 km in order to accommodate the amount of denudation inferred from the fission track data. However, it is possible that the effective flexural rigidity varies across the margin, becoming greater in the continental interior. Alternatively, the broad scale wavelength topography may be the result of magmatic underplating related to the Parana continental flood basalt event. If so, estimates of the volume of magma generated would need to be revised upward by as much as a factor of 5. Article in Journal/Newspaper Victoria Land University of St Andrews: Research Portal Transantarctic Mountains Victoria Land Journal of Geophysical Research: Solid Earth 99 B9 18117 18145 |
institution |
Open Polar |
collection |
University of St Andrews: Research Portal |
op_collection_id |
ftunstandrewcris |
language |
English |
topic |
SOUTHERN VICTORIA LAND TRANSANTARCTIC MOUNTAINS SOUTHEASTERN AUSTRALIA TECTONIC EVOLUTION SEDIMENTARY BASINS GENETIC ALGORITHMS BASEMENT APATITES THERMAL EVOLUTION FLANK UPLIFTS MANTLE PLUMES |
spellingShingle |
SOUTHERN VICTORIA LAND TRANSANTARCTIC MOUNTAINS SOUTHEASTERN AUSTRALIA TECTONIC EVOLUTION SEDIMENTARY BASINS GENETIC ALGORITHMS BASEMENT APATITES THERMAL EVOLUTION FLANK UPLIFTS MANTLE PLUMES GALLAGHER, K Hawkesworth, Chris MANTOVANI, M S M The denudation history of the onshore continental margin of SE Brazil inferred from apatite fission track data |
topic_facet |
SOUTHERN VICTORIA LAND TRANSANTARCTIC MOUNTAINS SOUTHEASTERN AUSTRALIA TECTONIC EVOLUTION SEDIMENTARY BASINS GENETIC ALGORITHMS BASEMENT APATITES THERMAL EVOLUTION FLANK UPLIFTS MANTLE PLUMES |
description |
A suite of 68 new apatite fission track analysis results from the onshore rift margin in southeast Brazil are presented. Some of the results reflect resetting related to the eruption of the Parana continental flood basalt (similar to 130 Ma), and four others are directly related to Late Cretaceous magmatism (similar to 80 Ma). The majority of the results were obtained from Precambrian basement rocks and sediments from the Parana Basin. The fission track ages broadly increase inland from 60-90 Ma on the coastal plain to > 300 Ma in the continental hinterland. The track length distributions show a characteristic trend, being negatively skewed at the coast and showing increasing bimodality inland, except for the oldest samples which are more unimodal. These trends do not reflect rift-related heating and resetting but are the result of protracted denudation since the opening of the South Atlantic. The results are consistent with more than 3 km of exhumation on the coastal plain but little more than 1 km in the hinterland. The topographic morphology in the northern region of the study area is complex and is clearly influenced by structure and bedrock lithology. For the region further south, model calculations of the isostatic response to the denudation suggest that isostatic rebound makes a minor contribution to the long-wavelength topography, unless the flexural rigidity is more than 10(25) N m. In this case the initial elevation of the rift margin would need to be >2.5 km in order to accommodate the amount of denudation inferred from the fission track data. However, it is possible that the effective flexural rigidity varies across the margin, becoming greater in the continental interior. Alternatively, the broad scale wavelength topography may be the result of magmatic underplating related to the Parana continental flood basalt event. If so, estimates of the volume of magma generated would need to be revised upward by as much as a factor of 5. |
format |
Article in Journal/Newspaper |
author |
GALLAGHER, K Hawkesworth, Chris MANTOVANI, M S M |
author_facet |
GALLAGHER, K Hawkesworth, Chris MANTOVANI, M S M |
author_sort |
GALLAGHER, K |
title |
The denudation history of the onshore continental margin of SE Brazil inferred from apatite fission track data |
title_short |
The denudation history of the onshore continental margin of SE Brazil inferred from apatite fission track data |
title_full |
The denudation history of the onshore continental margin of SE Brazil inferred from apatite fission track data |
title_fullStr |
The denudation history of the onshore continental margin of SE Brazil inferred from apatite fission track data |
title_full_unstemmed |
The denudation history of the onshore continental margin of SE Brazil inferred from apatite fission track data |
title_sort |
denudation history of the onshore continental margin of se brazil inferred from apatite fission track data |
publishDate |
1994 |
url |
https://risweb.st-andrews.ac.uk/portal/en/researchoutput/the-denudation-history-of-the-onshore-continental-margin-of-se-brazil-inferred-from-apatite-fission-track-data(39ea13ea-4b8d-4e54-b923-e4755ab81f07).html https://doi.org/10.1029/94JB00661 |
geographic |
Transantarctic Mountains Victoria Land |
geographic_facet |
Transantarctic Mountains Victoria Land |
genre |
Victoria Land |
genre_facet |
Victoria Land |
op_source |
GALLAGHER , K , Hawkesworth , C & MANTOVANI , M S M 1994 , ' The denudation history of the onshore continental margin of SE Brazil inferred from apatite fission track data ' , Journal of Geophysical Research , vol. 99 , no. B9 , pp. 18117-18145 . https://doi.org/10.1029/94JB00661 |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1029/94JB00661 |
container_title |
Journal of Geophysical Research: Solid Earth |
container_volume |
99 |
container_issue |
B9 |
container_start_page |
18117 |
op_container_end_page |
18145 |
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1766232646374916096 |