Ross Sea Mylonites and the timimg of intracontinental extension within the West Antarctic rift system
There are few direct constraints on the timing and style of faulting in the Ross Sea sector of the West Antarctic rift system, although Cretaceous plate reconstructions indicate that Ross Sea extension between East and West Antarctica occurred prior to breakup of the Gondwana margin ca. 80 Ma. Mylon...
Published in: | Geology |
---|---|
Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
Geological Society of America Inc
|
Subjects: | |
Online Access: | http://hdl.handle.net/1885/80324 https://doi.org/10.1130/G20005.1 |
id |
ftanucanberra:oai:openresearch-repository.anu.edu.au:1885/80324 |
---|---|
record_format |
openpolar |
spelling |
ftanucanberra:oai:openresearch-repository.anu.edu.au:1885/80324 2024-01-14T10:01:36+01:00 Ross Sea Mylonites and the timimg of intracontinental extension within the West Antarctic rift system Smith Siddoway, Christine Baldwin, Suzanne Fitzgerald, Paul G Fanning, Christopher Luyendyk, Bruce http://hdl.handle.net/1885/80324 https://doi.org/10.1130/G20005.1 unknown Geological Society of America Inc 0091-7613 http://hdl.handle.net/1885/80324 doi:10.1130/G20005.1 Geology Keywords: Plate boundary dynamics Thermal evolution Brittleness Carbonates Cooling Deformation Feldspar Granite Oceanography Geology Cretaceous extensional tectonics faulting geochronology mylonite rift zone Ross Sea Southern Ocean Intracontinental extension Thermochronology U-Pb SHRIMP West Antarctica Journal article ftanucanberra https://doi.org/10.1130/G20005.1 2023-12-15T09:37:27Z There are few direct constraints on the timing and style of faulting in the Ross Sea sector of the West Antarctic rift system, although Cretaceous plate reconstructions indicate that Ross Sea extension between East and West Antarctica occurred prior to breakup of the Gondwana margin ca. 80 Ma. Mylonitic gneisses dredged from the eastern Ross Sea indicate shear-zone deformation considerably earlier, at 98-95 Ma. Strain analysis of fabrics indicates 85%-100% extension. Overprinting brittle structures record translation of shear-zone gneisses into the upper crust. Samples yield sensitive high-resolution ion-microprobe U-Pb zircon ages of 102-97 Ma, correlated to Byrd Coast Granite onshore, and concordant 40Ar/39Ar biotite and K-feldspar ages of 98-95 Ma, indicating that granites were mylonitized soon after emplacement and cooled rapidly. Apatite fission-track data corroborate this rapid cooling event, and reveal a second rapid cooling event ca. 80 Ma. Evidence for contemporaneous deformation and a similar thermal evolution at Deep Sea Drilling Project Site 270 on the Ross Sea central high and for a migmatite dome on land attests to the regional extent of intracontinental extension. Extension occurred at a time of complex microplate interactions along the Cretaceous active Gondwana margin, suggesting that distributed deformation in the overriding Antarctic plate may be related to plate boundary dynamics. Article in Journal/Newspaper Antarc* Antarctic Antarctica Ross Sea Southern Ocean West Antarctica Australian National University: ANU Digital Collections Antarctic Southern Ocean Ross Sea West Antarctica Byrd Geology 32 1 57 |
institution |
Open Polar |
collection |
Australian National University: ANU Digital Collections |
op_collection_id |
ftanucanberra |
language |
unknown |
topic |
Keywords: Plate boundary dynamics Thermal evolution Brittleness Carbonates Cooling Deformation Feldspar Granite Oceanography Geology Cretaceous extensional tectonics faulting geochronology mylonite rift zone Ross Sea Southern Ocean Intracontinental extension Thermochronology U-Pb SHRIMP West Antarctica |
spellingShingle |
Keywords: Plate boundary dynamics Thermal evolution Brittleness Carbonates Cooling Deformation Feldspar Granite Oceanography Geology Cretaceous extensional tectonics faulting geochronology mylonite rift zone Ross Sea Southern Ocean Intracontinental extension Thermochronology U-Pb SHRIMP West Antarctica Smith Siddoway, Christine Baldwin, Suzanne Fitzgerald, Paul G Fanning, Christopher Luyendyk, Bruce Ross Sea Mylonites and the timimg of intracontinental extension within the West Antarctic rift system |
topic_facet |
Keywords: Plate boundary dynamics Thermal evolution Brittleness Carbonates Cooling Deformation Feldspar Granite Oceanography Geology Cretaceous extensional tectonics faulting geochronology mylonite rift zone Ross Sea Southern Ocean Intracontinental extension Thermochronology U-Pb SHRIMP West Antarctica |
description |
There are few direct constraints on the timing and style of faulting in the Ross Sea sector of the West Antarctic rift system, although Cretaceous plate reconstructions indicate that Ross Sea extension between East and West Antarctica occurred prior to breakup of the Gondwana margin ca. 80 Ma. Mylonitic gneisses dredged from the eastern Ross Sea indicate shear-zone deformation considerably earlier, at 98-95 Ma. Strain analysis of fabrics indicates 85%-100% extension. Overprinting brittle structures record translation of shear-zone gneisses into the upper crust. Samples yield sensitive high-resolution ion-microprobe U-Pb zircon ages of 102-97 Ma, correlated to Byrd Coast Granite onshore, and concordant 40Ar/39Ar biotite and K-feldspar ages of 98-95 Ma, indicating that granites were mylonitized soon after emplacement and cooled rapidly. Apatite fission-track data corroborate this rapid cooling event, and reveal a second rapid cooling event ca. 80 Ma. Evidence for contemporaneous deformation and a similar thermal evolution at Deep Sea Drilling Project Site 270 on the Ross Sea central high and for a migmatite dome on land attests to the regional extent of intracontinental extension. Extension occurred at a time of complex microplate interactions along the Cretaceous active Gondwana margin, suggesting that distributed deformation in the overriding Antarctic plate may be related to plate boundary dynamics. |
format |
Article in Journal/Newspaper |
author |
Smith Siddoway, Christine Baldwin, Suzanne Fitzgerald, Paul G Fanning, Christopher Luyendyk, Bruce |
author_facet |
Smith Siddoway, Christine Baldwin, Suzanne Fitzgerald, Paul G Fanning, Christopher Luyendyk, Bruce |
author_sort |
Smith Siddoway, Christine |
title |
Ross Sea Mylonites and the timimg of intracontinental extension within the West Antarctic rift system |
title_short |
Ross Sea Mylonites and the timimg of intracontinental extension within the West Antarctic rift system |
title_full |
Ross Sea Mylonites and the timimg of intracontinental extension within the West Antarctic rift system |
title_fullStr |
Ross Sea Mylonites and the timimg of intracontinental extension within the West Antarctic rift system |
title_full_unstemmed |
Ross Sea Mylonites and the timimg of intracontinental extension within the West Antarctic rift system |
title_sort |
ross sea mylonites and the timimg of intracontinental extension within the west antarctic rift system |
publisher |
Geological Society of America Inc |
url |
http://hdl.handle.net/1885/80324 https://doi.org/10.1130/G20005.1 |
geographic |
Antarctic Southern Ocean Ross Sea West Antarctica Byrd |
geographic_facet |
Antarctic Southern Ocean Ross Sea West Antarctica Byrd |
genre |
Antarc* Antarctic Antarctica Ross Sea Southern Ocean West Antarctica |
genre_facet |
Antarc* Antarctic Antarctica Ross Sea Southern Ocean West Antarctica |
op_source |
Geology |
op_relation |
0091-7613 http://hdl.handle.net/1885/80324 doi:10.1130/G20005.1 |
op_doi |
https://doi.org/10.1130/G20005.1 |
container_title |
Geology |
container_volume |
32 |
container_issue |
1 |
container_start_page |
57 |
_version_ |
1788067365605343232 |