Low-temperature thermochronology of the northern Thomson Orogen: implications for exhumation of basement rocks in NE Australia

Verdel, Charles, Stockli, Daniel and Purdy, David (2016) Low-temperature thermochronology of the northern Thomson Orogen: implications for exhumation of basement rocks in NE Australia. Tectonophysics, 666 1-11. doi:10.1016/j.tecto.2015.08.031


Author Verdel, Charles
Stockli, Daniel
Purdy, David
Title Low-temperature thermochronology of the northern Thomson Orogen: implications for exhumation of basement rocks in NE Australia
Journal name Tectonophysics   Check publisher's open access policy
ISSN 0040-1951
Publication date 2016-01-15
Year available 2016
Sub-type Article (original research)
DOI 10.1016/j.tecto.2015.08.031
Open Access Status Not Open Access
Volume 666
Start page 1
End page 11
Total pages 11
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Language eng
Subject 1908 Geophysics
1904 Earth-Surface Processes
Abstract The Tasmanides of eastern Australia record much of the Phanerozoic tectonic development of the retreating Pacific-Australia plate boundary and are an oft-cited example of an orogen that has undergone "tectonic mode switching." To begin to constrain the timing of exhumation of basement rocks that are now exposed in portions of the NE Tasmanides, we measured apatite and zircon (U-Th)/He ages from the Thomson Orogen and overlying Paleozoic strata in the back-arc of the New England Orogen in NE Australia. Zircon (U-Th)/He ages from basement samples (including those recovered from boreholes at depths of up to 1.1 km) are characterized by large inter- and intra-sample variability and range from approximately 180 Ma (Early Jurassic) to 375 Ma (Late Devonian). (U-Th)/He zircon ages from several individual samples are negatively correlated with effective uranium (eU), a pattern that is also true of the dataset as a whole, suggesting that variations in U and Th zoning and radiation damage are partially responsible for the age variability. The oldest zircon (U-Th)/He cooling ages coincide with the formation of regionally extensive Late Devonian-early Carboniferous back-arc basins, suggesting that Late Devonian extension played a significant role in exhumation of parts of the northern Thomson Orogen. Apatite (U-Th)/He ages from a basement sample and a late Permian sandstone in the overlying Bowen Basin, which are also marked by intra-sample variability and age-eU correlations, span from the Early Cretaceous through Oligocene, in general agreement with previous apatite fission track data. In conjunction with observations of key geologic relationships and prior K-Ar and Ar/Ar data, our results suggest four overall phases in the thermal history of the northern Thomson Orogen: (1) Cambrian-early Silurian metamorphism during the Delamerian and Benambran Orogenies; (2) protracted cooling during the Late Devonian through mid-Permian that likely resulted from extensional exhumation; (3) Permian-Triassic reheating during burial beneath thick sedimentary basins; and (4) Cretaceous and Paleogene cooling during uplift and erosion.
Formatted abstract
The Tasmanides of eastern Australia record much of the Phanerozoic tectonic development of the retreating Pacific-Australia plate boundary and are an oft-cited example of an orogen that has undergone "tectonic mode switching." To begin to constrain the timing of exhumation of basement rocks that are now exposed in portions of the NE Tasmanides, we measured apatite and zircon (U-Th)/He ages from the Thomson Orogen and overlying Paleozoic strata in the back-arc of the New England Orogen in NE Australia. Zircon (U-Th)/He ages from basement samples (including those recovered from boreholes at depths of up to 1.1 km) are characterized by large inter- and intra-sample variability and range from approximately 180 Ma (Early Jurassic) to 375 Ma (Late Devonian). (U-Th)/He zircon ages from several individual samples are negatively correlated with effective uranium (eU), a pattern that is also true of the dataset as a whole, suggesting that variations in U and Th zoning and radiation damage are partially responsible for the age variability. The oldest zircon (U-Th)/He cooling ages coincide with the formation of regionally extensive Late Devonian-early Carboniferous back-arc basins, suggesting that Late Devonian extension played a significant role in exhumation of parts of the northern Thomson Orogen. Apatite (U-Th)/He ages from a basement sample and a late Permian sandstone in the overlying Bowen Basin, which are also marked by intra-sample variability and age-eU correlations, span from the Early Cretaceous through Oligocene, in general agreement with previous apatite fission track data. In conjunction with observations of key geologic relationships and prior K-Ar and 40Ar/39Ar data, our results suggest four overall phases in the thermal history of the northern Thomson Orogen: (1) Cambrian-early Silurian metamorphism during the Delamerian and Benambran Orogenies; (2) protracted cooling during the Late Devonian through mid-Permian that likely resulted from extensional exhumation; (3) Permian-Triassic reheating during burial beneath thick sedimentary basins; and (4) Cretaceous and Paleogene cooling during uplift and erosion.
Keyword (U-Th)/He thermochronology
Tectonic mode switching
Tectonics
Thomson Orogen
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: HERDC Pre-Audit
School of Earth Sciences Papers
 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 1 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 2 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Tue, 23 Feb 2016, 10:44:14 EST by System User on behalf of Learning and Research Services (UQ Library)