Heterogeneous Exhumation of the Mount Isa Orogen in NE Australia After 1.6 Ga Nuna Assembly: New High-Precision 40Ar/39Ar Thermochronological Constraints
The circa 1.60 Ga Isan Orogeny in NE Australia has been ascribed to the collision of Australia and Laurentia (North America), marking the final assembly of the Proterozoic supercontinent Nuna. However, details regarding the tectonic evolution of the orogen remain poorly constrained. To investigate t...
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| Format: | Journal Article |
| Language: | English |
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AMER GEOPHYSICAL UNION
2020
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| Online Access: | http://purl.org/au-research/grants/arc/FL150100133 http://hdl.handle.net/20.500.11937/90607 |
| _version_ | 1848765400910659584 |
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| author | Li, Jiangyu Pourteau, Amaury Li, Zheng-Xiang Jourdan, Fred Nordsvan, Adam Collins, William Volante, Silvia |
| author_facet | Li, Jiangyu Pourteau, Amaury Li, Zheng-Xiang Jourdan, Fred Nordsvan, Adam Collins, William Volante, Silvia |
| author_sort | Li, Jiangyu |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | The circa 1.60 Ga Isan Orogeny in NE Australia has been ascribed to the collision of Australia and Laurentia (North America), marking the final assembly of the Proterozoic supercontinent Nuna. However, details regarding the tectonic evolution of the orogen remain poorly constrained. To investigate the late orogenic to postorogenic thermal evolution and exhumation history, 40Ar/39Ar dating on hornblende, muscovite, and biotite was conducted in the Mount Isa Inlier, NE Australia, where intense crustal imbrication occurred during the Proterozoic continental collision. Published thermochronological results were recalculated using the current decay constant. Petrological examination and calculation of sample-specific 40Ar/39Ar closure temperatures and cooling rates were used to reconstruct the pressure-temperature evolution of individual structural domains. Diachronous cooling histories are revealed between western, central, and eastern belts through ~525–330°C, mainly between 1.53 and 1.48 Ga. Contrasting cooling across postmetamorphic fault zones records the reactivation of inherited normal (i.e., early basinal) and reverse (i.e., orogenic) faults. Estimated exhumation rates are generally low (< ~0.5 mm yr−1), pointing to a modest local relief of < ~1,000 m which is comparable to modern analogs, and suggest a “soft” collision with limited crust thickening. Exhumation shortly following orogenesis was contemporaneous with felsic magmatism (1.55–1.48 Ga) in the eastern belt. Magmatism transitioning from trondhjemitic to A-type granitoids over this period suggests progressive heating of the orogen base, ascribed to lower crust delamination. Thus, thermochronological data reveal a regionally heterogeneous exhumation history controlled by orogenic collapse-related extensional faulting following the final assembly of the supercontinent Nuna. |
| first_indexed | 2025-11-14T11:34:39Z |
| format | Journal Article |
| id | curtin-20.500.11937-90607 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:34:39Z |
| publishDate | 2020 |
| publisher | AMER GEOPHYSICAL UNION |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-906072023-03-24T04:49:47Z Heterogeneous Exhumation of the Mount Isa Orogen in NE Australia After 1.6 Ga Nuna Assembly: New High-Precision 40Ar/39Ar Thermochronological Constraints Li, Jiangyu Pourteau, Amaury Li, Zheng-Xiang Jourdan, Fred Nordsvan, Adam Collins, William Volante, Silvia Science & Technology Physical Sciences Geochemistry & Geophysics EASTERN FOLD BELT HIGH-TEMPERATURE METAMORPHISM HEAT-PRODUCING GRANITES SNAKE CREEK ANTICLINE MA THERMAL HISTORY MT-ISA CLONCURRY DISTRICT LOW-PRESSURE NORTHERN AUSTRALIA AGE CONSTRAINTS The circa 1.60 Ga Isan Orogeny in NE Australia has been ascribed to the collision of Australia and Laurentia (North America), marking the final assembly of the Proterozoic supercontinent Nuna. However, details regarding the tectonic evolution of the orogen remain poorly constrained. To investigate the late orogenic to postorogenic thermal evolution and exhumation history, 40Ar/39Ar dating on hornblende, muscovite, and biotite was conducted in the Mount Isa Inlier, NE Australia, where intense crustal imbrication occurred during the Proterozoic continental collision. Published thermochronological results were recalculated using the current decay constant. Petrological examination and calculation of sample-specific 40Ar/39Ar closure temperatures and cooling rates were used to reconstruct the pressure-temperature evolution of individual structural domains. Diachronous cooling histories are revealed between western, central, and eastern belts through ~525–330°C, mainly between 1.53 and 1.48 Ga. Contrasting cooling across postmetamorphic fault zones records the reactivation of inherited normal (i.e., early basinal) and reverse (i.e., orogenic) faults. Estimated exhumation rates are generally low (< ~0.5 mm yr−1), pointing to a modest local relief of < ~1,000 m which is comparable to modern analogs, and suggest a “soft” collision with limited crust thickening. Exhumation shortly following orogenesis was contemporaneous with felsic magmatism (1.55–1.48 Ga) in the eastern belt. Magmatism transitioning from trondhjemitic to A-type granitoids over this period suggests progressive heating of the orogen base, ascribed to lower crust delamination. Thus, thermochronological data reveal a regionally heterogeneous exhumation history controlled by orogenic collapse-related extensional faulting following the final assembly of the supercontinent Nuna. 2020 Journal Article http://hdl.handle.net/20.500.11937/90607 10.1029/2020TC006129 English http://purl.org/au-research/grants/arc/FL150100133 AMER GEOPHYSICAL UNION fulltext |
| spellingShingle | Science & Technology Physical Sciences Geochemistry & Geophysics EASTERN FOLD BELT HIGH-TEMPERATURE METAMORPHISM HEAT-PRODUCING GRANITES SNAKE CREEK ANTICLINE MA THERMAL HISTORY MT-ISA CLONCURRY DISTRICT LOW-PRESSURE NORTHERN AUSTRALIA AGE CONSTRAINTS Li, Jiangyu Pourteau, Amaury Li, Zheng-Xiang Jourdan, Fred Nordsvan, Adam Collins, William Volante, Silvia Heterogeneous Exhumation of the Mount Isa Orogen in NE Australia After 1.6 Ga Nuna Assembly: New High-Precision 40Ar/39Ar Thermochronological Constraints |
| title | Heterogeneous Exhumation of the Mount Isa Orogen in NE Australia After 1.6 Ga Nuna Assembly: New High-Precision 40Ar/39Ar Thermochronological Constraints |
| title_full | Heterogeneous Exhumation of the Mount Isa Orogen in NE Australia After 1.6 Ga Nuna Assembly: New High-Precision 40Ar/39Ar Thermochronological Constraints |
| title_fullStr | Heterogeneous Exhumation of the Mount Isa Orogen in NE Australia After 1.6 Ga Nuna Assembly: New High-Precision 40Ar/39Ar Thermochronological Constraints |
| title_full_unstemmed | Heterogeneous Exhumation of the Mount Isa Orogen in NE Australia After 1.6 Ga Nuna Assembly: New High-Precision 40Ar/39Ar Thermochronological Constraints |
| title_short | Heterogeneous Exhumation of the Mount Isa Orogen in NE Australia After 1.6 Ga Nuna Assembly: New High-Precision 40Ar/39Ar Thermochronological Constraints |
| title_sort | heterogeneous exhumation of the mount isa orogen in ne australia after 1.6 ga nuna assembly: new high-precision 40ar/39ar thermochronological constraints |
| topic | Science & Technology Physical Sciences Geochemistry & Geophysics EASTERN FOLD BELT HIGH-TEMPERATURE METAMORPHISM HEAT-PRODUCING GRANITES SNAKE CREEK ANTICLINE MA THERMAL HISTORY MT-ISA CLONCURRY DISTRICT LOW-PRESSURE NORTHERN AUSTRALIA AGE CONSTRAINTS |
| url | http://purl.org/au-research/grants/arc/FL150100133 http://hdl.handle.net/20.500.11937/90607 |