The role of radiogenic heat in prolonged intraplate reworking: The Capricorn Orogen explained?

Korhonen, Fawna J.; Johnson, Simon P.

doi:10.1016/j.epsl.2015.06.039

Cited by 23 publications

(24 citation statements)

References 37 publications

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“…The 1,680–1,620 Ma Durlacher Supersuite represents the last major magmatic event in the orogen, which has present‐day heat production values (~4.6 μ W m −3 ; Figure a) exceeding typical granite values (=2.5 μ W m −3 ; Haenel, Rybach, & Stegena, ) and those of the adjacent Cratons (=1.76–2.01 μ W m −3 ; Bodorkos & Sandiford, ). Within the Mutherbukin Zone, the middle crust is dominated by the Davey Well Granite (Figure b), a phase of the Durlacher Supersuite that has the highest present‐day heat production values in the province (>4.6 μ W m −3 ; Korhonen & Johnson, ). The Davey Well batholith is a tabular intrusion (Johnson et al., ), likely emplaced near the brittle–ductile transition.…”

Section: Discussionmentioning

confidence: 99%

“…1,840 and 1,810 Ma that extended across much of the region (Leake Spring Metamorphics; Figure a). These rocks have a range of heat production values calculated at 1,320 Ma of 0.1–4.2 μ W m −3 (Korhonen & Johnson, ); however, the pelitic to psammitic lithologies that make up a majority of the rock types are generally between 3 and 4 μ W m −3 .…”

Section: Discussionmentioning

confidence: 99%

“…An important consequence of this radiogenic crust is that slight thickening would have resulted in the creation of a thermal lid. Conductive heat transfer models have shown that thin‐skinned, upper crustal thickening of radiogenic crust, characteristic of the Gascoyne Province, can produce the metamorphic conditions preserved in the Mutherbukin Zone over the appropriate time scales (Korhonen & Johnson, ). Based on these models, the spread of ages ranging from c .…”

Section: Discussionmentioning

confidence: 99%

“…(a) Simplified geological map showing division of the region into structural–metamorphic zones. **Present‐day heat production values ( μ W m −3 ) for magmatic rocks from Korhonen and Johnson (). (b) Geological cross‐section though the Gascoyne Province, combining deep crustal seismic lines 10 GA – CP 2 and 10 GA – CP 3 (Johnson et al., ).…”

Section: Geological Settingmentioning

confidence: 99%

“…Commonly the inclusion trails are curved so that toward the edges of the porphyroblasts they are parallel to the dominant south-dipping S 2 fabric. This implies that staurolite and garnet grew during Korhonen and Johnson (2015). (b) Geological crosssection though the Gascoyne Province, combining deep crustal seismic lines 10GA-CP2 and 10GA-CP3 .…”

Section: Structural Settingmentioning

confidence: 99%

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Radiogenic heating and craton‐margin plate stresses as drivers for intraplate orogeny

Korhonen

Johnson

Wingate

et al. 2017

Journal Metamorphic Geology

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The Proterozoic belts that occur along the margins of the West Australian Craton, as well as those in intraplate settings, generally share similar geological histories that suggest a common plate‐margin driver for orogeny. However, the thermal drivers for intraplate orogenesis are more poorly understood. The Mutherbukin Tectonic Event records a protracted period of Mesoproterozoic reworking of the Capricorn Orogen and offers significant insight into both the tectonic drivers and heat sources of long‐lived intraplate orogens. Mineral assemblages and tectonic fabrics related to this event occur within a 50 km‐wide fault‐bound corridor in the central part of the Gascoyne Province in Western Australia. This zone preserves a crustal profile, with greenschist facies rocks in the north grading to upper amphibolite facies rocks in the south. The P–T–t evolution of 13 samples from 10 localities across the Mutherbukin Zone is investigated using phase equilibria modelling integrated with in situ U–Pb monazite and zircon geochronology. Garnet chemistry from selected samples is used to further refine the P–T history and shows that the dominant events recorded in this zone are prolonged D1 transpression between c. 1,320 and 1,270 Ma, followed by D2 transtension from c. 1,210 to 1,170 Ma. Peak metamorphic conditions in the mid‐crust reached >650°C and 4.4–7 kbar at c. 1,210–1,200 Ma. Most samples record a single clockwise P–T evolution during this event, although some samples might have experienced multiple perturbations. The heat source for metamorphism was primarily conductive heating of radiogenic mid‐ and upper crust, derived from earlier crustal differentiation events. This crust was thickened during D1 transpression, although the thermal effects persisted longer than the deformation event. Peak metamorphism was terminated by D2 transtension at c. 1,210 Ma, with subsequent cooling driven by thinning of the radiogenic crust. The coincidence of a sedimentary basin acting as a thermal lid and a highly radiogenic mid‐crustal batholith restricted to the Mutherbukin Zone accounts for reworking being confined to a discrete crustal corridor. Our results show that radiogenic regions in the shallow to mid crust can elevate the thermal gradient and localize deformation, causing the crust to be more responsive to far‐field stresses. The Mutherbukin Tectonic Event in the Capricorn Orogen was synchronous with numerous Mesoproterozoic events around the West Australian Craton, suggesting that thick cratonic roots play an important role in propagating stresses generated at distant plate boundaries.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Structural Settingmentioning

confidence: 99%

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