Strain and displacement in the harts range detachment zone: a structural study of the Bruna Gneiss from the western margin of the Entia Dome, central Australia

James, Patrick; MacDonald, P.J.; Parker, M.E.

doi:10.1016/0040-1951(89)90313-2

Cited by 14 publications

(2 citation statements)

References 52 publications

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“…The metamorphic minerals defining the foliation do not show evidence of internal strain, suggesting the assemblage recrystallized during D3. Shear sense indicators suggest the fabric formed during south‐directed transport (see also James et al ., 1989 ; Collins & Teyssier, 1989b). Average temperature calculations ( Powell & Holland, 1994) give around 650 °C at a reference pressure of 6 kbar ( Table 1).…”

Section: Samplesmentioning

confidence: 99%

Sm–Nd evidence for high‐grade Ordovician metamorphism in the Arunta Block, central Australia

Mawby¹,

Hand²,

Foden³

1999

Journal Metamorphic Geology

122

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Sm–Nd ages from the Harts Range in the south‐eastern Arunta Inlier in central Australia indicate that regional metamorphism up to granulite facies occurred in the Early Ordovician (c. 475 Ma). This represents a radical departure from previous tectonic models for the region and identifies a previously unrecognized intraplate event in central Australia. Peak metamorphic assemblages (800 °C and 10.5 kbar) formed at around 476±14 Ma and underwent approximately 4 kbar of near‐isothermal decompression at 475±4 Ma. A coarse‐grained unfoliated garnet–clinopyroxene‐bearing marble inferred to have recrystallized late in the decompressional evolution, gives an age of 469±7 Ma. Two lines of evidence suggest the Early Ordovician tectonism occurred in an extensional setting. First, the timing of the high‐grade lower crustal deformation coincides with a period of marine sedimentation in the Amadeus and Georgina basins that was associated with a seaway that developed across central Australia. Second, isothermal decompression of lower crustal rocks was associated with the formation of a regional, sub‐horizontal mid‐crustal foliation. In the Entia Gneiss Complex, which forms the structurally lowest part of the Harts Range, upper‐amphibolite facies metamorphism (c. 700 °C, 8–9 kbar) occurred at 479±15 Ma. There is no evidence that P–T conditions in the Entia Gneiss Complex were as high as in the overlying units. This implies that the extensional system was reworked during a later compressional event. Sm–Nd data from the mid‐amphibolite facies (c. 650 °C and 6 kbar) detachment zone that separates the Irindina Supracrustal Assemblage and Entia Gneiss Complex give an age of 449±10 Ma. This age corresponds to the timing of a change in the pattern and style of sedimentation in the Amadeus and Georgina basins, and indicates that the change in basin dynamics was associated with mid‐crustal deformation. It also suggests that compressional deformation culminating in the Devonian to Carboniferous (400–300 Ma) Alice Springs Orogeny may have begun as early as c. 450 Ma. At present, the extent of Early Ordovician tectonism in central Australia is unknown. However, granulite facies metamorphism and associated intense deformation imply an event of regional extent. An implication of this work is that high‐grade lower crustal metamorphism and intense deformation occurred during the development of a broad, shallow, slowly subsiding intraplate basin.

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Section: Samplesmentioning

confidence: 99%

Sm–Nd evidence for high‐grade Ordovician metamorphism in the Arunta Block, central Australia

Mawby¹,

Hand²,

Foden³

1999

Journal Metamorphic Geology

122

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“…These south-directed thrusts (D3 of formed at upper amphibolite facies conditions, postdating the peak of metamorphism in the Harts Range Group, and have Sm-Nd isochron ages of 448 4-7 Ma and 445-t-51 Ma . interpreted the D3 event in the Harts Range as reflecting a change from extensional to compressional deformation in the eastern Arunta Inlier, due to apparent south-directed reverse kinematics in D3 shear zones (James et al 1989) as well as a change in the distribution of sedimentation in the surrounding basins at c. 450 Ma (e.g. Shaw et al 1991).…”

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High-grade reworking of Proterozoic granulites during Ordovician intraplate transpression, eastern Arunta Inlier, central Australia

Scrimgeour

Raith

2001

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In the Huckitta region of the eastern Arunta Inlier, central Australia, two terrains with distinct metamorphic histories are separated by a zone of sinistral strike-slip mylonitic deformation and reworking, the Entire Point Shear Zone (EPSZ). To the south of the EPSZ, in the Harts Range Group, Ordovician (c. 470 Ma) intraplate granulite facies metamorphism (c. 800°C, 8-10 kbar) was followed by decompression to c. 7 kbar. In contrast, the Kanandra Granulite, to the north of the EPSZ, is characterized by Palaeoproterozoic high-grade metamorphism at 770-850°C and 5-7 kbar, followed by inferred near-isobaric cooling. Juxtaposition of these terrains along the EPSZ occurred at upper amphibolite facies conditions (700°C, 7 kbar), and resulted in extensive reworking of the Kanandra Granulite. Monazite growth within EPSZ mylonites is dated at 445-4-5

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Central Australia (Arunta Complex and Amadeus Basin)—history of work and outline of problems

Rickard

1989

Tectonophysics

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Strain and displacement in the harts range detachment zone: a structural study of the Bruna Gneiss from the western margin of the Entia Dome, central Australia

Cited by 14 publications

References 52 publications

Sm–Nd evidence for high‐grade Ordovician metamorphism in the Arunta Block, central Australia

Sm–Nd evidence for high‐grade Ordovician metamorphism in the Arunta Block, central Australia

High-grade reworking of Proterozoic granulites during Ordovician intraplate transpression, eastern Arunta Inlier, central Australia

Central Australia (Arunta Complex and Amadeus Basin)—history of work and outline of problems

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