Structural and metamorphic geology of the Windmill Islands, east Antarctica: Field evidence for repeated tectonothermal activity

Paul, E.; Stüwe, Kurt; Teasdale, Jon; Worley, B.

doi:10.1080/08120099508728216

Cited by 33 publications

(25 citation statements)

References 10 publications

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“…These were originally believed to preserve a southwards increase in grade developed during a single tectonic event (Blight & Oliver 1977, but actually reflect a younger M2/D2 granulite-facies overprint on early M1/D1 amphibolite-facies assemblages (Paul et al 1995;Post et al 1997). Their tectonic history has been constrained by SHRIMP U-Pb data (Post et aL 1997;Post 2000), which are consistent with the reconnaissance U-Pb data of Oliver et al (1983) and Williams et aL (1983), but not the discredited data of Lovering et al (1981).…”

Section: Windmill Islandsmentioning

confidence: 98%

Proterozoic basement provinces of southern and southwestern Australia, and their correlation with Antarctica

Fitzsimons

2003

288

256

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Three Precambrian basement provinces extend from the southern coast of Australia into East Antarctica when reconstructed in a Gondwana configuration. These are, from east to west, the Mawson Craton, and the Albany-Fraser and Pinjarra Orogens. The Mawson Craton preserves evidence for tectonic activity from the late Archaean until the earliest Mesoproterozoic. It is exposed in the Gawler Craton of South Australia, the Terre Adélie and King George V Land coastline of East Antarctica, and the Miller Range of the central Transantarctic Mountains. It may form a significant part of the ice-covered East Antarctic Shield, although insufficient data are available to constrain its lateral extent. The Mawson Craton underwent late Palaeoproterozoic tectonism along its eastern margin (the Kimban Orogeny) and the occurrence of c. 1700Ma eclogites in the Transantarctic Mountains implies that this was, in part, a collisional event, although elsewhere it was characterized by low P/T metamorphism. The western margin of the Mawson Craton collided with a continental fragment comprising the Nawa Domain of the Gawler Craton, the Coompana Block and the Nornalup Complex of Western Australia at c. 1560Ma during the Kararan Orogeny. The western edge of the Nornalup Complex later collided with the Biranup and Fraser Complexes and Yilgarn Craton to form the Albany-Fraser Orogen during two stages of tectonism at c. 1350–1260 and 1210–1140Ma. The Pinjarra Orogen truncates the western margin of the Yilgarn Craton and Albany-Fraser Orogen, and contains allochthonous 1100–1000Ma gneissic blocks transported along the craton margin during at least two stages of Neoproterozoic transcurrent movement. It divides East Gondwana into Australo-Antarctic and Indo-Antarctic domains, which are distinct continental fragments with different Proterozoic histories that were juxtaposed by oblique collision at 550–500Ma during the assembly of Gondwana. The path taken by the Pinjarra Orogen beneath the Antarctic ice sheet is unknown, but it is of similar width and length to the East African Orogen, and must have been a fundamental Neoproterozoic boundary of critical importance to supercontinent assembly and breakup.

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Section: Windmill Islandsmentioning

confidence: 98%

Proterozoic basement provinces of southern and southwestern Australia, and their correlation with Antarctica

Fitzsimons

2003

288

256

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“…Detailed structural work shows that the northern Windmill Islands region (Cameron Island and northern Clark Peninsula) preserves S 1 foliations that are parallel to compositional layering and metamorphic evidence for M 1 (Paul et al., ; Post, ). South of Clark Peninsula, the M 1 assemblages are interpreted to be progressively overprinted by the higher‐grade M 2 event.…”

Section: Discussionmentioning

confidence: 99%

“…Garnet-bearing orthogneiss and charnockite are the dominant rock types and make up~70% of the outcrop (Figure 2; Zhang et al, 2012). Detailed descriptions of each lithology and their distribution are given in Paul, St€ uwe, Teasdale, and Worley (1995) and Post (2000).…”

Section: Geological Settingmentioning

confidence: 99%

A curious case of agreement between conventional thermobarometry and phase equilibria modelling in granulites: New constraints on P–T estimates in the Antarctica segment of the Musgrave–Albany–Fraser–Wilkes Orogen

Morrissey

Hand

Kelsey

2017

Journal Metamorphic Geology

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The Windmill Islands region in Wilkes Land, east Antarctica, preserves granulite facies metamorphic mineral assemblages that yield seemingly comparable P–T estimates from conventional thermobarometry and mineral equilibria modelling. This is uncommon in granulite facies terranes, where conventional thermobarometry and phase equilibria modelling generally produce conflicting P–T estimates because peak mineral compositions tend to be modified by retrograde diffusion processes. In situ U–Pb monazite geochronology and calculated metamorphic phase diagrams show that the Windmill Islands experienced two phases of high thermal gradient metamorphism during the Mesoproterozoic. The first phase of metamorphism is recorded by monazite ages in two widely separated samples and occurred at c. 1,305 Ma. This event was regional in extent, involved crustally derived magmatism and reached conditions of ~3.2–5 kbar and 690–770°C corresponding to very high thermal gradients of >150°C/kbar. The elevated thermal regime is interpreted to reflect a period of extension or increased extension in a back‐arc setting that existed prior to c. 1,330 Ma. The first metamorphic event was overprinted by granulite facies metamorphism at c. 1,180 Ma that was coeval with the intrusion of charnockite. This event involved peak temperatures of ~840–850°C and pressures of ~4–5 kbar. A phase of granitic magmatism at c. 1,250–1,210 Ma, prior to the intrusion of the charnockite, is interpreted to reflect a phase of compression within an overall back‐arc setting. Existing conventional thermobarometry suggests conditions of ~4 kbar and 750°C for M1 and 4–7 kbar and 750–900°C for M2. The apparent similarities between the phase equilibria modelling and existing conventional thermobarometry may suggest either that the terrane cooled relatively quickly, or that the P–T ranges obtained from conventional thermobarometry are sufficiently imprecise that they cover the range of P–T conditions obtained in this study. However, without phase equilibria modelling, the veracity of existing conventional P–T estimates cannot be evaluated. The calculated phase diagrams from this study allow the direct comparison of P–T conditions in the Windmill Islands with phase equilibria models from other regions in the Musgrave–Albany–Fraser–Wilkes Orogen. This shows that the metamorphic evolution of the Wilkes Land region is very similar to that of the eastern Albany–Fraser Orogen and Musgrave Province in Australia, and further demonstrates the remarkable consistency in the timing of metamorphism and the thermal gradients along the ~5,000 km strike length of this system.

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“…The Windmill Islands consist of a metamorphic Proterozoic supracrustal sequence of para-and orthogneiss intruded by an extensive charnockite suite, minor porphyritic granites and late-stage dolerite dykes (Oliver 1972;Blight and Oliver 1977;Williams et al 1983;Oliver et al 1983;Paul et al 1995;Post et al 1996;Post 2000). From north to south the metamorphic grade changes from upper-amphibolite to granulite facies (Blight and Oliver 1977).…”

Section: Geological Settingmentioning

confidence: 98%

Crustal residence history and garnet Sm–Nd ages of high-grade metamorphic rocks from the Windmill Islands area, East Antarctica

Möller

Post

Hensen

2002

Int J Earth Sci (Geol Rundsch)

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Nd whole-rock data from the Windmill Islands area yield early Proterozoic to middle Archaean Nd model ages. These crustal residence times are consistent with regional correlations with other parts of Antarctica (Bunger Hills, Denman Glacier area) and the AlbanyFraser Orogen of south-western Australia during the Mid-Proterozoic and thus support reconstructions with a continuous Mid-Proterozoic orogen in these areas. The new Nd isotope data provide strong evidence that no age boundary exists between the higher-and lower-grade parts of the Windmill Islands area, and that the metamorphic complex represents a single terrane with a common crustal history. The data support the notion of a time-link between the occurrence of intrusive charnockites (C-type magmas) and high-grade metamorphism. The magmatic rocks and orthogneisses in the area are interpreted to have a mixed source consisting of older crustal components, i.e. older sediments (ca. 3.2-2.6 Ga) and a younger mafic component (ca. 1.9 Ga). Two garnet Sm-Nd isochrons yield ages of 1156±17 Ma and 1137±2.5 Ma and are identical to SHRIMP U-Pb results on monazite from these samples. A garnet Sm-Nd age of 1123±13 Ma for the Ford granite is significantly younger than the SHRIMP U-Pb zircon age for this sample. The difference relates to the different closure temperature of each isotopic system and is thus interpreted as initial cooling after granulite facies metamorphism.

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Structural and metamorphic geology of the Windmill Islands, east Antarctica: Field evidence for repeated tectonothermal activity

Cited by 33 publications

References 10 publications

Proterozoic basement provinces of southern and southwestern Australia, and their correlation with Antarctica

Proterozoic basement provinces of southern and southwestern Australia, and their correlation with Antarctica

A curious case of agreement between conventional thermobarometry and phase equilibria modelling in granulites: New constraints on P–T estimates in the Antarctica segment of the Musgrave–Albany–Fraser–Wilkes Orogen

Crustal residence history and garnet Sm–Nd ages of high-grade metamorphic rocks from the Windmill Islands area, East Antarctica

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