Contrasting Archaean crustal records in western part of the Napier Complex, East Antarctica: New constraints from SHRIMP geochronology

Horie, Kenji; Hokada, Tomokazu; Hiroi, Yoshikuni; Motoyoshi, Yoichi; Shiraishi, Kazuyuki

doi:10.1016/j.gr.2011.08.013

Cited by 33 publications

(44 citation statements)

References 29 publications

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“…Both contain mesoperthites that indicate minimum temperatures of >920-940°C based on ternary feldspar thermometry using the calibration of Fuhrman and Lindsley (1988). Ovoid, weakly sector-planar zoned and chemically homogeneous zircons in a patch leucosome yield a spread in U-Pb ages along Concordia, from 2590 to 2480 Ma, but preserve a robust 206 Pb/ 238 U age of 2586 ± 8 Ma for the oldest cluster of analyses, an age that overlaps with the minimum depositional age for metaquartzite protoliths as inferred by Horie et al (2012) based on zircon population analysis (Fig. 6).…”

Section: Slow Archaean Uht: the Napier Complex East Antarcticamentioning

confidence: 74%

“…Similarly, zircon U-Pb age data compiled for anatectic leucosomes and migmatitic gneisses from the Napier Complex (Fig. 6: Carson et al, 2002;Hokada and Harley, 2004;Kelly and Harley, 2005;Horie et al, 2012) shows at least four crystallisation 'events' from perhaps 2585 Ma through to 2510 ma and even 2490 Ma. Again, rather than invoking T fluctuations it is conceivable that local melt / wall rock interactions governed zircon crystallisation under UHT conditions.…”

Section: Constraining Temperature and Time In Uht Metamorphismmentioning

confidence: 83%

“…The youngest protolith age for an in-situ orthogneiss from the Napier Complex, 2626 ± 28 Ma (Carson et al, 2002), constrains UHT to be <2620 Ma. Horie et al (2012) report~2580 Ma ages for igneous zoned zircon cores in one quartzofeldspathic gneiss and two metaquartzites from Mt Cronus, and from these results infer a maximum possible age of UHT of~2580 Ma. Sm-Nd and Lu-Hf mineral isochrons indicate cooling through 800-650°C by~2450-2350 Ma .…”

Section: Slow Archaean Uht: the Napier Complex East Antarcticamentioning

confidence: 88%

“…All published studies of the region have yielded monazite ages that range up to ~2480-2500 Ma but are are usually much younger than the UHT event itself (e.g., <2400 Ma: Suzuki et al, 2006). Concordant U-Pb ages obtained from zircon inferred to have grown or been modified in the UHT metamorphic episode are commonly in the range 2530-2485 Ma (Grew et al, 2001;Carson et al, 2002;Crowe et al, 2002Kelly and Harley 2005;Grew et al, 2006;Horie et al, 2012), but ages of 2585 and 2555-2550 Ma have also been recorded from zircons inferred on textural grounds to be of UHT origin (Harley et al, 2001;Carson et al, 2002). The duration of UHT can also be bracketted by age data on the youngest pre-metamorphic intrusives and detrital zircons in metasediments and cooling ages provided by complementary isotopic systems such as garnet-rock Sm-Nd and Lu-Hf mineral isochrons.…”

Section: Slow Archaean Uht: the Napier Complex East Antarcticamentioning

confidence: 99%

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A matter of time: The importance of the duration of UHT metamorphism

Harley

2016

Journal of Mineralogical and Petrological Sciences

142

110

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The duration of granulite (G) and ultra-high temperature (UHT) conditions in regional metamorphism is critical to arguments regarding the tectonic settings of granulites and their relationships to Supercontinent assembly. Analysis of zircon geochronology integrated with trace element (REE) constraints on the timing of zircon growth or modification and evidence for metamorphic temperatures from Ti-in-zircon reveals that zircon can form episodically at or near the metamorphic peak in long-lived UHT granulites. This reflects the segregation, transfer and stagnation or trapping of melts which leads to local melt-rock interactions that promotes zircon crystallisation. In contrast, although rutile can retain UHT information in short duration ('fast') G-UHT terrains it is afflicted by Zr loss in long duration ('slow') terrains and yields temperatures significantly lower than those preserved by zircons formed in the same G-UHT events. An assessment of the age-duration evidence from several well-documented G-UHT terrains reveals that most are 'slow', having durations of UHT, Δt 900 , in the range 30-100 Myr. Some UHT terrains previously considered to be short-lived (Δt 900 < 10 Myr) have longer durations of UHT in the light of recent geochronology and hence are also classed as 'slow'. Of the models proposed to account for UHT metamorphism, the 'large hot orogen' (LHO) model for collisional orogeny provides the best setting for the formation of such 'slow' UHT granulites. LHO models can account not only for the P-T paths, which can range from UHT with near-isothermal decompression (UHT-ITD) through to decompression-cooling and UHT followed by near-isobaric cooling (UHT-IBC), but also for residence times under UHT conditions. The Napier Complex, the Earth's premier UHT terrain, probably formed as trapped deep crust in the hot underbelly of a late-Archaean LHO. Shorter duration UHT and near-UHT granulites also exist, mostly with Δt 900 less than 10 Myr. A number of these are likely to have formed as a consequence of severe lithospheric thinning and crustal extension accompanied by voluminous magmatism, which could occur in arc and back-arc settings affected by subduction roll-back or, as advocated by previous workers, continental arcs undergoing extension. However, attaining long-lived UHT conditions in these settings is unlikely unless the crust has inherently high radioactive heat production in addition to the transient heat added during extension and magmatism.

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Section: Slow Archaean Uht: the Napier Complex East Antarcticamentioning

confidence: 74%

Section: Constraining Temperature and Time In Uht Metamorphismmentioning

confidence: 83%

Section: Slow Archaean Uht: the Napier Complex East Antarcticamentioning

confidence: 88%

Section: Slow Archaean Uht: the Napier Complex East Antarcticamentioning

confidence: 99%

See 2 more Smart Citations

A matter of time: The importance of the duration of UHT metamorphism

Harley

2016

Journal of Mineralogical and Petrological Sciences

142

110

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“…Metamorphosed and deformed mafic dykes in the Rayner Complex were thought to be equivalents of undeformed~1200 Ma dykes in the Napier Complex (e.g., Sheraton et al 1980;Sheraton and Black, 1982;Clarke, 1988). The Napier Complex contains felsic igneous precursors to orthogneisses as old as~3800 Ma, and most lithologies were formed or metamorphosed during the late Archean, but the timing of peak UHT metamorphism is controversial (Horie et al, 2012, and references therein). Some geochronological works suggested that the UHT metamorphism occurred no earlier than 2840 Ma, and possibly from 2590 to 2550 Ma (e.g., Harley et al, 2001;Crowe et al, 2002;Kelly and Harley, 2005), whereas other researchers interpret the younger~2500-2450 Ma age to represent the UHT event (e.g., Grew, 1998;Carson et al, 2002;Hokada et al, 2003;Hokada and Harley, 2004).…”

Section: Regional Geologymentioning

confidence: 99%

U–Pb zircon geochronology in the western part of the Rayner Complex, East Antarctica

Horie

Hokada

Motoyoshi

et al. 2016

Journal of Mineralogical and Petrological Sciences

Self Cite

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U-Pb zircon geochronology was applied to nine metasedimentary samples collected from Mt. Yuzhnaya, Condon Hills, and Mt. Lira in the inland region of the Rayner Complex of western Enderby Land, East Antarctica, in order to define the eastern limits of the western Rayner Complex that underwent the Pan-African metamorphism and to evaluate potential source areas of metasedimentary rocks. Condon Hills and Mt. Lira revealed metamorphic ages of~894 and~934 Ma, respectively, which are consistent with previously reported metamorphism in association with Rayner Structural Episode (RSE). Mt. Yuzhnaya samples affected by the RSE contain zircon grains rejuvenated during 590-570 Ma, which indicates that the Pan-African reworking can be extended up to Mt. Yuzhnaya. On the other hand, the Condon Hills samples include Archean detritus, and the age peaks from 3850 to 2491 Ma are the oldest components in the Rayner Complex of western Enderby Land. There is no evidence of reworked Napier Complex rocks in the studied Rayner samples.

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Multi-stage ultrahigh temperature metamorphism in the lower crust of the Kaapvaal craton recorded by U–Pb ages of garnet

Shu,

Beranoaguirre,

Albert

et al. 2024

Contrib Mineral Petrol

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U–Pb ages were determined by split-stream LA-SF/MC-ICPMS in garnets from UHT granulite xenoliths (Star mine, South Africa; 124 Ma). They give a considerable age range of 400 million years with well-defined maximas at 3.09, 3.01 and 2.75 Ga. The oldest peak overlaps with the changeover from tonalites to K-granites at 3.14–3.04 Ga and with zircon ages of the mid-crustal granulites of the Vredefort dome (3.1 Ga) in the wake of the 3.2 Ga collision of three terrains that compose the Witwatersrand block. Subduction (or sagduction) of the uppermost crust in an ultrahot orogen setting brought shales and greenstones to the lower crust. Ultrahigh temperature (UHT) conditions are the result of high mantle potential temperatures and self- heating by the radioactive inventory of the subducted lithologies. Metamorphism, anatexis to very high degrees and melt extraction left UHT granulites as residue. Rejuvenation of UHT conditions was brought about by Dominion Group magmatism between 3.0 and 2.95 Ga. Magmatic uprise caused intense shearing in the lower crust followed by recrystallisation of the shear zones to generate the younger garnet age group. Ventersdorp flood basalt volcanism caused similar processes at around 2.72 Ga and generated the third garnet age group. Zircon gives U–Pb ages mainly around 2.72 Ga (both literature and our own data) i.e. zircon adjusted or newly crystallized at the youngest UHT event. Only few zircon grains retained older ages up to 2.94 Ga. Still unconstrained, but very high closure temperatures (≥ 1100 °C) for the U–Pb system in garnet keep the memory of the oldest ages in UHT granulites. Such ages can only be reset by recrystallization. This way, garnet records a prolonged high-temperature history of the lower crust of the Kaapvaal craton.

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Contrasting Archaean crustal records in western part of the Napier Complex, East Antarctica: New constraints from SHRIMP geochronology

Cited by 33 publications

References 29 publications

A matter of time: The importance of the duration of UHT metamorphism

A matter of time: The importance of the duration of UHT metamorphism

U–Pb zircon geochronology in the western part of the Rayner Complex, East Antarctica

Multi-stage ultrahigh temperature metamorphism in the lower crust of the Kaapvaal craton recorded by U–Pb ages of garnet

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