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Naturaliste Plateau: constraints on the timing and evolution of the Kerguelen Large Igneous province and its role in Gondwana breakup

Citation

Direen, NG and Cohen, BE and Maas, R and Frey, FA and Whittaker, JM and Coffin, MF and Meffre, S and Halpin, JA and Crawford, AJ, Naturaliste Plateau: constraints on the timing and evolution of the Kerguelen Large Igneous province and its role in Gondwana breakup, Australian Journal of Earth Sciences, 64, (7) pp. 851-869. ISSN 0812-0099 (2017) [Refereed Article]

Copyright Statement

Copyright 2017 Geological Society of Australia

DOI: doi:10.1080/08120099.2017.1367326

Abstract

Volcanism associated with the Kerguelen Large Igneous Province is found scattered in southwestern Australia (the ca 136 to ca 130 Ma Bunbury Basalts, and ca 124 Ma Wallaby Plateau), India (ca 118 Ma Rajmahal Traps and Cona Basalts), and Tibet (the ca 132 Ma Comei Basalts), but apart from the ∼70 000 km2 Wallaby Plateau, these examples are spatially and volumetrically minor. Here, we report dredge, geochronological and geochemical results from the ∼90 000 km2 Naturaliste Plateau, located ∼170 to ∼500km southwest of Australia. Dredged lavas and intrusive rocks range from mafic to felsic compositions, and prior geophysical analyses indicate these units comprise much of the plateau substrate. 40Ar/39Ar plagioclase ages from mafic units and UPb zircon ages from silicic rocks indicate magmatic emplacement from 130.6 1.2 to 129.4 1.3 Ma for mafic rocks and 131.8 3.9 to 128.2 2.3 Ma for silicic rocks (2σ). These Cretaceous Naturaliste magmas incorporated a significant component of continental crust, with relatively high 87Sr/86Sr (up to 0.78), high 207Pb/204 Pb ratios (15.515.6), low 143Nd/144Nd (0.5110.512) and primitive-mantle normalised Th/Nb of 11.3 and La/Nb of 3.97. These geochemical results are consistent with the plateau being underlain by continental basement, as indicated by prior interpretations of seismic and gravity data, corroborated by dredging of Mesoproterozoic granites and gneisses on the southern plateau flank. The Cretaceous Naturaliste Plateau igneous rocks have signatures indicative of extraction from a depleted mantle, with trace-element and isotopic values that overlap with Kerguelen Plateau lavas reflect crustal contamination. Our chemical and geochronological results therefore show the Naturaliste Plateau contains evidence of an extensive igneous event representing some of the earliest voluminous Kerguelen hotspot magmas. Prior work reports that contemporaneous correlative volcanic sequences underlie the nearby Mentelle Basin, and the Enderby Basin and Princess Elizabeth Trough in the Antarctic. When combined, the igneous rocks in the Naturaliste, Mentelle, Wallaby, Enderby, Princess Elizabeth, Bunbury and Comei-Cona areas form a 136124 Ma Large Igneous Province covering >244 000 km2.

Item Details

Item Type:Refereed Article
Keywords:Naturaliste Plateau, Kerguelen hotspot, Gondwanaland breakup, geochronology, geochemistry, Tibet, Wallaby Plateau
Research Division:Earth Sciences
Research Group:Geology
Research Field:Tectonics
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Direen, NG (Dr Nicholas Direen)
Author:Whittaker, JM (Dr Jo Whittaker)
Author:Coffin, MF (Professor Mike Coffin)
Author:Meffre, S (Dr Sebastien Meffre)
Author:Halpin, JA (Dr Jacqueline Halpin)
Author:Crawford, AJ (Professor Anthony Crawford)
ID Code:121618
Year Published:2017
Deposited By:Centre for Oceans and Cryosphere
Deposited On:2017-10-05
Last Modified:2017-11-13
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