Naturaliste Plateau: constraints on the timing and evolution of the Kerguelen Large Igneous Province and its role in Gondwana breakup
Authors:Direen, N. G. Cohen, B. E. Maas, R. Frey, F. A. Whittaker, J. M. Coffin, M. F. Meffre, S. Halpin, J. A. Crawford, A. J.
Volume:64
DOI:10.1080/08120099.2017.1367326
Published:2017
Document Type:Article
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 similar to 70 000 km(2) Wallaby Plateau, these examples are spatially and volumetrically minor. Here, we report dredge, geochronological and geochemical results from the similar to 90 000 km(2) Naturaliste Plateau, located similar to 170 to similar to 500 km 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. Ar-40/Ar-39 plagioclase ages from mafic units and U-Pb 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 (2s). These Cretaceous Naturaliste magmas incorporated a significant component of continental crust, with relatively high Sr-87/Sr-86 (up to 0.78), high Pb-207/(204) Pb ratios (15.5-15.6), low Nd-143/Nd-144 (0.511-0.512) 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 136-124 Ma Large Igneous Province covering >244 000 km(2).
Author Information
Corresponding Author:Direen, NG (通讯作者)，Univ Tasmania, Sch Phys Sci, Private Bag 126, Hobart, Tas 7001, Australia.;Direen, NG (通讯作者)，Univ Tasmania, Inst Marine & Antarctic Studies, Private Bag 126, Hobart, Tas 7001, Australia.
Reprint Address:Direen, NG (通讯作者)，Univ Tasmania, Sch Phys Sci, Private Bag 126, Hobart, Tas 7001, Australia.;Direen, NG (通讯作者)，Univ Tasmania, Inst Marine & Antarctic Studies, Private Bag 126, Hobart, Tas 7001, Australia.
Addresses:[Direen, N. G.; Meffre, S.; Halpin, J. A.; Crawford, A. J.] Univ Tasmania, Sch Phys Sci, Private Bag 126, Hobart, Tas 7001, Australia; [Direen, N. G.; Whittaker, J. M.; Coffin, M. F.; Halpin, J. A.] Univ Tasmania, Inst Marine & Antarctic Studies, Private Bag 126, Hobart, Tas 7001, Australia; [Cohen, B. E.] Univ Queensland, Sch Earth Sci, St Lucia, Qld 4072, Australia; [Cohen, B. E.] Scottish Univ Environm Res Ctr, E Kilbride G75 0QF, Lanark, Scotland; [Maas, R.] Univ Melbourne, Sch Earth Sci, Parkville, Vic 3010, Australia; [Frey, F. A.] MIT, Earth Atmosphere & Planetary Sci, 77 Massachusetts Ave, Cambridge, MA 02139 USA; [Coffin, M. F.] Woods Hole Oceanog Inst, Woods Hole, MA 02543 USA; [Coffin, M. F.] Univ Maine, Sch Earth & Climate Sci, Orono, ME 04473 USA; [Meffre, S.; Halpin, J. A.; Crawford, A. J.] Univ Tasmania, ARC Ctr Excellence Ore Deposits, Private Bag 126, Hobart, Tas 7001, Australia
E-mail Addresses:n_direen@utas.edu.au