TY  - STD
AU  - Xu, G.
AU  - Frey, F. A.
AU  - Weis, D.
AU  - Scoates, J. S.
AU  - Giret, A.
PY  - 2007//
TI  - Flood basalts from Mt. Capitole in the central Kerguelen Archipelago: Insights into the growth of the archipelago and source components contributing to plume-related volcanism
BT  - Geochem. Geophys. Geosyst.
VL  - 8
PB  - American Geophysical Union
KW  - Kerguelen mantle plume
KW  - Kerguelen Archipelago
KW  - Mt. Capitole
KW  - lower continental crust
KW  - Sr
KW  - Nd
KW  - Hf
KW  - Pb isotopic ratios
KW  - 1037 Geochemistry: Magma genesis and partial melting
KW  - 1038 Geochemistry: Mantle processes
KW  - 1065 Geochemistry: Major and trace element geochemistry
N2  - The Kerguelen Archipelago, constructed on the submarine Northern Kerguelen Plateau, is attributed to Cenozoic volcanism arising from the Kerguelen hot spot. Geochemical studies of 325 to 1000 m thick lava sections of the ?30 to 25 Ma flood basalt forming the bulk of the archipelago show a temporal change from older tholeiitic basalt to younger slightly alkalic basalt. This compositional transition is expressed in a 630 m lava section at Mt. Capitole where the lava sequence is lowermost tholeiitic basalt overlain by slightly alkalic basalt overlain by plagioclase-rich cumulates that are mixtures of plagioclase-phyric basalt and more evolved magmas. During growth of the archipelago, magma supply from the hot spot was variable and at times sufficiently low to enable extensive crystal fractionation; e.g., at Mt. Capitole and nearby Mt. Tourmente only 10 of 120 lava flows have >6 wt% MgO. On the basis of this study and previous isotopic data for the ?34 Ma submarine lavas erupted on the Northern Kerguelen Plateau, other flood basalt sections in the Kerguelen Archipelago, and younger lavas erupted in the archipelago and at Heard Island, there is significant Sr, Nd, Hf, and Pb isotopic heterogeneity that can be explained by two stages of mixing. The first mixing event, best shown by the submarine lavas, is between components that are related to Indian Ocean mid-ocean ridge basalt (MORB) and the Kerguelen hot spot. From ?34 Ma to <1 Ma, on average the proportion of the MORB-related component decreased. Subsequently, a second mixing process involved addition of a component with relatively high 87Sr/86Sr (>0.7060) and low 143Nd/144Nd (<0.5125) and 176Hf/177Hf (<0.2827) and nonradiogenic Pb isotope ratios (<17.9 for 206Pb/204Pb). We infer that this component was lower continental crust.
SN  - 1525-2027
L1  - https://sciences.ipev.fr/polar_references/files/5532_444_Xu et al2007.pdf
UR  - http://dx.doi.org/10.1029/2007GC001608
N1  - exported from refbase (http://publi.ipev.fr/polar_references/show.php?record=5532), last updated on Fri, 17 Apr 2009 17:04:15 +0200
ID  - Xu_etal2007
ER  -