Kerguelen Plateau crustal structure and basin formation from seismic and gravity data

We use multichannel seismic data, gravity, and subsidence modeling, in conj unction with plate reconstructions, to evaluate the crustal origin and comp osition of the Kerguelen Plateau. Predominantly oceanic crust of the southe rn and parts of the central Kerguelen Plateau appears to include continenta l fragments related to the breakup of India and Antarctica; these fragments may have been metamorphosed during emplacement of the main plateau. The up per crust is basaltic, the middle crust is intrusive mafic rock and intrude d continental crust, and the lower crust is a plagioclase-rich metamorphic rock. The Labuan Basin crust is predominantly oceanic with stranded Kerguel en Plateau fault blocks. High-density lower crust in the Labuan Basin is pr obably composed of serpentinized peridotites formed during slow rifting and spreading. Plate reconstruction models indicate opening between eastern Br oken Ridge and southern Kerguelen Plateau at similar to 90 Ma, heralding th e formation of the Labuan Basin and Diamantina Zone; crustal attenuation an d slow accretion of oceanic crust continued until the Australian and Antarc tic plates separated at C18 time (similar to 40 Ma). Plate reconstructions of the free-air gravity field indicate that the Naturaliste Plateau fits ag ainst Antarctica and that Elan Bank and India were juxtaposed until similar to 110 Ma, Both Naturaliste Plateau and Elan Bank are probable microcontin ents. A similar to1 km positive residual depth anomaly in the oceanic basin s adjacent to the plateau, along with the positive geoid anomaly centered b eneath the northern Kerguelen Plateau, imply that the lithosphere is partia lly dynamically supported by an upwelling hot asthenosphere of the Kerguele n hot spot.