Young basaltic knolls have been discovered on the old oceanic lithosphere, namely petit-spot volcanoes. Based on their geochemical signatures, they have presumably originated from partial melts in the asthenosphere. However, there is no direct information on the depth provenance of petit-spot formation. Here we report new geothermobarometric data of rare mantle xenoliths discovered from petit-s...

_Abstract. Two major hypotheses have been advanced for the formation of the long wavelength (100-300 km) undulations of oceanic basement and overlying sediments developed in the central Indian Ocean basin: whole layer folding (buckling) and local thickening (inverse boudinage). Using appropriately scaled two-layer analogue models for the oceanic lithosphere comprising a brittle layer above a du...

6 [1] We present evidence for the existence of an Australian-Antarctic Mantle Anomaly 7 (AAMA), which trends northwest-southeast (NW-SE) through the Australian-Antarctic 8 Discordance (AAD) on the Southeast Indian Ridge (SEIR), is confined to the upper 9 120 km of the mantle beneath the AAD, and dips shallowly to the west so that it extends to 10 a depth of about 150 km west of the AAD. Average...

[1] We present evidence for the existence of an Australian-Antarctic Mantle Anomaly (AAMA), which trends northwest-southeast (NW-SE) through the Australian-Antarctic Discordance (AAD) on the Southeast Indian Ridge (SEIR), is confined to the upper 120 km of the mantle beneath the AAD, and dips shallowly to the west so that it extends to a depth of about 150 km west of the AAD. Average temperatur...