WLIFT MOVEMENTS IN NEW CALEDONIA-LOYALTY ISLANDS AREA AND THEIR PLATE TECTONICS INTERPRETATION

Abstract

ABSTRACT Dubois, J., Launay, J. and Recy, J., 1974. Uplift movements in New Caledonia-Loyalty Islands area and their plate tectonics interpretation. Tectonophysics, 24: 133-150. The uplift movements of the New Caledonia and the Loyalty Islands, which are located on the Indian lithospheric plate that descends beneath the New Hebrides arc, have been studied in the geological context. This paper concentrates on the older (since Oligocene) uplift of the ultramafic peneplain in New Caledonia and the younger (since about 2 m.y.) regional uplift of the Loyalty Islands and southern New Caledonia. We computed the amount of uplift and deformation caused by three possible processes: erosional unloading, eustatism, and flexure of the lithosphere as it underthrusts beneath the New Hebrides island arc. The calculations indicate that the older uplift cannot be completely explained by erosional unloading of New Caledonia and may be partially caused by dynamic factors not yet understood. Eustatic uplift of New Caledonia in compensation for the rise in sealevel is also of insufficient amplitude to explain the uplift observed since about the last 2 m.y. Studies of the flexure of the lithosphere caused by subduction beneath the New Hebrides arc provide an explanation for the observed recent uplift of the emergent atolls of the Loyalty Islands