CONSTRAINING THE AGE OF THE NOUMEA BASIN: ISOTOPE AGES AND PALEOMAGNETIC DATA FROM NEW CALEDONIA

New Caledonia lies on the Norfolk Ridge in the southwest Pacific Ocean just off the present day Australian and Pacific plate margin. The Noumea basin trends northwest from the capitol of Noumea and contains a bi-modal sequence of silisic and mafic volcanic rocks. Preliminary interpretations show the silisic rocks predate the basaltic suit and provide an upper limit on the age of the basin. In addition, the historic magnetic orientations of the Noumea basin rocks have not been examined. U/Pb and Ar/Ar isotope ages of the rock suits will constrain the geologic age of the Noumea basin. Polarity zones taken from the paleomagnetic cores will further constrain the temporal relationships when compared to the global magnetochron record. Identifying the age of these volcanic rocks could help correlate volcanic activity seen throughout the south Pacific at this time. The paleomagnetic orientation of the rocks will help recreate the historic plate motion of the Noumea basin. These data will provide further insight on the perplexing Australian and Pacific plate subduction zone interaction of the late Cretaceous. The combination of the isotope and paleomagnetic data will help develop the Cretaceous to Eocene geologic history of New Caledonia by expanding what we know about the tectonics controlling the historic micro-plate motion of the south Pacific.