The transgressive sedimentary sequence of the Notnnea Basin contains rhyolitic lavas and less voluminous mafic and
intermediate volcanims of shoshonitic affinities which erupted simultaneously during the late Cretaceous. The shoshonitic
volcanism shows a trend from early inafic to younger evolved intermediate lithologies. The rhyolites are consistently calc- alkaline. There is no evidence of 'mixing, of, the two magma types. The shoshonitic volcanism is the result of a short-lived
subduction event related to sprcadime in the New Caledonia Basin and involved reactivation of an earlier Mesozoic
subduction zone.