Magnetic and Tectonic Fabric of the North Fiji Basin and Lau Basin

Abstract

Detailed airborne and shipboard magnetic studies conducted over the eastern marginal basins of the southwest Pacific between New Zealand and the Solomon Islands suggest that seafloor spreading in the North Fiji Basin, which began in the latest Miocene, continues today. The North Fiji Basin is marked by at least two tripie junctions, located in the central (16°50'S, 173°45'E) and northeastern (14°S, 179°30'E) parts of the basin. Both were apparently formed during the past five million years in response to continuing adjustments in the strike of the active spreading centers in the North Fiji Basin. Two additional contemporary spreading centers appear to have formed within the last one million years to the north and immediately to the west of Viti Levu. Although magnetic anomalies from 1 to 3 (0-5 Ma) are seen to form a cIearly defined lineation pattern over the North Fiji Basin, earthquake foci suggest that only portions of the present North FijiJLau Basin spreading center system are currently active.