Evolution of the Louisiade triple junction

We derived new finite rotations for the opening of the Coral Sea using revi sed magnetic anomaly interpretations and fracture zone data from a gravity anomaly grid based on from satellite altimetry. These rotations differ from the finite rotations that describe the opening of the Tasman Sea; this con firms the existence of a triple junction between the Australian Plate, the Mellish Rise, and the Louisiade Plateau active during the opening of the Co ral Sea (62 to 52 Ma). Magnetic anomalies, fracture zones visible on the gr avity grid, and strike-slip faults indicate that extension occurred between the Mellish Rise and the Louisiade Plateau, and extensional and transform motion occurred between Australia and the Mellish Rise (attached to the Che sterfield and Kenn Plateaus). The configuration of the triple junction from chron 27 to 26 was either ridge-ridge-ridge (RRR) or ridge-fault-fault (RF F). At chron 26 (58 Ma) the triple junction had a RFF configuration and mig rated southward as the relative motion between the Louisiade Plateau and th e Mellish Rise was transferred to the boundary between the Mellish Rise and the Kenn Plateau. The gravity low between the Kenn Plateau and the Mellish Rise is interpreted as a strike-slip fault active from about 57 to 52 Ma. This configuration lasted until seafloor spreading ceased in the Coral and Tasman seas at about 52 Ma. Our model implies extension in the Osprey Embay ment that might explain small areas of oceanic crust west of the Coral Sea Basin. The western boundary of the Coral Sea was a NE-SW strike-slip fault, active between 58 and 52 Ma.