Further evidence for the Early Cretaceous breakup of Gondwanaland off southwestern Australia

Abstract

Magnetic anomalies adjacent to the northwest margin of the Naturaliste Plateau are identified as Early Cretaceous reversals M-0 through M-4. These lineations indicate that northwest—southeast sea-floor spreading began off the present Naturaliste Plateau circa 118 m.y. B.P., 8 m.y. later than along the adjacent continental margin off Perth. The Naturaliste and Perth lineation sequences are offset 130 km dextrally by a fracture zone which passes near DSDP Site 257. The data indicate that an intracratonic small ocean basin existed seaward of Perth from about 126 to 118 m.y. B.P.