The southwest pacific area during the last 90 million years

Maps of the southwest Pacific area at 90, 60, 53, 83, 29, 21, and 10 m.y. are accompanied by brief descriptions of the data and palaeogeographic developments in each major area within the region. There are four stages in. the regional palaeogeographic development: I (80–60 m.y.): Tasman Basin and New Caledonia Trough formed; II (60–53 m.y.): Coral Sea Basin formed; III (53–21 m.y.): A great Melanesian marginal sea formed, bounded by Cainozoic island arcs; IV (21 m.y. to present): Much of northern part of Melanesian marginal sea consumed during retrograde motion of island arcs. These developmental stages cannot be adequately explained by interaction between the Pacific and Australian crustal plates. A comprehensive explanation is given using the zonal spreading model proposed by Crook (1977).