Part 1. East Autralian margin and the western marginal basins: The relationship between structures on the southeast Australian margin and in the Tasman Sea

Abstract

A study of the magnetic anomaly pattern in the Tasman Sea has shown that it opened by a process of sea floor spreading between about 80 and 60 my.b.p. (Hayes and Ringis, 1973). The spreading pattern appears to have been quite complex. The basin is disected by many fracture zones (transform faults) and there appears to have been considerable variation in spreading rates within blocks bounded by these fracture zones. This is clearly shown by the varying widths of crustal blocks generated in periods of 5 m.y., as shown in Figure 1. Further, the trend of the magnetic pattern, and hence crustal isochrons, intersects the trend of the southeast Australian margin at an angle of about 45° to 50° . As a result, progressively older oceanic crust is absent north of Bass Strait.