Exploration Geophysics - Volume 9, Issue 3, 1978

Stage maps of the SW Pacific for 90, 60, 53, 38, 29, 21, 10 and 0 m.y. are interpreted using the geodynamic postulate that arc-marginal sea terrains are a response to complex zonal rotational flow in the asthenosphere. The zonal spreading model derived from this postulate explains the major phases of SW Pacific development and many of its specific features.

Olistostromes found in a number of major fold belts are of an age comparable with the start of under-thrusting as indicated by attendant arc-related volcanism. They occur at the inner edge of inferred accretionary wedges, and are commonly associated with contemporaneous basaltic rocks. These olistostromes may result from disruption of the crust during Hthosphere fracturing at the commencement of subduction. Components of the olistostromes provide evidence concerning the site of initial underthrusting.