Publications

The Banda Arc in eastern Indonesia is at the core of the three-plate collisional interaction between Australia, Sundaland and the Pacific. Arc-continent collision around the Banda Arc has developed largely since the Late Miocene, but earlier key tectonic events include backarc spreading in the North Banda Basin commencing during the Middle Miocene, and earlier phases of arc-continent collision and strike-slip translation extending back to the Oligocene or Early Miocene. New plate reconstructions for the Banda Arc region are presented at 1m.y. intervals since 30Ma. Two fundamental differences between the new and previous reconstructions (e.g. Hall, in Spakman and Hall, 2010) are a substantial (>30°) counterclockwise rotation of the Bird’s Head since ~6Ma, and the origin of backarc spreading in the North and South Banda Basins by a process of ‘fixed slot’ subduction geometry, not trench rollback. Since 30Ma, 4 distinct phases of plate movement are interpreted: • 30-18Ma: Initial collision and then indentation of the ‘Greater Sula Spur’ Australian continental promontory into an eastward continuation of the present Sunda Arc subduction system. • 18-12Ma: Terranes north of the Sorong Fault Zone including eastern Sundaland moving WSW relative to Australia, with the motion of the Pacific plate. • 12-6Ma: Development of the proto-Banda Arc, with relative motion between Sundaland and Australia accommodated by fixed-slot backarc spreading in the North Banda Basin. • 6-0Ma: Collision around the Banda Arc, and overtightening of the arc curvature by the counterclockwise rotation of the Bird’s Head.