ABSTRACT: A Plate Kinematic Framework for the Evolution of Basins in North New Guinea

TOWNSEND, PHIL, British Petroleum, Uxbridge, Middlesex, United Kingdom

The New Guinea margin of the Australian plate is a collage of terranes with a complex Cenozoic history. The sparcity of data from the basins requires alternative constraints on basin evolution. Quantitative plate kinematics provides a regional constraint to the Cenozoic evolution of the margin.

Published data are used to describe the relative motion of the Australia and Pacific plates through the Cenozoic. Prior to 42Ma there was little relative motion between the two plates. Local extension of the dominantly passive margin by propagation of Coral Sea spreading was approximately balanced by subduction beneath an island arc.

Post 42Ma there was rapid oblique convergence between the two plates. The convergence was distributed between several processes. Subduction led to collision of arcs with resultant dip slip mountain building continentward of, and strike slip basin formation oceanward of, the suture. Back arc spreading was also important. Reconstructions are presented which balance the above processes for particular time slices.

For the North New Guinea basins a generalized model is as follows. The passive margin was affected by earliest Tertiary diachronous extension to form a number of marginal oceanic basins. Post 42Ma subduction occurred both at the margin and at island arcs. Arc collision formed foreland basins, mountain belts and small collision basins on the sutures. Oblique processes then generate strike slip basins on the accreted terrane. Later further compression results from further collision or rapid subduction. The timing of the phases varies for the Ramu, Sepik, and North Irian Jaya basins and can be predicted from the kinematic model.

AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)