PALAEOZOIC TECTONICS, AMADEUS BASIN, CENTRAL AUSTRALIA

Abstract

The Amadeus Basin is divided into a number of structural provinces that developed during the Palaeozoic Alice Springs Orogeny, the course of which is described in terms of: Early Palaeozoic preorogenic crustal extension and basin development; Late Ordovician-Carboniferous NE-SW compressional orogenesis; and Late Carboniferous-(?)Early Permian NW-SE compression.

The Southern Province is composed largely of Proterozoic formations that had been deformed during the Petermann Ranges Orogeny. The Central Anticlinal Province is a shear zone of four en echelon trends. The Parana Hills and Mereenie trends have a left lateral orientation to each other and formed during the first phase of orogenesis; the Gardiner Range and James Range trends are right lateral and formed during the second stage. Structures in the Northern Province were created by decollement within the evaporite-bearing Bitter Springs Formation and, to a lesser extent, in the Cambrian Chandler Formation, and by collapse of the basin fill under the burden of the Brewer Conglomerate in a style similar to the formation of diapirs along the northern front of the Pyrenees. The MacDonnell Homocline is a mountain front tip line that resembles the Triangle Zone of the Canadian Rocky Mountains. The Allambi Thrust Zone separates the Northern Province from the Camel Flat Platform that bears diapiric salt walls derived from the Chandler Formation.

The varying stress field and revised time scale for orogeny may be of significance to evaluation of reservoir fracture patterns and source rock maturation curves.