Stratigraphic correlation across an arc‐continent collision zone: timor and the Australian northwest shelf

Abstract

The Kolbano area of southern West Timor comprises the subaerially exposed upper part of an imbricate stack at the leading edge of the Timor arc‐continent collision zone. Rocks of Permian to Plio‐Quaternary age are exposed in the Kolbano Complex. Detailed stratigraphic correlation between the Kolbano area and the Northwest Shelf of Australia (as recorded from petroleum exploration wells) demonstrates that the Kolbano area has close stratigraphic links with the Northwest Shelf, in particular with the Ashmore Block and Sahul Platform. Reconstruction of Jurassic‐Neogene palaeoenvironments for the Kolbano area indicates that the Kolbano area represents the outermost edge of the precollisional Australian passive margin. The region has been considerably shortened by Pliocene tectonism, but retains a predeformational distribution of facies with respect to Australia. The northern half of Timor is composed largely of Australian continental margin material. As this now lies to the north of the Kolbano area, interpretations of Timor involving primarily vertical crustal movements would seem to be inadequate. A new model for the evolution of Timor invokes a significant component of wrench faulting in the deformation.