Tectonic evolution of the northern Bonaparte Basin: impact on continental shelf architecture and sediment distribution during the Pleistocene

Abstract

The Bonaparte Basin (NW Australia) forms a rare, recent example where Neogene deformation shaped a very wide platform (630 km wide) in which a mixed carbonate-silliciclastic sedimentary sequence developed. This study combines structural and stratigraphic analysis and provides new insights as to the role of tectonics in controlling platform shape and sediment distribution in wide shallow water settings. Detailed analysis of the structure and stratigraphy of the northern part of the Bonaparte Basin allowed identification of the main regimes and phases of deformation and their control on sedimentation during the Neogene. The results reveal that the distribution of Neogene sediments across the northern Bonaparte Basin is mainly controlled by flexure-induced deformation mechanisms associated locally with extensional faults and low-strain, left-lateral strike-slip. These processes ultimately shaped the geometry and sedimentary architecture of the wide continental shelf. They led to the development of two different types of tectonically induced shelf depocentres that controlled the gross distribution of Quaternary sediments. In particular, deformation processes enhanced the formation of the carbonate-dominated, 200 m-deep Malita intra-shelf basin. The Bonaparte Basin is a prime natural laboratory to describe the links between tectonics and sedimentation along a very large, mixed carbonate/clastic platform and could be used as a modern analogue to similar settings in the past Earth's history.