Normal fault growth and its function on the control of sedimentation during basin formation: A case study from field exposures of the Upper Cambrian Owen Conglomerate, West Coast Range, western Tasmania, Australia

Abstract

The evolution of a complex, ancient, segmented basin-margin fault system was examined using integrated structural relationships, lithostratigraphic architecture, facies architecture, and paleoflow trends to define the control on synrift development during the deposition of the Upper Cambrian Owen Conglomerate, West Coast Range, western Tasmania, Australia. Four distinct stages are recognized during the evolution of the normal fault array. The rift initiation stage defined early fault nucleation and isolated growth before fault interaction led to strain localization and the abandonment of antithetic faults. Renewed fault initiation led to further fault growth prior to the transition to rift climax stage, with the development of a throughgoing, linked array. Boundary faults propagated to near-maximum length prior to significant basin formation, whereas segment interaction clearly exerted a primary control on synrift distribution and paleogeography. Temporal fault evolution is marked by highly varied displacement patterns and pronounced lateral shifts in maximum synrift thickness accumulations. The case study presented here is compared with existing models of fault growth and provides a field example for the assessment of basin formation, particularly in polydeformed terranes, which can offer crucial high-resolution temporal data on fault system evolution, associated stratal architectures, and sediment dispersal patterns.