Ancient fluid flow recorded by remarkably long, buried pockmark trains observed in 3D seismic data, Exmouth Plateau, Northern Carnarvon Basin

Abstract

We present 3D seismic data from the Exmouth Plateau, offshore northwest Australia shows 275 paleo-pockmarks of latest Jurassic age, organised into three linear NNW-SSE oriented pockmark trains, the longest exceeding 72 km. Spatial statistics indicate a high probability that these linear pockmark arrangements are not random. The trains are parallel to an array of linked normal faults with similar NNW-SSE strikes, with pockmarks underlain by feeder pipes that nucleate along or close to the fault planes. We interpret the faults to have intersected an overpressured unit and acted as a spatial control on the development of the feeder pipes and pockmarks. Our results reveal an important role of faults in controlling laterally extensive pockmark trains, and highlight the value of 3D seismic data in identifying large-scale ancient fluid flow within sedimentary basins.