Enigmatic seafloor structures in the Perth Basin (Houtman Sub-basin), offshore Western Australia: deep-water carbonate mounds or volcanic cones?

摘要

Deep-water mounds located in greater than 1500m water offshore Perth Basin in Western Australia are imaged by several vintages of seismic-reflection lines. The majority of the mounds, concentrated south of the deeply-incised submarine Murchison Canyon, are sharply defined with a pinnacle-like morphology, suggesting little erosion and a recent origin. The morphology of these mounds is discussed and either a bioherm origin, a volcanic origin or a combination of the two is considered likely. Should these mounds be related to hydrocarbon seepage, their presence may indicate an active hydrocarbon system. Other mounds appear to be igneous plugs or diatremes: proof of such an origin may require a reappraisal of the tectonic and magmatic history of the offshore Perth Basin and the maturation history of petroleum source beds.