Discriminating between the origins of remotely sensed circular structures; carbonate mounds, diapirs or periclinal folds? Purbeck Limestone Group, Weymouth Bay, UK

Many sedimentary rock successions contain plan-view circular structures such as impacts, diapirs and carbonate buildups. When remotely sensed, it can be difficult to discriminate between their formation mechanisms. Here we examine this problem by assessing the origins of circular structures imaged in high-resolution multibeam bathymetric data from Weymouth Bay (UK). The imagery shows 30-150 m across, concave-down structures within the upper Purbeck Limestone Group on the southern limb of the Purbeck Anticline. Similar structures have not been identified in the extensive outcrops around the Bay.