Structure and development of giant carbonate mounds at the SW and SE Rockall Trough margins, NE Atlantic Ocean

High-resolution seismic reflection profiling carried out in 1997–1999 showed that giant carbonate mounds occur between 500 and 1200 m water depth along both the SE and SW margins of Rockall Trough. The mounds rise 5–300 m above the surrounding seafloor and have diameters at their bases of up to 5 km. Buried mounds, at relatively shallow depths below the seafloor, are also found. Both individual and complex clusters of mounds can be recognized. Smaller and individual, sometimes buried mounds are found at the upper slope. On the SW Rockall Trough margin, higher, steeper and individual mounds are found deeper downslope (900–1100 m). At the middle slope the mounds merge into a complex structure and form complex clusters with a very irregular upper surface and an apparent lack of internal reflectors (600–1000 m depth). Initial results of high-resolution 3D-seismic profiling at 30 m line spacing in August 2000 in two boxes of 750 m×14.5 km covering a small, central part of the SW Rockall Trough mound area indicate two stages of mound development here, the latest probably of Pliocene–Holocene age. This age, based on the presence of a regionally recognizable unconformity below the mounds, is also assumed for the mounds of the SE Rockall Trough (Porcupine Bank) margin. [Copyright &y& Elsevier]