High-resolution facies zonation within a cold-water coral mound: The case of the Piddington Mound, Porcupine Seabight, NE Atlantic

Abstract

Framework-forming cold-water corals (CWC's) such as Lophelia pertusa and Madrepora oculata generate positive topographic features on the seabed called CWC mounds. In the North East Atlantic, CWC mounds have been studied in detail and reveal heterogeneous spatial on-mound organisation of coral patches. Many of these studies are limited by a paucity of remotely-sensed and video imagery at an appropriate resolution and coverage. This study is the first attempt to video mosaic an entire CWC mound (the Piddington Mound of the Moira Mounds, Porcupine Seabight, Irish margin). The mosaic is divided into 18,980 0.25m2 cells with a manual classification applied to each within a geographic information system (GIS). Geospatial analysis shows that cell distribution is not random but clustered significantly across the mound surface. These clusters of cells make up a ring-like facies pattern. A model for the processes that lead to this facies pattern is suggested based on contemporary environmental controls. Parallels to shallow-water reef atolls are also drawn which subsequently has implications for interpreting fossil coral outcrops.