The giant Mauritanian cold-water coral mound province: Oxygen control on coral mound formation

• Published in: Quaternary science reviews 2018-04, Vol.185, p.135-152
• Main Authors: Wienberg, Claudia, Titschack, Jürgen, Freiwald, André, Frank, Norbert, Lundälv, Tomas, Taviani, Marco, Beuck, Lydia, Schröder-Ritzrau, Andrea, Krengel, Thomas, Hebbeln, Dierk
• Format: Article
• Language: English
• Subjects: Atlantic-Ocean; Continental interfaces, environment; Coral mound; covered carbonate mound; deep-sea corals; Dissolved oxygen concentration; Earth Sciences; Ecology; Ekologi; Gulf-of-Mexico; Last glacial; last glacial maximum; Lophelia pertusa; lophelia-pertusa scleractinia; Mauritanian margin; mingulay reef complex; Mound aggradation rate; Northeast Atlantic; Northwest Africa; Oceanografi, hydrologi, vattenresurser; Oceanography; Oceanography, Hydrology, Water Resources; rockall trough margin; Sciences of the Universe; South Atlantic Central Water; Submarine canyon; Uranium-series dating
• ISSN: 0277-3791; 1873-457X
• DOI: 10.1016/j.quascirev.2018.02.012

The largest coherent cold-water coral (CWC) mound province in the Atlantic Ocean exists along the Mauritanian margin, where up to 100 m high mounds extend over a distance of ∼400 km, arranged in two slope-parallel chains in 400–550 m water depth. Additionally, CWCs are present in the numerous submarine canyons with isolated coral mounds being developed on some canyon flanks. Seventy-seven Uranium-series coral ages were assessed to elucidate the timing of CWC colonisation and coral mound development along the Mauritanian margin for the last ∼120,000 years. Our results show that CWCs were present on the mounds during the Last Interglacial, though in low numbers corresponding to coral mound aggradation rates of 16 cm kyr−1. Most prolific periods for CWC growth are identified for the last glacial and deglaciation, resulting in enhanced mound aggradation (>1000 cm kyr−1), before mound formation stagnated along the entire margin with the onset of the Holocene. Until today, the Mauritanian mounds are in a dormant state with only scarce CWC growth. In the canyons, live CWCs are abundant since the Late Holocene at least. Thus, the canyons may serve as a refuge to CWCs potentially enabling the observed modest re-colonisation pulse on the mounds along the open slope. The timing and rate of the pre-Holocene coral mound aggradation, and the cessation of mound formation varied between the individual mounds, which was likely the consequence of vertical/lateral changes in water mass structure that placed the mounds near or out of oxygen-depleted waters, respectively. •Enhanced formation of Mauritanian coral mounds during the last glacial and deglacial.•Coral mound aggradation reached rates of up to 16 m kyr−1•Mauritanian corals mounds are in a dormant state since the Early Holocene.•Dissolved oxygen concentrations represent an important control on mound formation.•Submarine canyons offer a refuge for cold-water corals and act as source for larvae supply.