Sedimentation patterns on a cold-water coral mound off Mauritania

• Published in: Deep Sea Research Part II: Topical Studies in Oceanography
• Main Authors: Eisele, Markus, Frank, Norbert, Wienberg, Claudia, Titschack, Jürgen, Mienis, Furu, Beuck, Lydia, Tisnerat-Laborde, Nadine, Hebbeln, Dierk
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2014
• Subjects: Lophelia pertusa; Planktonic foraminifera
• Online Access: https://oceanrep.geomar.de/id/eprint/29781/; https://oceanrep.geomar.de/id/eprint/29781/1/1-s2.0-S0967064513002762-main.pdf; https://doi.org/10.1016/j.dsr2.2013.07.004

Highlights: • Cold-water coral mound formation is mainly influenced by the baffling of fine grained material within a coral framework. • Mass wasting appears to be an important mound progradation process. • Even heavily reworked sediments contain valuable information on the original mound aggradation processes. Abstract: An unconformity-bound glacial sequence (135 cm thick) of a coral-bearing sediment core collected from the flank of a cold-water coral mound in the Banda Mound Province off Mauritania was analysed. In order to study the relation between coral framework growth and its filling by hemipelagic sediments, U-series dates obtained from the cold-water coral species Lophelia pertusa were compared to 14C dates of planktonic foraminifera of the surrounding matrix sediments. The coral ages, ranging from 45.1 to 32.3 ka BP, exhibit no clear depositional trend, while on the other hand the 14C dates of the matrix sediment provide ages within a much narrower time window of <3000 yrs (34.6–31.8 cal ka BP), corresponding to the latest phase of the coral growth period. In addition, high-resolution computer tomography data revealed a subdivision of the investigated sediment package into three distinct parts, defined by the portion and fragmentation of corals and associated macrofauna as well as in the density of the matrix sediments. Grain size spectra obtained on the matrix sediments show a homogeneous pattern throughout the core sediment package, with minor variations. These features are interpreted as indicators of redeposition. Based on the observed structures and the dating results, the sediments were interpreted as deposits of a mass wasting event, namely a debris flow. During this event, the sediment unit must have been entirely mixed; resulting in averaging of the foraminifera ages from the whole unit and giving randomly distributed coral ages. In this context, for the first time mass wasting is proposed to be a substantial process of mound progradation by exporting material from the mound top to the ...