CARBONATE: Mid latitude carbonate systems: complete sequences from cold-water coral carbonate mounds in the northeast Atlantic
Zusammenfassung der Projektergebnisse
The CARBONATE project supported by the European Science Foundation (ESF) focused on the investigation of cold‐water coral mounds in a variety of mound settings along the NE Atlantic margin comprising the northern Norwegian shelf (70°N) and the Irish, Moroccan and Mauritanian margins (17°N). The cold‐water coral species Lophelia pertusa and Madrepora oculata are the key agents being responsible for the build‐up of these up to 380 m high mound structures. The range of study areas allowed for a clear definition of the spatial variability of coral mounds and environmental controls on mound development. The contribution of the German project partners in Bremen (MARUM) and Wilhelmshaven (SaM) provided various highlights, which contributed significant new knowledge in particular to the (most probably climate‐related) long‐term development of cold‐water coral mounds and reefs: With coral ages of up to 10.9 ka BP, the colonisation of the northern Norwegian shelf by cold‐water corals needs to be preponed by ~2 kyrs compared to previous studies. This implies a very rapid emplacement of the Norwegian coral ecosystem during the Preboreal only 750 yrs after the termination of the Younger Dryas cold phase. Coral mound growth rates of up to 614 cm ka^-1 as indicated for a Stjernsund coral mound are 2‐3 times higher than previously reported fastest rates from Irish coral mounds and from the Norwegian Fugløy reef. High mound growth rates during the Preboreal are likely caused by enhanced meltwater discharge associated with enhanced input of terrestrial siliciclastic material. A specific benthic foraminifera fauna has been identified that is associated with Norwegian cold‐water coral growth periods. The stabilisation of cold‐water coral mounds along the Rockall Trough (where the tallest known mounds with >380 m in height exist) is enhanced by the occurrence of lithified layers, which have not been found in other coral mound areas such as the close‐by Porcupine Seabight. This observation has been attributed to compositional differences in the mound matrix sediments, which especially for the Rockall Trough sites is characterised by rather high carbonate contents. Cold‐water coral mounds along the Moroccan margin are almost as numerous as along the Irish margin but are much smaller (average height: 20‐30 m) compared to their Irish counterparts (max. height: 380 m). The occurrence of reef‐forming cold‐water corals along the Atlantic Moroccan margin was largely limited to the last glacial period (and prior glacial periods) as 95% of all available Moroccan coral ages plot into cold climate periods. The pronounced glacial coral growth coincides with conditions of enhanced primary production which resulted in enhanced food availability for the corals. In the upwelling area off Mauritania, cold‐water corals (alive and fossil) and coral mounds are common along an impressive 400‐km‐long continental margin sector. A very first coral age data set obtained from one individual Mauritanian coral mound point to enhanced coral growth during the last glacial (32‐65 ka BP). Enhanced bottom current strength and productivity‐related food supply are potential suspects to be the controlling environmental factors for Mauritanian coral growth. A see‐saw pattern in cold‐water coral growth along the NE Atlantic with the corals occurring predominantly north (interglacials) or south (glacials) of ~50°N reveals a strong climate influence on the geographical distribution and sustained development of these deep‐sea ecosystems. However, environmental control on sustained coral growth needs to be considered on a rather regional scale, although increased productivity and enhanced bottom current strength seem to be the primary controlling factors.
Projektbezogene Publikationen (Auswahl)
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(2008). Cruise report of R.V. Celtic Explorer cruise CE0810 INS_Deep Drill: Integrated National Strategic Deep‐Water Seabed Drilling Campaign: Long (>70m) Core Sample Recovery through Cold‐Water Coral Carbonate Mounds and Stratigraphically Strategic Sequences. Galway – Galway, 10th August – 8th September 2008, 50 pp.
Wheeler A, Dorschel B, de Haas H, Joseph N, Meyvis B, Wienberg C
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(2008). Pre‐drilling topographic, biological, hydrographical and seismic surveying of cold water coral carbonate mounds at the Rockall Trough margins. Cruise Report of R.V. Pelagia cruise M07II (64PE276), Galway – Galway, 30th September – 22nd October 2007, 18 pp.
de Haas H
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(2009). Holocene environmental variability in cold‐water coral reefs in Stjernsund, northern Norway, deduced from benthic foraminifera. In: Paläontologie. Schlüssel zur Evolution. 79. Jahrestagung der Paläontologischen Gesellschaft, 5.‐7. Oktober 2009, Bonn. Terra Nostra 2009/3: 57
Joseph N, López Correa M, Freiwald A
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(2010). Glacial cold‐water corals growth in the Gulf of Cádiz: Implications of increased palaeo‐productivity. Earth & Planetary Science Letters 298: 405‐416
Wienberg C, Frank N, Mertens KN, Stuut JB, Marchant M, Fietzke J, Mienis F, Hebbeln D
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(2010). Manche mögen's kalt – Der europäische Korallengürtel von Norwegen bis ins Mittelmeer. In: Wefer G, Schmieder F (eds), Expedition Erde. MARUM – Center for Marine Environmental Sciences, University of Bremen, pp 394‐401
Hebbeln D, Freiwald A
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(2010). The geology of European cold‐water coral carbonate mounds: the CARBONATE project. The Eggs (E.G.U.), Issue 30: 16‐22
Wheeler A, de Haas H, López Correa M, Wienberg C
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(2011). Die hängenden Gärten von Linosa. In: Jakobi N, von Neuhoff H, Springer B (eds), 25 Jahre FS Meteor – Ein Forschungsschiff und seine Geschichte(n). Hauschild, Bremen, pp. 108‐111
Freiwald A, Beuck L
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(2011). Northeastern Atlantic cold‐water coral reefs and climate. Geology 39 (8): 743‐746
Frank N, Freiwald A, López Correa M, Wienberg C, Eisele M, Hebbeln D, Van Rooij D, Henriet JP, Colin C, van Weering T, de Haas H, Buhl‐Mortensen P, Roberts JM, De Mol B, Douville E, Blamart D, Hatte C
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(2011). Sind Kaltwasserkorallen durch den Klimawandel gefährdet? In: Lozán JL, Graßl H, Karbe L, Reise K (eds) Warnsignal Klima: Die Meere – Änderungen und Risiken. Wissenschaftliche Auswertungen, Hamburg, pp. 183‐188
Freiwald A, Beuck L
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(2012). Preboreal onset of Norwegian cold‐water coral growth beyond the Arctic Circle revealed by radiocarbon and U‐series dating and neodymium isotopes. Quaternary Science Reviews 34: 24‐43
López Correa M, Montagna P, Joseph N, Rüggeberg A, Fietzke J, Flögel S, Dorschel B, Goldstein SL, Wheeler A, Freiwald A
