Imprint of Holocene Climate Variability on Cold-Water Coral Reef Growth at the SW Rockall Trough margin, NE Atlantic
Type | Article | ||||||||
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Date | 2018-08 | ||||||||
Language | English | ||||||||
Author(s) | Bonneau Lucile1, 2, 3, Colin Christophe2, Pons-Branchu Edwige1, Mienis Furu4, 5, Tisnerat-Laborde Nadine1, Blamart Dominique1, Elliot Mary6, Collart Tim7, Frank Norbert3, Foliot Lorna1, Douville Eric1 | ||||||||
Affiliation(s) | 1 : Univ Paris Saclay, CEA CNRS UVSQ, Lab Sci Climat & Environm, LSCE IPSL, Gif Sur Yvette, France. 2 : Univ Paris Saclay, Univ Paris Sud, Lab GEOsci Paris Sud GEOPS, CNRS,UMR 8148, Orsay, France. 3 : Heidelberg Univ, Heidelberg, Germany. 4 : Royal Netherlands Inst Sea Res NIOZ, Den Burg, Netherlands. 5 : Univ Utrecht, Den Burg, Netherlands. 6 : Univ Nantes, LPGNantes, Nantes, France. 7 : Univ Ghent, Dept Geol, Ghent, Belgium. |
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Source | Geochemistry Geophysics Geosystems (1525-2027) (Amer Geophysical Union), 2018-08 , Vol. 19 , N. 8 , P. 2437-2452 | ||||||||
DOI | 10.1029/2018GC007502 | ||||||||
WOS© Times Cited | 12 | ||||||||
Abstract | U‐Th ages and temperatures derived from Li/Mg have been measured on coral fragments of Lophelia pertusa and Madrepora. oculata collected from two sediment cores, which were taken from cold‐water coral (CWC) mounds at 700 ‐ 790 m water depth at the SW Rockall Trough margin. Our data, combined with previous published data, have allowed us to firstly estimate the occurrence of CWC at the SW Rockall Trough margin during the Holocene and, secondly, to better constrain the environmental conditions driving variability in CWC growth. CWC abundance is marked by a pronounced increase in the mid‐Holocene (∼6 ka) and is modulated by millennial‐scale variability throughout the late Holocene. The mid‐Holocene proliferation of CWC coincides with lowest IRD abundances and a major re‐organization of the circulation at thermocline depth in the Rockall Trough, marked by the progressive replacement of the fresh‐cold SubArctic Intermediate Water (SAIW) by the saltier and nutrient‐rich Eastern North Atlantic Water (ENAW). This event must have established a modern‐like winter mixed layer and thermocline structure, generating suitable conditions for enhanced surface productivity, downslope transport of food particles, bottom current acceleration at mound depth and thus CWC growth. Several short time intervals of decreased CWC occurrences closely match prominent increases in North Atlantic drift ice and storminess in Northern Europe. We, therefore, propose that high detrital supply and/or changes in the vertical density gradient associated with millennial‐scale ice rafted detritus (IRD) events are the likely controlling factors for CWC growth and subsequent mound formation on the SW Rockall Trough margin. |
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