Microstructure, growth banding and age determination of a primnoid gorgonian skeleton (Octocorallia) from the late Younger Dryas to earliest Holocene of the Bay of Biscay.

Noé, Sibylle, Lembke-Jene, Lester, Reveillaud, Julie and Freiwald, Andre (2007) Microstructure, growth banding and age determination of a primnoid gorgonian skeleton (Octocorallia) from the late Younger Dryas to earliest Holocene of the Bay of Biscay. Facies, 53 (2). pp. 177-188. DOI 10.1007/s10347-007-0104-6.

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Abstract

A fossil primnoid gorgonian skeleton (Octocorallia) was recovered on the eastern Galician Massif in the Bay of Biscay (NE Atlantic) from 720 m water depth. The skeleton shows a growth banding of alternating Mg–calcitic and organic (gorgonin) increments in the inner part, surrounded by a ring of massive fibrous calcite. Three calcite-dominated cycles, bounded by thick organic layers, consist of five light-dark couplets of calcite and gorgonin. Two AMS-14C datings of the fossil skeleton give ages of 10,880 and 10,820 ± 45 14C years before present (BP). We arrive at a calibrated age range of 11,829–10,072 cal. years BP (two σ), which comprises the late Younger Dryas to the earliest part of the Holocene. The cyclic calcitic–organic growth banding may be controlled by a constant rate of calcite secretion with a fluctuating rate of gorgonin production, possibly related to productivity cycles. The skeletal fabric change of alternating calcitic–organic increments to massive fibrous calcite may be the result of hydrographic changes during the deglaciation as reflected by preliminary stable isotope data. If this hypothesis proves to be correct, primnoid gorgonians are able to match with varying hydrodynamic conditions by changing their biomineralisation mode.

Document Type: Article
Keywords: Primnoid gorgonian, Microstructure, Growth banding, Radiocarbon dating, Younger Dryas to Holocene, Bay of Biscay
Research affiliation: OceanRep > Leibniz-Institut für Meereswissenschaften
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1007/s10347-007-0104-6
ISSN: 0172-9179
Date Deposited: 03 Dec 2008 16:51
Last Modified: 05 Jan 2017 08:28
URI: http://oceanrep.geomar.de/id/eprint/6941

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