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Accueil > Publications > Recherche par années > Années 1990 > 1999

Barbieri, R ; D’Onofrio, S ; Melis, R ; Westall, F

R-Selected benthic foraminifera with associated bacterial colonies in Upper Pleistocene sediments of the Ross Sea (Antarctica) : implications for calcium carbonate preservation

Palaeogeography Palaeoclimatology Palaeoecology 149 (1-4) 41-57

par Administrateur - publié le

Abstract :

Investigations on foraminifera from Upper Pleistocene-Holocene sediments cored in the continental slope of the western Ross Sea (2383 m water depth) revealed that the record of calcareous assemblages was restricted to a limited time interval (approximately 6 kyr) and characterized by a dominance of phytodetritus-exploiting taxa, such as Alabaminella weddellensis and Epistominella exigua. Rod-shaped calcified, fossil bacteria infest the partially dissolved calcareous foraminiferal surfaces, either as clusters or as isolated cells, suggesting that significant changes (from under-to oversaturated conditions with respect to calcium carbonate) in the chemistry of the seawater developed before the final burial of the foraminiferal tests. We postulate that bacterial activity on a microenvironmental scale (interface and pore water) in the sea floor could influence pore water conditions in such a way as to preserve carbonate in deep marine regions where environmental conditions usually prevent the establishment of carbonate secreting communities. (C) 1999 Elsevier Science B.V. All rights reserved.