Late Cretaceous to Early Tertiary Agglutinated Benthic Foraminifera in the Labrador Sea

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Abstract
A major faunal change occurred at the end of the Eocene in the deep Labrador Sea (Deep Sea Drilling Project Site 112). Predominantly agglutinated Eocene benthic foraminiferal assemblages are replaced by an Oligocene calcareous assemblage. This replacement correlates with similar changes in the Canadian margin and the North Sea where the exit of agglutinated foraminifera is associated with a change in depositional environment. In Site 112 lithology, percent carbonate and percent organic C are relatively constant across the faunal change. At least in the deep sea, these properties may not be critical to the development of predominantly agglutinated assemblages. Certain hydrographic properties (low O2, high CO2, low pH and thus more corrosive waters) probably favor the development of agglutinated assemblages. The replacement of agglutinated foraminifera in the deep Labrador Sea probably was due to a change in hydrographic properties. Seismic evidence from this region indicates initiation of northern sources of bottom water in the Late Eocene to Early Oligocene which may have resulted in a change in hydrography and the exit of agglutinated foraminifera. Despite diachrony of certain occurrences in Site 112 and the Canadian margin, compared with previously reported ranges of agglutinated taxa from the North Sea, European flysch basin and the deep sea, agglutinated foraminifera are useful in the zonation of Labrador Sea sediments.

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