AGGLUTINATED BENTHIC FORAMINIFERAL BIOSTRATIGRAPHY OF SITES 909 AND 913, NORTHERN NORTH ATLANTIC

Lisa E. Osterman and Dorothee Spiegler

ABSTRACT

  Agglutinated benthic foraminifers occur in Eocene to Miocene sediments at Ocean Drilling Program (ODP) Sites 909 and 913 in the northern North Atlantic Ocean. At Site 909, in the Fram Strait, four assemblages, dominated by Reticulophragmium ex gr. Rotundidorsata and Reticulophragmium amplectens, range in age from middle to late Miocene. At Site 913, in the Greenland Basin, five assemblages, containing Reticulophragmium amplectens and Reophax abyssorum, range in age from the early Eocene to Miocene. The stratigraphic ranges of the agglutinated benthic foraminifers of Site 913 agree with previously published species ranges. However, the stratigraphic ranges of many of the agglutinated species at Site 909 extend into the upper Miocene. These are the youngest reported ranges for some agglutinated species in the North Atlantic basins. These newly reported occurrences provide information about the deep-water exchange between the North Atlantic and the Arctic ocean during the Eocene to Miocene. This study suggests that during the Miocene, the Fram Strait was a high sedimentation-rate, depositional basin with isolated bottom water. This depositional environment favored the preservation of the agglutinated benthic foraminiferal assemblages long after their disappearance from the rest of the North Atlantic.

Date of initial receipt: 5 July 1995
Date of acceptance: 21 December 1995


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