QUATERNARY PALEOCEANOGRAPHIC AND PALEOCLIMATIC CHANGES, PEDRO BANK REGION, NORTHERN NICARAGUA RISE (CARIBBEAN SEA): A COMPARISON OF PLANKTIC FORAMINIFERAL BIOSTRATIGRAPHY AND MARINE ISOTOPE STAGE RECORDS

The Globorotalia menardii complex, a group of highly temperature sensitive planktic foraminifera, is used here to develop a biostratigraphic framework and as a paleoclimatic proxy for a piston core, sediment record recovered from 1203 m of water SE of Pedro Bank, northern Nicaragua Rise (Caribbean). The foraminifera of the G. menardii complex are warm, surface water dwellers which are typically absent from cold surface waters. Thus they can be used to infer climatic changes based on changing surface water temperatures. Ericson zones Z-V, based on the presence/absence and abundance of G. menardii complex, were identified in the core. These zones, which reflect changing sea surface temperatures, suggest that four glacial-interglacial climatic shifts have occurred over the duration of sediment deposition. An δ¹⁸O record from this core shows Marine Isotope Stages (MIS) 1-7 to be present. A comparison of the biostratigraphic and δ¹⁸O records indicate the occurrence of several glacial-interglacial climatic shifts and suggest possible changes in ocean circulation and sediment accumulation patterns. A future hypothesis to examine in light of these results is that benthic foraminiferal assemblages will reflect similar glacial-interglacial and ocean circulation changes as well as variations in sediment accumulation and distribution patterns.