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McCARTHY, LLYNNE D., University College London / British Museum (Natural History)

ABSTRACT: Colombian Late Cretaceous Tropical Planktonic Foraminifera: Redressing the Imbalance!

Recent work involving Late Cretaceous planktonic foraminifera has concentrated on European and other areas in the Northern Hemisphere. Many of the biostratigraphical and evolutionary models reflect this geographical restriction and ignore earlier studies from tropical areas. In 1955 Rolando Gandolfi described many new species and subspecies from Colombia and provided a different view of the evolutionary development of planktonic foraminifera. A re-examination of the Gandolfi type collection using Scanning Electron Micrography (Environmental Chamber technique) integrated with Colombian well samples from onshore Guajira area, Middle and Upper Magdalena Valley and Putumayo Basin has given a new view into the evolutionary development of Late Cretaceous planktonic foraminifera. This has en bled a modified globigerine Late Cretaceous biostratigraphy to be constructed for Colombia. This work redresses the imbalance between studies of tropical and northern high latitude Late Cretaceous planktonic foraminifera and provides an insight into the palaeoenvironmental and palaeoclimatological factors influencing the Colombian region at the time.

AAPG Search and Discovery Article #90988©1993 AAPG/SVG International Congress and Exhibition, Caracas, Venezuela, March 14-17, 1993.