14. BOLBOFORMA BIOSTRATIGRAPHY FROM THE SOUTHEAST GREENLAND MARGIN, HOLE 918D¹

Silvia Spezzaferri² and Dorothee Spiegler³

ABSTRACT

Bolboforma is a problematic marine protophytic algae present in temperate and cool regions in both northern and southern hemispheres. It is the best calcareous microfossil group for biostratigraphic correlation of middle–upper Miocene sequence at high latitudes.

Bolboforma was found in Hole 918D during Leg 152 in the Irminger Basin (Southeast Greenland Margin). The recovered sedimentary sequence spans the interval from the middle Eocene to the Holocene. Seventeen species were identified in the interval spanning the upper Oligocene–upper Miocene. Eight zones were recognized and correlated to planktonic foraminiferal biozones and the calcareous nannoplankton zonation. The middle and upper Miocene Bolboforma zones were correlated to those identified in North Atlantic Deep Sea Drilling Project and Ocean Drilling Program Holes 116, 408, 555, 642B, 643A, and 646B. Bolboforma groenlandica n. sp. is introduced.

¹Saunders, A.D., Larsen, H.C., and Wise, S.W., Jr. (Eds.), 1998. Proc. ODP, Sci. Results,152: College Station, TX (Ocean Drilling Program).
²Dipartemento di Scienze delle Terra, Università di Milano, Via Mangiagalli 34, 20133 Milano, Italy. (Present address: ETH-Zentrum, Geologisches Institut, Sonneggstrasse 5, 8092, Zurich, Switzerland.) silvia@erdw.ethz.ch
³GEOMAR, Research Center for Marine Geoscience, Wischhofstrasse 1-3, Building 4, 24148 Kiel, Federal Republic of Germany.