PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY OF THE AVEDAT GROUP (EOCENE) IN THE NORTHERN NEGEV, ISRAEL

The planktonic foraminifera of the early and middle Eocene 'Avedat Group were studied with the aid of the SEM. Forty-seven species belonging to 14 genera were recognized. Their distribution allows the subdivision of the four formations of the 'Avedat Group, i.e., the Mor, Nizzana, Horsha and Matred Formations, into the standard planktonic zones proposed by Bolli (1957a, b, 1966). Between two of the zones (Planorotalites palmerae and Hantkenina aragonensis) there is a stratigraphic interval clearly belonging to neither; a new zone, the 'Sphaeroidinellopsis' senni Zone, is proposed for this interval. Evolutionary relationships of middle Eocene foraminifera are discussed, and important taxa are illustrated.