Bulletin van de Belgische Vereniging voor Geologie vol:103 issue:3-4 pages:267-280
The microfossil content of the upper Paleocene parts of the Nahal Avdat section (Negev Desert, Israel) and the Abu Rudeis section (Sinai Desert, Egypt) was studied. Direct correlation of planktonic foraminiferal and calcareous nannofossil zonations results in positioning the NP9/NP10 zonal boundary within the top part of Zone P6a. Benthic foraminiferal assemblages in the two areas are diverse and very similar: 92 % of the more abundant species are observed at both s1tes. These sites were situated in the deeper parts of a NE-SW trending basin at a paleodepth of 500-700 m. The well-known deep-sea benthic extinction (within Zones P6a, NP9) is easily recognized by the sudden disappearance of Gavelinella beccariiformis, Angulogavelinella avnimelechi, Pullenia coryelli and other species within a 50 Kyr. times pan. In contrast to deep ocean sites, simple diversity drops only 17%, since the abundant shallow-water species in the assemblages are not affected. Post-extinction faunas are dominated by Nuttallides truempyi (up to 29%). In addition to this species a number of other species occur which seem to invade the deeper parts of the basin from shallow waters, immediately after the extinction. Infaunal morphotype abundance does not increase across the extinction level, indicating stable bottom water oxygenation. On the basis of these data, it is concluded that the hypothes1s involving a temporal shift of bottom water formation from high to low latitude, inducing warm saline bottom water to spread through all oceanic basins, is tenable. However, oxygen deficiency ofth1s postulated watermass originating at low latitudes, can not be the controlling factor 1n the worldwide extinction. A change in other properties, e.g. salinity and/or temperature, must at least have played a role as well.