REWORKED JURASSIC-NEOGENE CALCAREOUS NANNOFOSSILS IN THE CENTRAL ARCTIC

Over 130 different reworked calcareous nannofossil taxa, ranging from the Lower Jurassic to the Neogene, are recorded in Quaternary sediment s from the central Arctic Ocean. Species with Mesozoic and Tertiary st ratigraphic ranges occur together. This suggests that the reworked spe cimens are not primarily derived from the local bedrock, but are trans ported to the central Arctic Ocean from the surrounding shelves and la ndmasses. Sea ice provides a possible means of transport. The reworked nannofossil assemblages in the Arctic are a result of geologic and cl imatic developments in the source areas, both during the time of their deposition and during their subsequent erosion and transportation in the Quaternary. Only two specimens restricted to the Lower Jurassic we re observed and none restricted to the Middle and Upper Jurassic. The Lower Cretaceous is represented by at least four species restricted to that interval, together with other long ranging taxa. The presence of Micrantholithus speetonensis Perch-Nielsen is the first record of thi s species outside northwest Europe. The other Lower Cretaceous species observed are all typical of temperate to high latitude assemblages of both the southern and northern hemispheres. The nannofossils reworked from the Upper Cretaceous strata are the dominant component of the as semblages. Nephrolithus corystus Wind is recorded in the northern hemi sphere for the first time. Some of the distinctive high latitude speci es present in the southern hemisphere have not been observed in the Ar ctic. Helioliths, discoasters and sphenoliths indicate relatively warm surface water conditions in the Arctic-subarctic areas during the Pal eocene and Eocene.