Biostratigraphy and paleoecologic inferences during the late Campanian-Maastrichtian interval: Evidence based on calcareous nannofossils from Goban Spur

This paper presents a biostratigraphic revision and a quantitative study of the calcareous nannofossils from DSDP Leg 80 - Hole 550B. A total of 42 samples were analyzed, revealing 78 species whose preservation varied from slightly to moderately dissolved with slight to severe overgrowth. Biostratigraphy indicates deposition during the late Campanian to late Maastrichtian, incorporating zones UC15d to UC20b. The quantitative nannofossil data recovered shows that Watznaueria barnesiae and Micula staurophora dominate the assemblages, which can be attributed to a low preservation potential for the depositional environment. Cold-water taxa (Kamptnerius magnificus, Ahmuellerella octoradiata, and Arkhangelskiella cymbiformis) are present in very low percentages, with their maximum values occurring inside the UC17 biozone.