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Tertiary dinoflagellate biostratigraphy of sites 907, 908, and 909 in the Norwegian-Greenland Sea.
| Poulsen,N.E., Manum, S.B., Williams, G.L and Ellegaard, M. | |
| 1996 | |
| Proceedings of the Ocean Drilling Program, Scienlific Results, Vol. 151, p. 255-287.Proceedings of the Ocean | |
| Tertiary dinoflagellate biostratigraphy of sites 907, 908, and 909 in the Norwegian-Greenland Sea. |
Poulsen,N.E., Manum, S.B., Williams, G.L and Ellegaard, M., 1996. Tertiary dinoflagellate biostratigraphy of sites 907, 908, and 909 in the Norwegian-Greenland Sea. Proceedings of the Ocean Drilling Program, Scienlific Results, Vol. 151, p. 255-287. ABSTRACT Oligocene and Miocene cores from Ocean Drilling Program Leg 151 Holes 907A, 908A, 909C, and 913B in the Norwegian-Greenland Sea were studied palynologically, using a total of 300 samples. Dinoflagellate cysts are present in all samples, allowing age interpretations for all holes. At Site 907 on the Iceland Plateau, the deepest sediments show a Langhian-Serravallian assemblage and the highest section studied (Cores 151-907A-16X to 9H) has an undifferentiated Tortonian to Pliocene assemblage. Oceanic conditions warmer than the present day and poor nutrient conditions are deduced from the taxonomic composition. Sites 908 and 909 in the Fram Strait are less than 50 km apart in very contrasting situations: Site 909 is in 2500 m water depth on the Greenland-Spitsbergen Sill and Site 908 is on the Hovgard Ridge, elevated to more than 1000 m above the surrounding seafloor. Organic residues from both sites are dominated by terrestrially derived palynomorphs and plant fragments (many >100 tlm), and dinocyst/pollen ratios are relatively low. This indicates relatively nearshore depositional environments almost to the end of the Miocene. Palynology supports and supplements the plate tectonic model for the origin of the Hovgard Ridge as a micro-continental sliver from the Svalbard Platform. At Site 909, dinoflagellates date a near complete Miocene succession with two possible stratigraphic breaks in the Langhian-Serravallian interval. Throughout the Langhian-Serravallian to Messinian-Zanclean? interval, warm-water species indicate temperate conditions. At Site 908, 160 m of late Rupelian-early Chattian sediments are unconformably overlain by late Miocene sediments, leaving a hiatus of 15 to 18 m.y. A series of conspicuous acmes observed within three species at Site 909 could be used to date the truncated Miocene section at Site 908. Cyst reworking in the sediments at Sites 908 and 909 is consistently of late Early Cretaceous and early Paleogene ages and shows a Late Cretaceous gap corresponding to the Albian-Paleogene hiatus observed in the late Mesozoic-Cenozoic formations on Spitsbergen.