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Relatively rich marine palynomorph assemblages consisting mainly of dinocysts, but also of microforaminifers and acritarchs, occur throughout the Apto-Albian sequences in Holes 400A and402A. Of the sporomorphs, bisaccate pollen grains are always abundant and spores are relatively frequent only in Hole 402A. Dating was effected by the comparison of dinocyst distributions here with those in southern England and France. The early-late Aptian boundary is situated between Sections 72-3 and 70-0 in Hole 400A, and near Section 33-6 in Hole 402A. The Apto-Albian boundary is placed immediately above Section 67-0 in Hole 400A and between Sections 26-1 and 25-5 in Hole 402A. Lower Albian was not positively identified and, in Hole 400A, Sections 66-3, 65-2, and probably 64-3 are considered to be of middle Albian age. Only upper Albian was identified above the latter section. The Albian in Hole 402A could not be identified above the latter section. The Albian in Hole 402A could not be subdivided. Palynomorph distribution indicates that the Apto-Albian in Hole 400A was deposited at a reasonable distance from the landmass and probably not on the continental shelf. In contrast, contemporaneous deposition at Site 402A is considered to be nearshore. The characteristics of oceanic and epicontinental assemblages are discussed. The richness of the dinocyst assemblages has necessitated a section on their systematics; three new genera, Bacchidinium, Hapsocysta, and Nexosispinum, and twelve new species,B. sarmentum, Codoniellapsygma, Gonyaulacystapolythris, H. dictyota, N, hesperum, Nematosphaerospsis singularis, Oligosphaeridium verrucosum, Ovoidinium diversum, O. implantum, Spiniferites confossus, Surculosphaeridium trunculum, and Systematophora cretacea are proposed. INTRODUCTION Hole 400A Hole 400A (47°22.90'N, 09°11.90'W) is located at the foot of the Meriadzek Escarpment near the ocean-continent boundary on the northern continental margin of the Bay of Biscay. It is situated about 300 kilometers west of Brest (Brittany) in a water depth of 4399 meters. The top of the Albian was penetrated at 654 meters and the hole terminated at 777.5 meters within the lower Aptian. The Albian is overlain by a thin Campanian-Maestrichtian interval. Cores 62 to 74 were taken in the Apto-Albian sequence, which consists principally of interbedded marly nanno-chalk and sapropelic mudstone; samples from all of these cores, except Core 73, have been analyzed palynologically. Hole 402A Hole 402A (47°52.48'N, 08°50.44'W) is located on a spur of the northern continental margin of the Bay of Biscay north 'By permission of the Director, Institute of Geological Sciences, Great Britain. Present address: Robertson Research International Limited, 'Ty'nY-Coed', Llanrhos, Llandudno, Gywnedd, North Wales, United Kingdom. of the Meriadzek Escarpment in a water depth of 2339.5 meters. It is situated about 320 kilometers west of Brest (Brittany). The top of the Albian was penetrated at 175 meters and the hole terminated at 469.5 meters within the lower Aptian. The Albian is overlain by a middle to upper Eocene interval. Cores 5 to 35 were taken in the Apto-Albian sequence, but, due to poor core recovery, only Cores 11 to 35 have been analyzed palynologically. These cores consist mainly of carbonaceous marly limestones assignable to the "black shale fades." PALYNOLOGIC RESULTS General Discussion Emphasis during this study has been on the dinocysts; it is mainly their distributions that have been used in dating, by comparison with known ranges established in accurately dated English and French sections. This information is to be found in the following publications dealing with French Apto-Albian sections: Davey and Verdier, 1971 (Albian), 1973 (upper Albian) and 1974 (Aptian), and Verdier, 1975 (Apto-Albian); and in unpublished research on the AptoAlbian of southern England. Species ranges in Hole 400A (Figure 1) compare well with those in onshore sections but in Hole 402A marker species are rare and ranges are com-

Marine AptoAlbian Palynomorphs from Holes 400A and 402A, IPOD Leg 48, Northern Bay of Biscay

Marine AptoAlbian Palynomorphs from Holes 400A and 402A, IPOD Leg 48, Northern Bay of Biscay