Cenozoic Dinoflagellate Cysts and Acritarchs from the Bering Sea and Northern North Pacific, DSDP Leg 19

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Abstract
Dinoflagellate cysts and acritarchs occur in Eocene to Pleistocene sediments from DSDP [Deep Sea Drilling Project] sites in the Bering Sea and northern North Pacific and are particularly common in Upper Miocene to Pleistocene strata. Two new genera (FILISPHAERA, GELATIA ) and 10 new species [F. filifera (type species), G. inflata (type species), Impagidinium pacificum, I. pallidum, I. velorum, Kallosphaeridium curiosum, Nematosphaeropsis lemniscata, Spiniferites ovatus, Trinovantedinium boreale, Xandarodinium variabile ] of dinoflagellate cysts and 2 new genera (BERINGIELLA, HALODINIUM ) and 3 new species [B. fritilla (type species), H. major (type species), H. minor ] of acritarchs are erected. Eight concurrent-range-zones based on dinoflagellate cysts and acritarchs are proposed for the Eocene to Pleistocene and are calibrated with high latitude diatom and silicoflagellate-ebridian zonations in the Upper Miocene to Pleistocene. Age justification for the Eocene-Oligocene zones is based primarily on correlation with dinoflagellate cyst zones from other areas. Upper Miocene to Recent dinoflagellate assemblages are dominated by protoperidiniacean cysts which became abundant in the Bering Sea and northern North Pacific at the same time as diatoms because of major changes in oceanic circulation and sedimentation in the Late Miocene. A modern relationship is established between high productivity of diatoms and protoperidiniacean dinoflagellates and areas rich in dissolved nutrients, both in high latitudes and in upwelling regions. This probably results from the nonphotosynthetic nature of living protoperidiniacean dinoflagellates, which utilize dissolved nutrients and commonly become abundant immediately following the spring diatom bloom. Diatom and protoperidiniacean abundance may therefore be an indicator of ancient areas of nutrient-rich waters and high phytoplankton productivity, of relevance both to paleo-oceanographic reconstructions and to petroleum exploration.