(1) Pacific Insitute of Geography FEB RAS, Vladivostok, 690041, Russia;
(2) School of Natural Science, Hampshire College, Amherst, MA 01002, USA;
(3) Institute of Biology and Pedology FEB RAS, Vladivostok, 690041, Russia;
(4) Department of Geology and Geophysics, University of Alaska, Fairbanks, AK, 99709, USA;
(5) Northeastern Interdisciplinary Scientific Research Institute, Magadan, Russia.
(6) Department of Geosciences, University of Massachusetts, Amherst, MA, 01003, USA;
Studies of the diatom flora of the Cape Blossom and Hotham Inlet Formations of Baldwin Peninsula, northwestern Alaska contribute new information concerning the paleoceanography of Kotzebue Sound, Alaska, during middle Pleistocene time. All subarctic North Pacific datum species are present in sediments exposed along coastal bluffs of Baldwin Peninsula. These sediments contain extinct Rhizosolenia barboi, Rh. curvirostris, Actinocyclus ochotensis var fossilis, Thalassiosira nidulus var. nidulus, Th. jouseae, Th. gravida var. fossilis, and Pyxidicula dimorpha are which are correlated with the middle part of the Rhizosolenia barboi Zone (0.43-0.36 Ma). Based on the distribution of the zonal diatom species and on changes in the paleoecological structure of the diatom assemblages, we conclude that the marine deposits of the Cape Blossom Formation and lower Baldwin Silt member of the Hotham Inlet Formation formed under warm, high sea level conditions associated with the marine oxygen isotope stage 11 transgression. Glaciomarine sedimentation (middle and upper Baldwin Silt and Selawik members of the Hotham Inlet Formation) was initated during the stage 11 transgression and continued into stage 10. High latitude glacier growth during a global "interglacial" period was likely facilitated by warm surface waters on flooded continental shelves and limited regional sea ice cover.