Arctic ocean quaternary microfauna and its relation to paleoclimatology
Abstract Examination of 350 samples from seven deep-sea cores raised in the Arctic Ocean Basin indicates that: (1) faunal variations coincide with changes in sediment characteristics suggesting that regional climatic and hydrologic oscillations caused these alterations, and (2) two distinct sediment types are recognized in the Alpha Rise cores: brown Foraminifera-rich beds and tan or gray Foraminifera-poor beds. The brown beds repsent climatic conditions similar to those of the present, and the gray-tan beds were deposited during intervals with higher temperatures as evidenced by the coexistence of temperate and subartic planktonic Foraminifera with the polar sinistral Globigerina pachyderma. Based on data presently available, the following succession of climatic events emerges: Phase I, contained in the topmost brown bed, characterized by the predominance of cold-water sinistral G. pachyderma, extends from Recent through the Last Glacial, and encompasses approximately the last 70,000 years. Phase II represented by sediments deposited during a warmer interval as evidenced by the microfaunal composition, is thought to have been laid down during an interglacial. Phases III and V — comparable to Phase I, may represent former cold episodes. Phases IV and VI — are much like Phase II and may correspond to earlier interglacials. Radioisotope determinations indicate: (1) that rates of sedimentation were slow in the Arctic Basin, about 2 mm/1,000 years; and (2) that Phase I–II boundary has an age of approximately 70, 000 years.