Late Pleistocene paleoceanography of the Subarctic Pacific : derived from the diatom record

• Main Author: Ren, Jian
• Other Authors: Tiedemann, Ralf, Diekmann, Bernhard
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2015
• Subjects: Diatom; North Pacific; Late Pleistocene; Paleoceanography; Transfer Function; Summer Sea Surface Temperature; Sea Ice; 550; 550 Earth sciences and geology; ddc:550; Bering Sea; Okhotsk; Pacific; North Atlantic; Sea ice; Subarctic
• Online Access: https://media.suub.uni-bremen.de/handle/elib/980; https://nbn-resolving.org/urn:nbn:de:gbv:46-00104950-11

Paleoceanography and climate variability of the Late Pleistocene is of vital importance to understand the mechanisms of glacial-interglacial cycles and abrupt climate changes during deglaciations. In relation to the paleoceanography studies carried out in the North Atlantic, rather few recent research has been done in the North Pacific. Developments of sea surface temperature and sea ice in the past provide crucial information on paleoceanographic variability. The aim of this thesis is to establish a diatom-based transfer function for sea surface temperature and to reconstruct the Late Pleistocene paleoceanographic history based on diatom assemblages, in order to improve the understanding of the North Pacific s role in the global glacial-interglacial climate changes. The thesis consists of three studies, of which the results are presented in three manuscripts. In the first study, a new diatom data set was generated from 422 surface sediments, covering a broad range of environmental variables of the northern North Pacific, the Sea of Okhotsk and the Bering Sea. The diatom biogeographic distribution patterns of 38 species and species groups were mapped. Statistical analysis discloses that 32 species and species groups have strong correspondence with the pattern of summer sea surface temperature (SSST). This close relationship between diatom assemblages and the SSST is useful in deriving a transfer function in the northern North Pacific for the quantitative paleoceanographic studies. In addition, the relative abundance of the sea ice indicator diatoms Fragilariopsis cylindrus and F. oceanica of >20% in the diatom composition is used to represent the winter sea ice maximum extent in the Bering Sea. In the second research project, a new diatom-based transfer function for SSST reconstructions was established based on 206 surface sediment samples with 32 species and species groups recovered in the northern North Pacific and its marginal seas. The SSST was estimated by three different techniques: the Imbrie and Kipp ...