The occurrence of the North Pacific diatom Neodenticula seminae in the North Atlantic during the Pleistocene with a correlation to planktonic foraminifera at ODP Site 983.

• Main Author: Scott, Kenneth J.
• Other Authors: School of Geography, Earth and Environmental Science, Faculty of Science
• Format: Thesis
• Language: unknown
• Published: University of Plymouth 2007
• Subjects: Arctic; Pacific; Canadian Archipelago; Foraminifera*; Fram Strait; Labrador Sea; Neogloboquadrina pachyderma; North Atlantic; Planktonic foraminifera
• Online Access: http://hdl.handle.net/10026.2/280

The middle to high latitude North Pacific diatom Neodenticula seminae appeared in the North Atlantic between the ages of ~1.2 and -0.8 Ma. It has recently been rediscovered in the North Atlantic during Continuous Plankton Recorder surveys (CPR) in the Labrador Sea which suggests that the same climatic conditions that were present in the early to mid-Pleistocene are now re-occurring during modem times allov^ng North Pacific currents to make their way through the Canadian Archipelago and/or Fram Strait, through Arctic waters and mto the North Atlantic. Forty four sediment samples were processed and analysed from ODP Site 983, Hole 983A for planktonic foraminifera abundances and then compared against the FO and LO of Neodenticula seminae within the early to mid-Pleistocne (-1.2 to -0.8 Ma). The most significant taxa: Neogloboquadrina pachyderma (mean 48.71%), Neogloboquadrina incompta (mean 22.86%), and Turborotalita quinqueloba (mean 8.59%) revealed a tripartite response to changes in sea temperatures with N. pachydrma showing an inverse relationship to N. incompta. These findings were then correlated against an age model and three main intervals within the stratigraphic imit based on the FO and LO of Neodenticula seminae. The interval shown in-between the FO and LO of N. seminae does seem to show a pulse of colder water that entered the North Atlantic between -1.2 and -0.8 Ma as shown by the high abundances of N. pachyderma, but due to the high amount of barren samples aroimd the boimdaries, there is no way of separating any cold pulse of Arctic water, caused by glacial melting, from the background glacial/interglacial signal shown by the age model. It is therefore recommended that further investigations should be applied to constraining the defmite age of N. seminae and repeating studies using a smaller size fraction (<125 |xm) and/or benthic foraminifera.