North American ice sheet dynamics controlled by obliquity (41 ka) during the early Pleistocene

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Author(s): Naafs, B. D. A.; Hefter, J.; Acton, G.; Haug, G. H.; Martinez-Garcia, A.; Pancost, R.; Stein, R.
Author Affiliation(s): Primary:
Alfred Wegener Institute for Polar and Marine Research, Department of Marine Geology and Paleontology, Bremerhaven, Germany
Potsdam University, Germany
University of California at Davis, United States
University of Bristol, United Kingdom
Volume Title: Goldschmidt 2012 abstract volume
Source: Mineralogical Magazine, 76(6), p.2151; Goldschmidt 2012, Montreal, QC, Canada, June 24-29, 2012. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0026-461X CODEN: MNLMBB
Note: In English. 2 refs.
Summary: During the Pleistocene, large continental ice sheets episodically appeared in the Northern Hemisphere, covering large parts of Europe and North America. Besides the results based on benthic oxygen isotope records, which predominantly represent variations in global ice volume, little is know about the timing of and astronomical control on the advances and retreats of the continental ice sheets in the Northern Hemisphere during the late Pliocene and early Pleistocene (3-2 million years (Ma) ago). Here we therefore present the first orbitally-resolved records of terrestrial higher plant leaf wax input to the North Atlantic covering the last 3.5 Ma, based on the accumulation of long-chain n-alkanes and n-alkanl-1-ols at IODP Site U1313. These lipids are a major component of dust, even in remote ocean areas, and have a predominantly aeolian origin in distal marine sediments. Our results demonstrate that around 2.7 Ma, coinciding with the intensification of the Northern Hemisphere glaciation (NHG), the aeolian input of terrestrial material to the North Atlantic increased drastically. Since then, during every glacial the aeolian input of higher plant material was up to 30 times higher than during interglacials. We argue that the increased aeolian input at Site U1313 during glacials is predominantly related to the episodic appearance of continental ice sheets in North America and the associated strengthening of glaciogenic dust sources. The records thus reflect the timing of the advances and retreats of the North American ice sheets. Evolutional spectral analyses of the n-alkane records were therefore used to determine the dominant astronomical forcing in North American ice sheet advances over the last 3.5 Ma. These results demonstrate that during the early Pleistocene North American ice sheet dynamics responded predominantly to variations in obliquity (41 ka), which argues against previous suggestions of precession-related variations in Northern Hemisphere ice sheets during the early Pleistocene.
Year of Publication: 2012
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Atlantic Ocean; Canada; Cenozoic; Deglaciation; Expedition 306; Expeditions 303/306; Glacial geology; Glaciation; Glaciers; IODP Site U1313; Ice sheets; Integrated Ocean Drilling Program; Mid-Atlantic Ridge; North America; North Atlantic; Paleoclimatology; Pleistocene; Quaternary; United States; Upper Pleistocene
Coordinates: N410000 N410000 W0325700 W0325700
Record ID: 2014024969
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland