Helium isotopes in marine sediments as tracers of continental input, accumulation and provenance over the last 6 Ma

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http://abstractsearch.agu.org/meetings/2012/FM/PP51B-2116.html
Author(s): Bhattacharya, A.; Higgins, Sean M.; Mukhopadhyay, Sujoy; Middleton, J. L.
Author Affiliation(s): Primary:
Harvard University, Earth and Planetary Science, Cambridge, MA, United States
Other:
Lamont-Doherty Earth Observatory, United States
Volume Title: AGU 2012 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2012; American Geophysical Union 2012 fall meeting, San Francisco, CA, Dec. 3-7, 2012. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The Miocene to Pleistocene marks a transition from warm, humid, low orbital frequency driven climate regime to cooler, more arid, northern glaciation driven climate regime, with marked change occurring between the late Pliocene through the early Pleistocene. In this study, we use helium isotopes at IODP site U1313 in the sub-polar North Atlantic Ocean to reconstruct a record of input, accumulation and provenance of detrital material over the last 6 Ma. Our record indicates a gradual increase in terrigenous flux concomitant with the cooling climatic regime from the late Pliocene that culminated into northern glaciation through the Marine Isotope Stage (MIS) 8 in the late Pleistocene. The increased accumulation of terrestrial material resulted in a switch from a carbonate controlled to a more clay controlled sedimentation pattern at site U1313 ∼1 Ma. There is an abrupt increase in terrigenous flux ∼2.4 Ma followed by at least four such instances through the late Pleistocene. The dramatic increase in terrigenous flux starting at 2.4 Ma and temporal evolution of 4He henceforth is concomitant with the onset and periodic growth of ice sheets in the northern hemisphere. The composition of detrital sediments that is have eroded and been deposited at site U1313 is reflects reorganization of ocean circulation in the sub-polar North Atlantic that in turn is related to expansion of the ice sheets in the northern hemisphere.
Year of Publication: 2012
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Cenozoic; Expedition 306; Expeditions 303/306; He-4/He-3; Helium; IODP Site U1313; Integrated Ocean Drilling Program; Isotope ratios; Isotopes; Marine sediments; Mid-Atlantic Ridge; Neogene; Noble gases; North Atlantic; Pliocene; Quaternary; Sediments; Stable isotopes; Tertiary
Coordinates: N410000 N410000 W0325700 W0325700
Record ID: 2014075238
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