Shifting ocean productivity patterns during the intensification of Northern Hemisphere glaciation

Author(s): Lawrence, Kira T.; Herbert, Timothy; Cleaveland, Laura C.; Liu, Zhonghui
Author Affiliation(s): Primary:
Lafayette College, Geology and Environmental Geosciences, Easton, PA, United States
Brown University, United States
Luther College, United States
Yale University, United States
Volume Title: Geological Society of America, Northeastern Section, 44th annual meeting
Source: Abstracts with Programs - Geological Society of America, 41(3), p.35; Geological Society of America, Northeastern Section, 44th annual meeting, Portland, ME, March 22-24, 2009. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: Previous studies have suggested that the onset of ocean stratification in the Subarctic Pacific and Southern Ocean gave rise to an abrupt decline in biological productivity in both these regions synchronous with the intensification of Northern Hemisphere Glaciation (NHG) (∼2.75 Ma). Using the concentration of alkenones, organic compounds exclusively produced by a few species of haptophyte algae, derived from ocean sediments we document the continuous evolution of ocean productivity over the past 4 Myr at an array of sites in both hemispheres as well as in all ocean basins (ODP 982, DSDP 607, ODP 662, ODP 1014, ODP 1090, ODP 846, ODP 1123, ODP 722). We find that biological productivity in all high latitude regions declines precipitously in association with the intensification of NHG. In contrast, productivity in mid to low latitude regions of the Atlantic and Pacific Oceans, rises sharply during the same time interval eventually declining again between ∼1.5 and 1 Ma. In mid latitude regions of the Southern Hemisphere, preliminary low-resolution data suggest a rise in productivity after ∼1.5 Ma. These broad productivity patterns suggest major redistributions of ocean nutrients in association with Northern Hemisphere Glaciation as well as the mid-Pleistocene transition. High latitude regions in the North Pacific and Southern Ocean are instrumental in supplying nutrients to most mid and low latitude regions in the world's oceans. Thus, we hypothesize that nutrients that may have been inhibited from being utilized at high latitudes by the onset of water column stratification were instead entrained into the source waters for low and mid latitude regions causing the dramatic rise in productivity that occurred in these regions in association with NHG. The decline in productivity that occurred in Northern Hemisphere mid to low latitude regions between 1 and 1.5Ma and the corresponding rise in productivity in the mid latitude regions of the Southern Hemisphere may be related to the migration of the Southern Hemisphere polar front in association with the mid-Pleistocene transition.
Year of Publication: 2009
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Algae; Alkenones; Atlantic Ocean; Biomass; Cenozoic; DSDP Site 607; Deep Sea Drilling Project; East Pacific; Equatorial Atlantic; Glaciation; IPOD; Ketones; Leg 108; Leg 162; Leg 167; Leg 94; Microfossils; Mid-Atlantic Ridge; North Atlantic; North Pacific; Northeast Atlantic; Northeast Pacific; Northern Hemisphere; Nutrients; ODP Site 1014; ODP Site 662; ODP Site 982; Ocean Drilling Program; Organic compounds; Pacific Ocean; Plantae; Pleistocene; Productivity; Quaternary; Rockall Bank; Sea water; South Atlantic; Subarctic regions
Coordinates: N573100 N573100 W0155200 W0155200
N410004 N410005 W0325726 W0325727
S012325 S012324 W0114421 W0114421
N325002 N325002 W1195853 W1195853
Record ID: 2009092114
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