HR: 0800h
AN: PP21C-1587    [Abstracts]
TI: Gardar mudwave accumulation history as a proxy for variability of NCW flux since Marine Isotope Stage 5e
AU: * Elmore, A C
EM: aelmore@eden.rutgers.edu
AF: Rutgers University Geological Sciences, Wright- Reimann Building 610 Taylor Rd., Piscataway, NJ 08854
AU: Wright, J D
EM: jdwright@rci.rutgers.edu
AF: Rutgers University Geological Sciences, Wright- Reimann Building 610 Taylor Rd., Piscataway, NJ 08854
AU: Manley, P L
EM: manley@middlebury.edu
AF: Middlebury College Geology Department, McCardell Bicentenial Hall, Middlebury, VT 05753
AU: Mountain, G S
EM: gmtn@rci.rutgers.edu
AF: Rutgers University Geological Sciences, Wright- Reimann Building 610 Taylor Rd., Piscataway, NJ 08854
AU: Earley, R J
EM: rearley@eden.rutgers.edu
AF: Rutgers University Geological Sciences, Wright- Reimann Building 610 Taylor Rd., Piscataway, NJ 08854
AU: Neitzke, L C
EM: lneitzke@eden.rutgers.edu
AF: Rutgers University Geological Sciences, Wright- Reimann Building 610 Taylor Rd., Piscataway, NJ 08854
AB: Changes in ocean circulation and climate are linked on orbital to millennial time-scales. We describe results of stable isotope and total carbonate analyses in cores collected within a sediment wave field on Gardar Drift 946 km south of Iceland. Two jumbo piston cores (JPCs) collected from either side of a km-scale migrating mudwave during Knorr cruise 166-14 were sampled at a down-core spacing of 5cm, yielding a resolution of ~ 600yr. We use % CaCO₃, δ¹⁸O and magnetic susceptibility to correlate events from cores JPC 9 and JPC 11 (2720 and 2707 m water depth, respectively). We were able to confidently correlate between the cores down to Marine Isotope Stage (MIS) 5e. Using this technique of mudwave analysis, much can be inferred about current strength and direction around the Gardar Drift and deep North Atlantic Circulation. During MIS 5e (120 - 110 kyr), both core locations accumulated sediment at a nearly identical rate of ~ 30 cm/ kyr, indicating a uniform, laminar flow regime over the undulating seafloor topography. However, immediately following MIS 5e, the average sedimentation rates from both cores decreased dramatically. For the last 110 kyrs, JPC 11 (up-current side of the mudwave) accreted at ~ 11 cm/kyr. At JPC 9 (down-current side), sediments accreted at only ~ 8 cm/kyr. While these sedimentation rates varied over time, the ratio of sedimentation rates of JPC 9 to JPC 11 remained ~ 70% throughout the last 110 kyr. This preferential accretion has continued to the present day and indicates a classic migrating mudwave in a uniform flow regime (Flood, 1988). The stark contrast between the 5e and post-5e flow regimes indicates a large-scale reorganization of currents at ~ 110 kyr. The post-5e regime remained constant over the last ~ 110 kyr, indicating little variation in sediment source, current strength and/or current direction. Previous paleoceanographic research suggests strong glacial-interglacial variability in deep water formation as water mass sources switched between deep and intermediate modes. This study indicates that a relatively constant flux of bottom water bathed the study area despite large-scale oscillations in North Hemisphere climate.
DE: 0460 Marine systems (4800)
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1635 Oceans (1616, 3305, 4215, 4513)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005