GSA Annual Meeting in Denver, Colorado, USA - 2016

Paper No. 116-5
Presentation Time: 11:00 AM


HENDY, Ingrid1, BROWN, Erik T.2, HINNOV, Linda A.3, SCHIMMELMANN, Arndt4 and DU, Xiaojing1, (1)Department of Earth and Environmental Sciences, University of Michigan, 2534 C.C. Little Bldg, 1100 N. University Ave, Ann Arbor, MI 48109, (2)Large Lakes Observatory & Dept of Geol. Sci, University of Minnesota Duluth, RLB-109, 10 University Drive, Duluth, MN 55812, (3)Atmospheric, Oceanic and Earth Sciences, George Mason University, Fairfax, VA 22030, (4)Department of Geological Sciences, Indiana University, Bloomington, IN 47405-1405,

Extreme Southern California weather events include both drought and intense rainfall the elemental composition of Santa Barbara Basin (SBB) sediments records signals of these diverse weather patterns. Extreme precipitation events in the region occur when strong zonal flow brings warm, moist tropical across the Pacific (i.e. ‘atmospheric rivers’). Here we present an annually resolved 9,000 year record of the elemental composition of laminated sediment providing a Holocene reconstruction of regional river discharge to the SBB. The upper 8 meters of jumbo piston core MV0811-14JPC (34°16.906’N; 120°02.162W, 582 m water depth) were scanned with a second generation ITRAX XRF core scanner using a Mo tube at 200 µm intervals at the Large Lakes Observatory, Duluth, MN providing 3 to 7 analyses per year. Flood events identified by non-laminated grey layers and high siliciclastic element contents can be stratigraphically tied to other regional cores and express a typical recurrence inteval of ~110 years. Flood events are more common between 4,200 and 2,000 years BP with a 85 year recurrence when subdecadal interannual variabililty in annual river input is high. The longest flood-free interval of 535 years occurs during the Medieval Climate Anomaly. The period between 6,500 and 4,500 years BP commonly associated with dry conditions in California showed fewer flood events (recurrence interval of 176 years) and a reduced subdecadal interannual variability.