HR: 1340h
AN: PP33B-1574    [Abstracts]
TI: Multi-Decadal to Millennial Scale Holocene Hydrologic Variation in the Southern Hemisphere Tropics of South America
AU: * Ekdahl, E J
EM: eekdahl2@unl.edu
AF: Department of Geosciences, University of Nebraska-Lincoln 214 Bessey Hall, Lincoln, NE 68588-0340 United States
AU: Fritz, S C
EM: sfritz2@unl.edu
AF: Department of Geosciences, University of Nebraska-Lincoln 214 Bessey Hall, Lincoln, NE 68588-0340 United States
AU: Baker, P A
EM: pbaker@duke.edu
AF: Division of Earth and Ocean Sciences, Duke University, Durham, NC 27708 United States
AU: Burns, S J
EM: sburns@geo.umass.edu
AF: Department of Geosciences, University of Massachusetts, Amherst, MA 01002 United States
AU: Coley, K
EM: K.H.Coley@rhul.ac.uk
AF: Department of Geography, Royal Holloway College, Egham, Surrey, TW20 0EX United Kingdom
AU: Rigsby, C A
EM: rigsbyc@mail.ecu.edu
AF: Department of Geology, East Carolina University, Greenville, NC 27858 United States
AB: Numerous sites in the Northern Hemisphere show multi-decadal to millennial scale climate variation during the Holocene, many of which have been correlated with changes in atmospheric radiocarbon production or with changes in North Atlantic oceanic circulation. The manifestation of such climate variability in the hydrology of the Southern Hemisphere tropics of South America is unclear, because of the limited number of records at suitably high resolution. In the Lake Titicaca drainage basin of Bolivia and Peru, high-resolution lacustrine records reveal the overall pattern of Holocene lake-level change, the influence of precessional forcing of the South American Summer Monsoon, and the effects of high-frequency climate variability in records of lake productivity and lake ecology. Precessional forcing of regional precipitation is evident in the Lake Titicaca basin as a massive (ca. 85 m) mid-Holocene decline in lake level beginning about 7800 cal yr BP and a subsequent rise in lake level after 4000 cal yr BP. Here we show that multi-decadal to millennial-scale climate variability, superimposed upon the envelope of change at orbital time scales, is similar in timing and pattern to the ice-rafted debris record of Holocene Bond events in the North Atlantic. A high-resolution carbon isotopic record from Lake Titicaca that spans the entire Holocene suggests that cold intervals of Holocene Bond events are periods of increased precipitation, thus indicating an anti-phasing of precipitation variation on the Altiplano relative to the Northern Hemisphere tropics. A similar pattern of variation is also evident in high-resolution (2-30 yr spacing) diatom and geochemical records that span the last 7000 yr from two smaller lakes, Lagos Umayo and Lagunillas, in the Lake Titicaca drainage basin.
DE: 0429 Climate dynamics (1620)
DE: 0458 Limnology (1845, 4239, 4942)
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1630 Impacts of global change (1225)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005