HR: 16:15h
AN: GC54B-02    [Abstracts]
TI: Insights Into Deglacial Through Holocene Climate Variability At The Peru-Chile Margin From Very High Sedimentation Rate Marine Cores
AU: * Chazen, C
EM: caitlinchazen@gmail.com
AF: Department of Geological Science, Brown University, 324 Brook Street, Box 1846, Providence, RI 02912, United States
AU: DeJong, H
EM: Hans_dejong@brown.edu
AF: Department of Geological Science, Brown University, 324 Brook Street, Box 1846, Providence, RI 02912, United States
AU: Altabet, M
EM: maltabet@umassd.edu
AF: School of Marine Science, University of Massachusetts, Dartmouth, 265 Riverside Street, Lowell, MA 01854, United States
AU: Herbert, T
EM: timothy_herbert@brown.edu
AF: Department of Geological Science, Brown University, 324 Brook Street, Box 1846, Providence, RI 02912, United States
AB: The Peru-Chile upwelling system is situated at the epicenter of the modern ENSO System. The high settling flux of organic materials and poor ventilation of subsurface waters makes the Peru upwelling system one of the world's three major oxygen minimum/denitrification zones (Codispoti and Christensen, 1985). Extremely high sedimentation rates and permanent hypoxic/anoxic subsurface waters create excellent conditions for the preservation of organic matter. Despite the significance of this region in regards to paleoceanography and paleoclimatology, relatively little work has been done to characterize past Peruvian climate because carbonate dissolution hinders the use of conventional paleoclimate methods and hiatuses frequently interrupt the record. However, using nitrogen isotopes and alkenone paleothermometry on multiple sediment cores from the Margin we have managed to overcome many of these challenges to create a nearly continuous SST (Uk`₃₇), productivity (C₃₇total), biogenic opal and denitrification (δN¹⁵) record from the LGM through the late Holocene. Remarkably, recent work has revealed an annually laminated core, which spans from 1.4-8.0ka uninterrupted, providing a unique window into Holocene climate variability. Modern-day upwelling induced climate at the Peru-Chile margin is characterized by cold temperatures (21.5°C) high productivity and strong denitrification, which has persisted since the mid Holocene (4ka). The mid Holocene also marks the beginning of a dramatic increase in seasonality and ENSO variability consistent with other tropical climate indicators. Climate variability in the Mid-early Holocene shows a distinctively different pattern from that of the late Holocene; unproductive warm temperatures persist through the early Holocene in what can be described as a permanent El Niño-like state. Early tropical warming occurred near 17ka along with an unprecedented increase in denitrification, which is decoupled from local productivity. Early onset of denitrification relative to deglaciation indicates a high latitude remote forcing that was rapidly translated to the tropics at the close the last glacial period.
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1626 Global climate models (3337, 4928)
DE: 1635 Oceans (1616, 3305, 4215, 4513)
DE: 1724 Ocean sciences
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting