HR: 17:00h
AN: PP14B-05    [Abstracts]
TI: High-Resolution Late Holocene Temperature and Biogeochemical Records From Southwest Greenland
AU: * D'Andrea, W J
EM: William_DAndrea@brown.edu
AF: Brown University, Department of Geological Sciences, Providence, RI 02912
AU: Khatib, F
EM: Fatma_Nazihah_M_Khatib@brown.edu
AF: Brown University, Department of Geological Sciences, Providence, RI 02912
AU: Huang, Y
EM: Yongsong_Huang@brown.edu
AF: Brown University, Department of Geological Sciences, Providence, RI 02912
AB: Greenland ice cores have provided high-resolution Holocene temperature and precipitation records. However, Greenland is characterized by large spatial variations in climate and the controlling factors thereof. Notably, temperature at the summit of the Greenland ice sheet shows little correlation, whereas temperature in southwest coastal Greenland shows strong negative correlation with the North Atlantic Oscillation (NAO). We previously reported unusually high concentrations of long-chain alkenones (LCAs) in sediments from a suite of laminated lakes in southwestern Greenland. DNA analyses from lake sediments suggest that the Greenland alkenone producers are very closely related to known alkenone producers and belong to the same order, Isochrysidales. Here we demonstrate that the alkenone unsaturation patterns (i.e., the indices U^K₃₇ and U^K'₃₇) in the lake sediments reflect regional climate in the Sondre Stromfjord region of southwestern Greenland. High-resolution (~15yr) records of U^K₃₇ and U^K'₃₇ from different lakes in the region are remarkably correlative, showing the same broad- and fine-scale patterns of variability and suggesting that regional temperature, rather than lake-specific conditions, control alkenone unsaturation patterns in the lakes. Records of sedimentary LCA concentration are also correlative among the lakes, implying a regional control over the productivity of prymnesiophyte algae. While total organic carbon (TOC) and loss-on-ignition (LOI) records can yield clues to the overall productivity of a lake basin, LCAs are purely aquatic in origin and therefore represent ideal biomarkers for autochthonous productivity and facilitate refined paleolimnologic and paleoclimatic interpretation. A ~6000yr record of alkenone unsaturation (U^K₃₇ and U^K'₃₇) and alkenone concentration represents the first independent record of temperature variability and autochthonous production, respectively, for the Sondre Stromfjord region. Ongoing work on the saline lakes includes determining high resolution bulk/compound-specific isotopic values from sediment cores, algal culturing, and further ribosomal DNA fingerprinting. Up-to-date results will be presented in the meeting.
DE: 0424 Biosignatures and proxies
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
DE: 1637 Regional climate change
DE: 4239 Limnology (0458, 1845, 4942)
DE: 4855 Phytoplankton
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005