New insights on how microbes mediate dolomite formation!
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First comprehensive flood reconstruction of the Alps covering the last 2500 years
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Helmut Weissert receives Jean Baptiste Lamarck Medal 2013
for his fundamental contribution to the application of carbon-isotope geochemistry to stratigraphy and palaeoceanography.
Help to digitize historical climate data
Lake Petén-Itzá is located at ~16o 55'N, 89o 50'W in the Maya Lowlands of northern Guatemala. It lies in a climatically sensitive region where rainfall is highly seasonal and related to the seasonal migration of the Intertropical Convergence Zone (ITCZ). Lake Petén Itzá is a closed basin and, with its maximum water depth of 160 m, the deepest lake in the tropical lowlands of Central America. Its lake level is highly sensitive to the hydrological balance and varies dependent on the changes in the ratio of evaporation/precipitation. The sediment record of Lake Petén Itzá is more than 100 m thick and it tracks climatic changes sensitively with variations in lithology and physical properties (Anselmetti et al, 2006).
As part of an International Continental Deep Drilling Program (ICDP), we recovered in early 2006 over 1.3 km of lake sediment at seven sites in varying water depths in Lake Petén Itzá using the GLAD800 RV/Kerry Kelts superbarge.
Our main goals of this drilling campaign are related to three broad scientific themes:
1. Paleoclimatic history of the northern lowland Neotropics on orbital to suborbital time scales emphasizing marine-terrestrial linkages (e.g., Cariaco Basin, Greenland ice cores, etc.).
2. Paleoecology and biogeography of the Maya tropical lowland forest including the history of vegetation change and disturbance by humans, climate change, and fire.
3. Biogeochemical cycling in deep lake sediments emphasizing integrated studies of microbiology, geochemistry (interstitial waters), and mineral authigenesis/diagenesis.
Preliminary results of our paleoclimatic interpretations are focused on Site 6, and are limited to the last ~40 ka because this is the period for which we currently have reliable age control.
Our results support the hypothesis that summer precipitation in the Circum Caribbean area was controlled by migrations in the meridional position of the Atlantic ITCZ during the Marine Isotope Stage MIS 3 (40 to 23 ka) and during the last deglaciation (18 to 10 ka). The ITCZ was located farther south during cold periods, especially during Heinrich Events, and arid conditions prevailed in the northern hemisphere Neotropics. Contrary to previous findings, the last Glacial Maximum LGM (23 to 18 ka) was moist in the Petén lowlands (Hodell et al, in press).
Anselmetti, F.S., Ariztegui, D., Hodell, D.A., Hillesheim, M.B.,
Brenner, M., Gilli, A., McKenzie, J.A., and Mueller, A.D., 2006, Late
Quaternary climate-induced lake level variations in Lake Peten Itza,
Guatemala, inferred from seismic stratigraphic analysis: Palaeogeography Palaeoclimatology Palaeoecology, v. 230, p. 52-69. (pdf, 2.1MB)
Hodell, D.A., Anselmetti, F.S., Ariztegui, D., Brenner, M., Curtis,
J.H., Gilli, A., Grzesik, D.A., Guilderson, T.J.,
Müller. A.D., Bush, M.B., Correa-Metrio, A., Escobar, J., and Kutterolf, S., 2008, An 85-ka record of climate change
in lowland Central America: Quaternary Science Reviews, v. 27, p. 1152-1165, doi:10.1016/j.quascirev.2008.02.008. (pdf, 2.3MB)
Hodell, D., Anselmetti, F.S., Brenner, M., Ariztegui, D. and the PISDP Scientific Party, 2006, The Lake Petén Itzá Scientific Drilling Project: Scientific Drilling, v. 3, p. 25-29. (pdf, 528KB)
Hodell, D., Anselmetti, F.S., Ariztegui, D. Brenner, M., Curtis. J., and the PISDP Scientific Party, 2006, 1.3 km of sediment recovered by the Lake Petén Itzá Scientific Drilling Project: DOSECC News, v. 4/1, p.1-2. (pdf, 248KB)
Hodell, D., Anselmetti, F.S., Ariztegui, D. Brenner, M., Curtis. J., and the PISDP Scientific Party, 2006, Preliminary results of the Lake Petén Itzá Scientific Drilling Project: DOSECC News, v. 4/2, p. 5-6. (pdf, 720KB)
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