Beschreibung
We propose to use GLAD800 to drill a series of sites in Lake Peten-Itza, northern Guatemala, to recover sedimentary sequences along a depth transect from ~30 m to near the deepest point (~150 m) in the lake. Six primary and four alternative drilling sites have been identified on the basis of two detailed seismic surveys. A sequence stratigraphic approach will be employed to constrain the vertical range of past lake level variations for glacial, interstadial, and interglacial stages during the late Pleistocene. The basal age of the sections to be drilled is not certain but we estimate that sequences should span at least the last several glacial-to-interglacial cycles. The sediment archives and pore waters recovered by drilling will be used to test hypotheses 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. The research proposed here will result in the first comprehensive investigation into the microbial ecology and dominant geomicrobiological mediated processes occurring in deep subsurface lacustrine sediments. Science management and drilling operation plans are proposed to successfully achieve both scientific and technical objectives of the project. An international team of research scientists has been assembled to produce a comprehensive suite of paleoenvironmental and biogeochemical measurements on the cores and pore fluids recovered from Lake Peten-Itza.