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PASADO geomicrobiological investigations

The distribution and diversity of microbes in marine sediments have been already studied for several years, but these investigations are still missing for their lacustrine counterparts. For the first time in an ICDP campaign, researchers decided to look at microbes settled within sediments. As previous studies mainly focused on the water column and/or very shallow sediments, we performed a systematic sampling down to 93 m depth on an hydraulic core retrieved from Lake Potrok Aike in October 2008.

Since the directing idea of the present thesis dissertation was to determine the impact of microbial activity during early stages of diagenesis, a protocol was specially defined for minimizing contamination risks and conditioning samples so that initial microbial signals would be preserved. Diverse microbiology techniques, like in situ ATP detections, cell counts, DGGE (16S rDNA gene fingerprinting technique) were selectively applied in parallel to a complete geochemical lacustrine multiproxy (bulk characteristics, pore water chemistry, phosphorus forms) to establish microbial colonization of sedimentary horizons in link to their paleoclimatic conditions. Clone libraries further allowed the characterization of microbial assemblages throughout depth, while authigenic minerals and lipidic biomarkers were inspected in order to define the recording and preservation of former and ongoing microbial processes. The final outlook of this project was to determine the influence of microbiological nutrient cycles on the recorded signal.

Our results help clarify interactions between microbes and minerals in actual freshwater environment, as well as evidence microbial diagenetic imprints on sedimentary organic matter in order to bring further distinctions in its use in paleoclimatic reconstructions.  


Vuillemin A., Ariztegui D., De Coninck A.S., Lücke A., Mayr C., Schubert C.J., and the PASADO Science Team, in press. Origin and significance of diagenetic concretions in sediments of Laguna Potrok Aike, southern Argentina. Journal of Paleolimnology. Published online May 2013. doi:10.1007/s10933-013-9723-9

Vuillemin A., Ariztegui D., and the PASADO Science Team, in press. Geomicrobiological investigations in subsaline maar lake sediments over the last 1500 years. Quaternary Science Reviews, published online May 2012. doi:10.1016/j.quascirev.2012.04.011

Vuillemin A., Ndiaye M., Martini R., and Davaud E., 2011. Cement stratigraphy: Image probes of cathodoluminescent facies. Swiss Journal of Geosciences 104, 55-66. doi:10.1007/sd00015-10-0047-8

Vuillemin A., Ariztegui D., Vasconcelos C., and the PASADO Scientific drilling party, 2010. Establishing sampling procedures in lake cores for subsurface studies: Assessing in situ microbial activity. Scientific Drilling 10, 35-39. doi:10.2204/

Vuillemin A., Ariztegui D., 2013: Bulk sediment characteristics and geomicrobiology of sediment core 5022-1J from Laguna Potrok Aike, southern Patagonia. Dataset #811523

Vuillemin A. et al., 2013: Geomicrobiology, bulk sediment characteristics and pore water chemistry of sediment cores from Laguna Potrok Aike, southern Patagonia. Dataset #811524