Organic Compounds; Microbiolites; Nanotchnology; Dolomite; EPS; Paleothermometer; Biomineralization; stromatolites; microbial mats; organic signatures; clumped isotope
Bahniuk Anelize (2015), Development of microbial carbonates in the Lower Cretaceous Codó Formation (north-east Brazil): Implications for interpretation of microbialite facies associations and palaeoenvironmental conditions, in Sedimentology
, 62, 155-181.
Pacton M Ariztegui D. Wacey D. Kilburn M.R. Rollion-Bard C. Farah R. Vasconcelos C. (2012), Going nano: a new step toward understanding the processes governing freshwater ooid formation, in Geology
Sánchez-Román M. Romanek C.S. Fernández-Remolar D.C. Sánchez-Navas A. McKenzie J.A. Amils (2011), Aerobic biomineralization of Mg-rich carbonates: implications for natural environments, in Chemical Geology
, 281, 143-150.
Pacton M. Gorin G. Vasconcelos C. (2011), Amorphous organic matter: microbes as a new clue for palaeoenvironmental reconstructions, in Review of Palaeobotany and Palynology
, 166, 253-267.
Meister P. Gutjahr M. Frank M. Bernasconi S.M. Vasconcelos C. and McKenzie J.A. (2011), Dolomite formation within the methanogenic zone induced by tectonically-driven fluids in the Peru accretionary prism, in Geology
, 39(6), 563-566.
Sánchez M. McKenzie J.A. Wagener A. de L. Romanek C.S. Sánchez-Navas A. and Vasconcelos C. (2011), Experimentally determined biomediated Sr partition coefficient for dolomite: Significance and implication for natural dolomite, in Gecochem. Cosmochem. Acta
, 75, 887-904.
Ferry J. M. Passey B.H. Vasconcelos C. and Eiler J. M. (2011), Formation of dolomite at 40–80 °C in the Latemar carbonate buildup, Dolomites, Italy, from clumped isotope thermometry, in Geology
, 39(6), 571-574.
Templer S.P. Wehrmann L.M. Zhang Y. Vasconcelos C. and McKenzie J.A. (2011), Microbial community composition and biogeochemical processes in cold-water-coral carbonate mounds in the Gulf of Cadiz, on the Moroccan margin, in Marine Geology
, 282, 138-148.
Pacton M. & Gorin G.E. (2011), Nan(n)obacteria, in Joachim Reitner & Volker Thiel (ed.), Springer Science+Business Media, New York City, 677-680.
Warthmann R. Vasconcelos C. Bittermann A.G. and McKenzie J.A. (2011), The role of purple sulphur bacteria in carbonate precipitation of modern and possibly Early Precambrian stromatolites, in Lecture Notes in Earth Sciences
, 131, 141-149.
Maizatto J. R. Queiroz Neto J. V. Pedrão E. F. & Bahniuk A. M., Palinomorfos e ostracodes não-marinhos de afloramentos da Formação Codó, Bacia do Parnaíba. Paleontologia: Cenários de Vida, in Carvalho S. I. Srivastava N. K. Strohschoen O and Lana C. C. (ed.), Editora Interciência, Rio de Janeiro, Brazil, 365-375.
Summary: The discovery of modern dolomite forming under anaerobic conditions in hypersaline lagoons along the Rio de Janeiro coast of Brazil added a microbial factor to the list of essential requirements for dolomite formation. Within the context of 4 SNF-sponsored doctoral theses and related research projects, we have combined laboratory culture experiments with field studies in modern environments and comparative analysis of ancient analogues and have succinctly demonstrated the important role played by sulfate-reducing bacteria in the low-temperature precipitation of dolomite (Warthmann et al., 2000; van Lith, 2001; van Lith et al., 2002, 2003a,b). In addition, through the study of porewater and sediment cored at sites on the Peru Margin (ODP Leg 201), we were able to locate the focus of dolomite formation in deep-sea hemipelagic sediments at the microbially active transition between the zone of bacterial sulfate reduction and anaerobic methane oxidation (Meister, 2005; Meister et al., 2007). Furthermore, we have evaluated the importance of aerobic respiration using moderately halophylic bacteria to mediate dolomite precipitation (Sánchez-Román, 2006; Sánchez-Román et al., in press). We have applied microbial experiments to study the incorporation of geochemical tracers in microbial dolomite that can be used as indicators of depositional conditions during the formation of ancient dolomite, such as the oxygen-isotope ratio (Vasconcelos et al., 2005) or strontium composition (Sánchez-Román, 2006). We are in the process of finalizing our comparative microbial study of the semitropical hypersaline coastal system in Brazil with the classic sabkha environment in Abu Dhabi, U.A.E., where dolomite forms in association with evaporate minerals under extreme arid conditions (Bontognali, thesis 2008). Finally, we are now able to maintain and cultural microbial mats and stromatolites under laboratory conditions, which enables us to evaluate the specific metabolisms of the living communities that are associated with Ca-Mg carbonate biomineralization (Vasconcelos et al., 2006). Thus, combining culture experiments, field studies and analysis of ancient analogues, we have demonstrated the importance of diverse microbes in carbonate precipitation under sedimentary conditions. The fact that dolomite and other Ca-Mg-carbonate minerals are commonly associated with bio-structures, known as microbiolites, reinforces our hypothesis that these minerals are associated in time and space with metabolic processes and environmental conditions. With the completion of this essential background research on the origin of microbial dolomite, we would now propose: (1) To use this knowledge to study carbonate biomineralization on a nanoscale. New nanotechnology, available at the ETH-Zürich, will allow us to image the processes occurring at the cell wall (i.e. using very high-resolution AFM, TEM and SEM) and to characterize the organic compounds involved in the carbonate mineral precipitation (i.e. using EELS and TERS). (2) To develop and calibrate a new oxygen-carbon isotope “clumped” method for dolomite, in collaboration with researchers at Caltech, which will enable us to distinguish between paleosalinity and paleotemperature data, achieved from our dolomite-water isotope fractionation equation (Vasconcelos et al., 2005). And, finally (3) To test and apply these newly calibrated techniques to the geologic record. In particular, we will use information gleaned from parts (1) and (2) to study the paleo-environmental conditions of biomineral formation and the geochemical indicators of the range of metabolism involved in the formation of Precambrian, Triassic and Recent microbiolite structures.