Aquatic Sciences Meeting, Albuquerque 2001

SS43 Biogeochemical Processes in Stromatolites: A 3 b.y.old ecosystem (Spatial and Temporal Connections)

Date: Monday, February 12, 2001, Time: 4:15:00 PM

Location: Cimarron

Visscher, P, T, Dept. Marine Sciences, University of Connecticut, Groton, USA, pieter.visscher@uconn.edu

SULFUR CYCLING IN MODERN MARINE STROMATOLITES MEDIATES CALCIUM CARBONATE PRECIPITATION AND DISSOLUTION

Microbial metabolism facilitates precipitation and dissolution of calcium carbonate and as such potentially impacts formation of lithified and unlithified laminae in stromatolites: photosynthesis (PS) leads to precipitation and aerobic respiration (AR) dissolves calcium carbonate. Field observations in modern marine stromatolites, Bahamas, and laboratory studies with pure cultures demonstrate that in addition to PS and AR, sulfate-reducing bacteria (SRB) facilitate calcium carbonate precipitation and sulfide-oxidizing bacteria (SOB) depending on their oxidation product either enable precipitation or dissolution events. Microelectrode studies indicate that in situ temporal and spatial uncoupling of sulfate reduction (i.e. sulfide production; SR) and sulfide oxidation (SO) could in part be responsible for the observed pattern of lithified and unlithified laminae. Furthermore, comparison of microscale measurements of SR rates and petrographic slides clearly indicates involvement of SR in formation of lithified layers.

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Aquatic Sciences Meeting, Albuquerque 2001

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