Mineral precipitation on modern siliciclastic tidal flats colonized by microbial mats

CUADRADO DIANA G.; CARMONA, NOELIA B.; BOURNOD, CONSTANZA N.

SEDIMENTARY GEOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012 vol. 271 p. 58 - 66

0037-0738

The preservation and cementation of sedimentary structures under the influence of microorganisms insiliciclastic environments have been poorly studied in contrast to carbonatic settings, where they havebeen extensively investigated. Whereas in carbonatic environments, microbial mat-induced precipitationof calcium carbonate results in a cementation process producing a quick lithification, in siliciclastic environmentsother minerals would act as cement. The focus of this paper is to document the presence of authigenicminerals within a biosedimentary fabrics and the possible link of these minerals with the extensive microbialmats that colonize the tidal flat of the temperate Bahía Blanca estuary. ?Anoxic? minerals (e.g. pyrite) andauthigenic zeolites such as analcime, clinoptilolite, mordenite, phillipsite and chabazite were recognizedthrough SEM and EDX analyses. These minerals were most likely formed by alteration of volcanic ash,which is present in this tidal flat and also silica may result from dissolution of frustules of benthic diatoms.Minerals precipitated in this setting are significant as they would act as early cement in the eogenesis, enhancingthe preservation of sedimentary and biogenic structures.