Publication Date:
2017-04-04
Description:
Alkaline lakes like the hydrothermally affected lake Specchio di Venere (Pantelleria Island, Central
Mediterranean) are typical geological settings harbouring calcified microbial mats. The present work is
focused on the discrimination between biotic and abiotic processes driving carbonate precipitation in
this lake, using hydrochemical, mineralogical and isotopic data. Hydrochemical analyses demonstrate
that the lake is nearly 10 fold supersaturated with regard to aragonite and seasonally reaches hydromagnesite
supersaturation. Microscopic observations depict organosedimentary laminated structures
consisting of microbial communities and aragonitic precipitates, which are rather disseminated in pores
than directly linked to microorganisms. Oxygen isotopic data indicate that authigenic carbonate crystallisation
from evaporating water is the dominant precipitation process, further suggested by the
absence of textural evidence of diagenetic processes. Conversely, the observed d13C values reflect an
influence of extracellular polymeric substances (EPS) on carbon fractionation during the precipitation
process, due to the selective sequestration of 12C in the biomass. The above considerations suggest that at
lake Specchio di Venere the carbonate precipitation is mainly of inorganic nature, but a minor role played
by biologically influenced processes in microbial mats is not excluded.
Description:
Published
Description:
168-176
Description:
4V. Vulcani e ambiente
Description:
JCR Journal
Description:
restricted
Keywords:
alkaline lake
;
carbonate precipitation
;
hydrochemistry
;
Pantelleria
;
03. Hydrosphere::03.01. General::03.01.07. Physical and biogeochemical interactions
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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