RT Journal Article
T1 Biomineralization of ordered dolomite and magnesian calciteby the green alga Spirogyra.
A1 Buey Fernández, Pablo del
A1 Sanz Montero, María Esther
AB The formation of ordered dolomite under Earth’s surface conditions remains a challenge, although many researchers have now shown that microbes can facilitate the precipitation of this common mineral. This study provides the first evidence of dolomite biomineralization by the green alga Spirogyra (Zygnematales, Chlorophyta), a globally dispersed lacustrine genus. Microbial mats formed by Spirogyra occur in the hyperalkaline and ephemeral lake Caballo Alba, located in Central Spain and characterized by water solutions with high Mg/Ca ratios. Microscopic, geochemical, mineralogical and cytochemical studies have shown that accumulations of carbonates occur within different cells and locations of the alga. Biominerals mostly consist of single crystals of magnesian calcite and dolomite with variable proportions of Ca2+ and Mg2+. High-resolution transmission electron microscopy and selected area electron diffraction patterns of the carbonates confirm the pervasive presence of super-lattice reflections typical of ordered dolomite in compositions with greater than 32 mol% MgCO3. The curved surfaces of some carbonate crystals and their attachment to the organic surfaces represent imprints of a confined growth in compartments that act as a template for crystal nucleation and shape the crystals. Dyes reveal chemical differences in these compartments which explain the polymineral biomineralization and suggest that the alga do not strictly control the precipitation process. Zygnematales algae related with Spirogyra date back possibly to the Early Palaeozoic, thus suggesting that dolomite biomineralization could have been a common process through the Phanerozoic. This discovery provides new insight into the biotic formation of orderly dolomite and aids in the reconstructions of past lacustrine environments of dolomite deposition.
PB Wiley
SN 0037-0746, ESSN: 1365-3091
YR 2022
FD 2022-10-09
LK https://hdl.handle.net/20.500.14352/72530
UL https://hdl.handle.net/20.500.14352/72530
LA eng
NO CRUE-CSIC (Acuerdos Transformativos 2022)
NO Ministerio de Economía y Competitividad (MINECO)/FEDER
NO Universidad Complutense de Madrid
DS Docta Complutense
RD 20 abr 2025