Two coralligenous bioconstructions, along the Mediterranean shelf in front of the Marzamemi village (Sicily, Italy), have been collected in the frame of the project FISR 04543 “CRESCIBLUREEF - Grown in the blue: new technologies for knowledge and conservation of Mediterranean reefs”. They allow to study the main builders of the biostructures and to investigate the role of the non-skeletal organisms in their morphology and depositional geometry. The primary framework is mainly built by crustose coralline algae, which in turn crevices and together with soft algae, they represent the main organisms of the external surface. Fine micritic type derives from physical processes, notably erosion, transport and deposition; it shows dense texture and is composed of sub-euhedral low-magnesium calcite minerals. Under UV-excitation, this micrite does not over time after the primary framework is formed. The second type, high-magnesium calcite in composition, mediated by organic matter decay (Perry et al., 2007; Dupraz et al., 2009; Görgen et al., 2020). The occurrence of this component allows hypothesizing a possible contribution of non-skeletal carbonate in the strengthening of the primary framework due to its syndepositional cementation. The strict connection of the autochthonous micrite with sponge spicules suggests organomineralization phenomena of sponge ‘tissue’ but further micromorphological and biogeochemical analyses will allow to depict the mineralization process involved in its deposition.
Autochthonous vs allochthonous micrite in Mediterranean coralligenous: ecological and depositional implications
Bertolino M.;
2022-01-01
Abstract
Two coralligenous bioconstructions, along the Mediterranean shelf in front of the Marzamemi village (Sicily, Italy), have been collected in the frame of the project FISR 04543 “CRESCIBLUREEF - Grown in the blue: new technologies for knowledge and conservation of Mediterranean reefs”. They allow to study the main builders of the biostructures and to investigate the role of the non-skeletal organisms in their morphology and depositional geometry. The primary framework is mainly built by crustose coralline algae, which in turn crevices and together with soft algae, they represent the main organisms of the external surface. Fine micritic type derives from physical processes, notably erosion, transport and deposition; it shows dense texture and is composed of sub-euhedral low-magnesium calcite minerals. Under UV-excitation, this micrite does not over time after the primary framework is formed. The second type, high-magnesium calcite in composition, mediated by organic matter decay (Perry et al., 2007; Dupraz et al., 2009; Görgen et al., 2020). The occurrence of this component allows hypothesizing a possible contribution of non-skeletal carbonate in the strengthening of the primary framework due to its syndepositional cementation. The strict connection of the autochthonous micrite with sponge spicules suggests organomineralization phenomena of sponge ‘tissue’ but further micromorphological and biogeochemical analyses will allow to depict the mineralization process involved in its deposition.
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