Calcite syntaxial

In the graded storm layers with abundant planktonic foraminifers microcrystalline, moderately fer-roan calcite replaced clayey/marly matrix (Fig. 6C). Some bioclasts display their original composition or show a well-preserved original shell texture, owing to pseudomorphic neomorphism to low-Mg calcite, but others are totally recrystallized/replaced by drusiform or equant mosaic calcite. Blocky calcite and syntaxial overgrowths display non-luminescent... 

Calcite cementation in bioclastic hybrid and lithic arenites of the Bismantova-Termina succession is pervasive along layers and concretionary horizons. Cementation in the hybrid shelf arenites was mostly precompactional and began with marine calcite rims, syntaxial overgrowths on echinoderms, K-feldspar and dolomite overgrowths, chloritic clay rims, framboidal pyrite and heulandite, followed by... 

Fig. 15. Paragenetic sequence for the Namur Sandstone, Gidgealpa Field. Calcite cementation is the major, most recent pore-filling event in the Lower Namur Sandstone, where syntaxial quartz overgrowths are minimal. In the Upper Namur Sandstone, where major calcite-cemented zones are absent, quartz cementation could have continued until relatively recent times.

Calcite cement occurs as minor iron-free calcite, early ferroan and late ferroan calcite, and fills a maximum 32% of pore space. Ferroan calcite is also observed as fracture-filling cement. Iron-free calcite cement forms syntaxial overgrowths on fossil fragments, especially echinoderm fragments, and is probably the earliest calcite cement. 

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