Calcite cave pool precipitates often display a variety of potential biosignatures from the macroscopic to the submicroscopic. A fossil cave pool in Cottonwood Cave, New Mexico, exhibits older stalactites and stalagmites that are completely coated in brown, laminated calcitic crust that extends down as pool fingers and u-loops. The pool fingers and u-loops are mainly micrite to clotted micrite, ...

The diagenetic changes of the Lower-Middle Eocene limestones in the area to the west of AssiutMinia Stretch include the following processes: compaction, cementation, neomorphism, silicification, glauconitization and ferrugination. The compaction is represented by mechanical and chemical types. Cementation is either shallow submarine (represented by micrite, fibrous calcite and isopachous calcit...

Pelagic micritic limestones within an upper Cretaceous accretionary complex in the Tavşanlı Zone, NW Turkey, preserve textures indicating incomplete prograde transformation of micritic calcite to aragonite, representing the only known example of this type. Aragonitization starts at the central parts of the micritic limestone beds and advances towards the lower and upper parts of the layers at t...

Microbialites (benthic microbial carbonate deposits) were discovered in a hypersaline alkaline lake on Eleuthera Island (Bahamas). From the edge towards the centre of the lake, four main zones of precipitation could be distinguished: (1) millimetre-sized clumps of Mg-calcite on a thin microbial mat; (2) thicker and continuous carbonate crusts with columnar morphologies; (3) isolated patches of ...

Lower Triassic carbonate sedimentary rocks exhibit fabrics and facies indicative of reduced bioturbation and reduced abundance of skeletal animals and algae relative to their Permian counterparts. Widespread microbial mounds are one widely cited example. Micritic spheroids of probable microbial origin occur at a few horizons in the Spathian (uppermost Lower Triassic) Virgin Limestone Member of ...

Methane-related carbonates from Hydrate Ridge typically show several macroscopically distinguishable mineral phases, namely whitish aragonite, lucent aragonite, and gray micrite. The relationship of these phases to particular microorganisms or biogeochemical processes is as yet unclear. We used a miniaturized biomarker technique on mg samples, combined with factor analysis and subsequent electr...

A thin (3–25 cm), persistent conglomerate-sandstone unit occurs at the base of the transgressive systems tract of an Upper Pennsylvanian cyclothem below a transgressive limestone in outcrop and subsurface in SE Kansas and NE Oklahoma. It has an erosional base and a sharp top, and is composed of calcitic clasts, some shell fragments and quartz sand, and rare coal fragments. Clasts are rounded, e...

The present study concerns the Holocene inland beachrocks that are exposed in Red Sea coastal plain at mouth of Wadi Al-Hamd, South Al-Wajh City, Saudi Arabia, and their utility as an indicator for climate sea level changes. In addition, framework composition, carbon oxygen isotopic data, employed to interpret origin cement. beachrock consists mainly gravel coarse-grained terrigenous sediments ...

Abstract The main goal of the paper is reconstruction a Middle Triassic buildup cropping out in central part Southern Apennines. reefs western Tethys realm are well known Northern and Alps. In contrast, few studies Anisian–Ladinian carbonate platforms southern Apennines available, due to diagenetic alteration tectonic disruption that hinder their paleoenvironmental stratigraphic reconstruction....