The present work uncovers the geochemical control on nature (tunnel size) of tectomanganates formed from layered precursors, and thus provides insights into formation Mn oxides in natural environments. Large tunnel sizes are favored under circum-neutral conditions, whereas low pH conditions favor with smaller sizes. Both increased proportions Mn(III) vernadite/birnessite layers resulting subseq...

Neoproterozoic banded iron formations (BIF) and ironstones occur in the Urucum mining district (Pantanal, Brazil). Microbially mediated formation as microbialites has been proposed for these deposits. This study aims to provide a high resolution characterization of micro-textural features, mineral assemblage distribution gather evidence two microbial ore forming systems: Fe- Mn-oxidizing metabo...

Modern fluvial deposits can be affected by early diagenetic element mobilization at redox boundaries between oxygenated, and oxygen free zones near the groundwater level. The visible product of transformation Fe is sediment colour. Distinct red black layers have been studied in eight shallow (<4.2 m depth) sections floodplain Morava River, Czechia. aim was to investigate composition, origin, ra...

Caves are dark subsurface environments with relatively constant temperatures that allow studying bio-mineralization processes and paleoenvironmental or climate changes in optimal conditions. In the extreme oligotrophic cave environment, manganese patinas having stromatolite-like features uncommon. Here we provide first detailed mineralogical, geochemical, microbiological investigation of fine-g...

the nasirabad manganese deposit is located 5 km south of nasirabad, 8 km sw of neyriz in the fars province. structurally, the area is placed in the southeastern part of zagros thrust belt. in this area, the manganese mineralization occurred as ore layers and nodules, interlayered with pichakun radiolarite chert deposits. in this study, mineralogy and geochemistry of uranium, thorium and lead is...

Our understanding of the up to 7 orders magnitude partitioning thallium (Tl) between seawater and ferromanganese (FeMn) deposits rests upon two foundations: (1) being able quantify Tl(I)/Tl(III) ratio that reflects extent oxidative scavenging Tl by vernadite (?-MnO2), principle manganate mineral in oxic suboxic environments, (2) determine sorption sites bonding environments Tl(I) Tl(III) comple...

Attention is now being given to Ni isotope systematics in hydrogenetic marine ferromanganese (Fe-Mn) crusts as paleoceanographic proxies. Previous work focused on identifying both mineralogy (post-depositional) and source effects (Gall et al. 2013; Gueguen 2016), particular regarding hydrothermal inputs the oceans response of biogeochemical cycling through time. The most important sink for Fe-M...

Abstract Fe–Mn concretions and mineralizations, associated with condensed horizons hardground, are significant archives in ancient carbonate rocks. Their petro-chemical study allows an assessment of the palaeoenvironmental context which they were formed also connected to their biotic or abiotic origin. At western side Monte Inici (Fornazzo section, north-western Sicily) a well exposed outcrop p...

Paranhos constitutes one of the main water galleries excavated in the granite substratum of Porto City (Portugal) to gather the groundwater for public use during the past six centuries. The interest of this water gallery is double: a) Cultural Heritage and scientific value, b) Underground geoturism. A multidisciplinary research to study the microclimatology, geochemistry, mineralogy and geomicr...