0000000000466047
AUTHOR
Abdullah Al-amri
showing 3 related works from this author
Microanalytical methods for in-situ high-resolution analysis of rock varnish at the micrometer to nanometer scale
2015
Abstract A wide range of analytical techniques were used to investigate rock varnish from different locations (Negev, Israel; Knersvlakte, South Africa; Death Valley and Mojave Desert, California): a 200 nm-femtosecond laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS), an electron probe microanalyzer (EPMA), focused ion beam (FIB) slicing, and scanning transmission X-ray microscopy–near edge X-ray absorption fine structure spectroscopy (STXM–NEXAFS). This combination enables comprehensive high-spatial-resolution analysis of rock varnish. Femtosecond LA-ICP-MS and EPMA were used for quantitative determination of element concentrations. In-situ measurements were conducte…
Geochemical insights into the relationship of rock varnish and adjacent mineral dust fractions
2020
Abstract Rock varnishes are μm-thin, dark, manganese(Mn)-rich crusts that accrete in the order of few μm/ka on weathering-resistant lithologies. Although these crusts can form in all climates, they are best known in arid to semi-arid settings. Aeolian dust is understood as a major contributor to the distinct trace metal and REE enrichments in rock varnish. However, the exact proportions of abiotic and biotic formation mechanisms that may explain the oxidation-reactions of Mn2+ to Mn4+, present as Mn oxyhydroxides in the varnish, are still a matter of ongoing debate. We present here the first systematic study of trace element enrichment processes between the uppermost layer of the varnish se…
Characterization and differentiation of rock varnish types from different environments by microanalytical techniques
2017
© 2017 Elsevier B.V. We investigated rock varnishes collected from several locations and environments worldwide by a broad range of microanalytical techniques. These techniques were selected to address the challenges posed by the chemical and structural complexity within the micrometer- to nanometer-sized structures in these geological materials. Femtosecond laser ablation-inductively coupled plasma-mass spectrometry (fs LA-ICP-MS), scanning transmission X-ray microscopy-near edge X-ray adsorption fine structure spectroscopy (STXM-NEXAFS) in combination with scanning electron microscopy (SEM) of focused ion beam (FIB) ultra-thin (100–200 nm) sections, conventional and polarization microscop…