Rock varnish is generally understood to be a 5-500 micrometer thick nanostratigraphic coating consisting of approximately 70% clay glued together by 30% iron and manganese oxides, which forms on the surfaces of rocks in most semi-arid to hyper-arid climates. Many investigators believe that manganese exists in rock varnish mainly as birnessite, and that varnish has at least a partial biological ...

INTRODUCTION THE NAME illite was proposed by Grim, Bray and Bradley in 1937 for the mica-type mineral occurring in argillaceous sediments. It was specifically stated that "the term is not proposed as a specific mineral name, but as a general term for the clay mineral constituent of argillaceous sediments belonging to the mica group". Abundant research has shown that many soils, clays and shales...

High-resolution mapping by visible and near-infrared orbital spectrometers has revealed a diversity of hydrated mineral deposits on the surface of Mars. Quantitative analysis of mineral abundances within these deposits has the potential to distinguish depositional and diagenetic processes. Such analysis can also provide important constraints on the nature of putative global and local-scale mine...

Introduction: For nearly a decade, the international program of Mars exploration has been guided by a remarkably useful framework that describes how Mars' environmental conditions have evolved in the context of time-dependent changes in the mineralogy of rock and regolith deposits at the Martian surface [1]. Built on the basis of observations by the OMEGA spectrometer onboard ESA's Mars Express...

Bioerosion increases the topographic complexity of soft rock habitats, thereby increasing species diversity. This increase in species diversity may either be associated with an increase in complexity or may simply be a consequence of the increase in available surface area for colonisation. The influence of habitat modification by piddocks on intertidal species richness was investigated through ...

Seismic techniques for direct hydrocarbon indication rely on the changes in seismic character which accompany changes in pore fluid content. Interpretation and modeling of direct hydrocarbon indicators (DHIs) require an understanding of the factors affecting seismic velocities and reflection coefficients which are, in turn, dependent on pore fluid properties, rock frame properties, and fluid su...

productivity of an oil well is an important parameter in any oil field development. low production rate of the wells, impose more production wells drilling which directly jeopardizes the economical feasibility of the project. oil production rate in some of the wells is very low due to low permeability of the reservoir rock. several practice like hydraulic fracturing and acid fracturing is very ...