Dismicrite is a type of micritic limestone that contains irregular patches or pockets of sparry calcite (coarse crystalline calcite) within a fine-grained micritic matrix. The term is derived from : Features or Properties of Dismicrite Texture : Fine grained (micritic) with sparry calcite patches. Composition : Mainly micrite (carbonate mud, CaCO3) with coarser sparry calcite […]
The Alizarin Res S Test is a staining technique used in petrology to distinguish between calcite and dolomite. How it works Procedure “If the rock contains both dolomite and calcite, only the calcite areas will stain red, while the dolomite remains unstained.” Applications of Alizarin Res S Test
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Sandstone maturity refers to the degree of weathering, sorting, and rounding of grains within a sandstone, as well as the composition of the rock. It’s a measure of how far the sand has been transported and reworked, reflecting the degree of sedimentary cycle. Maturity is assessed through both textural and compositional characteristics. Mineralogical maturity (also called as compositional
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Imbricate structure (or imbrication) is a geological fabric seen in clastic sedimentary rocks—especially in conglomerates and gravels—where elongated or flat clasts (like pebbles) are stacked or aligned in a consistent overlapping pattern, much like fallen dominoes or roof shingles. Mechanism Imbrication occurs due to the directional flow of water or wind, which exerts force on
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Mud cracks are the fracture patterns that formed in the muddy sediments, in sub-aerial environment. They are of two types :- Desiccation Cracks Syneresis Cracks Why are mud cracks important ?
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On the basis of mineral replacement and intergrowths, four oxide series are recognized among the sandstones – Stages of diagenesis From the type of reaction and the principal sequence of occurence three stages of diagenesis are established as follows – Among sandstones, the progress of diagenesis may be arrested at either the locomorphic or phyllomorphic
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Chemical weathering may be defined as the spontaneous and irreversible thermodynamic process that causes degradation of the mineral phases under the prevailing environmental conditions at the surface of the Earth. It is usually considered to be the solid/solution interactive process occurring in contact with the atmosphere. In other words chemical weathering may be defined as that set of processes
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This plot shows the average current velocities necessary for the erosion, transportation and deposition of the sediment particles of different sizes. The lower curve on the diagram, it shows that once eroded and moving a clay particle, but not a fine particles of sand can be transported by a week current. This is because the
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Marine isotope stages (MIS), marine oxygen-isotope stages, or oxygen isotope stages (OIS) are alternating warm and cool periods in the Earth’s paleoclimate, deducted from oxygen isotope data derived from deep sea core samples. Working backwards from the present, MIS 1 in the scale, stages with even numbers have high levels of O18 and represents cold
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Sapropel is a term used in marine geology to describe dark-colored sediments that are rich in organic matter. Sapropels events occurs periodically (around each 21000yr) and are specific to the Mediterranean sea. Organic carbon concentration in sapropels commonly exceeds 2% in weight. Their occurrence has been found to be related of the Earth’s orbital parameter.
