The relief indicates the difference between the RI (Refractive Indices) of the mineral grains and the surrounded cement material. The RI of the grain can be Greater than, Less than or equal to that of the surrounding material. “Backe Line Test” is carried out to determine weather the RI of mineral is higher or lower […]
“Cl” stands for lvuna-type, named after the lvuna meteorite that fall in Tanzania in 1938. The 1 indicates the petrologic type, with 1 = most primitive (least altered by heat but highly altered by water) Key Characteristics Features Description Type Carbonaceous chondrite (Cl group) Alteration Extensively altered by water (aqueous alteration) Chondrules Absent or extremely
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In sedimentary petrology and diagenesis, terms like neochemical, allochemical, protochemical and post chemical reactions are used to describe various stages or types of chemical changes. Term Timing Main Process Example Protochemical Very early (surface or shallow) Microbial activity, initial mineral formation Pyrite from sulfate reduction Neochemical Early diagenesis Authigenic mineral growth Dolomite replacing calcite Allochemical
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Zingg diagram is used for the classification of clastic sediment grain shapes (pebbles) based on three orthogonal axes : long (a), intermediate (b), and short (c). Method : Grain shape is defined by the ratios – Uses :
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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A wrench fault, also known as strike-slip fault, is a type of fault where the movement of blocks is primarily horizontal and is parallel to the strike of the fault plane. These can be either : These faults often form in transform plate boundaries or in strike-slip tectonic regimes and can be associated with complex
Wrench Fault in Hydrocarbons industry Read More »
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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