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Lithology is the basis of subdividing rock sequences into individual lithostratigraphic units for the purposes of mapping and correlation between areas. In certain applications, such as site investigations , lithology is described using a standard terminology such as in the European geotechnical standard Eurocode 7 .
Lithostratigraphic units are recognized and defined on the basis of observable physical rock characteristics. The lithology of a unit includes characteristics such as chemical and mineralogical composition, texture, color, primary depositional structures, fossils regarded as rock-forming particles, or other organic materials such as coal or ...
Lithology: A description of the rock's physical characteristics, such as grain size, composition and texture. [4] By studying the lithology of local geological outcrops and core samples, geoscientists can use a combination of log measurements, such as natural gamma, neutron, density and resistivity, [2] to determine the lithology down the well.
a mud-supported carbonate lithology containing >10% grains. Packstone a grain-supported fabric containing 1% or more mud-grade fraction. Grainstone a grain-supported carbonate rock with <1% mud. Recognising that these classes did not encompass all carbonate lithologies, Dunham defined two additional classes within his scheme: Boundstone
The Summerville Formation is composed of alternating thin beds of two lithologies, mudstone and sandstone, penetrated by veins of a third lithology, gypsum. The boundaries of a formation are chosen to give it the greatest practical lithological consistency. Formations should not be defined by any criteria other than lithology.
Units of formation or higher rank are usually named for the unit's type location, and the formal name usually also states the unit's rank or lithology. A lithostratigraphic unit may have a change in rank over a some distance; a group may thin to a formation in another region and a formation may reduce in rank for member or bed as it "pinches out".
The term Seismic stratigraphy was introduced in 1977 by Vail [2] as an integrated stratigraphic and sedimentologic technique to interpret seismic reflection data for stratigraphic correlation and to predict depositional environments and lithology. This technique was initially employed for petroleum exploration and subsequently evolved into ...
In the petroleum industry, lithology, or more specifically mud logging, is the graphic representation of geological formations being drilled through and drawn on a log called a mud log. As the cuttings are circulated out of the borehole , they are sampled, examined (typically under a 10× microscope) and tested chemically when needed.