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The Belt Supergroup, an assemblage of rocks of late Precambrian (Mesoproterozoic) age, includes thick sequences of argillite, as well as other metamorphosed or semi-metamorphosed mudstones. [1] It is exposed primarily in western Montana , including the Bitterroot Valley and Bitterroot Mountains , the Missoula area, Flathead Lake , and Glacier ...
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g., kaolin, Al 2 Si 2 O 5 4) and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite. [1] Shale is characterized by its tendency to split into thin layers less than ...
Oil shale geology is a branch of geologic sciences which studies the formation and composition of oil shales–fine-grained sedimentary rocks containing significant amounts of kerogen, and belonging to the group of sapropel fuels. [1] Oil shale formation takes place in a number of depositional settings and has considerable compositional variation.
The effect of bioturbation has been documented well in shale cores sampled: past variable critical depths where burrowing organisms can no longer survive, shale fissility will become more pervasive and better defined. Fissility is used by some geologists as the defining characteristic which separates mudstone (no fissility) from shale (fissile ...
There are many varieties of shale, including calcareous and organic-rich; however, black shale, or organic-rich shale, deserves further evaluation. In order for a shale to be a black shale, it must contain more than one percent organic carbon. A good source rock for hydrocarbons can contain up to twenty percent organic carbon.
[1] [2] The most common types include coal, lignite, oil shale, or black shale. [2] The organic material may be disseminated throughout the rock giving it a uniform dark color, and/or it may be present as discrete occurrences of tar , bitumen , asphalt, petroleum , coal or carbonaceous material.
Source rocks are classified from the types of kerogen that they contain, which in turn governs the type of hydrocarbons that will be generated: [1]. Type I source rocks are formed from algal remains deposited under anoxic conditions in deep lakes: they tend to generate waxy crude oils when submitted to thermal stress during deep burial.
Oil shale is an organic-rich fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons can be produced. In addition to kerogen, general composition of oil shales constitutes inorganic substance and bitumens.