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Coquina (/ k oʊ ˈ k iː n ə /) is a sedimentary rock that is composed either wholly or almost entirely of the transported, abraded, and mechanically sorted fragments of mollusks, trilobites, brachiopods, or other invertebrates. [1] [2] The term coquina comes from the Spanish word for "cockle" and "shellfish". [3] [4]
Uluru (Ayers Rock) is a large sandstone formation in Northern Territory, Australia.. Sedimentary rocks can be subdivided into four groups based on the processes responsible for their formation: clastic sedimentary rocks, biochemical (biogenic) sedimentary rocks, chemical sedimentary rocks, and a fourth category for "other" sedimentary rocks formed by impacts, volcanism, and other minor processes.
The type of kerogen depends also on the degree of heat and pressure it has been subjected to, and the length of time the geological processes ran. The result is that a complex mixture of organic compounds reside in sedimentary rocks, serving as the precursor for the formation of hydrocarbons such as oil and gas. In short, kerogen amounts to ...
Shelly limestones are mainly found near where marine life live or where marine life once occupied. The unique qualities of a shelly limestone are formed with the help of calcite, acting as a sticking agent for small shell fragments, dead marine organism and other minerals. Typically, the rock is composed of approximately 10 percent calcium ...
Chert (/ tʃ ɜːr t /) is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, [1] the mineral form of silicon dioxide (SiO 2). [2] Chert is characteristically of biological origin, but may also occur inorganically as a chemical precipitate or a diagenetic replacement, as in petrified wood.
Organic-rich sedimentary rocks may act as source rocks which generate hydrocarbons that accumulate in other sedimentary "reservoir" rocks [2] (see oil sands and petroleum geology). Potential source rocks are any type of sedimentary rock that the ability to dispel available carbon from within it (limestone is a classic example of a source rock ...
Conglomerate (/ k ən ˈ ɡ l ɒ m ər ɪ t /) is a sedimentary rock made up of rounded gravel-sized pieces of rock surrounded by finer-grained sediments (such as sand, silt, or clay). The larger fragments within conglomerate are called clasts, while the finer sediment surrounding the clasts is called the matrix.
Approximately 75% of surface sediments are in shallow marine environments, holding most Phanerozoic and Precambrian sedimentary rock. [3] This is visible in the North American and Caribbean regions. However, shallow marine sediment quantity varies significantly over geologic time due to supercontinent breakup and shifting tectonic plate processes.