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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.
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.
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 ...
Some Archean rock formations show macroscopic similarity to modern microbial structures, leading to the inference that these structures represent evidence of ancient life, namely stromatolites. However, others regard these patterns as being the result of natural material deposition or some other abiogenic mechanism.
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.
Individual studies on microbial mat-induced sedimentary structures are summarized and illustrated in several recent books, including Atlas of microbial mat features preserved in the siliciclastic rock record [18] and Microbial Mats in Siliciclastic Depositional Systems Through Time. [19]
Diagenesis (/ ˌ d aɪ. ə ˈ dʒ ɛ n ə s ɪ s /) is the process that describes physical and chemical changes in sediments first caused by water-rock interactions, microbial activity, and compaction after their deposition. Increased pressure and temperature only start to play a role as sediments become buried much deeper in the Earth's crust. [1]