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Dinosterane
Dinosterane is a steroidal alkane, also known as 4α,23,24-trimethylcholestane. It is used in geochemistry as a biomarker, interpreted as an indication of dinoflagellate presence due to its derivative dinosterol high occurrence in extant dinoflagellate species and its rarity in other taxa, although it has been shown to be produced by a single species of marine diatom as well. History of use as a biomarker A 1984 study was conducted which established the dinoflagellate origin for dinosterane based on distributions of modern dinoflagellates and dinosterane abundance in sediment. In 1993, dinosteranes were discovered in a section of the Bristol Trough that was dated to the Rhaetian Age. Due to the co-deposition of these dinosteranes with dinoflagellate cysts and comparison of microfossil abundance with hydrocarbon abundance, the dinosterane was associated with marine dinoflagellates. This was the first stratigraphic evidence for Mesozoic dinoflagellates. In 1998, dinostera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cholestane
Cholestane is a saturated tetracyclic triterpene. This 27-carbon biomarker is produced by diagenesis of cholesterol and is one of the most abundant biomarkers in the rock record. Presence of cholestane, its derivatives and related chemical compounds in environmental samples is commonly interpreted as an indicator of animal life and/or traces of O2, as animals are known for exclusively producing cholesterol, and thus has been used to draw evolutionary relationships between ancient organisms of unknown phylogenetic origin and modern metazoan taxa. Cholesterol is made in low abundance by other organisms (e.g., rhodophytes, land plants), but because these other organisms produce a variety of sterols it cannot be used as a conclusive indicator of any one taxon. It is often found in analysis of organic compounds in petroleum. Background Cholestane is a saturated C-27 animal biomarker often found in petroleum deposits. It is a diagenetic product of cholesterol, which is an organic molec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sterane
Sterane (cyclopentanoperhydrophenanthrenes) compounds are a class of tetracyclic compounds derived from steroids or sterols via diagenetic and catagenetic degradation and saturation. Steranes have an androstane skeleton with a side chain at carbon C-17. The sterane structure constitutes the core of all sterols. Steranes are sometimes used as biomarkers for the presence of eukaryotic cells. Steranes may be rearranged to diasteranes during diagenesis (C-27 to C-30, rearrangement at C-18 and C-19, no R at C-24). Oils from clastic source rocks tend to be rich in diasteranes. Cholesterol and its derivatives (such as progesterone, aldosterone, cortisol, and testosterone), are common examples of compounds with the cyclopentanoperhydrophenanthrene nucleus. See also * Cholestane Cholestane is a saturated tetracyclic triterpene. This 27-carbon biomarker is produced by diagenesis of cholesterol and is one of the most abundant biomarkers in the rock record. Presence of cholestane, its d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biomarker (petroleum)
In chemistry and geology, biomarkers are any suite of complex organic compounds composed of carbon, hydrogen and other elements or heteroatoms such as oxygen, nitrogen and sulfur, which are found in crude oils, bitumen, petroleum source rock and eventually show simplification in molecular structure from the parent organic molecules found in all living organisms. Essentially, they are complex carbon-based molecules derived from formerly living organisms.Wang, Z.; Stout, S.; Fingas, M. ''Environmental Forensics'', 2006 7, 105-146. Each biomarker is quite distinctive when compared to its counterparts, as the time required for organic matter to convert to crude oil is discreet. Most biomarkers also usually have high molecular mass. Some examples of biomarkers found in petroleum are pristane, triterpanes, steranes, phytane and porphyrin. Such petroleum biomarkers are produced via chemical synthesis using biochemical compounds as their main constituents. For instance, triterpanes ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinoflagellate
The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are mostly marine plankton, but they also are common in freshwater habitats. Their populations vary with sea surface temperature, salinity, and depth. Many dinoflagellates are photosynthetic, but a large fraction of these are in fact mixotrophic, combining photosynthesis with ingestion of prey (phagotrophy and myzocytosis). In terms of number of species, dinoflagellates are one of the largest groups of marine eukaryotes, although substantially smaller than diatoms. Some species are endosymbionts of marine animals and play an important part in the biology of coral reefs. Other dinoflagellates are unpigmented predators on other protozoa, and a few forms are parasitic (for example, ''Oodinium'' and ''Pfiesteria''). Some dinoflagellates pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinosterol
Dinosterol is a type of steroid produced by several genera of dinoflagellates. It is a 4α-methyl sterol (4α,23,24-trimethyl-5α-cholest-22E-en-3β-ol), a derivative of dinosterane, rarely found in other classes of protists. This sterol and others have been considered as class-specific, being biomarkers for dinoflagellates, although dinosterol is produced in minor amounts by a small number of other phytoplankton, such as the marine diatom ''Navicula speciosa''. and Prymnesiophytes of the genus ''Pavlova''. Dinosterols show similar abundances as dinocysts. Other studies found a nonlinear or did not find a direct link between dinocyst abundances and sterol concentrations. Dinosterol has been used as indicator for dinoflagellate production in the Cariaco Basin. Hydrogen isotope ratios in dinosterols can serve to reconstruct salinity semi-quantitatively. Some studies have shown that certain dinoflagellates The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diatom
A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising several genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of the Earth's biomass: they generate about 20 to 50 percent of the oxygen produced on the planet each year, take in over 6.7 billion metric tons of silicon each year from the waters in which they live, and constitute nearly half of the organic material found in the oceans. The shells of dead diatoms can reach as much as a half-mile (800 m) deep on the ocean floor, and the entire Amazon basin is fertilized annually by 27 million tons of diatom shell dust transported by transatlantic winds from the African Sahara, much of it from the Bodélé Depression, which was once made up of a system of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bristol Trough
Bristol () is a city, ceremonial county and unitary authority in England. Situated on the River Avon, it is bordered by the ceremonial counties of Gloucestershire to the north and Somerset to the south. Bristol is the most populous city in South West England. The wider Bristol Built-up Area is the eleventh most populous urban area in the United Kingdom. Iron Age hillforts and Roman villas were built near the confluence of the rivers Frome and Avon. Around the beginning of the 11th century, the settlement was known as (Old English: 'the place at the bridge'). Bristol received a royal charter in 1155 and was historically divided between Gloucestershire and Somerset until 1373 when it became a county corporate. From the 13th to the 18th century, Bristol was among the top three English cities, after London, in tax receipts. A major port, Bristol was a starting place for early voyages of exploration to the New World. On a ship out of Bristol in 1497, John Cabot, a Venetian, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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