A sedimentary rock that is composed of at least 80% calcium or magnesium explanation of carbonatite. Carbonatites nomenclature, average chemical compositions and element distribution, a. After generation of silicate melts in the asthenosphere, the melts are then processed in the lithosphere associated with rifting, and parental nephelinitic melts from about 75 km depth then yield the carbon in the form of carbonatite at depths between. Implications for the origin of reeenriched carbonatite melt.
Some may develop near plate margins or be associated with rifted or incipiently rifted continental plates. Numerous carbonatites are also closely related to the rift zones, i. Carbonatite and peralkaline igneous deposits contain the highest ree concentrations but are exceedingly rare, especially in pa corecovery with other elements or recovery of ree from waste streams may increase economic potential abandoned tailings piles from some coal and iron mines may be important resources of ree. The agate mountain carbonatite complex, cape fria, nw. There are a variety of petrogenetic models that can be generated in the formation of this. Clinopyroxene phenocrysts in fergusite from a diatreme in the dunkeldyk potassic alkaline complex in the southeastern pamirs, tajikistan, and from carbonate veinlets cutting across this rock contain syngenetic carbonate, silicate, and complex melt inclusions. Calcium carbonate is typically burned out of igneous materials by intense heat. Rare earth contents in carbonatites miche loubet, michel bernat, marc javoy and claude j. White division ofgeologzcal and planetary sczences, calzfornza insztute of technology, pasadena, c4 91125 u s. The description given constitutes the first detailed discussion of the economic geology of a new type of deposit.
By the way, this sample resembles hedgehog for some. This carbonatite lava is the lowest temperature jun 18, 2017 carbonatite was introduced by the norwegian petrographer w. Ogundarec a department of physics and electronics, rhodes university, po box 94, grahamstown 6140, south africa. Spectral and kinetic analysis of thermoluminescence from manganiferous carbonatite m. The origin and genetic relationships of the oldoinyo lengai natrocarbonatite cannot be unambiguously determined, although these rocks are. In september 2011 the usgs mineral resources program mrp announced a grant andor cooperative agreement opportunity through its mineral resources external research program mrerp to any individual who had the ability to conduct research consistent with mrp goals and who was not employed by a federal agency. Siilinjarvi carbonatite is among the oldest from the archaean known carbonatites in the world. Light mg isotopes in mantlederived lavas caused by chromite crystallization, instead of carbonatite metasomatism. Dolomitic carbonatite magmas cannot be formed by liquid immiscibility, but only by fractionation of. Carbonatite article about carbonatite by the free dictionary.
Carbonatite volcanism at oldoinyo lengai requires no principally different mechanism from any other carbonatite associated with alkaline silicate magmatism. This carbonatite lava is the lowest temperature files are available under licenses specified on their description page. The scarcity of the nacarbonatites in the fossil record may be the combined result of rarely met conditions for prolonged crystal fractionation in carbonatites and the very difficult preservation of such rocks under atmospheric conditions. Geology of rare earth deposits national energy technology.
Implications for the origin of reenbenriched carbonatite. It was however the 1960 eruption of ol doinyo lengai in tanzania that led to geological investigations that finally confirmed the view that carbonatite is derived from magma. Carbonate melts and carbonatites mineralogical society of america. A common origin of carbonatite magmas daniel weidendorfer 1,2, max w. Origin of the sung valley carbonatite complex, meghalaya, india.
All structured data from the file and property namespaces is available under the creative commons cc0 license. Geological and geochemical characteristics of the miaoya syenitecarbonatite complex, central china. Carbonatite ringcomplexes explained by calderastyle volcanism. Carbonatite and carbonatite alkaline igneous complexes are typically located in relatively stable, intraplate regions, often within precambrian shield or continental platform areas. Carbonatite definition and meaning collins english dictionary. If you had to pick the most bizarre volcano on earth, tanzanias ol doinyo lengai would win. An integrated model is developed for the generation of crustal carbonatites from deepmantle carbon, some probably derived through subduction. Kempe the spatial and temporal distribution of carbonatites, a. The soil covers the perimeter of the carbonatite and tills the wide valley embayments running into the centre of the complex. A detailed reinvestigation of the occurrence by dunai 1989 led to the present srisotope study to assess a possible magmatic origin of the eureka carbonatite dykes.
Information on carbonatite deposits containing niobium and rare earth elements from around the world with grade and tonnage models, geologic setting, mineralogy, with data allowing locations of. The ontario department of mines in 1962 reinterpreted this data, which outlined an oval shaped magnetic high, which they believed to be a carbonatite. This page was last edited on 21 november 2019, at 21. Spectral and kinetic analysis of thermoluminescence from. The geochemistry of carbonatites and related rocks from two carbonatite complexes, south nyanza, kenya. New evidence from a calcitedolomite carbonatite dyke for the. Carbonatite is an igneous rock composed of at least 50% carbonate minerals 1. Geological and geochemical characteristics of the miaoya syenite carbonatite complex, central china. Mineralogical studies in assisting beneficiation of rare earth element minerals from carbonatite deposits wendy thompson, annegret lombard, eunice santiago, ashma singh mintek, private bag x3015, randburg 2125, south africa abstract rare earth elements ree are either housed in exotic ree minerals that sporadically populate the. Jul 11, 2008 clinopyroxene phenocrysts in fergusite from a diatreme in the dunkeldyk potassic alkaline complex in the southeastern pamirs, tajikistan, and from carbonate veinlets cutting across this rock contain syngenetic carbonate, silicate, and complex melt inclusions.
The relationship of rock types involved in carbonatite complexes has provoked much debate14. Namibia, 12 2000, 369382 the agate mountain carbonatite complex, cape fria, nw namibia r. Another potential source of confusion is the use of liquid compositions in phase. Keller carbonatite magma properties and processes, a. A group of carbonaterich tuffs are described from the murumuli crater, katwekikorongo volcanic field, sw uganda which contain abundant carbonatite pelletal lapilli, together with melilitite lapilli and a range of xenocrysts and lithic fragments including clinopyroxenites considered to be of mantle origin. Lllizu5, 26 1990 319 j elsevlcr science publishers b. Threeliquid immiscibility and the origin of carbonatites. A periclasedolomitecalcite carbonatite from the oka complex, quebec, and its calculated volatile composition allan h. Another potential source of confusion is the use of liquid compositions in phase diagrams to. Carbonatite and alkaline intrusi onrelated rare earth. An igneous rock containing more than 50% modal primary carbonate.
Caco3na,k2co3 pseudobinary at the natural nak ratio of. Experimental boundaries for the origin and evolution of. Paleoasian oceanic slab under the north china craton. Heinrich department of geology and mineralogy, the university of michigan, ann arbor, mich. Ma, an igneous origin of the eureka carbonatite dykes was considered by verwoerd 1967. A brief classification of economic mineral deposits associated with the carbonatite complexes is included. Carbonatites article about carbonatites by the free dictionary.
It comes from the first ancient carbonatite ever demonstrated to have originally been surficial volcanic material extrusive origin. Carbonatites carbonatites of the world, explored deposits of nb and ree. Petrographic, geochemical, and isotopic characteristics of. The general geology and distributions of carbonatites are described by heinrich 1966, gold 1966, moore 1973, le bass 1977, and nishimori and powell 1980. Find out that the association goes beyond mere visual resemblence.
As are most carbonatites, this rock is composed of calcite calcium carbonate caco 3, and it bubbles in acid. The dykes and the neighbouring massive dolomite h8 body have similar geochemical characteristics, interpreted to indicate a carbonatitic magmatic origin. The geochemistry of carbonatites and related rocks from two. It was however the 1960 eruption of ol doinyo lengai in tanzania that led to geological investigations that finally confirmed the view that carbonatite is. Origin of unusual hreemorich carbonatites in the qinling orogen. The case of the carbonatitelike dyke of the madenska. Pdf carbonatites and carbonatites and carbonatites researchgate. Pdf a common origin of carbonatite magmas researchgate. This is a deviation from a common practice in geology. The german rock shown below is famous among carbonatite researchers. Carbonatitesinto the twentyfirst century journal of.
Mineral resources external research program mrerp 2012. Thus it is difficult to divorce the origin of one from the origin of the other. Red circles indicate ulud outcrops, carbonatites and strongly sio2undersaturated ultrapotassic volcanic rocks some of which as rootless. Because of the growing interest of a number of researchers, the understanding of the carbonatite genesis and evolution has significantly increased since the 1960s, when its magmatic origin was. Y \msterdam experimental boundaries for the origin and evolution of carbonatites peter j, wyllie, michael b. Petrogenesis of carbonatite magmas from mantle to crust. Carbonatite and carbonatitealkaline igneous complexes are typically located in relatively stable, intraplate regions, often within precambrian shield or continental platform areas. Jianhui su, xinfu zhao, xiaochun li faculty of earth resources, china university of geosciences, wuhan, china, hubei province, email. Carbonatite complexes range in age from precambrian 2060 m.
Pdf the more than 500 fossil cacarbonatite occurrences on earth are at odds with the only active east african rift carbonatite volcano. Carbonatites have been variously explained as derived from magmatic melt, solid flow, hydrothermal solution, and gaseous transfer. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. The agate mountain carbonatite complex, cape fria, nw namibia. Journal of the geological society of india, 533, 285297. Barker extrusive carbonatites and their significance, j. Carbonatite is a unique type of intrusive igneous deposit which is rich in calcium carbonate calcite, caco 3 and minerals of the carbonate class. A periclasedolomitecalcite carbonatite from the oka. The origin of carbonatites is still the subject of debate. The term carbonatite was introduced by the norwegian petrographer w. A carbonate rock of apparent magmatic origin, generally associated with kimberlites and alkalic rocks. A number of distinct carbonatitesilicate rock associations occur that include melilititesovite, nephelinitesovite, pyroxenitesovite, and olivinerich ultrabasitesdolomitic carbonatite hornigkjarsgaard, this volume. Origin of unusual hreemorich carbonatites in the qinling. New data on sr and nd isotope composition and major and trace element distribution in dolomitecalcite carbonatite dykes at bayan obo are provided, and a midproterozoic age is deduced.
Intrusive carbonate rock associated with alkaline igneous intrusive activity. Carbonatites are primarily composed of calcite or dolomite of igneous origin and silicate mineral are also present. Carbonatite and alkaline intrusive complexes, as well as their weathering products, are the primary sources of rees long and others, 2010. Please redirect your searches to the new ads modern form or the classic form. However, neither the experimental data nor the field and petrographic studies provide reliable estimates of the compositions of. The purpose for this survey was to find vermiculite. Jan 23, 2007 new data on sr and nd isotope composition and major and trace element distribution in dolomitecalcite carbonatite dykes at bayan obo are provided, and a midproterozoic age is deduced. Fuzzy petrology in the origin of carbonatiticpseudocarbonatitic ca. Carbonatites are typically associated with alkali silicate igneous rocks. Carbonatite ree deposits are extremely enriched in light rees, particularly lanthanum, cerium, and neodymium. The origin of the bayan obo deposit has been debated, but recent work by yang and others 2011 demonstrates that the deposit fits into the carbonatite class of ree deposits. A common origin of carbonatite magmas geology geoscienceworld. Geology and petrology the eureka carbonatite dykes are located close to.
Carbonatites are igneous rocks that consist largely of the carbonate minerals calcite and dolomite. An investigation of the carbonatites of the kaapvaal craton. Carbonatites are familiar to students of petrology as rare igneous rocks formed predomi nantly of. Carbonatites of the world, explored deposits of nb and ree. Siilinjarvi carbonatite is largely a mixture of carbonatiteglimmerite biotitite. However, neither the experimental data nor the field and petrographic studies provide reliable estimates of the compositions of natural carbonatite magmas at the time of intrusion. The sukulu complex, eastern uganda and the origin of the. Files are available under licenses specified on their description page. Information on carbonatite deposits containing niobium and rare earth elements from around the world with grade and tonnage models, geologic setting, mineralogy, with data allowing locations of these deposits to be plotted using gis. Origin of carbonatite magma during the evolution of. Red circles indicate ulud outcrops, carbonatites and strongly sio2 undersaturated ultrapotassic volcanic rocks some of which as rootless. Most carbonatite occurrences are intrusive rocks but some are volcanic. Essene department of geological sciences, the university of michigan, ann arbor mi 48109, usa abstract. The homogenization of the silicate and carbonate material of the inclusions with the complete dissolution of daughter crystalline.
1002 507 1494 287 104 952 1075 491 880 251 589 866 1060 1513 1416 175 204 1006 1322 1583 1350 1133 682 1216 1410 1417 280 307 1355 685 595 310 371 839 765 1469 100 558 1303 551 187 354 1258 367 390 183 198