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Natural End Member Samples of pyrope and Grossular:A Cathodoluminescence-Microscopy and-Spectra Case Study

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Journal of Earth Science 2018年第5期29卷 989-1004页

作者： Hans-Peter Schertl Joana Polednia Rolf D.Neuser Arne P.Willner Ruhr-University Bochum Institute of GeologyMineralogy and GeophysicsD-44780 BochumGermany College of Earth Science&Engineering Shandong University of Science and TechnologyQingdao 266590China Bayerisches Geoinstitut Universitat BayreuthD-95440 BayreuthGermany

Garnet is one of the most significant minerals in metamorphic rocks, that provides key information on prograde, peak-metamorphic and retrograde parts of the pressure-temperature （PT） path. Such results require a detailed knowledge of its different growth domains. For iron-poor compositions, the cathodoluminescence （CL） microscopy is an important and often overlooked method and allows to identify the internal structures of all garnet grains in one thin section within only a few seconds. The advantage of the CL-microscope is to deliver low magnification images in true color, not only of garnet but also, for instance, of other rock forming silicates, carbonates, sulfates, etc., of metamorphic, but also of sedimentary and magmatic origin, using polished thin sections. Internal structures of grossular from Mexico and pyrope from the Italian Alps were characterized and visualized by CL-microscopy. The different growth domains were additionally studied using CL-spectra and electron microprobe （EMP） analysis. Grossular shows a patchy zonation in its core while in mantle and rim zones oscillatory zoning is observed. It contains zones of anomalous birefringence, zones of orange and bluish luminescence and zones lacking luminescence. Different but low amounts of the activator elements Mn2＋ and Eu2＋ are responsible for the orange and bluish luminescent domains. pyrope is also characterized by oscillatory growth zones, shows a dull luminescent core with a change of crystal morphology during growth, and displays an increase of brightness from core towards rim--the outermost rim, however, is lacking luminescence. The different luminescent zones are characterized by different amounts of Dy3＋, Tb3＋, Sm3＋ and Sm2＋ as activator elements. Because of slow diffusion rates of activators such as the REEs Sm, Dy and Tb, it can be still possible to visualize possible prograde and/or peak pressure stage growth domains of garnet, even if later high temperature events may have homogenized the m

关键词： pyrope grossular cathodoluminescence (CL) oscillatory zoning REE CL-spectra.

Garnet of the pyrope-Majorite Series from Coorara Meteorite and Lamprophyres of Central Timan

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Journal of Chemistry and Chemical Engineering 2011年第9期5卷 804-809页

作者： Natalya I. Bryanchaninova Alexander B. Makeyev Institute of Geology of Ore Deposits Petrography Mineralogy and Geochemistry （IGEM） RAS Moscow Russia

In kersantite and spessartite dikes of Chetlas Kamen＇ in Central Timan among accessory garnets, that are rather rare in lamprophyres, there was discovered few and for the first time high-majorite pyrope garnet with majorite minal Mg3Fe2[SiO4]3 （26-42%）, similar to majorite garnet originating from a meteorite. Majorite discovered in Coorara meteorite is very rare in the terrestrial rocks. As it is shown, there is 18% pyroxene admixture in original analysis of maj orite that is why a surplus of S i appeared in its formula. In rocks, where majorite garnet was found, there are also revealed microcrystalline diamonds.

关键词： Majorite pyrope lampropheres Coorara meteorite Timan.

Composition of the Diamond Indicator Minerals on the Mitchell Chart――Criteria of CLIPPIR Diamonds in Kimberlites and Conditions of their Mantle Crystallization

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Acta Geologica Sinica(English Edition) 2021年第S1期95卷 121-124页

作者： Vladimir N.ZINCHENKO Alexandr S.IVANOV Igor V.ASHCHEPKOV CATOCA Mining Society СatocaAngola ALROSA Ltd. MirnyRussia V.S.Sobolev Institute of Geology and Mineralogy SB RAS NovosibirskRussia

In the last decade,researchers have been particularly interested in IIa CLIPPIR type diamonds,which differ in composition and physical characteristics from diamonds of peridotite related"P"and eclogite related"E"***(Moore,2009)sought them as mantle kimberlite related megacrysts,but light C isotopy and chemical features needs special explanation.

关键词： CLIPPIR diamonds kimberlite mantle pyrope clinopiroxene chromite ilmenite

Composition of Hydrocarbons in Diamonds, Garnet, and Olivine from Diamondiferous Peridotites from the Udachnaya Pipe in Yakutia, Russia

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Engineering 2019年第3期5卷 471-478页

作者： Nikolay V. Sobolev Anatoly A. Tomilenko Taras A. Bul’bak Alla M. Logvinova V.S. Sobolev Institute of Geology and Mineralogy Siberian Branch of the Russian Academy of Sciences Novosibirsk 630090 Russia Department of Geology and Geophysics Novosibirsk State University Novosibirsk 630090 Russia

Volatile components in diamonds, associated garnet (pyrope), and olivine from two extremely rare xenoliths of diamondiferous peridotites recovered from the Udachnaya kimberlite pipe in Yakutia, Russia, were analyzed by gas chromatography–mass spectrometry (GC–MS) using a Focus DSQ II Series Single Quadrupole GC–MS (Thermo Scientific, USA). These xenoliths are pyrope lherzolite and pyrope dunite based upon compositions of coexisting minerals. Unlike the pyrope lherzolite, which contained pyrope with moderate calcium (Ca)-component content (about 15 mol%), the dunite contained subcalcic chromium (Cr)-pyrope with low Ca-component content (less than 10 mol%). All investigated minerals contained dominating hydrocarbons and their derivatives represented by aliphatic (paraffins, olefins), cyclic (naphthenes, arenes), oxygenated (alcohols, ethers), and heterocyclic (dioxanes, furans) hydrocarbons;nitrogenated, chlorinated, and sulfonated compounds;carbon dioxide (CO2);and water (H2O). The relative concentration (rel%) of total hydrocarbon was 79.7 rel% for diamonds, 69.1 rel% for garnet, and 92.6 rel% for olivine, with a general amount of components ranging from 161 to 206. New data on volatiles in diamonds, associated garnet, and olivine suggest the presence of a wide spectrum of hydrocarbons along with nitrogen (N2), CO2, and H2O in some upper mantle areas.

关键词： Diamond Volatiles Hydrocarbons pyrope Olivine Inclusions

Concerning Diamond and Gold-Bearing Astropipes of Mongolia

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International Journal of Astronomy and Astrophysics 2011年第2期1卷 98-104页

作者： Dorj Dorjnamjaa D. M. Voinkov L. S. Kondratov D. Selenge G. Altanshagai B. Enkhbaatar 不详

In this paper we present summation of thirteen year’s investigation of the all diamond-bearing structures of Mongolia. Four gold and diamond-bearing astropipe structures of exemplified by the Agit Khangay, Khuree Mandal, Bayan Khuree and Tsenkher astropipes of Mongolia. Detailed geological and gas-geochemical investigation of the diamond and gold-astropipe structures show that diamond genesis is an expression of collision of the lithospheric mantle with the explosion process initiated in an impact collapse meteor crater.

关键词： Astropipe Diamond Impact Crater Spherules Meteoritic Iron Shatter Cones pyrope