Tipokhimizm mineraliv luzhno-ul'traosnovnikh kompleksiv Ukrayins'kogo shchita yak indikator glibinnosti yikh formuvannya  [Typomorphism of minerals from alkaline ultramafic complexes in Ukrainian Shield as depth indicator]

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Alternate Title:Typomorphism of minerals from alkaline ultramafic complexes in Ukrainian Shield as depth indicator
Authors:Krivdik, S. G.; Dubina, O. V.
Author Affiliations:Primary:
Natsional'na Akademiya Nauk Ukrayini, Insitut Geokhimiyi, Mineralogiyi ta Rudoutvorennya, Kiev, Ukraine
Volume Title:Mineralogicheskiy Zhurnal
Source:Mineralogicheskiy Zhurnal, 27(1), p.64-76. Publisher: Natsional'naya Akademiya Nauk Ukrainy, Institut Geokhimii, Mineralogii i Rudoobrazovaniya, Kiev, Ukraine. ISSN: 0204-3548
Publication Date:2005
Note:In Ukrainian with Russian and English summaries. 29 refs.; illus.
Summary:By comparing different alkaline ultrabasic and carbonatitic complexes of the Ukrainian Shield and other regions of the world some peculiarities of chemical composition of rock-forming and accessory minerals and their dependencies on crystallization conditions have been found. The diversities of the composition of the same type minerals (olivine, clinopyroxene, amphiboles, micas of biotite-phlogopite series, alkaline feldspar, apatite and some accessory minerals) in hypabyssal and abyssal carbonatite complexes are shown. In hypabyssal complexes olivine in alkaline silicate rocks and carbonatites has a magnesian composition (forsterite), and in deep-eroded ones it is enriched very much in iron (up to Fe70). The composition of clinopyroxene evolves in the same way: in hypabyssal complexes it is represented by varieties of isomorphous diopside-aegirine series with minor quantity of hedenbergite minal, whereas in deep-eroded (abyssal) complexes the contents of aegirine's minal in this mineral does not exceed 30% at a significant amount (up to 40-60%) of hedenbergite minal. The variations of amphibole composition are analogous: in hypabyssal complexes they are represented by magnesian hastingsite, katophorite and riebeckite-arfvedsonite, while in abyssal complexes less magnesian amphiboles of hastingsite-katophorite and edenite-katophorite series and also richterite and winchite crystallize, but alkaline amphiboles (riebeckite, arfvedsonite) are not known. More enriched in iron biotite and phlogopites are also typical of alkaline rocks and carbonatites of hypabyssal complexes, while tetraferryphlogopites (characteristic of hypabyssal complexes) occur rather rarely. Fluorite and rare earth fluor-carbonates may form in hypabyssal conditions, whereas these minerals were not found in abyssal (deep-eroded) complexes and the fluorine is allocated (up to a full saturation) in apatite, amphiboles and micas. In carbonatite of deep-eroded complexes rock-forming carbonates are often enriched by FeO (up to 2-4% in calcite and up to 5-6% in dolomite). Crystallization of such infrequent mineral as Ce-fergusonite in dolomite-calcite and dolomite carbonatites of the Chernihovka massif (the Peri-Azovian area) may be probably explained by its abyssal formation conditions. Low fugacity of oxygen during formation of deep-eroded carbonatite complexes (in contrast to hypabyssal ones) is considered one of the main factors, which can explain the available features of mineral composition. This factor promotes the allocation of FeO into silicates and carbonates forming the variates of those minerals highly enriched by iron.
Sections:Geochemistry; Petrology
Subsections:Igneous petrology
Subjects:Alkalic composition; Amphibole group; Biotite; Carbonatites; Chain silicates; Chemical composition; Clinopyroxene; Crystal chemistry; Fergusonite; Fugacity; Hedenbergite; Igneous rocks; Intrusions; Kimberlite; Mica group; Nesosilicates; Olivine; Olivine group; Orthosilicates; Oxides; P-T conditions; Plutonic rocks; Pyroxene group; Sheet silicates; Silicates; Typomorphism; Ultramafics; Chernigov Ukraine; Commonwealth of Independent States; Europe; Russian Platform; Ukraine; Ukrainian Shield
Abstract Numbers:06M/1501
Record ID:2006017114
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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