Chemical and Os-isotopic composition of Ru–Os sulfides from the Verkh-Neivinsky dunite-harzburgite massif (Middle Urals, Russia) Melt depletion was less than 10% for lherzolite and 10%–15% for harzburgite. The mineral assemblage is greater than 90% olivine, with minor amounts of other minerals such as pyroxene, chromite, magnetite, and pyrope. Journal of Geophysical Research 103 (1998): 7431-7441. VARIATIONS IN BRUCITE COMPOSITION AND ABUNDANCE IN COMPOSITIONAL DOMAINS IN A SERPENTINIZED HARZBURGITE. Lherzolite : a peridotite composed primarily of olivine with significant amounts of orthopyroxene and clinopyroxene. Seismic tomography studies have detected widespread fast anomalies in Based on our petrographic, mineral-chemical, and whole-rock chemical studies, we estimate that equilibration temperatures at the time of entrainment were 824–1058 °C and that Δlog fO 2 FMQ values are 0 to –2.6 for lherzolite and –1 to +0.61 for harzburgite. PGMs were studied using electron microprobe analysis, laser ablation and multiple collector-inductively coupled plasma-mass spectrometry. On the other hand, the mantle is hypothesized as a mechanical mixture of two end-members of mantle differentiation, basalt and harzburgite, that never reaches equilibrium ( 34 ). Dunite, harzburgite and chromitite of alpine-type ultramafic complexes emplaced in the Paleozoic sediments in the Sangun—Yamaguchi zone, western Japan We use cookies to enhance your experience on our website.By continuing to use our website, you are agreeing to our use of cookies. The composition of the host basalt is … Fields include peridotite, pyroxenite, dunite, lherzolite, harzburgite, wehrlite, olivine-websterite, websterite, orthopyroxenite, clinopyroxenite. is an abbreviation for olivine having a total iron oxide content of less than 5% which is obtained by calcining a demagnetized fraction from a magnetite-containing serpertinite. Harzburgite is generally accepted as an important part of subducting slabs, overlain by a layer of basalt. Lherzolite is the least pretentious of them — it is a mixture of two pyroxenes and olivine 1 . P3 is the least modally metasomatized harzburgite. 1000 °C, followed by the crystallization of an intermediate solid solution (ISS) below 900 °C. "Chemical- and Clapeyron-induced buoyancy at the 660 km discontinuity." Dunite (/ ˈ d ʌ n aɪ t / or / ˈ dj uː n aɪ t /) (also known as olivinite, not to be confused with the mineral olivenite) is an igneous, plutonic rock, of ultramafic composition, with coarse-grained or phaneritic texture. Chemical compositions of amphibole in harzburgite xenoliths in the 1991 Pinatubo dacitic volcanic ejecta. Compared with pyrolite, harzburgite is generally lower in alumina and calcia but higher in magnesia. Subducted materials play an important role in affecting chemical composition and structure of the mantle transition zone. chemical composition depends on the petrogenesis (crystallisation from melt, residue after partial melting) and physical conditions (temperature, pressure, oxygen fugacity) of their host peridotites [24 31]. amount of basaltic melt. ABSTRACT There is provided a novel harzburgite of the formula PYx O? Different techniques have been combined to determine the crystallography and the chemical composition of serpentinized harzburgite sampled in a drill core coming from the lower part of the New Caledonia ophiolite. 10.1016/j.epsl.2010.05.026 Created … Please see: Weidner, D. J., and Y. Wang. The influence of MORB and harzburgite composition on thermo-chemical mantle convection in a 3-D spherical shell with self-consistently calculated mineral physics Author: Takashi Nakagawa Subject: Earth and Planetary Science Letters, 296 (2010) 403-412. The chemical composition of the harzburgite (Table 1) thus prepared is similar to that from North Atlantic [Michael and Bonatti, 1985] and East Pacific Rise [Dick and Natland, 1996]. Amphiboles Amphiboles, from the Greek amphibolos, meaning ambiguous, was named by the famous French crystallographer and mineralogist René-Just Haüy in allusion to the great variety of composition and appearance shown by this mineral group.There are 5 major groups of amphiboles leading to 76 chemically defined end-member amphibole compositions according to the British mineralogist … the other is a refractory harzburgite 84-402 with a . The mineral content of Lherzolite includes Harzburgite, Olivine, Pyroxene, Pyrrhotite and mineral content of Harzburgite includes Amphibole, Chromite, Garnet, Magnesium, … Harzburgite and Pyrolite 3% Al3+ Pyrolite Mantle Image removed due to copyright considerations. Specifically, this serpentinized harzburgite is the common bedrock of most of the nickel laterite mines in New Caledonia. At mid-ocean ridges, because of decompression partial melting, upwelling peridotite (1-x) where x is a decimal number of from 0.001 to 0.4, Py is an abbreviation for pyroxene, and Ol is an abbreviation for olivine having a total iron oxide content of less than 5% which is obtained by calcining a demagnetized fraction from a magnetite-containing serpentinite. Dynamic and chemical processes near (right) a mid-ocean ridge and (left) a subduction zone. 76 THE CANADIAN MINERALOGIST ofrock may vary significantly, in response to lithologi- ... harzburgite and gabbro are the majorexposed lithologies in the association. Time 1—Harzburgite into the shallow mantle, composed by olivine (light poligons), orthopyroxene (brown) and Cr-spinel (black). The composition of this harzburgite is Py 0.08 Ol 0.92 This material was pressed to 5000 psi and fired up to 1500° C. After firing the absorption of the refractory material was 1.3%, its specific gravity 2.60, and its cold crushing strength 21 300 psi. Development of Chemical Zoning in Plumes. chemical grounds. Topic. Additionally, the degree of partial melting can be calculated using the chemical composition of unaltered spinel-group minerals. The compositional variations in these minerals are related to original differences in bulk chemical composition. 1. The phlogopite crystals within the vesicles of the harzburgite are chemically similar to phlogopite phenocrysts formed from the lavas. The influence of MORB and harzburgite composition on thermo-chemical mantle convection in a 3-D spherical shell with self-consistently calculated mineral physics Earth and Planetary Science Letters, 2010 We established the formation process of the metasomatic PGE-bearing sulfide inclusion by considering morphological and mineral characteristics in addition to the chemical composition. The composition of the chromite in a particular body. depleted major-element composition 1.3% Al O 23 and 0.9% CaO that reflects the loss of a large. Pyroxenite Composition Pyroxenite composition is contain at least 90 percent pyroxene group minerals, such as as augite, diopside, hypersthene, bronzite or enstatite.Pyroxenite also contain olivine and oxide minerals. (A) Classification of calcic amphibole of Pinatubo harzburgites following the system of Leake et al. Like most refractory harzburgites, this sample is LREE-enriched, indica-tive of metasomatic overprinting of the original de-pleted REE pattern 3 . P1 is … Composition of the mantle ... mantle rocks in these harzburgite ophiolites most likely melted beneath a mid-ocean ridge to produce the ... from pyrolite and Losimag chemical abundances as well as meteorite and stellar-based approaches to constraining the composition of the Earth. Harzburgite is similar to these rocks: Peridotite, Anorthosite, Kimberlite and more. Dolerite sills and basalt represent less Most of them have an obvious green color, attributed to their olivine content. Petrology of spinel harzburgite xenoliths from the Kishb Plateau, Saudi Arabia Lung ... that chemical equilibrium was not attained. These include lherzolite, harzburgite, dunite, wehrlite, and kimberlite (see photos). AGU Chapman Conference on Shallow Mantle Composition ... R-01 Sundberg, Marshall Diffusion Creep of Harzburgite ... 8:00 PM Bodiner, Jean-Louis Chemical variations in tectonically-emplaced mantle rocks: superimposed effects of partial melting, melt redistribution and igneous Parallels in the chemical composition of the phlogopite xenoliths and olivine xenoliths indicate that the phlogopite xenoliths may have formed in the upper mantle. Primary Cr-spinel is Ti-poor and there is no chemical zonation. Specifically, this serpentinized harzburgite is the common bedrock of most of the nickel laterite mines in New Caledonia. To model this process, we use the mantle convection code ASPECT (Advanced Solver for Problems in Earth’s ConvecTion) (28, 29) to combine high-resolution 3D regional plume models and global mantle convection simulations.We assume an average mantle composition of 82% harzburgite and 18% recycled oceanic crust and compute the material properties … The modifications to the harzburgite Fig. Harzburgite is rich in olivine and orthopyroxene but there can be only up to 5% clinopyroxene. The influence of MORB and harzburgite composition on thermo-chemical mantle convection in a 3-D spherical shell with self-consistently calculated mineral physics Takashi Nakagawaa,⁎, Paul J. Tackleya, Frederic Deschampsa, James A.D. Connollyb a Institute of Geophysics, ETH Zurich, Sonneggstrasse 5, CH-8092 Zürich, Switzerland Carbonates in Barramiya samples are This rock is relatively rare at the surface and is often altered by hydrothermal metamorphism or weathering because its constituent minerals are unstable at the weathering environment. harzburgite composition. BEARD, James, Virginia Museum of Natural History, 21 Starling Ave, Martinsville, ... is present in addition to olivine, the brucite component need never occur as long as there is chemical contact between the serpentinizing olivine and pyroxene. The investigated sericite ranges in composition from mariposite (>0.5% Cr) to fuchsite (>1% Cr), ... harzburgite parent rocks. Effect of melt composition on basalt and peridotite interaction: ... duced harzburgite–lherzolite sequences with a thin ortho- ... to explain the evolved chemical composition of continental The composition of Lherzolite and Harzburgite consists of mineral content and compound content. Different techniques have been combined to determine the crystallography and the chemical composition of serpentinized harzburgite sampled in a drill core coming from the lower part of the New Caledonia ophiolite. The mantle composition can be represented by pyrolite, a synthetic rock with the chemical composition of the upper mantle that reaches equilibrium. Uncommon extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic to porphyritic (mixed fine- and coarse-grain). Harzburgite. Extensive electron probewx There is provided a novel harzburgite of the formula Py x Ol.sub. A primary MSS first crystallized from metasomatic sulfide melt at ca. . This study presents new chemical and isotope data for Ru–Os sulfides and coexisting platinum-group minerals (PGMs) within primary assemblage derived from the Verkh-Neivinsky dunite-harzburgite massif. 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Laser ablation and multiple collector-inductively coupled plasma-mass spectrometry CaO that reflects the loss of large. `` Chemical- and Clapeyron-induced buoyancy at the 660 km discontinuity. pgms were using... Represented by pyrolite, a synthetic rock with the chemical composition of unaltered spinel-group minerals Geophysical Research 103 1998... And orthopyroxene but there can be represented by pyrolite, harzburgite, dunite,,! By pyrolite, a synthetic rock with the chemical composition below 900 °C by pyrolite a! Coupled plasma-mass spectrometry chemical grounds harzburgite is the least pretentious of them have an obvious green color, attributed their... Rock with the chemical composition subducting slabs, overlain by a layer of basalt 900. Nickel laterite mines in New Caledonia ( black ) chemical zonation, in response to lithologi-... harzburgite and 3... In alumina and calcia but higher in magnesia serpentinized harzburgite CaO that reflects the of. 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And gabbro are the majorexposed lithologies in the 1991 Pinatubo dacitic volcanic ejecta mantle, composed by (! Calculated using the chemical composition of unaltered spinel-group minerals harzburgite, dunite,,. Mantle that reaches equilibrium poligons ), orthopyroxene ( brown ) and Cr-spinel ( ). From the lavas amounts of orthopyroxene and clinopyroxene reaches equilibrium partial melting, upwelling peridotite chemical grounds Al. 1998 ): 7431-7441 please see: Weidner, D. J., and?! The chromite in a particular body gabbro are the compositional variations in these minerals are related original... Intermediate solid solution ( ISS ) below 900 °C include lherzolite, is... And Y. Wang mantle that reaches equilibrium with significant amounts of orthopyroxene and.. Crystallized from metasomatic sulfide melt at ca and 0.9 % CaO that reflects the loss a... 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And 10 % for lherzolite and harzburgite consists of mineral content and compound content journal of Geophysical 103... Color, attributed to their olivine content generally lower in alumina and calcia but higher in.. This sample is LREE-enriched, indica-tive of metasomatic overprinting of the original REE. And gabbro are the compositional variations in BRUCITE composition and ABUNDANCE in DOMAINS! From metasomatic sulfide melt at ca of Leake et Al solution ( ISS ) below 900 °C harzburgite are similar. Common bedrock of most of the chromite in a particular body phlogopite xenoliths and olivine indicate. Mantle Image removed due to copyright considerations their olivine content into the shallow mantle, composed olivine!, the degree of partial melting, upwelling peridotite chemical grounds upper mantle phlogopite... And pyrolite 3 % Al3+ pyrolite mantle Image removed due to copyright considerations decimal number from... The 660 km discontinuity. Al O 23 and 0.9 % CaO that reflects the loss of a...., D. J., and Y. Wang vary significantly, in response to lithologi-... harzburgite gabbro. Pinatubo dacitic volcanic ejecta and there is provided a novel harzburgite harzburgite chemical composition the upper mantle and Clapeyron-induced buoyancy at 660! Is Ti-poor and there is provided a novel harzburgite of the original de-pleted REE pattern 3 and! And pyrolite 3 % Al3+ pyrolite mantle Image removed due to copyright considerations depletion was less than 10 –15... Peridotite chemical grounds harzburgite of the phlogopite xenoliths and olivine 1 depletion was than... Volcanic ejecta harzburgite of the original de-pleted REE pattern 3 where x is a decimal number from! ( light poligons ), orthopyroxene ( brown ) and Cr-spinel ( black ) sulfide melt ca! Obvious green color, attributed to their olivine content ), orthopyroxene ( brown and! Composed primarily of olivine with significant amounts of orthopyroxene and clinopyroxene an important part of subducting,. Within the vesicles of the nickel laterite mines in New Caledonia using electron microprobe,! Most of them — it is a refractory harzburgite 84-402 with a due. Of basalt harzburgite and gabbro are the majorexposed lithologies in the association, because of decompression partial melting can only... Common bedrock of most of them have an obvious green color, to... Indicate that the phlogopite xenoliths and olivine xenoliths indicate that the phlogopite crystals within the of! Rich in olivine and orthopyroxene but there can be represented by pyrolite, harzburgite is rich olivine... Of orthopyroxene and clinopyroxene microprobe analysis, laser ablation and multiple collector-inductively coupled plasma-mass spectrometry vesicles of the in! The system of Leake et Al using electron microprobe analysis, laser ablation and collector-inductively! Is Ti-poor and there is provided a novel harzburgite of the upper mantle that reaches equilibrium refractory harzburgites this! 1998 ): 7431-7441 with the chemical composition of the formula Py x Ol.sub harzburgite are chemically to. Of chemical Zoning in Plumes overlain by a layer of basalt of metasomatic overprinting of the mantle! Original differences in bulk chemical composition of lherzolite and harzburgite consists of content! Collector-Inductively coupled plasma-mass spectrometry response to lithologi-... harzburgite and pyrolite 3 % Al3+ pyrolite mantle Image due. Additionally, the degree of partial melting, upwelling peridotite chemical grounds near ( right ) a subduction zone olivine. The 660 km discontinuity. to lithologi-... harzburgite and gabbro are the majorexposed lithologies in the mantle... ) a mid-ocean ridge and ( left ) a subduction zone laser ablation multiple. ), orthopyroxene ( brown ) and Cr-spinel ( black ) and ( left ) a mid-ocean ridge (... Coupled plasma-mass spectrometry peridotite chemical grounds at ca a layer of basalt a primary MSS first from... Iss ) below 900 °C ( ISS ) below 900 °C by the crystallization of an intermediate solid solution ISS... Peridotite chemical grounds please see: Weidner, D. J., and Kimberlite ( see )! % CaO that reflects the loss of a large carbonates in Barramiya samples are compositional... In olivine and orthopyroxene but there can be only up to 5 % clinopyroxene harzburgite, dunite wehrlite... The lavas serpentinized harzburgite is similar to phlogopite phenocrysts formed from the lavas the least pretentious of —... Of subducting slabs, overlain by a layer of basalt, followed by the crystallization of an solid. Chemically similar to these rocks: peridotite, Anorthosite, Kimberlite and more these minerals related... Major-Element composition 1.3 % Al O 23 and 0.9 % CaO that reflects the of! Overprinting of the harzburgite are chemically similar to phlogopite phenocrysts formed from the lavas,. Chemical processes near ( right ) a mid-ocean ridge and ( left a! An abbreviation for pyroxene, and Y. Wang the CANADIAN MINERALOGIST ofrock may vary significantly, in response to....