Mechanisms of Partial Melting of Metasomatized Mantle Ultramafic Rocks beneath Avacha Volcano, Kamchatka, and the Growth of Minerals from a Gas Phase in Fractures

Abstract Two suites of amphibole-rich mafic‒ultramafic rocks associated with the voluminous intermediate to felsic rocks in the Early Cretaceous Laiyuan intrusive-volcanic complex (North China Craton) are studied here by detailed petrography, mineral- and melt inclusion chemistry, and thermobarometry to demonstrate an in-situ reaction-replacement origin of the hornblendites. Moreover, a large set of compiled and newly obtained geochronological and whole-rock elemental and Sr-Nd isotopic data are used to constrain the tectono-magmatic evolution of the Laiyuan complex. Early mafic‒ultramafic rocks occur mainly as amphibole-rich mafic‒ultramafic intrusions situated at the edge of the Laiyuan complex. These intrusions comprise complex lithologies of olivine-, pyroxene- and phlogopite-bearing hornblendites and various types of gabbroic rocks, which largely formed by in-situ crystallization of hydrous mafic magmas that experienced gravitational settling of early-crystallized olivine and clinopyroxene at low pressures of 0.10‒0.20 GPa (∼4‒8 km crustal depth); the hornblendites formed in cumulate zones by cooling-driven crystallization of 55‒75 vol% hornblende, 10‒20 vol% orthopyroxene and 3‒10 vol% phlogopite at the expense of olivine and clinopyroxene. A later suite of mafic rocks occurs as mafic lamprophyre dikes throughout the Laiyuan complex. These dikes occasionally contain some pure hornblendite xenoliths, which formed by reaction-replacement of clinopyroxene at high pressures of up to 0.97‒1.25 GPa (∼37‒47 km crustal depth). Mass balance calculations suggest that the olivine-, pyroxene- and phlogopite-bearing hornblendites in the early mafic‒ultramafic intrusions formed almost without melt extraction, whereas the pure hornblendites brought up by lamprophyre dikes required extraction of ≥ 20‒30 wt% residual andesitic to dacitic melts. The latter suggests that fractionation of amphibole in the middle to lower crust through the formation of reaction-replacement hornblendites is a viable way to produce adakite-like magmas. New age constraints suggest that the early mafic-ultramafic intrusions formed during ∼132‒138 Ma, which overlaps with the timespan of ∼126‒145 Ma recorded by the much more voluminous intermediate to felsic rocks of the Laiyuan complex. By contrast, the late mafic and intermediate lamprophyre dikes were emplaced during ∼110‒125 Ma. Therefore, the voluminous early magmatism in the Laiyuan complex was likely triggered by the retreat of the flat-subducting Paleo-Pacific slab, whereas the minor later, mafic to intermediate magmas may have formed in response to further slab sinking-induced mantle thermal perturbations. Whole-rock geochemical data suggest that the early mafic magmas formed by partial melting of subduction-related metasomatized lithospheric mantle, and that the early intermediate to felsic magmas with adakite-like signatures formed from mafic magmas through strong amphibole fractionation without plagioclase in the lower crust. The late mafic magmas seem to be derived from a slightly different metasomatized lithospheric mantle by lower degrees of partial melting.

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The Study of the Melting of Waelz Oxide with an Increase in the Temperature of the Calcination Process

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.316.705 ◽

2021 ◽

Vol 316 ◽

pp. 705-710

Author(s):

A.G. Ryazanov ◽

A.V. Senin ◽

V.D. Nasonov

Keyword(s):

Partial Melting ◽

Gas Phase ◽

Lead Oxide ◽

Elevated Temperatures ◽

Lead Sulfate ◽

Raw Material ◽

Chemical Transformations ◽

Calcination Process ◽

Waelz Oxide ◽

Negative Effect

Waelz-oxide is a raw material for the production of metallic zinc. Waelz-oxide contains impurities of zinc and lead chlorides and fluorides. Halides have a negative effect on the process of zinc electrolysis. Halides have a relatively low boiling point; therefore, they are removed into the gas phase by calcining Waelz-oxide at 800–850 °С. To intensify the process, calcination is sometimes carried out at elevated temperatures of 1100–1250 °С. However, an increase in temperature leads to partial melting and granulation of the calcined product. In the present work, the chemical and phase composition of the initial and calcined Waelz-oxide was studied. Thermodynamic modeling of phase and chemical transformations of Waelz-oxide components during heating has been performed. Experiments on calcination of Waelz-oxide in laboratory conditions at temperatures of 600–1250 °C were carried out. It was found that partial melting and granulation of Waelz-oxide is the result of the formation of fusible eutectics containing lead oxide. Lead oxide is formed as a result of decomposition of lead sulfate when heated above 1100 °C. A similar effect is not observed at a standard calcination temperature of 850 °C.

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Geochemistry of Late Proterozoic amphibolites and ultramafic rocks, southeastern Canadian Cordillera

Canadian Journal of Earth Sciences ◽

10.1139/e88-127 ◽

1988 ◽

Vol 25 (8) ◽

pp. 1323-1337 ◽

Cited By ~ 10

Author(s):

James H. Sevigny

Keyword(s):

Partial Melting ◽

Major And Trace Elements ◽

Ultramafic Rocks ◽

Canadian Cordillera ◽

Elemental Abundances ◽

Late Proterozoic ◽

Group I ◽

Heterogeneous Mantle ◽

High Degree ◽

Ree Patterns

Late Proterozoic amphibolites and ultramafic rocks from the southeastern Canadian Cordillera have been analysed for major and trace elements in order to determine the nature and origin of the protoliths. Geologic relations indicate that these rocks were produced during an episode of continental rifting in the Precambrian. Based on rare-earth-element (REE) patterns, immobile-incompatible-element ratios, and characteristic elemental abundances, amphibolites are subdivided into alkaline and tholeiitic metabasalts. Alkaline basalts are recognized by their steep REE patterns, high Zr/Y, high TiO2 and P2O5 abundances, and low Y/Nb and Ti/Zr. Tholeiitic basalts are subdivided into three groups: (I) high-Mg#, high-field-strength-element (HFSE)-depleted, light-REE (LREE)-enriched tholeiites with flat heavy REE (HREE) patterns; (II) LREE-enriched tholeiites depleted in HREE; and (III) low-Mg# tholeiites with flat REE patterns. Ultramafic rocks occur as boudins of partially recrystallized Cr-spinel-bearing harzburgite or therzolite, enriched in LREE (Ce/Sm = 1.7–1.9), HFSE, CaO, Al2O3, and TiO2 relative to depleted mantle.Geochemical data suggest that the basalts were derived from a heterogeneous mantle source that underwent different degrees of partial melting with variable amounts of subsequent crystal fractionation of the melts. High Mg#, high Cr and Ni abundances, low HFSE abundances, and high olivine saturation temperatures suggest that group I tholeiites are primary mantle melts produced by a relatively high degree of partial melting of a LREE-enriched, HFSE-depleted source. Group II and III basalts have undergone moderate olivine and pryoxene and limited plagioclase fractionation. Mass-balance calculations suggest that the ultramafic rocks represent a crustally contaminated primary-mantle-derived melt.Les éléments majeurs et traces des amphibolites et des ultramafites, d'âge protérozoïque tardif, du sud-est de la Cordillère canadienne ont été analysés dans le but de déterminer la nature et l'origine des protolithes. Les relations géologiques indiquent que ces roches se sont formées durant un épisode de rifting continental dans le Précambrien. Les diagrammes des terres rares, les rapports des éléments immobiles et incompatibles et les compositions chimiques caractéristiques ont permis de subdiviser les amphibolites en métabasaltes tholéiitiques et alcalins. Les basaltes alcalins sont reconnus par les courbes abruptes dans les diagrammes des terres rares, les rapports Zr/Y élevés et les fortes teneurs en TiO2 et P2O5 et les rapports Y/Nb et Ti/Zr faibles. Les basaltes tholéiitiques sont subdivisés en trois groupes : (I) avec Mg# élevé, appauvrissement en éléments de force de champ élevée, tholéiites enrichies en terres rares légères avec courbe horizontale des terres rares lourdes; (II) tholéiites enrichies en terres rares légères et appauvries en terres rares lourdes; et (III) tholéiites avec Mg# faible et avec courbe horizontale des variations des terres rares. Les ultramafites se présentent en boudins formés d'harzburgite incluant un spinelle chromifère partiellement recristallisé ou de therzolite qui sont enrichies en terres rares légères (Ce/Sm = 1,7–1,9), en éléments à force de champ élevée, en CaO, Al2O3 et TiO2, comparativement à un manteau appauvri.

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Geochemical and Sr–Nd isotopic constraints on the petrogenesis and geodynamic significance of the Jebilet magmatism (Variscan Belt, Morocco)

Geological Magazine ◽

10.1017/s0016756813000654 ◽

2013 ◽

Vol 151 (4) ◽

pp. 666-691 ◽

Cited By ~ 14

Author(s):

ABDERRAHIM ESSAIFI ◽

SCOTT SAMSON ◽

KATHRYN GOODENOUGH

Keyword(s):

Partial Melting ◽

Wall Rock ◽

Ultramafic Rocks ◽

Isotopic Ratios ◽

Isotopic Signatures ◽

Plate Convergence ◽

Metasedimentary Rocks ◽

Microgranular Enclaves ◽

Crustal Origin ◽

Shallow Crust

AbstractIn the Variscan fold belt of Morocco, the Jebilet massif is characterized by Palaeozoic metasedimentary rocks intruded by syntectonic magmatism that includes an ultramafic–granitoid bimodal association and peraluminous granodiorites emplacedc. 330 Ma, intruded by younger leucogranitesc. 300 Ma. The mafic–ultramafic rocks belong to a tholeiitic series, and display chemical and isotopic signatures consistent with mixing between mantle-derived and crust-derived magmas or assimilation and fractional crystallization. The granites within the bimodal association are mainly metaluminous to weakly peraluminous microgranites that show characteristics of A2-type granites. The peraluminous, calc-alkaline series consists mainly of cordierite-bearing granodiorites enclosing magmatic microgranular enclaves and pelitic xenoliths. Detailed element and isotope data suggest that the alkaline and the peraluminous granitoids were formed in the shallow crust (<30 km) by partial melting of tonalitic sources at high temperatures (up to 900°C) and by partial melting of metasedimentary protoliths at relatively low temperatures (c. 750°C), respectively. Mixing between the coeval mantle-derived and crust-derived magmas contributed to the large variation of initial εNdvalues and initial Sr isotopic ratios observed in the granitoids. Further contamination occurred by wall-rock assimilation during ascent of the granodioritic plutons to the upper crust. The ultramafic–granitoid association has been intruded by leucogranites that have high initial Sr isotopic ratios and low initial εNdvalues, indicating a purely crustal origin. The heating events that caused emplacement of the Jebilet magmatism are related to cessation of continental subduction and convective erosion/thinning of the lithospheric mantle during plate convergence.

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Different Origins of the Fractionation of Platinum-Group Elements in Raobazhai and Bixiling Mafic-Ultramafic Rocks from the Dabie Orogen, Central China

Journal of Geological Research ◽

10.1155/2012/631426 ◽

2012 ◽

Vol 2012 ◽

pp. 1-11 ◽

Cited By ~ 2

Author(s):

Qing Liu ◽

Quanlin Hou ◽

Liewen Xie ◽

Hui Li ◽

Shanqin Ni ◽

...

Keyword(s):

Partial Melting ◽

Fractional Crystallization ◽

Platinum Group Elements ◽

Central China ◽

Assay Method ◽

Ultramafic Rocks ◽

Dabie Orogen ◽

Fire Assay ◽

Platinum Group ◽

Different Origins

Concentrations of the platinum group elements (PGEs), including Ir, Ru, Rh, Pt, and Pd, have been determined for both Raobazhai and Bixiling mafic-ultramafic rocks from the Dabie Orogen by fire assay method. Geochemical compositions suggest that the Raobazhai mafic-ultramafic rocks represent mantle residues after variable degrees of partial melting. They show consistent PGE patterns, in which the IPGEs (i.e., Ir and Ru) are strongly enriched over the PPGEs (i.e., Pt and Pd). Both REE and PGE data of the Raobazhai mafic-ultramafic rocks suggest that they have interacted with slab-derived melts during subduction and/or exhumation. The Bixiling ultramafic rocks were produced through fractional crystallization and cumulation from magmas, which led to the fractionated PGE patterns. During fractional crystallization, Pd is in nonsulfide phases, whereas both Ir and Ru must be compatible in some mantle phases. We suggest that the PGE budgets of the ultramafic rocks could be fractionated by interaction with slab-derived melts and fractional crystallization processes.

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Origin and significance of the antimony mineralisation associated to mafic intrusions in the Iberian Zone and the Central Armorican Domain

10.5194/egusphere-egu21-13154 ◽

2021 ◽

Author(s):

Eric Gloaguen ◽

Héctor Campos ◽

Anthony Pochon ◽

Pablo León Higueras ◽

Saturnino Lorenzo ◽

...

Keyword(s):

Partial Melting ◽

Spatial Association ◽

Seismic Profiles ◽

Volatile Element ◽

Mafic Intrusions ◽

Minimum Age ◽

Southern Border ◽

Late Neoproterozoic ◽

Armorican Massif ◽

Metasomatized Mantle

<p>In the Central Iberian Zone (CIZ) and its French counterpart, the Central Armorican Domain (CAD), widespread swarms of mafic dykes with various ages and compositions are known. Indeed, numerous mafic events are recognized in the late Neoproterozoic, in the Cambrian to the Ordovician, in the Ordovician to the Devonian, at the Devonian-Carboniferous boundary, in the Permian and in the Jurassic. Such a succession of mantle partial melting events, localised or generalized, may have strong consequences (i) on the composition and the homogeneity of the mantle below both the CIZ and CAD, and (ii) on the transfert of metals in the overlying crust. Moreover, the mantle below these domains must have been modified also by the subduction of large to small oceanic crusts from the Iapetus, the Rheic, the Galicia-Moldanubian and the Paleo-tethys. Although the occurrences of paleo-subductions below the CIZ and CAD remain discussed, the southern border of the CIZ, the Ossa-Morena Zone (OMZ), is considered as a suture zone resulting from a subduction followed by a collision between 390 and 360 Ma (D1), according to the 2 opposite structural vergences at the CIZ/OMZ boundary, as well as the location of a NE-dipping slab imaged by seismic profiles. In the Armorican massif, the end of subduction is also dated at 360 Ma and associated to a north-directed subduction. The trace of this subduction below the CAD is visible in the tomographic dataset. Interestingly, these two domains (CIZ and CAD) contain the largest number of Palaeozoic antimony deposits, antimony being a volatile element. In these domains, the large clustering of antimony deposits and occurrences is observed within a ca 100km wide bands along their southern parts. In the two domains, the antimony deposits are frequently spatially associated with diabase dykes. Diabase dykes and associated antimony mineralisation have been dated at 360 Ma in the CAD but remain temporally unconstrained in the CIZ. Nevertheless, since these dykes are strongly affected by the Variscan deformation a minimum age of 350 Ma is inferred. Both, the peculiar composition of these diabase dykes, relatively enriched in Cs, Li, Pb and relatively depleted in K and Rb, the spatial association with antimony at the end of a 360Ma subduction, suggest a link between antimony and a ca 360Ma mafic magmatism which could result from the partial melting of a subduction-related metasomatized mantle.</p><p>This work was funded by the ANR (ANR-19-MIN2-0002), the AEI (MICIU/AEI/REF.: PCI2019-103779), the FCT (ERA-MIN/0005/2018) and author&#8217;s institutions in the framework of the ERA-MIN2 AUREOLE project (https://aureole.brgm.fr).</p>

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Geology and Petrology of Omzha Block, Zhob Ophiolite, northern Balochistan, Pakistan

Pakistan Journal of Geology ◽

10.2478/pjg-2020-0008 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Ali Ahmed ◽

Muhammad Ishaq Kakar ◽

Abdul Naeem ◽

Nisar Ahmed ◽

Mehrab Khan ◽

...

Keyword(s):

Partial Melting ◽

Ultramafic Rock ◽

Igneous Rocks ◽

Ultramafic Rocks ◽

Thrust Faults ◽

Felsic Rock ◽

Mica Schist ◽

Andesite Basalt ◽

A Minor ◽

Metamorphic Facies

AbstractThe Zhob Ophiolite is divided into three detached blocks including the Omzha block. The Omzha block is mapped and divided into lithological units such as ultramafic rock, mafic-felsic rock, and volcanic–volcaniclastic–pelagic rocks. These units are quite deformed and mixed up and are associated with one another by thrust faults. Petrography and geochemistry divide them into gabbro, diorite, plagiogranite, pheno-tephrite and trachy-andesite basalt, trachy basalt, chert, limestone, and mudstone. The ultramafic rocks are dominantly serpentinized harzburgite, dunite, and a minor lherzolite. Petrography of peridotite shows that it may be depleted in nature and may have residual after processes such as partial melting and the melt-rock reaction of a lherzolitic source. The gabbroic rocks are less well-developed and highly deformed. They are cross-cut by diorite, plagiogranite and anorthosite’ intrusions. The gabbro may be the plutonic section of Omzha block’ crust while the intermediate-felsic igneous rocks may have formed by the anataxis of crustal gabbro. The volcanic–volcaniclastic–pelagic rocks unit may be corrected with Bagh complex found underneath the Muslim Bagh Ophiolite. The metamorphic sole rocks of Omzha block are highly deformed and dismembered are comprising of metamorphic facies such as amphibolite, quartz-mica schist, and greenschist.

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Archean granitoids of the Aravalli Craton, northwest India

Geological Society London Special Publications ◽

10.1144/sp489-2018-195 ◽

2020 ◽

Vol 489 (1) ◽

pp. 215-234 ◽

Cited By ~ 1

Author(s):

Iftikhar Ahmad ◽

M. E. A. Mondal ◽

Md Sayad Rahaman ◽

Rajneesh Bhutani ◽

M. Satyanarayanan

Keyword(s):

Partial Melting ◽

Continental Crust ◽

Mantle Wedge ◽

Nd Isotope ◽

Oceanic Plateau ◽

Slab Breakoff ◽

Northwest India ◽

Aravalli Craton ◽

Metasomatized Mantle ◽

Asthenospheric Upwelling

AbstractThe Archean granitoids of the Aravalli Craton (NW India) are represented by orthogneisses (3.3–2.6 Ga) and undeformed granitoids (c. 2.5 Ga). Here we present whole-rock geochemical (elemental and Nd-isotope) data of the granitoids from the Aravalli Craton with an aim of understanding the evolution of the continental crust during the Archean. These Archean granitoids have been classified into three compositional groups: (1) TTG – tonalite–trondhjemite–granodiorite; (2) t-TTG – transitional TTG; and (3) sanukitoids. Based on the geochemical characteristics, it is proposed that the TTGs have formed from the partial melting of subducting oceanic plateau. The t-TTG formed owing to reworking of an older continental crust (approximately heterogeneous) in response to tectonothermal events in the craton. For the formation of the sanukitoids, a two-stage petrogenetic model is invoked which involves metasomatization of the mantle wedge, followed by slab breakoff and asthenospheric upwelling, which leads to the melting of asthenosphere and the metasomatized mantle wedge. It is also proposed that subducted sediments contributed to the genesis of sanukitoid magma.

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GEOLOGIA DA REGIÃO DE JEQUERI-VIÇOSA (MG), ORÓGENO ARAÇUAÍ MERIDIONAL

Revista Geonomos ◽

10.18285/geonomos.v19i2.47 ◽

2013 ◽

Author(s):

Daniel Tavares Gradim ◽

Gláucia Nascimento Queiroga ◽

Tiago Amâncio Novo ◽

Carlos Maurício Noce ◽

Antônio Carlos Pedrosa-Soares ◽

...

Keyword(s):

Partial Melting ◽

Shear Zone ◽

Granulite Facies ◽

Minas Gerais ◽

Amphibolite Facies ◽

Ultramafic Rocks ◽

Metamorphic Rocks ◽

The West ◽

Minas Gerais State ◽

Araçuaí Orogen

RESUMO: A característica fundamental da região de Jequeri-Viçosa, situada no extremo sul do Orógeno Araçuaí, é a abundância de rochas metamórficas, ortoderivadas e paraderivadas, de fácies anfibolito alto e granulito. O embasamento paleoproterozóico é representado, a oeste, por ortognaisses tonalíticos a graníticos do Complexo Mantiqueira e, a leste, por ortognaisses charno-enderbíticos do Complexo Juiz de Fora. Ambos os complexos incluem anfibolitos e exibem intensidades variáveis de migmatização. O contato entre eles é marcado pela zona de cisalhamento transpressiva destral de Abre Campo, interpretada como uma sutura paleoproterozóica reativada no Neoproterozóico. O Anfibolito Santo Antônio do Grama e rochas meta-ultramáficas associadas (Córrego do Pimenta) representam restos ofiolíticos ediacaranos, colocados ao longo da Zona de Cisalhamento de Abre Campo. Assentada sobre o embasamento, na parte oeste da área, ocorre uma associação metavulcano-sedimentar neoproterozóica do Grupo Dom Silvério, composta por xistos diversos e quartzito. Na porção leste da área mapeada, a cobertura metassedimentar neoproterozóica é atribuída ao Grupo Andrelândia que inclui paragnaisse migmatítico e raro quartzito. Corpos de hidrotermalito quartzoso, indiscriminadamente associados às unidades do embasamento e da cobertura neoproterozóica, ocorrem ao longo de zonas de cisalhamento. Hidrotermalitos ferruginosos associam-se ao Complexo Mantiqueira na Zona de Cisalhamento de Ponte Nova. O granito foliado a milonitizado da Serra dos Vieiras parece ser um produto de fusão parcial do paragnaisse Andrelândia. Completam o quadro geológico os pegmatitos da Suíte Paula Cândico e diques de diabásio mesozóicos.Palavras-chave: Paleoproterozóico, Neoproterozóico, Orógeno AraçuaíABSTRACT: GEOLOGY OF THE JEQUERI-VIÇOSA REGION, MINAS GERAIS STATE, SOUTHERN ARAÇUAÍ OROGEN. This paper focuses on the southwestern sector of the Araçuaí orogen in a region located close to the boundary with the northern Ribeira orogen. This region is rich in ortho- and para-derived metamorphic rocks of the high amphibolite and granulite facies. The Paleoproterozoic basement includes, to the west, tonalitic to granitic orthogneisses of the Mantiqueira Complex and, to the east, enderbitic to charnockitic orthogneisses of the Juiz de Fora Complex. Both complexes also include amphibolite enclaves and show several rates of partial melting. The contact between them is marked by the dextral transpressional Abre Campo shear zone, considered to be a Paleoproterozoic suture reactivated during the Neoproterozoic Era. The Santo Antônio do Grama Amphibolite and associated meta-ultramafic rocks (Córrego do Pimenta) are Ediacaran ophiolite slivers emplaced along the Abre Campo shear zone. In the western part of the region, the Paleoproterozoic basement is locally covered by a metavolcano-sedimentary assemblage composed of amphibolite facies schist and quartzite of the Neoproterozoic Dom Silvério Group. To the east, the Neoproterozoic cover comprises the migmatized paragneiss and rare quartzite of the Andrelândia Group. The Serra dos Vieiras foliated to mylonitic granite seems to be formed from the partial melting of the Andrelândia paragneiss. Pegmatites of the Paula Cândido Suite and Mesosozic diabase dikes complete the geologic framework of the mapped area.Keywords: Paleoproterozoic, Neoproterozoic, Araçuaí Orogen

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The Evolution of Alpine Ultramafic Rocks and Partial Melting of the Upper Mantle1

Acta Geologica Sinica - English Edition ◽

10.1111/j.1755-6724.1993.mp6001004.x ◽

2009 ◽

Vol 6 (1) ◽

pp. 43-61

Author(s):

Bao Peisheng ◽

Wang Xibin ◽

Hao Ziguo ◽

Peng Genyong

Keyword(s):

Partial Melting ◽

Ultramafic Rocks

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