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Published: 10 December 2022
Last updated: 28 January 2023

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1

Anonymous. "Mafic inclusions in granites." Eos, Transactions American Geophysical Union 69, no. 32 (1988): 777. http://dx.doi.org/10.1029/eo069i032p00777-03.

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2

Udoratina, О. V., М. A. Coble, A. S. Shuyskiy, and V. A. Kapitanova. "MAFIC INCLUSIONS (SOBSKY COMPLEX, POLAR URAL): U‐Pb (SIMS) DATA." Geodynamics & Tectonophysics 10, no. 2 (June 24, 2019): 265–88. http://dx.doi.org/10.5800/gt-2019-10-2-0414.

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The rocks of the Sobsky complex, composing the bulk of the Sobsky batholith in the Polar Urals, contain mafic inclusions. The geological, petrographic and petro‐geochemical data show that the mafic inclusions of the Sobsky rocks belong to igneous formations, which are similar in their characteristics to autoliths. According to all the characteristics, these are the structures non‐contrasting to host rocks and having different structural‐textural features, a more basic composition of minerals and a more basic composition of rocks. The contact with the rocks of the complex is sharp and clear. The rocks of the complex in contact with autoliths are medium‐grained massive diorite rocks, quartz diorites, tonalites, mafic inclusions rocks – fine‐grained gabbros, gabbro‐diorites, and diorites. Isotopicgeochemical (U‐Pb, SIMS) data on zircons from the mafic inclusions suggest that their age is close, within the error limits, to the age of zircons from the enclosing Sobsky complex rocks.
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3

Lobach-Zhuchenko, S. B., T. B. Kaulina, Yu B. Marin, A. V. Yurchenko, S. G. Skublov, Yu S. Egorova, O. L. Galankina, and S. A. Sergeev. "Paleoarchean U–Pb (SIMS SHRIMP-II) age of mafic granulites of the bug complex (Ukrainian shield)." Доклады Академии наук 484, no. 3 (April 15, 2019): 344–47. http://dx.doi.org/10.31857/s0869-56524843344-347.

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Mafic granulites (metamorphosed tholeite-komatiite volcanic rocks) represent the inclusions in gneissenderbite of the Bug complex (southwest of the Ukrainian shield). The studied mafic inclusion has two zircon generations of magmatic origin that yield, respectively, SHRIMP zircon U–Pb ages of 3628±58 Ma and 2845±65 Ma. The first age is the oldest date the earliest stage of basic magmatism on the Ukrainian shield. The age of the second zircon is interpreted as a result of partial melting, synchronous with the metamorphism in the area.
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4

Barker, Simon J., Michael C. Rowe, Colin J. N. Wilson, John A. Gamble, Shane M. Rooyakkers, Richard J. Wysoczanski, Finnigan Illsley-Kemp, and Charles C. Kenworthy. "What lies beneath? Reconstructing the primitive magmas fueling voluminous silicic volcanism using olivine-hosted melt inclusions." Geology 48, no. 5 (February 27, 2020): 504–8. http://dx.doi.org/10.1130/g47422.1.

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Abstract Understanding the origins of the mantle melts that drive voluminous silicic volcanism is challenging because primitive magmas are generally trapped at depth. The central Taupō Volcanic Zone (TVZ; New Zealand) hosts an extraordinarily productive region of rhyolitic caldera volcanism. Accompanying and interspersed with the rhyolitic products, there are traces of basalt to andesite preserved as enclaves or pyroclasts in caldera eruption products and occurring as small monogenetic eruptive centers between calderas. These mafic materials contain MgO-rich olivines (Fo79–86) that host melt inclusions capturing the most primitive basaltic melts fueling the central TVZ. Olivine-hosted melt inclusion compositions associated with the caldera volcanoes (intracaldera samples) contrast with those from the nearby, mafic intercaldera monogenetic centers. Intracaldera melt inclusions from the modern caldera volcanoes of Taupō and Okataina have lower abundances of incompatible elements, reflecting distinct mantle melts. There is a direct link showing that caldera-related silicic volcanism is fueled by basaltic magmas that have resulted from higher degrees of partial melting of a more depleted mantle source, along with distinct subduction signatures. The locations and vigor of Taupō and Okataina are fundamentally related to the degree of melting and flux of basalt from the mantle, and intercaldera mafic eruptive products are thus not representative of the feeder magmas for the caldera volcanoes. Inherited olivines and their melt inclusions provide a unique “window” into the mantle dynamics that drive the active TVZ silicic magmatic systems and may present a useful approach at other volcanoes that show evidence for mafic recharge.
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5

Zhou, Mei-Fu, Reid R. Keays, Peter C. Lightfoot, Gordon G. Morrison, and Michelle L. Moore. "Petrogenetic significance of chromian spinels from the Sudbury Ignecus Complex, Ontario, Canada." Canadian Journal of Earth Sciences 34, no. 10 (October 1, 1997): 1405–19. http://dx.doi.org/10.1139/e17-113.

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Chromian spinels occur in mafic–ultramafic inclusions in the Sublayer of the Sudbury Igneous Complex (SIC) as well as in mafic–ultramafic rocks in the immediate footwall of the Sublayer. The host rocks are pyroxenite and melanorite with minor dunite, harzburgite, and melatroctolite. As common accessory phases in these rocks, the chromian spinels display euhedral or subhedral forms and are included in olivine and orthopyroxene. Chromian spinel grains generally have ilmenite lamellae and contain abundant inclusions (zircon, olivine, diopside, plagioclase, biotite, and sulfide). All the chromian spinels have similar trace element abundances and are rich in TiO2 (0.5–15 wt.%). They have constant Cr# (100Cr/(Cr + Al)) (55–70) and exhibit a continuum in composition that traverses the normal fields of spinels in a Al–(Fe3+ + 2Ti)–Cr triangular diagram. This continuum extends to that of the composition of chromian magnetite in the host norite matrix to the mafic–ultramafic inclusions. This continuum in composition of the spinels suggests that the noritic matrix to the Sublayer formed from the same magma as the inclusions. A positive correlation between the Cr and Al contents of the spinels was probably produced by dilution of these elements by Fe3+ contributed, perhaps, by a plagioclase-saturated melt. Zircon inclusions in a chromian spinel grain reflect incorporation of crustal, felsic materials into the magma before crystallization of chromian spinel. The chemical characteristics and mineral inclusions of the spinels suggest that the Sublayer formed in response to magma mixing. It is suggested that subsequent to the formation of the crustal melt, mantle-derived high-Mg magmas mixed vigourously with this and generated the magmatic sulfides that eventually formed the Ni – Cu – platinum-group elements sulfide ore deposits. Some of the early crystallization products of the high-Mg magma settled to the chamber floor, where they partially mixed with the crustal melt and formed the mafic–ultramafic inclusions and footwall complexes.
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6

Lagroix, France, and Graham J. Borradaile. "Magnetic fabric interpretation complicated by inclusions in mafic silicates." Tectonophysics 325, no. 3-4 (October 2000): 207–25. http://dx.doi.org/10.1016/s0040-1951(00)00125-6.

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7

Saito, Genji, James A. Stimac, Yoshihisa Kawanabe, and Fraser Goff. "Mafic-felsic magma interaction at Satsuma-Iwojima volcano, Japan: Evidence from mafic inclusions in rhyolites." Earth, Planets and Space 54, no. 3 (March 2002): 303–25. http://dx.doi.org/10.1186/bf03353030.

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8

Cortini, Massimo, Annamaria Lima, and Benedetto De Vivo. "Trapping temperatures of melt inclusions from ejected Vesuvian mafic xenoliths." Journal of Volcanology and Geothermal Research 26, no. 1-2 (October 1985): 167–72. http://dx.doi.org/10.1016/0377-0273(85)90051-4.

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9

BLUNDY, J. D., and R. S. J. SPARKS. "Petrogenesis of Mafic Inclusions in Granitoids of the Adamello Massif, Italy." Journal of Petrology 33, no. 5 (October 1, 1992): 1039–104. http://dx.doi.org/10.1093/petrology/33.5.1039.

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10

Gavrilenko, Maxim, Michael Krawczynski, Philipp Ruprecht, Wenlu Li, and Jeffrey G. Catalano. "The quench control of water estimates in convergent margin magmas." American Mineralogist 104, no. 7 (July 1, 2019): 936–48. http://dx.doi.org/10.2138/am-2019-6735.

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AbstractHere we present a study on the quenchability of hydrous mafic melts. We show via hydrothermal experiments that the ability to quench a mafic hydrous melt to a homogeneous glass at cooling rates relevant to natural samples has a limit of no more than 9 ± 1 wt% of dissolved H2O in the melt. We performed supra-liquidus experiments on a mafic starting composition at 1–1.5 GPa spanning H2O-undersaturated to H2O-saturated conditions (from ~1 to ~21 wt%). After dissolving H2O and equilibrating, the hydrous mafic melt experiments were quenched. Quenching rates of 20 to 90 K/s at the glass transition temperature were achieved, and some experiments were allowed to decompress from thermal contraction while others were held at an isobaric condition during quench. We found that quenching of a hydrous melt to a homogeneous glass at quench rates comparable to natural conditions is possible at water contents up to 6 wt%. Melts containing 6–9 wt% of H2O are partially quenched to a glass, and always contain significant fractions of quench crystals and glass alteration/devitrification products. Experiments with water contents greater than 9 wt% have no optically clear glass after quench and result in fine-grained mixtures of alteration/devitrification products (minerals and amorphous materials). Our limit of 9 ± 1 wt% agrees well with the maximum of dissolved H2O contents found in natural glassy melt inclusions (8.5 wt% H2O). Other techniques for estimating pre-eruptive dissolved H2O content using petrologic and geochemical modeling have been used to argue that some arc magmas are as hydrous as 16 wt% H2O. Thus, our results raise the question of whether the observed record of glassy melt inclusions has an upper limit that is partially controlled by the quenching process. This potentially leads to underestimating the maximum amount of H2O recycled at arcs when results from glassy melt inclusions are predominantly used to estimate water fluxes from the mantle.
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11

Pan, Y., M. E. Fleet, and F. J. Longstaffe. "Melt-related metasomatism in mafic granulites of the Quetico subprovince, Ontario: constraints from O-Sr-Nd isotopic and fluid inclusion data." Canadian Journal of Earth Sciences 36, no. 9 (September 1, 1999): 1449–62. http://dx.doi.org/10.1139/e99-041.

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Mafic granulites in the Archean Quetico subprovince, north of Manitouwadge, Ontario, occur as isolated lenses or discontinuous layers in spatial association with tonalitic leucosomes in metasedimentary rocks and exhibit concentric zoning from a biotite-rich margin to an orthopyroxene-rich outer zone and a clinopyroxene-rich central zone, with internal orthopyroxene-bearing leucosomes and, rarely, patches of relict amphibolites within the clinopyroxene-rich zone. Microstructural and microchemical evidence suggests that the mafic granulites formed from amphibolites by combined infiltration-diffusion processes in the presence of a P-F-bearing silicate melt ((P2O5)melt = 0.24-0.28 wt.%) and a CO2-rich (hypersaline?) fluid. The whole-rock and mineral δ18O values of the mafic granulites (8-9‰ V-SMOW) indicate oxygen-isotope equilibration between amphibolites (6.6-6.9‰) and associated tonalitic leucosomes (9.5-10‰) at 700-800°C. Strontium- and Nd-isotope data and U-Pb zircon ages confirm isotopic homogenization at the leucosome-amphibolite boundaries during the peak granulite-facies metamorphism at about 2650 Ma. Texturally, early CO2-rich fluid inclusions in quartz and garnet yield P-T conditions similar to those of the peak granulite-facies metamorphism. Hypersaline fluid inclusions occur in textural coexistence with the early CO2-rich inclusions, but are invariably low in homogenization temperatures (178-234°C). This study shows that silicate melts not only provide a conduit for CO2-rich fluids but also interact directly with country rocks for the formation of granulites. Also, the O-Sr-Nd isotope data show that the documented mobility of rare-earth elements in the Quetico granulite zone is localized in scale and related to anatexis of local metasedimentary rocks during the granulite-facies metamorphism.
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12

Naumov, V. B., V. A. Dorofeeva, A. V. Girnis, and V. V. Yarmolyuk. "Mean contents of volatile components, major and trace elements in magmatic melts from main geodynamic settings of the earth. II. Silicic melts." Геохимия 64, no. 4 (May 5, 2019): 395–408. http://dx.doi.org/10.31857/s0016-7525644395-408.

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As a continuation of our previous study, we estimated the mean contents of volatile, major, and trace components in silicic (>66 wt % SiO2) magmatic melts from main terrestrial geodynamic settings on the basis of our database, which includes (as of middle 2017) more than 1 500 000 determination of 75 elements in melt inclusions and quench glasses from rocks. Among the geodynamic settings are those related to subduction processes (III, island-arc zones originated on oceanic crust and IV, magmatic zones of active continental margins, where continental crust is involved in magma formation) and intracontinent rift and continental hot-spot regions (V). For each geodynamic setting, we calculated the mean contents of elements with confidence limits separately for melt inclusions and groundmass glasses and for the entire data set. Systematic differences were found between the mean compositions of melt inclusions and groundmass glasses from these geodynamic settings. Primitive mantle normalized spider diagrams were constructed for all geodynamic settings. Some ratios of elements and volatile components (H2O/Ce, K2O/Cl, La/Yb, Nb/U, Ba/Rb, Ce/ Pb, etc.) in silicic and mafic melts were compared. Variations in the ratios of various elements to Th, which is one of the most incompatible elements in silicic and mafic melts, were discussed.
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13

Chen, Y. D., R. C. Price, A. J. R. White, and B. W. Chappell. "Mafic inclusions from the Glenbog and Blue Gum granite suites, southeastern Australia." Journal of Geophysical Research 95, B11 (1990): 17757. http://dx.doi.org/10.1029/jb095ib11p17757.

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14

BAN, MASAO, KOJI TAKAHASHI, TAKEHIRO HORIE, and NARUHISA TOYA. "Petrogenesis of Mafic Inclusions in Rhyolitic Lavas from Narugo Volcano, Northeastern Japan." Journal of Petrology 46, no. 8 (March 18, 2005): 1543–63. http://dx.doi.org/10.1093/petrology/egi025.

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15

Steiner, Arron R., Brandon L. Browne, and Christopher J. Nye. "Quenched mafic inclusions in ≤2200 years B.P. deposits at Augustine Volcano, Alaska." International Geology Review 54, no. 11 (December 19, 2011): 1241–70. http://dx.doi.org/10.1080/00206814.2011.636641.

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16

Zeck, H. P. "Restite-melt and mafic-felsic magma mixing and mingling in an S-type dacite, Cerro del Hoyazo, southeastern Spain." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 83, no. 1-2 (1992): 139–44. http://dx.doi.org/10.1017/s0263593300007823.

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ABSTRACTApproximately 10-15 vol% of the Neogene Hoyazo dacite consists of Al-rich restite rock inclusions (A12O3 = 20–45%) and monocrystal inclusions derived therefrom. Restite material and dacitic melt were formed syngenetically from a (semi-)pelitic rock sequence by means of anatexis. Restite rock fragments and dacite show similar high δ18O values (13–16‰) corresponding to those found for sedimentary material. Striking monocrystal restite inclusions in the dacite rock are graphite crystals measuring a few hundred μm, 0.5–10 mm blue cordierite crystals and 2–10 mm ruby red crystals of almandine-rich garnet (1.1 ± 0.2 vol%). Although the almandine crystals are perfectly euhedral, they are identical in every respect to the crystals found in the Al-rich restite rock inclusions and cannot be crystallisation products of the magmatic melt. The dacite also contains many inclusions of quartz gabbroic and basaltoid material which contains inclusions identical to the restite material found in the dacitic glass base. Many basaltoid inclusions show well-developed chilled borders. These inclusions may represent a more mafic magma of deeper origin which mixed with some dacite magma before mingling into it.
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17

Sutherland, Frederick, Khin Zaw, Sebastien Meffre, Jay Thompson, Karsten Goemann, Kyaw Thu, Than Nu, Mazlinfalina Zin, and Stephen Harris. "Diversity in Ruby Geochemistry and Its Inclusions: Intra- and Inter- Continental Comparisons from Myanmar and Eastern Australia." Minerals 9, no. 1 (January 5, 2019): 28. http://dx.doi.org/10.3390/min9010028.

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Ruby in diverse geological settings leaves petrogenetic clues, in its zoning, inclusions, trace elements and oxygen isotope values. Rock-hosted and isolated crystals are compared from Myanmar, SE Asia, and New South Wales, East Australia. Myanmar ruby typifies metasomatized and metamorphic settings, while East Australian ruby xenocrysts are derived from basalts that tapped underlying fold belts. The respective suites include homogeneous ruby; bi-colored inner (violet blue) and outer (red) zoned ruby; ruby-sapphirine-spinel composites; pink to red grains and multi-zoned crystals of red-pink-white-violet (core to rim). Ruby ages were determined by using U-Pb isotopes in titanite inclusions (Thurein Taung; 32.4 Ma) and zircon inclusions (Mong Hsu; 23.9 Ma) and basalt dating in NSW, >60–40 Ma. Trace element oxide plots suggest marble sources for Thurein Taung and Mong Hsu ruby and ultramafic-mafic sources for Mong Hsu (dark cores). NSW rubies suggest metasomatic (Barrington Tops), ultramafic to mafic (Macquarie River) and metasomatic-magmatic (New England) sources. A previous study showed that Cr/Ga vs. Fe/(V + Ti) plots separate Mong Hsu ruby from other ruby fields, but did not test Mogok ruby. Thurein Taung ruby, tested here, plotted separately to Mong Hsu ruby. A Fe-Ga/Mg diagram splits ruby suites into various fields (Ga/Mg < 3), except for magmatic input into rare Mogok and Australian ruby (Ga/Mg > 6). The diverse results emphasize ruby’s potential for geographic typing.
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18

ZHAO, GUOCHUN, SIMON A. WILDE, PETER A. CAWOOD, and LIANGZHAO LU. "Thermal evolution of two textural types of mafic granulites in the North China craton: evidence for both mantle plume and collisional tectonics." Geological Magazine 136, no. 3 (May 1999): 223–40. http://dx.doi.org/10.1017/s001675689900254x.

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Mafic granulites from the North China craton can be divided into two textural types, referred to as A- and B-types. A-type mafic granulites display garnet+quartz symplectic coronas, and outcrop in the eastern and western zones of the craton, whereas B-type mafic granulites exhibit orthopyroxene+plagioclase±clinopyroxene symplectites or coronas, and are mainly exposed in the central zone of the craton. Most A-type mafic granulites preserve the prograde (M1), peak (M2) and post-peak near-isobaric cooling (M3) assemblages, which are represented respectively by inclusions of hornblende+plagioclase+quartz, a peak mineralogy of orthopyroxene+clinopyroxene+plagioclase+quartz+garnet, and overprinted by garnet+quartz symplectic coronas. These mineral assemblages and their P–T (pressure-temperature) estimates define anticlockwise P–T evolutionary paths. The B-type mafic granulites preserve the peak (M1), post-peak near-isothermal decompression (M2) and cooling (M3) assemblages, which are represented by the peak assemblage of orthopyroxene+clinopyroxene+plagioclase+quartz+garnet±hornblende, post-peak orthopyroxene+plagioclase±clinopyroxene symplectites or coronas, and later hornblende+plagioclase+magnetite symplectites, respectively. These mineral assemblages and their P–T estimates define clockwise P–T paths.The anticlockwise P–T paths of the A-type mafic granulites in the eastern and western zones of the North China craton are consistent with a model of underplating and intrusion of mantle-derived magmas. In combination with lithological, structural and geochronological data, the eastern and western zones of the North China craton are considered to represent two continental blocks that developed through the interaction of mantle plumes with the lithosphere from the Palaeoarchaean to the Neoarchaean era. The B-type mafic granulites and associated rocks in the central zone represent a magmatic arc that was metamorphosed and deformed during amalgamation of the eastern and western continental blocks in the late Palaeoproterozoic era. The mineral reaction relations and clockwise P–T paths of the B-type mafic granulites from the central zone record the tectonothermal history of the collision that resulted in the final assembly of the North China craton at c. 1800 Ma.
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19

Sutthirat, C., S. Saminpanya, G. T. R. Droop, C. M. B. Henderson, and D. A. C. Manning. "Clinopyroxene-corundum assemblages from alkali basalt and alluvium, eastern Thailand: constraints on the origin of Thai rubies." Mineralogical Magazine 65, no. 2 (April 2001): 277–95. http://dx.doi.org/10.1180/002646101550253.

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AbstractAn inclusion of corundum (ruby) was found in a clinopyroxene xenocryst in alkali basalt from the late-Cenozoic Chanthaburi-Trat volcanics of eastern Thailand. The clinopyroxene is fairly sodic, highly aluminous and magnesian (0.12–0.14 Na, 0.31–0.33 AlIV and 0.36–0.40 AlVI per 6(O), and Mg/(Mg+Fe2+) > 0.9)) and is chemically similar to clinopyroxene inclusions in rubies from nearby alluvial gem deposits, suggesting a common origin for the two types of occurrence. Sapphirine (Mg/(Mg+Fe2+) = 0.91–0.94) and garnet (py56–67alm11–18grs18–23) also occur as inclusions in alluvial rubies. Thermodynamic calculation of the equilibrium 2 di + 2 crn = 2 cats + en constrains the temperatures of clinopyroxene + corundum crystallization to between 800 and 1150 ± 100°C. Use of other equilibria as stability limits places the pressures of crystallization between 10 and 25 kbar, implying depths of between 35 and 88 km. The most Fe-rich clinopyroxene crystallized at a pressure in the lower part of the range. The pyropic garnet inclusions in corundum crystallized at pressures of >18 kbar (i.e. at depths > ~63 km).The xenocrystic clinopyroxene could have coexisted in equilibrium with garnet of similar composition to the observed inclusions at the deduced temperatures of crystallization. The rubies probably crystallized in rocks of mafic composition, i.e. garnet-clinopyroxenites or garnet-pyriclasites, within the upper mantle.
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20

Rampilov, M. O., G. S. Ripp, E. I. Lastochkin, and I. A. Izbrodin. "MAFIC INCLUSIONS AND MINGLING STRUCTURES IN APLITES OF THE OSHURKOV MASSIF (WESTERN TRANSBAIKALIA)." Geodynamics & Tectonophysics 8, no. 2 (January 1, 2017): 269–81. http://dx.doi.org/10.5800/gt-2017-8-2-0241.

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21

López-Males, Gladys G., Thomas Aiglsperger, Núria Pujol-Solà, and Joaquín A. Proenza. "New mineralogical data on platinum-group minerals from the Río Santiago alluvial placer, Esmeraldas province, Ecuador." Boletín de la Sociedad Geológica Mexicana 72, no. 3 (November 28, 2020): A090720. http://dx.doi.org/10.18268/bsgm2020v72n3a090720.

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Mineralogical studies on platinum-group minerals found in placer deposits from the Río Santiago (Ecuador) are scarce. In this investigation, one sample collected from the Río Santiago alluvial placer was studied via a multi-disciplinary approach, including optical microscopy, scanning electron microscopy, electron microprobe, and Raman spectroscopy. Whole-rock geochemistry data of the sample confirms elevated Au and platinum-group elements contents and the chondrite-normalized pattern reveals pronounced positive Ir and Pt anomalies. Free grains of platinum-group minerals were separated via hydroseparation techniques and identified as: i) Pt-Fe alloy (Pt3Fe), ii) tulameenite (Pt2FeCu) and iii) hongshiite (PtCu). The most abundant platinum-group mineral is Pt-Fe alloy (85%) that occasionally hosts cuprorhodsite (CuRh2S4) inclusions. Although the primary source remains unknown, the geochemical and mineralogical data suggests that the source of platinum-group minerals in the Río Santiago alluvial placer is a mafic-ultramafic Ural-Alaska type complex. Possible primary sources are the mafic and ultramafic rocks found in the mafic basement of the coastal region and the Western Cordillera (Piñón, San Juan and Pallatanga units), which derive from the Late Cretaceous Caribbean Colombia Oceanic Plateau (CCOP).
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22

Belkin, Harvey E., and Andrew E. Grosz. "Platinum and gold placer from Tugidak Island, Alaska: Platinum-group minerals and their inclusions, gold, and chromite mineralogy." Canadian Mineralogist 59, no. 4 (July 1, 2021): 667–712. http://dx.doi.org/10.3749/canmin.2000016.

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ABSTRACT Black sand beach placers from Kodiak, Sitkinak, and Tugidak Islands, Alaska, have been mined intermittently for gold and minor platinum-group alloys for more than 100 years. High-grade platinum-rich magnetic separate and accompanying black sand from the southern beach placer of Tugidak Island were studied using electron microprobe WDS and scanning electron microscope EDS; mineral classification and identification were based on these techniques. The major platinum mineral is isoferroplatinum, followed by minor tetraferroplatinum and tulameenite, and rare ferronickelplatinum. Two types of alteration were identified in about 3–4% of the alloy grains: rim formation involving Pt loss and increased Fe, Ni, and/or Cu, and fracturing and vein filling by Cu-rich alloy. Ruthenium-Ir-Os-Pt alloys occur as inclusions and veins as well as form part of composite grains. Ten percent of the alloy grains contain a large variety of platinum-group minerals (PGM). Inclusions of cuprorhodsite, malanite, cuproiridsite, laurite, erlichmanite, cooperite, braggite, bowieite, kashinite, miassite, hollingworthite, irarsite, sperrylite, stillwaterite, genkinite, stibiopalladinite, keithconnite, zvyagintsevite, and probable palladodymite and vincentite were identified. Two unidentified inclusion phases also occur. Most of the PGM inclusions are primary and were trapped by a growing crystal from a melt; some inclusions exhibit textures that suggest trapping of an As,Te,S-rich immiscible melt. Secondary inclusions and evidence of deformation were observed in a few alloy grains. Associated with PGM inclusions or as separate inclusions are various base-metal sulfides. Two silicate-melt inclusions in one isoferroplatinum grain have an andesite–shoshonite composition. Minor gold and Ag-rich gold in the high-grade magnetic separate contain magnetite, pyrrhotite, and chromite inclusions. The gold composition suggests that their sources are the numerous quartz veins and apophyses related to granitoids on Kodiak Island. The composition of the placer chromite is similar to chromite from the Border Ranges mélange fault system and suggests that the Uyak Complex ultramafic and mafic rocks are part of a supra-subduction-zone ophiolite and are the source of the platinum-group minerals.
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Chaumba, Jeff B., and Caston T. Musa. "Geochemistry of the chromitite stringer at the contact of the mafic sequence and the ultramafic sequence in the Unki Mine area, Shurugwi Subchamber of the Great Dyke, Zimbabwe." Canadian Mineralogist 58, no. 3 (May 1, 2020): 313–33. http://dx.doi.org/10.3749/canmin.1900052.

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ABSTRACT Several models have been proposed to explain the origin of a chromitite stringer located at the contact between the Mafic and Ultramafic Sequences in the Unki Mine area of the Shurugwi Subchamber of the Great Dyke, Zimbabwe. A petrographic and geochemical study of this chromitite stringer was undertaken with the aim of constraining its origin. Forty-three chromite compositions were obtained from the studied chromitite stringer, which is characterized by a chromium number between 59.9 and 62.8 and a magnesium number which ranges from 37.8 to 46.4. The chromites at the contact zone in the Unki Mine commonly contains inclusions of sulfides, orthopyroxene, plagioclase, and/or amphiboles. The chromites likely formed early in the crystallization history of the Mafic Sequence, as they are commonly partially rimmed by sulfides and they occur as inclusions in plagioclase crystals. Unlike chromites from underlying Ultramafic Sequence chromitite layers, chromites at the contact zone contain low Cr2O3 contents which range from 39.4 to 42.6 wt.%. Furthermore, these chromites are enriched in Fe compared to most Great Dyke chromitites, which is interpreted to be a consequence of subsolidus exchange of Mg into orthopyroxene and Fe into the chromite. The absence of zoning in the chromites at this contact zone, and their low Mn, Fe contents, is consistent with attainment of equilibrium because the altered chromites often contain Cr-bearing magnetite rims. Two possible models for the formation of this chromitite stringer are mixing of relatively primitive and evolved magmas (i.e., ultramafic and anorthositic magma), possibly of different oxygen fugacities, and chemical diffusion across the contact between the Mafic and the Ultramafic sequences which resulted in melting at and below this boundary. The latter would have caused preferential loss of orthopyroxene from the underlying P1 Pyroxenite Layer, accompanied by re-precipitation of chromite at this contact.
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Schmidt, Madison A., Matthew I. Leybourne, Jan M. Peter, Duane C. Petts, Simon E. Jackson, and Daniel Layton-Matthews. "Development of a laser ablation ICP-MS method for the analysis of fluid inclusions associated with volcanogenic massive sulfide deposits." Geochemistry: Exploration, Environment, Analysis 21, no. 3 (March 17, 2021): geochem2020–043. http://dx.doi.org/10.1144/geochem2020-043.

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There is increasing acceptance of the presence of variable magmatic contributions to the mineralizing fluids in the formation of volcanogenic massive sulfide (VMS) deposits. The world-class Windy Craggy Cu-Co-Au deposit (>300 MT @ 2.12 wt% Cu) in northwestern British Columbia is of interest because, unlike most VMS deposits, fluid inclusions in quartz from within the deposit range from relatively low to intermediate salinity (most 6–16 wt% equivalent). In this study we used an excimer (193 nm) laser ablation system interfaced to a quadrupole inductively coupled plasma mass spectrometer to quantify key metals and metalloids that are considered by many to be indicative of magmatic contributions to hydrothermal ore deposits. Although LA-ICP-MS signals from these low-salinity inclusions are highly transient, we were able to quantify Na, Mg, K, Ca, Mn, Fe, Co, Cu, Zn, Sr, Sn, Ba, Ce, Pb and Bi consistently – of the 34 elements that were monitored. Furthermore, Cl, Sb, Cd, Mo, Rb, Br and As were also measured in a significant number of inclusions. Comparison of the fluid inclusion chemistry with unaltered and altered mafic volcanic and sedimentary rocks and mineralized samples from the deposit indicate that enrichment in the main ore metals (Cu, Zn, Fe, Pb) in the inclusions reflects that of the altered rocks and sulfides. Metals and metalloids that may indicate a magmatic contribution typically show much greater enrichments in the fluid inclusions over the host rocks at the same Cu concentration; in particular Bi, Sn and Sb are significantly elevated when compared to the host rock samples. These data are consistent with the ore-forming fluids at Windy Craggy having a strong magmatic contribution.Supplementary material: fluid inclusion data for temperature of homogenization and salinity, and full analytical results for laser ablation ICP-MS analyses of individual inclusions for the two analytical sessions are available at https://doi.org/10.6084/m9.figshare.c.5443094
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25

Mercier, Maxime, Andrea Di Muro, Nicole Métrich, Daniele Giordano, Olfa Belhadj, and Charles W. Mandeville. "Spectroscopic analysis (FTIR, Raman) of water in mafic and intermediate glasses and glass inclusions." Geochimica et Cosmochimica Acta 74, no. 19 (October 2010): 5641–56. http://dx.doi.org/10.1016/j.gca.2010.06.020.

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26

Rao, D. Rameshwar, Rajesh Sharma, and N. S. Gururajan. "Mafic granulites of the Schirmacher region, East Antarctica: fluid inclusion and geothermobarometric studies focusing on the Proterozoic evolution of the crust." Transactions of the Royal Society of Edinburgh: Earth Sciences 88, no. 1 (1997): 1–17. http://dx.doi.org/10.1017/s0263593300002285.

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AbstractIn the Proterozoic complex of the Schirmacher region of East Antarctica, a retrograde pressure–temperature (P–T) history has been inferred through quantitative geothermobarometry and fluid inclusion studies of the mafic granulites. Microthermometric investigations of the fluid phases trapped in quartz and garnet identified three types of inclusions, namely, earliest pure CO2 inclusions (0·987–1·057 g cm−3), CO2–H2O inclusions and aqueous inclusions.The temperature and pressure of metamorphism have been estimated through different calibrations of geothermometers and geobarometers. The mineral reactions and compositional zoning in the minerals record P–T conditions from nearly 837 ± 26°C, 7·1±0·2 kbar to 652 ± 33°C, 5·9 ± 0·3 kbar. A good correlation between the fluid and mineral data is observed. The isochores typical of highdensity CO2 fluids fall well within the P–T box estimated by mineral thermobarometry. The abundance of primary CO2 inclusions in early metamorphic minerals (notably quartz and primary garnet) and the general correspondence between fluid and mineral P–T data indicate a ‘fluid-present’ carbonic regime for the high-grade metamorpism; however, from the present data largescale CO2 advection could not be envisaged. The subsequent stages involved a decrease in CO2 density, a progressive influx of hydrous fluids and the generation of retrograde amphibolite facies metamorphism in the area.The estimated P–T conditions of the region suggest that the rocks were metamorphosed at a depth of 19–24 km, with a geothermal gradient of c. 3°5C km−1. The estimated P–T conditions of the rocks imply a clockwise P–T–t path with a gradual decrease in temperature of around 250°C and a decrease in pressure of around 1700 bar. They have a dP/dT gradient of ≈7 ± l bar °C−1, arguing for an isobaric cooling history of the terrane under normal thickened crust after the underplating of mantle-derived material.
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Chen, Y. D., and I. S. Williams. "Zircon inheritance in mafic inclusions from Bega batholith granites, southeastern Australia: An ion microprobe study." Journal of Geophysical Research 95, B11 (1990): 17787. http://dx.doi.org/10.1029/jb095ib11p17787.

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28

Ferrsrio, A., and G. Garuti. "Platinum-group mineral inclusions in chromitites of the Finero mafic-ultramafic complex (Ivrea-Zone, Italy)." Mineralogy and Petrology 41, no. 2-4 (April 1990): 125–43. http://dx.doi.org/10.1007/bf01168491.

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29

Humphreys, Madeleine C. S., Thomas Christopher, and Vicky Hards. "Microlite transfer by disaggregation of mafic inclusions following magma mixing at Soufrière Hills volcano, Montserrat." Contributions to Mineralogy and Petrology 157, no. 5 (November 7, 2008): 609–24. http://dx.doi.org/10.1007/s00410-008-0356-3.

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De Vivo, B., A. Lima, and V. Scribano. "CO2 fluid inclusions in ultramafic xenoliths from the Iblean Plateau, Sicily, Italy." Mineralogical Magazine 54, no. 375 (June 1990): 183–94. http://dx.doi.org/10.1180/minmag.1990.054.375.05.

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AbstractThe Iblean Plateau (Southeastern Sicily, Italy) consists of a thick Meso-Cenozoic carbonate sequence with interbedded volcanic horizons (alkaline and tholeiitic basalts). The alkaline basalts contain ultramafic (peridotites and pyroxenites) and mafic xenoliths. The peridotites are spinel-bearing lherzolites and lherzolitic harzburgites, with porphyroblastic to protogranular texture. Pyroxenites consist of Cr-diopside-bearing and Al-augite-bearing websterites. The mineral chemistry of the nodules indicates temperatures between 700 and 1050°C.Fluid inclusions containing CO2 and (sometimes) various proportions of silicate glass have been studied in olivine, orthopyroxene and clinopyroxene. The secondary inclusions occur as trails of CO2-rich inclusions, often cross-cutting deformation lamellae. The few primary inclusions, generally empty, show clear evidence of decrepitation. Of the 390 inclusions examined, 97% homogenized to the liquid phase (Th → L = −43.9 to +30.9°C); 3% homogenized to the vapour phase (Th → V = + 20.5 to +30.3°C, yelding CO2 densities in the range 0.20–1.13 g/cm3. Assuming a trapping temperature of 1100°C, the corresponding trapping pressure for a pure CO2 system lies in the range 0.6–11.0 kbar, i.e. a depth of ∼2.2 to 42 km.The majority of CO2 trapping events in the xenoliths occurred from 2.2 to 11.0 kbar, with no major trapping events at pressures less than 2.3 kbar, indicating the absence of a shallow magma reservoir below the Iblean Plateau.
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31

Powell, Wayne G., and Edward D. Ghent. "Low-pressure metamorphism of the mafic volcanic rocks of the Rossland Group, southeastern British Columbia." Canadian Journal of Earth Sciences 33, no. 10 (October 1, 1996): 1402–9. http://dx.doi.org/10.1139/e96-105.

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Mafic volcanic rocks of the Rossland Group have been metamorphosed in the subgreenschist to lower amphibolite faciès. Subgreenschist-facies regional metamorphic rocks are subdivided into prehnite–pumpeilyite zone and prehnite–epidote zone. Fluid inclusions in two subgreenschist-facies veins yielded mean homogenization temperatures of 139 and 151 °C. Assuming a reasonable maximum temperature limit of 275 °C for the subgreenschist fades, the fluid-inclusion isochores indicate a pressure <250 MPa for regional metamorphism in the subgreenschist facies. This is consistent with the widespread occurrence of prehnite–chlorite-bearing assemblages. Metamorphic grade increases sharply northward approaching the large plutons of the Nelson suite. The contact aureoles of the Nelson batholith and the related Bonnington pluton encompass most of the region, producing an extensive region underlain by rocks within the hornblende–oligoclasc zone. Intrusion of the Nelson plutonic suite overlapped with the development of the Hall Creek syncline and Silver King shear zone. The pattern of isograds across the Rossland Group indicates superimposed contact and regional metamorphism rather than progressively deeper structural levels northward.
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Cashman, Katharine V., and Marie Edmonds. "Mafic glass compositions: a record of magma storage conditions, mixing and ascent." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2139 (January 7, 2019): 20180004. http://dx.doi.org/10.1098/rsta.2018.0004.

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The trans-crustal magma system paradigm is forcing us to re-think processes responsible for magma evolution and eruption. A key concept in petrology is the liquid line of descent (LLD), which relates a series of liquids derived from a single parent, and therefore tracks the inverse of the crystallization path. It is common practice to attribute multiple magma compositions, and/or multiple melt compositions (from melt inclusions and matrix glass), to a single LLD. However, growing evidence for rapid, and often syn-eruptive, assembly of multiple magma components (crystals and melts) from different parts of a magmatic system suggests that erupted magma and melt compositions will not necessarily represent a single LLD, but instead may reflect the multiple paths in pressure–temperature space. Here, we use examples from mafic magmatic systems in both ocean island and arc settings to illustrate the range of melt compositions present in erupted samples, and to explore how they are generated, and how they interact. We highlight processes that may be deduced from mafic melt compositions, including the mixing of heterogeneous primitive liquids from the mantle, pre-eruptive magma storage at a range of crustal and sub-Moho depths, and syn-eruptive mixing of melts generated from these storage regions. The relative dominance of these signatures in the glasses depends largely on the water content of the melts. We conclude that preserved melt compositions provide information that is complementary to that recorded by the volatile contents of crystal-hosted melt inclusions and coexisting mineral compositions, which together can be used to address questions about both the pre- and syn-eruptive state of volcanic systems. This article is part of the Theo Murphy meeting issue ‘Magma reservoir architecture and dynamics’.
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33

Rosatelli, G., F. Stoppa, and A. P. Jones. "Intrusive calcite-carbonatite occurrence from Mt. Vulture volcano, southern Italy." Mineralogical Magazine 64, no. 4 (August 2000): 615–24. http://dx.doi.org/10.1180/002646100549643.

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AbstractIntrusive calcite-carbonatite ejecta (sovite) in the lowermost tephra layers of the Mt. Vulture alkaline mafic-ultramafic volcano (Upper Pleistocene), is the first intrusive carbonatite sample from southern Europe. The sovite is of coarse granularity and shows some textural and mineralogical layering. It is mainly formed of calcite (up to 3.5 wt.% MgO, and 0.53 wt.% SrO), less dolomite (average 18.2 wt.% MgO, and up to 2.1 wt.% SrO), spinel (60 wt.% Al2O3, 26.5 wt.% MgO, 10.7 wt.% FeO) and olivine (Fo99). Perovskite and apatite have been found only as microlites. Intergranular vugs are scattered throughout the rocks and small composite inclusions occur in calcite.The mineral chemistry, high temperature melt inclusions, overall isotopic compositions, and the REE distribution are consistent with a primary igneous origin. Compared with world average sovite compositions, the Vulture sovite has lower LILE and HFSE but Rb, Sr, Th and U are high. The REE abundance is typical of carbonatites, having an LREE/HREE value of ∼100. The δ13C (−4.8% SMOW) is in the range for mantle-derived carbonatites. The 143Nd/144Nd (0.512648±15) and 87Sr/86Sr (0.705978±10) ratios show close similarity between the sovite and the Vulture alkaline mafic rocks. The sovite ejecta are interpreted as a crystallization product of carbonate ultramafic liquid. In common with many shallow-level carbonatites from other localities, the recrystallization of rather pure Mg-calcite, the presence of dissolution vugs and the depletion of some HFSE and the relatively high δ18O values, suggest that a secondary process, such as hydrothermal leaching, affected the rock.
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Ichinose, Teiko, Kenji Shuto, and Ryuichi Yashima. "Ultramafic and mafic inclusions in Nodegamiyama basalts from the eastern part of Fukushima prefecture, northeast Japan." Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists 81, no. 9 (1986): 384–91. http://dx.doi.org/10.2465/ganko1941.81.384.

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35

Volodichev, Oleg I., Oleg A. Maksimov, Tatiana I. Kuzenko, and Alexander I. Slabunov. "Archean Zircons with Omphacite Inclusions from Eclogites of the Belomorian Province, Fennoscandian Shield: The First Finding." Minerals 11, no. 10 (September 22, 2021): 1029. http://dx.doi.org/10.3390/min11101029.

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Early Precambrian retrogressed eclogites are abundant in the central and northern parts of the Belomorian Province of the Fennoscandian Shield (Gridino + Keret and Salma + Kuru-Vaara study areas, respectively). Older and younger eclogites are recognized and their Archean and Paleoproterozoic ages are argued. Archean eclogites are intensely retrogressed and occur in amphibolite boudins in the tonalite-trondhjemite-granodiorite (TTG) gneiss matrix of the Archean Gridino eclogite-bearing mélange. Less retrogressed Paleoproterozoic eclogites form patches in mafic dikes and some amphibolite boudins; their Paleoproterozoic age is supported by U-Pb/SIMS data on zircons depleted in heavy rare earth elements (REE) with omphacite, garnet, and kyanite inclusions, and Sm-Nd and Lu-Hf mineral isochrons. Archean eclogites contain Archean heavy rare-earth elements (REE)-depleted zircons with garnet and zoisite inclusions and Archean garnets. No omphacite inclusions were found in these zircons, and this fact was considered as evidence against the existence of Archean eclogites. This study reports on the first finding of omphacite (23–25% Jd) inclusions in 2.68 Ga metamorphic zircons from eclogites from the Gridino eclogite-bearing mélange. The zircons are poorly enriched in heavy REE and display a weak negative Eu-anomaly but a poor positive Ce-anomaly typical of eclogitic zircons. Thus, zircons with these decisive features provide evidence for an Archean eclogite-facies metamorphism.
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36

Rutter, Michael J., and Peter J. Wyllie. "Experimental study of interaction between hydrous granite melt and amphibolite." Geological Magazine 126, no. 6 (November 1989): 633–46. http://dx.doi.org/10.1017/s0016756800006932.

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AbstractWe have investigated the reaction between crystalline amphibolite and hydrous granite melt in static experiments at 810 °C and 1.5 kbar. Boundary layer concentration gradients in quenched silicate glass for the major element oxides and the volatile components, water and carbon dioxide, were measured using electron probe analysis and Fourier Transform Infrared Spectroscopy, respectively. We found a measurable change in the concentration of all components adjacent to the amphibolite in experiments of 66 and 330 hours duration. After I hour there was no detectable change in the concentration of major element oxides in the granitic glass, but steep concentration profiles were determined for carbon dioxide and water. A bubble-free zone developed adjacent to the amphibolite in the 66 hour experiment, and this zone increased in width after 330 hours. Reaction is controlled by dissolution of amphibolite and by transport of dissolved material through the granite melt. The rate-controlling process is chemical diffusion in the melt phase. Results confirm that in the absence of convective heat transfer and/or mechanical disaggregation of mafic inclusions, assimilation of mafic rocks by granite melt is very slow, corresponding to on the order of 10 mm for SiO2 in 1000 years.
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37

Oziegbe, E. J., V. O. Olarewaju, and O. O. Ocan. "MINERAL CHEMISTRY AND GEOCHEMISTRY OF HYPERSTHENE-BEARING DIORITE FROM ERUSU AKOKO, SOUTHWESTERN NIGERIA." Malaysian Journal of Geosciences 4, no. 1 (February 7, 2020): 13–18. http://dx.doi.org/10.26480/mjg.01.2020.13.18.

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Samples of mafic intrusive rock were analyzed for their mineralogical and chemical properties. The textural relationship was studied using the petrographic microscope, elemental composition of minerals was determined using the Electron Microprobe and the whole rock chemical analysis was done using the XRF and ICP-MS. The following minerals were observed in order of abundance; pyroxene, amphibole, plagioclase, biotite, opaque minerals, quartz and chlorite, with apatite and zircon occurring as accessory mineral. Two types of pyroxenes were observed; orthopyroxene (hypersthene) and clinopyroxene. Texturally, amphiboles have inclusions of plagioclase and pyroxene. The plagioclase has undergone sericitization. The chemical composition of the pyroxene is En51.95Fs44.53Wo3.52, biotite has Fe/(Fe+Mg):0.42, Mg/(Fe+Mg):0.59, and plagioclase is Ab63.5An34.55Or1.95. Whole rock chemistry shows a chemical composition; SiO2: 45.15 %, Al2O3: 14.04 %, Fe2O3: 16.01 %, MgO: 5.65 %, CaO: 7.58 % and TiO2: 3.59 %. There is an enrichment of LREE and a depletion of HREE. Based on the minerals, mineral chemistry and the geochemistry of the studied rock, the rock is mafic and hydrous minerals formed by hydration recrystallization of pyroxene. The rock has extensively retrogressed but has not been affected by any form of deformation.
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38

Boehnke, Patrick, Elizabeth A. Bell, Thomas Stephan, Reto Trappitsch, C. Brenhin Keller, Olivia S. Pardo, Andrew M. Davis, T. Mark Harrison, and Michael J. Pellin. "Potassic, high-silica Hadean crust." Proceedings of the National Academy of Sciences 115, no. 25 (June 4, 2018): 6353–56. http://dx.doi.org/10.1073/pnas.1720880115.

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Understanding Hadean (>4 Ga) Earth requires knowledge of its crust. The composition of the crust and volatiles migrating through it directly influence the makeup of the atmosphere, the composition of seawater, and nutrient availability. Despite its importance, there is little known and less agreed upon regarding the nature of the Hadean crust. By analyzing the 87Sr/86Sr ratio of apatite inclusions in Archean zircons from Nuvvuagittuq, Canada, we show that its protolith had formed a high (>1) Rb/Sr ratio reservoir by at least 4.2 Ga. This result implies that the early crust had a broad range of igneous rocks, extending from mafic to highly silicic compositions.
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39

Sharygin, Victor V. "Mineralogy of Silicate-Natrophosphate Immiscible Inclusion in Elga IIE Iron Meteorite." Minerals 10, no. 5 (May 13, 2020): 437. http://dx.doi.org/10.3390/min10050437.

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Rare type of silicate inclusions found in the Elga iron meteorite (group IIE) has a very specific mineral composition and shows silicate (≈90%)–natrophosphate (≈10%) liquid immiscibility due to meniscus-like isolation of Na-Ca-Mg-Fe phosphates. The 3 mm wide immiscible inclusion has been first studied in detail using optical microscopy, scanning electron microscopy, electron microprobe analysis and Raman spectroscopy. The silicate part of the inclusion contains fine-grained quartz-feldspar aggregate and mafic minerals. The relationships of feldspars indicate solid decay of initially homogenous K-Na-feldspar into albite and K-feldspar with decreasing of temperature. Some mafic minerals in the silicate part are exotic in composition: the dominant phase is an obertiite-subgroup oxyamphibole (amphibole supergroup), varying from ferri-obertiite NaNa2Mg3Fe3+Ti[Si8O22]O2 to hypothetical NaNa2Mg3Fe2+0.5Ti1.5[Si8O22]O2; minor phases are the aenigmatite-subgroup mineral (sapphirine supergroup) with composition close to median value of the Na2Fe2+5TiSi6O18O2-Na2Mg5TiSi6O18O2 join, orthopyroxene (enstatite), clinopyroxene of the diopside Ca(Mg,Fe)Si2O6–kosmochlor NaCrSi2O6-Na(Mg,Fe)0.5Ti0.5Si2O6 series and chromite. The alteration phases are represented by Fe-dominant chlorite, goethite and hydrated Na2O-rich (2.3–3.3 wt.%) Fe-phosphate close to vivianite. Natrophosphate part consists of aggregate of three orthophosphates (brianite, czochralskiite, marićite) and minor Na-Cr-Ti-clinopyroxene, pentlandite, rarely taenite. Czochralskiite Na4Ca3Mg(PO4)4 is rich in FeO (2.3–5.1 wt.%) and MnO (0.4–1.5 wt.%). Brianite Na2CaMg(PO4)2 contains FeO (3.0–4.3 wt.%) and MnO (0.3–0.7 wt.%) and marićite NaFe(PO4) bears MnO (5.5–6.2 wt.%), MgO (5.3–6.2 wt.%) and CaO (0.5–1.5 wt.%). The contact between immiscible parts is decorated by enstatite zone in the silicate part and diopside–kosmochlor clinopyroxene zone in the natrophosphate ones. The mineralogy of the studied immiscible inclusion outlines three potentially new mineral species, which were first identified in meteorites: obertiite–related oxyamphibole NaNa2Mg3Fe2+0.5Ti1.5[Si8O22]O2, Mg-analog of aenigmatite Na2Mg5TiSi6O18O2 and Na-Ti-rich clinopyroxene Na(Mg,Fe)0.5Ti0.5Si2O6.
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Ernst, W. G. "Petrochemical comparison of 3.5 Ga old mafic amphibolite inclusions from eastern Hebei province with Archean mafic — ultramafic supracrustals of uncertain antiquity, southern Jilin eastern Liaoning provinces, China." Chinese Journal of Geochemistry 8, no. 2 (April 1989): 97–111. http://dx.doi.org/10.1007/bf02840434.

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41

Smirnov, Vladimir N., Kirill S. Ivanov, Yuriy L. Ronkin, and Yuriy V. Erokhin. "Results of 147Sm–143Nd (ID-TIMS) and U–Pb (SHRIMP-II) Dating of Rocks and Minerals of the Chromite-Bearing Kluchevskoy Ophiolite Massif (the Eastern Segment of the Urals) and Their Geological Interpretation." Minerals 12, no. 11 (October 27, 2022): 1369. http://dx.doi.org/10.3390/min12111369.

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The Urals is one of the reference mobile belts of the mafic type characterized by a wide development of ophiolites which are associated with numerous deposits of chromites of significant industrial importance. In this regard, the estimation of the age of the rocks of the ophiolite association will be useful for analyzing the regularities of the formation of chromite deposits. This work presented the results of age dating of the rocks of the chromite-bearing Kluchevskoy mafic–ultramafic massif, one of the most representative of all the ophiolite-type massifs in the Urals, by two isotopic methods. The U–Pb (SHRIMP-II, VSEGEI) dating of the zircon dominated assemblage from rocks of different composition of both crustal and mantle sections of the Kluchevskoy ophiolite massif yielded similar dates ranging from 456 to 441 Ma. The study of the composition of silicate inclusions in zircon grains of this assemblage showed that they are represented by typical metamorphic minerals: low-T amphibole, albite, and an epidote-group mineral. The P–T conditions of zircon crystallization established via the examination of the composition of minerals in these inclusions showed that the crystallization of the predominant fraction of zircons coincides in time with the lower epidote–amphibolite and upper green-schist facies metamorphism of rocks happening under the decompression conditions, i.e., during their exhumation from the deep crustal level (8–13 km). A small amount of zircons of late generation showed a wide spread in age (277.4–318.1 Ma). The time of their crystallization corresponds to the stage of metamorphism associated with the collision orogeny in the Ural mobile belt. The more ancient 147Sm–143Nd age of 514 Ma should be assumed as the formation time of the rocks (or its upper age boundary).
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42

NICOLL, GRAEME R., MARIAN B. HOLNESS, VALENTIN R. TROLL, COLIN H. DONALDSON, EOGHAN P. HOLOHAN, C. HENRY EMELEUS, and DAVID CHEW. "Early mafic magmatism and crustal anatexis on the Isle of Rum: evidence from the Am Màm intrusion breccia." Geological Magazine 146, no. 3 (March 25, 2009): 368–81. http://dx.doi.org/10.1017/s0016756808005864.

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AbstractThe Rum Igneous Centre comprises two early marginal felsic complexes (the Northern Marginal Zone and the Southern Mountains Zone), along with the later central ultrabasic–basic layered intrusions. These marginal complexes represent the remnants of near-surface to eruptive felsic magmatism associated with caldera collapse, examples of which are rare in the North Atlantic Igneous Province. Rock units include intra-caldera collapse breccias, rhyolitic ignimbrite deposits and shallow-level felsic intrusions, as well the enigmatic ‘Am Màm intrusion breccia’. The latter comprises a dacitic matrix enclosing lobate basaltic inclusions (~1–15 cm) and a variety of clasts, ranging from millimetres to tens of metres in diameter. These clasts comprise Lewisian gneiss, Torridonian sandstone and coarse gabbro. Detailed re-mapping of the Am Màm intrusion breccia has shown its timing of emplacement as syn-caldera, rather than pre-caldera as previously thought. Textural analysis of entrained clasts and adjacent, uplifted country rocks has revealed their thermal metamorphism by early mafic intrusions at greater depth than their present structural position. These findings provide a window into the evolution of the early mafic magmas responsible for driving felsic magmatism on Rum. Our data help constrain some of the physical parameters of this early magma–crust interaction and place it within the geochemical evolution of the Rum Centre.
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Wehrmann, H., K. Hoernle, M. Portnyagin, M. Wiedenbeck, and K. Heydolph. "Volcanic CO2output at the Central American subduction zone inferred from melt inclusions in olivine crystals from mafic tephras." Geochemistry, Geophysics, Geosystems 12, no. 6 (June 2011): n/a. http://dx.doi.org/10.1029/2010gc003412.

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Hansteen, Thor H., Tom Andersen, Else-Ragnhild Neumann, and Hielke Jelsma. "Fluid and silicate glass inclusions in ultramafic and mafic xenoliths from Hierro, Canary Islands: implications for mantle metasomatism." Contributions to Mineralogy and Petrology 107, no. 2 (April 1991): 242–54. http://dx.doi.org/10.1007/bf00310710.

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45

Gaulin, R., and P. Trudel. "Caractéristiques pétrographiques et géochimiques de la minéralisation aurifère à la mine Elder, Abitibi, Québec." Canadian Journal of Earth Sciences 27, no. 12 (December 1, 1990): 1637–50. http://dx.doi.org/10.1139/e90-173.

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The Elder deposit is located on the southeast border of the Flavrian Batholith, which intrudes the Blake River Group of archean volcanic rocks. The ore zone is composed of veins 1, 3, 5, and 4. The first three veins are a series of brecciated quartz veins having mean strike and dip of N72°E and 28°SE. Least important is vein 4, striking N20°W and dipping 28°NE. A reverse fault and a mafic dike are associated with the main vein 1, which occurs within trondhjemite in contact with hybrid rocks. The mafic dike represents an important metallotect. The ore zone is marked by abundant carbonates and pyrite, is slightly enriched in hematite and rutile, and is lightly depleted in sericite and chlorite. The mineralogical variation depends on CaO, MgO, CO2, S, TiO2, Fe2O3, MnO, and P2O5 enrichments and SiO2, Na2O, Al2O3, and H2Odepletions. A gold-bearing halo 8 m wide surrounds the ore zone. Seventy-nine per cent of the gold grains are associated with pyrite; otherwise gold occurs mostly as inclusions in the plagioclase matrix. Gold enrichment and rare-earth-element (REE) losses in the ore zone are similar to those observed in other Abitibi gold mines. In veins 1, 3, and 5, divergences in Ag and As enrichments, gold content, and REE concentrations suggest different ore-forming solutions.[Journal Translation]
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46

Grozeva, Niya G., Frieder Klein, Jeffrey S. Seewald, and Sean P. Sylva. "Chemical and isotopic analyses of hydrocarbon-bearing fluid inclusions in olivine-rich rocks." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2165 (January 6, 2020): 20180431. http://dx.doi.org/10.1098/rsta.2018.0431.

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We examined the mineralogical, chemical and isotopic compositions of secondary fluid inclusions in olivine-rich rocks from two active serpentinization systems: the Von Damm hydrothermal field (Mid-Cayman Rise) and the Zambales ophiolite (Philippines). Peridotite, troctolite and gabbroic rocks in these systems contain abundant CH 4 -rich secondary inclusions in olivine, with less abundant inclusions in plagioclase and clinopyroxene. Olivine-hosted secondary inclusions are chiefly composed of CH 4 and minor H 2 , in addition to secondary minerals including serpentine, brucite, magnetite and carbonates. Secondary inclusions in plagioclase are dominated by CH 4 with variable amounts of H 2 and H 2 O, while those in clinopyroxene contain only CH 4 . We determined hydrocarbon abundances and stable carbon isotope compositions by crushing whole rocks and analysing the released volatiles using isotope ratio monitoring—gas chromatography mass spectrometry. Bulk rock gas analyses yielded appreciable quantities of CH 4 and C 2 H 6 in samples from Cayman (4–313 nmol g −1 CH 4 and 0.02–0.99 nmol g −1 C 2 H 6 ), with lesser amounts in samples from Zambales (2–37 nmol g −1 CH 4 and 0.004–0.082 nmol g −1 C 2 H 6 ). Mafic and ultramafic rocks at Cayman exhibit δ 13 C CH 4 values of −16.7‰ to −4.4‰ and δ 13 C C 2 H 6 values of −20.3‰ to +0.7‰. Ultramafic rocks from Zambales exhibit δ 13 C CH 4 values of −12.4‰ to −2.8‰ and δ 13 C C 2 H 6 values of −1.2‰ to −0.9‰. Similarities in the carbon isotopic compositions of CH 4 and C 2 H 6 in plutonic rocks, Von Damm hydrothermal fluids, and Zambales gas seeps suggest that leaching of fluid inclusions may provide a significant contribution of abiotic hydrocarbons to deep-sea vent fluids and ophiolite-hosted gas seeps. Isotopic compositions of CH 4 and C 2 H 6 from a variety of hydrothermal fields hosted in olivine-rich rocks that are similar to those in Von Damm vent fluids further support the idea that a significant portion of abiotic hydrocarbons in ultramafic-influenced vent fluids is derived from fluid inclusions. This article is part of a discussion meeting issue ‘Serpentinite in the Earth system’.
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Cai, Ya-Chun, Hong-Rui Fan, M. Santosh, Fang-Fang Hu, Kui-Feng Yang, Xuan Liu, and Yongsheng Liu. "Silicate melt inclusions in clinopyroxene phenocrysts from mafic dikes in the eastern North China Craton: Constraints on melt evolution." Journal of Asian Earth Sciences 97 (January 2015): 150–68. http://dx.doi.org/10.1016/j.jseaes.2014.10.024.

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48

Michael, Peter J. "Partition coefficients for rare earth elements in mafic minerals of high silica rhyolites: The importance of accessory mineral inclusions." Geochimica et Cosmochimica Acta 52, no. 2 (February 1988): 275–82. http://dx.doi.org/10.1016/0016-7037(88)90083-x.

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49

Rutter, Michael J. "The nature of the lithosphere beneath the Sardinian continental block: Mantle and deep crustal inclusions in mafic alkaline lavas." Lithos 20, no. 3 (June 1987): 225–34. http://dx.doi.org/10.1016/0024-4937(87)90010-7.

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Wang, Yujian, C. Michael Lesher, Peter C. Lightfoot, Edward F. Pattison, and J. Paul Golightly. "Shock metamorphic features in mafic and ultramafic inclusions in the Sudbury Igneous Complex: Implications for their origin and impact excavation." Geology 46, no. 5 (March 14, 2018): 443–46. http://dx.doi.org/10.1130/g39913.1.

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