Cl-rich hydrous mafic mineral assemblages in the Highiș massif, Apuseni Mountains, Romania

Bonin, Bernard; Tatu, Mihai

doi:10.1007/s00710-015-0419-x

Cited by 12 publications

(38 citation statements)

References 46 publications

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“…The increase in K and Al IV with increasing Cl abundances in amphiboles, as observed in the present study, has also been reported worldwide in many natural Cl‐rich amphiboles (e.g., Bonin & Tatu, ; Léger et al, ; McCormick & McDonald, ; Xiao, Hoefs, & Kronz, ). This is due to the accommodation of much larger Cl anion (radius 1.81 Å) into the crystal structure of amphibole by replacing OH anion (radius 1.32 Å) at the octahedral—O(3)—site, which is accompanied by the projection of Cl − out of octahedral site into the A‐site.…”

Section: Discussionsupporting

confidence: 88%

“…The variations in halogen contents are principally controlled by the activity of Cl and F in the fluid/melt with which the amphibole and biotite last equilibrated as advocated by many (e.g., Kullerud & Erambert, ; Makino, Tomita, & Suwa, ; Oberti et al, ; Vanko, ; Zhang et al, ). The unusual variably Cl‐enriched amphiboles in the studied intrusions have the highest Cl contents ever reported in the literature for A‐type granites (Bonin & Tatu, ). Since the Cl contents in the melt remain nearly constant over the crystallisation course above 700°C and decrease strongly at near solidus temperature due to fluid exsolution (Zhang et al, ), the highly variable enriched Cl contents further point to their redistribution between amphibole and biotite due to the easy remobility of large and incompatible Cl anion by the hydrothermal fluids either at late magmatic or post‐solidus stage.…”

Section: Discussionmentioning

confidence: 49%

“…Analysed biotite compositions in the (a) X Fe (Fe +2 /[Fe +2 + Mg]) (apfu) versus Al IV (apfu) classification diagram (Deer, Howie, & Zussman, ) and (b) Mg# (MgO/[MgO + MnO + FeO]) in wt% versus Ti# (10 × TiO 2 /[10 × TiO 2 + FeO + MgO + MnO]) in wt% diagram (Bonin & Tatu, ; Nachit, Ibhi, Abia, & Ohoud, ) [Colour figure can be viewed at wileyonlinelibrary.com]…”

Section: Petrography and Chemistry Of Amphibole And Biotitementioning

confidence: 99%

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Chlorine‐rich amphibole and biotite in the A‐type granites, Rajasthan, NW India: Potential indicators of subsolidus fluid–rock interaction and metallogeny

2018

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The A-type granites in the northern Delhi fold belt, Rajasthan, India, comprise Clenriched amphibole and biotite. These hydrous phases, in general, show significant variation in the Cl and F contents on the scale of individual intrusions and also at times on thin-section scale. This variation of the hydrous phases that equilibrated with the fluid is principally controlled by the variation in the fluid activity ratios of a Cl -/a OHand a F -/a OH -. The activity gradients in the fluid developed due to the interaction between the granites and an externally derived Cl-bearing fluid coupled with limited integrated fluid flux. The fraction of the fluid that reached the least albitised granite was highly Cl-rich as a consequence of preferential extraction of water from the grain-boundary fluid for the formation of hydrous phases like epidote and sericite. The occurrence of Cl-rich amphibole and biotite coupled with the variation in their halogen contents in the A-type granites can act as potential indicators of hydrothermal fluid activity and the subsequent mineralisation in a region.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 49%

Section: Petrography and Chemistry Of Amphibole And Biotitementioning

confidence: 99%

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Chlorine‐rich amphibole and biotite in the A‐type granites, Rajasthan, NW India: Potential indicators of subsolidus fluid–rock interaction and metallogeny

2018

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“…Black squares are Ca-amphibole end-members, grey squares are (Fe,Mg,Mn)-amphibole end-members (Hawthorne et al , 2012). Modified after Robinson et al (1982) and Bonin and Tatu (2016). …”

Section: Resultsmentioning

confidence: 99%

“…A prograde origin for the ALC noritic temperatures can be excluded, because clinopyroxene is expected to coexist with amphibole at such high temperatures (See ‘Age considerations and anatexis’, below; Green et al , 2016; Palin et al , 2016), which is not observed. Low Ti content in biotite is usually ascribed to re-equilibration of primary magmatic biotite (Bonin and Tatu, 2016) and the variable TiO 2 in Amikoq noritic biotite also suggests re-equilibration. The lowest TiO 2 is observed in biotite from an intensely retrogressed norite (1.0–1.4 wt.%) with near-complete alteration of orthopyroxene to anthophyllite (Fig.…”

Section: Discussionmentioning

confidence: 99%

The Mesoarchean Amikoq Layered Complex of SW Greenland: Part 1. Constraints on theP–Tevolution from igneous, metasomatic and metamorphic amphiboles

Aarestrup

Jørgensen

Armitage

et al. 2020

MinMag

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The metamorphic history of the Mesoarchean Amikoq Layered Complex within the Akia terrane of SW Greenland was characterised by electron microprobe mineral data and detailed petrography on 12 representative samples, integrated with zircon U–Pb geochronology and petrology. The complex intruded into a >3004 Ma supracrustal association now consisting of granoblastic metabasites with subordinate quartz-rich gneiss. Supracrustal host rocks contain a relict high-temperature assemblage of orthopyroxene–clinopyroxene (± pigeonite exsolution lamellae, exsolved at ~975–1010°C), which is interpreted to pre-date the Amikoq intrusion. Cumulate to granoblastic-textured rocks of the main Amikoq Layered Complex range modally from leuconorite to melanorite, orthopyroxenite to harzburgite/dunite and rare hornblende melagabbro. Observed mineralogy of main complex noritic lithologies is essentially relict igneous with orthopyroxene–biotite and hornblende–plagioclase thermometers yielding temperatures of ~800–1070°C. An anatectic zircon megacryst from a patchy quartzo–feldspathic leucosome hosted in an orthopyroxene-dominated Amikoq rock reflects local anatexis at peak metamorphic P–T conditions and yields an intrusion minimum age of 3004 ± 9 Ma. Field observations indicate local anatexis of orthopyroxene-dominated lithologies, possibly indicating a post-intrusion peak temperature of >900°C. The last preserved stages of retrogression are recorded in paragneiss plagioclase–garnet, biotite–garnet and host rock ilmenite–magnetite pairs (≤3 kbar and ~380–560°C). The Amikoq Complex intruded a MORB-like crustal section and the former remained relatively undisturbed in terms of modal mineralogy. Preservation of igneous textures and mineralogy are related to an anhydrous, high-grade metamorphic history that essentially mimics igneous crystallisation conditions, whereas local high-strain zones acted as fluid pathways resulting in hydrous breakdown of igneous minerals. There is no evidence of equilibration of the intrusion at sub-amphibolite-facies conditions.

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Halogen Contents of Mineralized Versus Unmineralized Potassic Igneous Rocks

Müller¹,

Groves²

2018

Potassic Igneous Rocks and Associated Gold-Copper Mineralization

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Cl-rich hydrous mafic mineral assemblages in the Highiș massif, Apuseni Mountains, Romania

Cited by 12 publications

References 46 publications

Chlorine‐rich amphibole and biotite in the A‐type granites, Rajasthan, NW India: Potential indicators of subsolidus fluid–rock interaction and metallogeny

Chlorine‐rich amphibole and biotite in the A‐type granites, Rajasthan, NW India: Potential indicators of subsolidus fluid–rock interaction and metallogeny

The Mesoarchean Amikoq Layered Complex of SW Greenland: Part 1. Constraints on theP–Tevolution from igneous, metasomatic and metamorphic amphiboles

Halogen Contents of Mineralized Versus Unmineralized Potassic Igneous Rocks

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