The evolution of aqueous–carbonic fluids in the Amba Dongar carbonatite, India: implications for fenitisation

Williams‐Jones, Anthony E.; Palmer, D.A.

doi:10.1016/s0009-2541(01)00409-0

Cited by 75 publications

(32 citation statements)

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“…These temperatures are within the range of ∼250-500 ∘ C estimated based on calcite-dolomite solvus thermometry for Panwad-Kawant and Amba Dongar carbonatites [37]. The composition of the dilute CO 2 -rich aqueous fluids observed in quartz xenocrysts is roughly similar to those exsolved during final stages of evolution of the Amba Dongar carbonatites [38]. Extensive carbonatite metasomatism is clearly visible in the sample studied; however, since the carbonates are devoid of fluid inclusions, their genetic relationship with the secondary inclusions in quartz is uncertain.…”

Section: Discussionsupporting

confidence: 58%

Fluid Inclusion Study of Quartz Xenocrysts in Mafic Dykes from Kawant Area, Chhota Udaipur District, Gujarat, India

Randive

Hurai

2015

Open Geosciences

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Unusual mafic dykes occur in the proximity of the Ambadongar Carbonatite Complex, Lower Narmada Valley, Gujarat, India. The dykes contain dense population of quartz xenocrysts within the basaltic matrix metasomatised by carbonate-rich fluids. Plagioclase feldspars, relict pyroxenes, chlorite, barite, rutile, magnetite, Fe-Ti oxides and glass were identified in the basaltic matrix. Quartz xenocrysts occur in various shapes and sizes and form an intricate growth pattern with carbonates. The xenocrysts are fractured and contain several types of primary and secondary, single phase and two-phase fluid inclusions. The two-phase inclusions are dominated by aqueous liquid, whereas the monophase inclusions are composed of carbonic gas and the aqueous inclusions homogenize to liquid between 226 ∘ C and 361 ∘ C. Majority of the inclusions are secondary in origin and are therefore unrelated to the crystallization of quartz. Moreover, the inclusions have mixed carbonic-aqueous compositions that inhibit their direct correlation with the crustal or mantle fluids. The composition of dilute CO 2 -rich fluids observed in the quartz xenocrysts appear similar to those exsolved during the final stages of evolution of the Amba Dongar carbonatites. However, the carbonates are devoid of fluid inclusions and therefore their genetic relation with the quartz xenocrysts cannot be established.

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Section: Discussionsupporting

confidence: 58%

Fluid Inclusion Study of Quartz Xenocrysts in Mafic Dykes from Kawant Area, Chhota Udaipur District, Gujarat, India

Randive

Hurai

2015

Open Geosciences

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“…It is reasonable to assume that SiO 2 was concentrated in the residual fluids. Williams-Jones & Palmer (2002) documented the significant concentrations of Si in the carbonatitic fluid at depths of 3-5 km. Silica, like REE, can accumulate in residual fluid because there is a low mineral/melt partition coefficient in the primary minerals (calcite, apatite).…”

Section: Discussionmentioning

confidence: 96%

“…Evidence of high activity of aluminum at Amba Dongar can be seen in the feldsparrich fenites , Viladkar 1996. Moreover, according to Williams-Jones & Palmer (2002), the fluid inclusions in apatite from sövites contain significant concentrations of Al (up to 46 at.%.). The carbonatitic magma in Amba Dongar did contain minor Al, which is evident in presence of phlogopite in some sövites.…”

Section: Discussionmentioning

confidence: 99%

“…NaCl), lowtemperature (100-150°C) CO 2 -bearing aqueous fluids. Williams-Jones & Palmer (2002) based their study of fluid inclusions on apatite in sövites and on quartz from surrounding fenitized sandstones; they showed that the fluid evolution in the Amba Dongar carbonatite started with the exsolution from the magma of a sulfate-and potassium-rich, CO 2 -CH 4 -bearing aqueous fluid. Later, at relatively shallow depths, a second solute-rich aqueous fluid exsolved, with lower values of K/Na and S/Cl, and significant concentrations of Ca, Al and Si.…”

Section: Composition Of the Mineralsmentioning

confidence: 99%

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Hydrothermal Ree Mineralization in the Amba Dongar Carbonatite Complex, Gujarat, India

Doroshkevich¹,

Viladkar²,

Рипп³

et al. 2009

The Canadian Mineralogist

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We have studied two groups of overprinted (altered) carbonatites at Amba Dongar, India: weakly overprinted and strongly overprinted. The mineral association of quartz, florencite-(Ce), strontianite, barite and sparse bastnäsite -parisite -synchysite typical of weakly overprinted carbonatites shows evidence of a high activity of OH -, (SO 4 ) 2-, Al and Si in the fluid. Later, the fluid was characterized by an increased activity of F -, (SO 4 ) On the basis of field observations, two phases of alvikite dikes have been recognized. Phase I is coeval with the main intrusion of sövite, and cross-cuts the sandstone, carbonatite breccia and pre-carbonatite basalt, whereas phase-II dikes were emplaced later. Ankeritic carbonatite, which is younger than the calciocarbonatite, invades sövite at several outcrops in the form of dikes and plugs of varying size. The ankeritic carbonatite occurs in three distinct phases. The first phase consists of thin dikes intruding sövite and fenite; the second phase forms large plugs within the sövite ring-dike, whereas the last phase is characterized by high radioactivity owing to the high abundances of cerite, monazite-(Ce), and thorite (Viladkar 1996). Veins of sideritic carbonatite, which are found in ankeritic carbonatites, also contain cerite, monazite and thorite. Locally, the total REE content is well above 15 wt.% (Viladkar 1996). The carbonatite activity appears to have ended with fluorite mineralization.

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“…The upper limit of fenitization is not as well constrained, but probably approaches 700°C, based on consensus of measured temperatures between 600 and 700°C at Amba Dongar (> 700°C, Williams-Jones and Palmer, 2002); Iivaara, Finland (660°C, Sindern and Kramm, 2000); and Alnö (640°C - Skelton et al, 2007). This temperature is supported by the stability of alkali amphiboles such as riebeckite and arfvedsonite, which are constrained between 650 and 800°C (Kovalenko et al, 1977).…”

Section: Properties and Chemistry Of Fenitizing Fluidsmentioning

confidence: 99%

Fenites associated with carbonatite complexes: A review

Elliott

Wall

Chakhmouradian

et al. 2018

Ore Geology Reviews

151

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A B S T R A C TCarbonatites and alkaline-silicate rocks are the most important sources of rare earth elements (REE) and niobium (Nb), both of which are metals imperative to technological advancement and associated with high risks of supply interruption. Cooling and crystallizing carbonatitic and alkaline melts expel multiple pulses of alkali-rich aqueous fluids which metasomatize the surrounding country rocks, forming fenites during a process called fenitization. These alkalis and volatiles are original constituents of the magma that are not recorded in the carbonatite rock, and therefore fenites should not be dismissed during the description of a carbonatite system. This paper reviews the existing literature, focusing on 17 worldwide carbonatite complexes whose attributes are used to discuss the main features and processes of fenitization. Although many attempts have been made in the literature to categorize and name fenites, it is recommended that the IUGS metamorphic nomenclature be used to describe predominant mineralogy and textures. Complexing anions greatly enhance the solubility of REE and Nb in these fenitizing fluids, mobilizing them into the surrounding country rock, and precipitating REE-and Nb-enriched micro-mineral assemblages. As such, fenites have significant potential to be used as an exploration tool to find mineralized intrusions in a similar way alteration patterns are used in other ore systems, such as porphyry copper deposits. Strong trends have been identified between the presence of more complex veining textures, mineralogy and brecciation in fenites with intermediate stage Nb-enriched and later stage REE-enriched magmas. However, compiling this evidence has also highlighted large gaps in the literature relating to fenitization. These need to be addressed before fenite can be used as a comprehensive and effective exploration tool.

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The evolution of aqueous–carbonic fluids in the Amba Dongar carbonatite, India: implications for fenitisation

Cited by 75 publications

References 20 publications

Fluid Inclusion Study of Quartz Xenocrysts in Mafic Dykes from Kawant Area, Chhota Udaipur District, Gujarat, India

Fluid Inclusion Study of Quartz Xenocrysts in Mafic Dykes from Kawant Area, Chhota Udaipur District, Gujarat, India

Hydrothermal Ree Mineralization in the Amba Dongar Carbonatite Complex, Gujarat, India

Fenites associated with carbonatite complexes: A review

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