Carbon isotopes in Kerguelen plume-derived carbonatites: evidence for recycled inorganic carbon

Ray, Jyotisankar; Ramesh, R.; Pande, Kanchan

doi:10.1016/s0012-821x(99)00112-0

Cited by 121 publications

(47 citation statements)

References 33 publications

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“…of ore with 11.05% P 2 O 5 under the 'probable category' was indicated in the carbonatites and associated apatitemagnetite rocks around Sung village [18]. Several workers have presented the geology of the Sung Valley complex and discussed the magmatic source of the carbonatites and associated silicate rocks [6,7,9,[19][20][21][22]. Viladkar et al [19] suggested that a carbonated nephelinite-derived magma was the source of the carbonatites and associated silicate rocks in the SUAC complex.…”

Section: Geological Backgroundmentioning

confidence: 99%

“…Viladkar et al [19] suggested that a carbonated nephelinite-derived magma was the source of the carbonatites and associated silicate rocks in the SUAC complex. Veena et al [9] and Ray et al [20,21] correlated the source of the magma with mantle plume activity. Veena et al [9] suggested the involvement of sub-continental lithosphere that had been metasomatised by fluids derived from an upwelling mantle plume and subsequent partial melting of this mantle source.…”

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REE mineralization in the carbonatites of the sung valley ultramafic-alkaline-carbonatite complex, Meghalaya, India

2014

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The Early Cretaceous Sung Valley Ultramafic-Alkaline-Carbonatite (SUAC) complex intruded the ProterozoicShillong Group of rocks and located in the East Khasi Hills and West Jaintia Hills districts of Meghalaya. The SUAC complex is a bowl-shaped depression covering an area of about 26 km 2 and is comprised serpentinised peridotite forming the core of the complex with pyroxenite rim. Alkaline rocks are dominantly ijolite and nepheline syenite, occur as ring-shaped bodies as well as dykes. Carbonatites are, the youngest intrusive phase in the complex, where they form oval-shaped bodies, small dykes and veins. During the course of large scale mapping in parts of the Sung Valley complex, eleven carbonatite bodies were delineated. These isolated carbonatite bodies have a general NW-SE and E-W trend and vary from 20-125 m long and 10-40 m wide. Calcite carbonatite is the dominant variety and comprises minor dolomite and apatite and accessory olivine, magnetite, pyrochlore and phlogopite. The REE-bearing minerals identified in the Sung Valley carbonatites are bastnäsite-(Ce), ancylite-(Ce), belovite-(Ce), britholite-(Ce) and pyrochlore that are associated with calcite and apatite. IntroductionCarbonatites are known to host high concentrations of rare earth elements (REE) [1]. Moreover, syenites, phonolites, alkali granite, pegmatite and secondary or supergene en- * E-mail: mohd.sadiq.gsi@gov.in richment in some bauxite, laterite, phosphorites, placers and beach sands are also potential hosts for REE's. Rare Earth Metals are becoming a critical strategic resource with an increase in demand mainly from scientific and military applications. About 95% of the REE export market is dominated by China who is a leading producer of REEs. In China, production is mainly from the Bayan Obo REE-iron ore deposits and clay deposits in southern China, and rest of the world has comparatively limited production [2]. Prior to the rise of Chinese REE production, monazite and xenotime-beach placer deposits in India, Brazil and Australia had been the main source for REEs. With the discovery of carbonatite-hosted REE deposits (mainly bastnäsite-(Ce)), carbonatite has become a primary resource of world REE production e.g. Mountain Pass, USA. In India, the first carbonatite-hosted REE deposit has been discovered at Kamthai, Barmer district, Rajasthan and contains a highest LREE grade of 17.31 wt% and a weighted average grade is 2.97 wt% LREO with a total volume of 1,38,428 tonnes [2]. The Shillong Plateau of northeastern India hosts four intrusive alkaline-carbonatite complexes, the Samchampi, Sung Valley, Jasra-Barpung and Swangkre complexes [3,4]. Sung Valley was the first carbonatite complex reported from north east India [5]. These complexes, especially the Sung Valley complex, has drawn attention of many researchers mainly for two reasons. Firstly, its petrogenesis, emplacement age and relationship with associated silicate rocks and secondly to assess mineral potential of the alkaline-carbonatite complex [3,4,[6][7][8][9][10][11]...

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Section: Geological Backgroundmentioning

confidence: 99%

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confidence: 99%

REE mineralization in the carbonatites of the sung valley ultramafic-alkaline-carbonatite complex, Meghalaya, India

2014

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“…The oxygen and carbon isotope compositions for the carbonatite calcite from the analyzed samples in this study (Table) are typical of those carbonatite complexes in other parts of the world (Deines, 1989) and do not show any of the effects of late hydrothermal alteration, which tend to exhibit elevated carbon and oxygen isotope composition. According to Deines (1970) Ray et al (1999), indicating crystallization from magma derived from "normal" mantle; they are not the result of any primary or secondary magmatic fractional processes.…”

Section: Discussionmentioning

confidence: 99%

The case of the carbonatite-like dyke of the Madenska River complex at the Kriva Lakavica section in the Republic of Macedonia: oxygen and carbon isotopic constraints

Dolenec¹,

Serafimovski²,

Daneu³

et al. 2015

Turkish J Earth Sci

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The oxygen and carbon isotope compositions of carbonate samples from the carbonatite-like dyke of the Madenska River complex at the Kriva Lakavica section, samples of calcite skarns from the Damjan Fe-ore deposit and the Sasa Pb-Zn ore deposit, and samples of marbles from the Pohorje Mountains were analyzed to provide critical evidence in favor of the magmatic or sedimentary origin of this carbonatite-like dyke. We suggest that the carbonatite-like dyke is not a "normal" carbonatite, but instead represents melted carbonates, which can be associated with an unexposed, deep-seated, causative magmatic body. This dyke has a fluidal texture and carries xenoliths of ultramafic rocks that can be up to 35 cm in size. Its isotopic composition plots between primary unaltered carbonatites and marine carbonates, and ranges between 13.79‰ and 18.89‰ for δ 18 O VSMOW and between -1.22‰ and 1.31‰ for δ 13 C VPDB . These values are significantly lower than those observed in carbonatites analyzed during this study and range between 6.53‰ and 8.10‰ for δ 18 O VSMOW and between -5.82‰ and -4.32‰ for δ 13 C VPDB , which is the primary isotope signature of most magmatic carbonatites. Similarly high δ 18 O and δ 13 C values were found in skarns of the Damjan Fe deposit close to the Madanska River complex and in the Sasa Pb-Zn deposit, as well as in highgrade regional metamorphic calcitic marbles of the Pohorje massive. The emplacement levels of the carbonatite-like dyke, due to several tectonic processes, are uncertain. The type of country rocks (sedimentary carbonates, ultramafic, mafic, and granitic rocks), hydrothermal alternation, and metasomatic and regional metamorphic processes seem to be the most important parameters that affect the O and C isotopic patterns found in the Kriva Lakavica carbonatitelike dyke and in the investigated samples.

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“…A spatial and temporal association of this magmatism with Kerguelen hotspot-mantle plume system of Indian Ocean has been proposed (Ray et al 1999;Kent et al 2002). The ultramafic-mafic-alkalinecarbonatite intrusive complexes representing late stage differentiation of Sylhet Trap magmas occur as small, isolated, circular bodies along a NE trending zone in Shillong Plateau (Mamallan et al 1994;Sinha 2004, 2007) (figure 1).…”

Section: Introductionmentioning

confidence: 98%

Evaluation of phase chemistry and petrochemical aspects of Samchampi-Samteran differentiated alkaline complex of Mikir Hills, northeastern India

et al. 2010

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The Samchampi-Samteran alkaline complex occurs as a plug-like pluton within the Precambrian granite gneisses of Mikir Hills, Assam, northeastern India and it is genetically related to Sylhet Traps. The intrusive complex is marked by dominant development of syenite within which ijolitemelteigite suite of rocks is emplaced with an arcuate outcrop pattern. Inliers of alkali pyroxenite and alkali gabbro occur within this ijolite-melteigite suite of rocks. The pluton is also traversed by younger intrusives of nepheline syenite and carbonatite. Development of sporadic, lumpy magnetite ore bodies is also recorded within the pluton. Petrographic details of the constituent lithomembers of the pluton have been presented following standard nomenclatorial rules. Overall pyroxene compositions range from diopside to aegirine augite while alkali feldspars are typically orthoclase and plagioclase in syenite corresponds to oligoclase species. Phase chemistry of nepheline is suggestive of Na-rich alkaline character of the complex. Biotite compositions are typically restricted to a uniform compositional range and they belong to 'biotite' field in the relevant classification scheme. Garnets (developed in syenite and melteigite) typically tend to be Ti-rich andradite, which on a closer scan can be further designated as melanites. Opaque minerals mostly correspond to magnetite. Use of Lindsley's pyroxene thermometric method suggests an equilibration temperature from ∼ 450 • -600 • C for melteigite/alkali gabbro and ∼ 400 • C for syenite. Critical assessment of other thermometric methods reveals a temperature of equilibration of ∼ 700 • -1350 • C for ijolite-melteigite suite of rocks in contrast to a relatively lower equilibration temperature of ∼ 600 • C for syenite. Geobarometric data based on pyroxene chemistry yield an equilibration pressure of 5.32-7.72 kb for ijolite, melteigite, alkali pyroxenite, alkali gabbro and nepheline syenite. The dominant syenite member of the intrusive plug records a much higher (∼ 11 kb) equilibration pressure indicating a deeper level of intrusion. Major oxide variations of constituent lithomembers with respect to differentiation index (D.I.) corroborate a normal magmatic differentiation. A prominent role of liquid immiscibility is envisaged from field geological, petrographic and petrochemical evidences. Tectonic discrimination diagrams involving clinopyroxene chemistry strongly suggest within plate alkaline affinity for the parental magma which is in conformity with the regional plume tectonics.

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Carbon isotopes in Kerguelen plume-derived carbonatites: evidence for recycled inorganic carbon

Cited by 121 publications

References 33 publications

REE mineralization in the carbonatites of the sung valley ultramafic-alkaline-carbonatite complex, Meghalaya, India

REE mineralization in the carbonatites of the sung valley ultramafic-alkaline-carbonatite complex, Meghalaya, India

The case of the carbonatite-like dyke of the Madenska River complex at the Kriva Lakavica section in the Republic of Macedonia: oxygen and carbon isotopic constraints

Evaluation of phase chemistry and petrochemical aspects of Samchampi-Samteran differentiated alkaline complex of Mikir Hills, northeastern India

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