Amphibole—a key indicator mineral for petrogenesis of the Purulia carbonatite, West Bengal, India

Chakrabarty, Aniket; Sen, Amit; Ghosh, Tamal

doi:10.1007/s00710-008-0024-3

Cited by 29 publications

(11 citation statements)

References 8 publications

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“…2b) and the other with light green colored amphibole showing pale-green to light green pleochroism (richterite). A detailed work on the alkali-amphiboles by Chakrabarty et al (2009) has suggested a shallow depth of intrusion of this carbonatite and also advocated a sudden change in pressure during its emplacement.…”

Section: Carbonatitesmentioning

confidence: 99%

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Enigmatic association of the carbonatite and alkali-pyroxenite along the Northern Shear Zone, Purulia, West Bengal: A saga of primary magmatic carbonatite

Chakrabarty

Sen

2010

J Geol Soc India

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The Purulia carbonatite, 'carbonatite'-'alkali-pyroxenite'-'apatite-magnetite rock' association, is located at Beldih area of Purulia district, West Bengal and falls within the 100 km long Northern Shear Zone (NSZ). Published literature suggests that the Purulia carbonatite was formed by the process of liquid immiscibility from under-saturated silicate parent magma. However, no silica under-saturated rocks like ijolite, nepheline-syenite etc. is known from the area. The trace element geochemistry (Ba/La, Nb/Th, Nb/Pb and Y/Ce ratios in the present study) also does not support this view. Present study indicates that the Purulia carbonatite is enriched in 6REE and incompatible elements but the carbonatite is also poorer in Nb, Th and Pb compared to the world average of calicocarbonatites. The lower value of Nb is characteristics of carbo(hydro)thermal carbonatite where carbonatite is associated with alkali-pyroxenite and suggests probable origin of the carbonatite as carbothermal residua evolved from an unknown parentage. However, the field, petrographic and geochemical data indicate the genesis of this carbonatite from a primary carbonatitic magma of mantle decent. The 87 Sr/ 86 Sr ratio of the carbonatite and apatite separated from the carbonatite (~0.703) implies primary magmatic derivation of the Purulia carbonatite. Close similarity of the apatite of the apatite-magnetite rock with the mantle apatite (of type Apatite B) indicates that they are also of primary magmatic origin. The present work portrays a unique example where primary magmatic carbonatite is associated with the alkali-pyroxenite.

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Section: Carbonatitesmentioning

confidence: 99%

“…1) (Kumar et al 1985;Basu, 1993Basu, , 2003Chakrabarty et al 2009). These rocks are intruded within the Chandil formation of 1.5-1.6 Ga age and lies in the close proximity of the Chotanagpur Granite Gneissic Complex (CGGC).…”

Section: Introductionmentioning

confidence: 99%

Enigmatic association of the carbonatite and alkali-pyroxenite along the Northern Shear Zone, Purulia, West Bengal: A saga of primary magmatic carbonatite

Chakrabarty

Sen

2010

J Geol Soc India

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“…Previous research has relied on fluid inclusion data, mineral chemical evidence and limited textural observations to gain an understanding of carbonatite petrogenesis (e.g. Katz and Keller 1981;Viladkar and Wimmenauer 1992;Costanzo et al 2006;Chakhmouradian et al 2008;Chakrabarty et al 2009). This study documents the texture, cathodoluminescence and mineral chemistry of major rock-forming minerals of the Eppawala carbonatites, Sri Lanka.…”

Section: Introductionmentioning

confidence: 99%

Petrogenesis of the Eppawala carbonatites, Sri Lanka: A cathodoluminescence and electron microprobe study

Pitawala

Lottermoser

2012

Miner Petrol

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Field and petrographic investigations, cathodoluminescence (CL) studies as well as microprobe analyses of major rock-forming minerals were conducted to establish the crystallization processes in the Eppawala carbonatites, Sri Lanka. The well preserved magmatic textures and crystal morphologies combined with the chemistry of apatite, calcite and dolomite indicate two major stages of crystal growth, which were accompanied by dynamic crystallization conditions. Initially, nucleation of apatite, ilmenite and possibly olivine was associated with rapid crystal growth during slow cooling of the carbonatite melt at depth. The heat loss through the roof and crystallization processes induced the development of turbulent convective currents, which in turn prevented further nucleation and growth of crystals and led to the dispersion of these earlier formed crystals within the magma chamber. Then, rapid upward movement of magma along structural weaknesses led to (i) the transport of mineral clusters, (ii) deformation of ilmenite, (iii) fracturing of apatite and (iv) the emplacement of the carbonatite melt as dykes. Here, the conditions were favourable for the simultaneous crystallization of magnetite, calcite and dolomite in a non-turbulent environment. Subsequent subsolidus alteration caused the hydrothermal overprint of the documented mineral assemblages, particularly along grain boundaries. The study demonstrates that detailed textural examinations of carbonatites combined with mineral chemical analyses and CL investigations can reveal the crystallization processes within carbonatite melts.

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“…The SPSZ is an east-west to east-southeast-west-northwest trending shear zone that extends almost 150 km in length (Chakrabarty et al, 2009). The shear zone lies between Chhotanagpur Granite Gneissic Complex (CGGC) in the north and Singhbhum Group in the south.…”

Section: The Field Examplementioning

confidence: 99%

“…Because the target is located below a thick soil cover, the absence of a surface signature in the radiation measurements Figure 9. Geologic map of the study area (after Chakrabarty et al, 2009) and seven VLF measuring profiles in the area of 300 × 300 m.…”

Section: Parametersmentioning

confidence: 99%

3D modeling and inversion of VLF and VLF-R electromagnetic data

2012

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Three-dimensional linearized nonlinear electromagnetic inversion is developed for revealing the subsurface conductivity structure using isolated very low frequency (VLF) and VLF-resistivity anomalies due to conductors that may be arbitrarily directed towards the measuring profiles and the VLF transmitter. We described the 3D model using a set of variables in terms of geometric and physical parameters. These model parameters were then optimized (parametric inversion) to obtain their best estimates to fit the observations. Two VLF transmitters, i.e., the H x , E y ("E") and the H y , E x ("H") polarizations, respectively, can be considered jointly in inversion. After inverting several noise-free and noisy synthetic data, the results revealed that the estimated model parameters and the functionality of the approach were very good and reliable. The inversion procedure also worked well for the field data. The reliability and validity of the results after the field data inversion have been checked using data from a shear zone associated with uranium mineralization.

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Amphibole—a key indicator mineral for petrogenesis of the Purulia carbonatite, West Bengal, India

Cited by 29 publications

References 8 publications

Enigmatic association of the carbonatite and alkali-pyroxenite along the Northern Shear Zone, Purulia, West Bengal: A saga of primary magmatic carbonatite

Enigmatic association of the carbonatite and alkali-pyroxenite along the Northern Shear Zone, Purulia, West Bengal: A saga of primary magmatic carbonatite

Petrogenesis of the Eppawala carbonatites, Sri Lanka: A cathodoluminescence and electron microprobe study

3D modeling and inversion of VLF and VLF-R electromagnetic data

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