Reaction enhanced channelised fluid-flux along mid- crustal shear zone: An example from Mesoproterozoic Phulad Shear Zone, Rajasthan, India

Chatterjee, Sadhana M.; Choudhury, Manideepa Roy; Das, Subrata

doi:10.1007/s12040-016-0740-8

Cited by 6 publications

(3 citation statements)

References 26 publications

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“…Since the PSZ metamorphic temperatures ( T = ~ 600 to 630°C) are ~300°C lower than the experimentally determined blocking temperature for intracrystalline Pb diffusion in monazite ( T > 900°C) [ Cherniak et al ., ], the recrystallization of newer monazites at the expense of Grenvillian age monazite is likely to have been induced by fluid‐aided dissolution‐recrystallization [ Rasmussen and Muhling , ; Hetherington et al ., ; Rekha et al ., ]. Intense strain and permeation of hydrothermal fluid—manifested in widespread fluid—assisted retrograde metamorphism in the associated metamarls, and expansive emplacement of pegmatite veins in the PSZ [ Chatterjee et al ., ] caused the Grenvillian age monazites in the hanging wall schists in the SDFB to dissolve and reprecipitate at ~810 Ma monazites in and neighboring the PSZ. These mid‐Neoproterozoic ages are lacking in the eastern parts of the SDFB (Figure ) and farther east within the banded gneiss complex and the Mangalwar Complex across the Kaliguman Shear Zone in the ADFB.…”

Section: Discussionmentioning

confidence: 99%

Significance and dynamics of the Neoproterozoic (810 Ma) Phulad Shear Zone, Rajasthan, NW India

et al. 2017

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The Phulad Shear Zone (PSZ) in northwestern India demarcates the boundary between Grenvillian age para‐metamorphics of the South Delhi Fold Belt (SDFB) to the east and variably deformed Neoproterozoic granitoids of the Marwar Craton to the west. In calcareous and quartzofeldspathic mylonites in and around Phulad, the shear zone is characterized by steep SE dipping mylonitic fabric and a steep oblique stretching lineation. The shear zone is developed in a ductile regime with top‐to‐the‐west reverse sense of movement coupled with pronounced flattening across the PSZ. MnNCKFMASH pressure‐temperature pseudosection analysis of closely spaced specimens of garnet‐bearing mica schists reveals that the stabilization of syn/post‐garnet porphyroblasts in the hanging wall experienced near‐isothermal decompression followed by cooling in the retrograde arm of a clockwise P‐T path. The retrieved P‐T paths are consistent with reverse motion of SDFB mica schist over the cratonic foreland. U‐Th‐Pb (total) monazite age determinations in hanging wall mica schists indicate that reverse motion on the PSZ occurred at 810 ± 6 Ma. The pre‐shearing Grenvillian age (~970 ± 9 Ma) metamorphic monazites of the SDFB occur as embayed cores, in the interiors of younger monazite grains. Intense high‐temperature deformation and the emplacement of mica‐bearing pegmatites during reverse shearing caused recrystallization of monazites by dissolution‐precipitation, mantling older monazites in the hanging wall SDFB schists. It is suggested that the PSZ may represent a terrane boundary shear zone along which the Greater India landmass accreted with the Marwar Craton at ~810 Ma.

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Section: Discussionmentioning

confidence: 99%

Significance and dynamics of the Neoproterozoic (810 Ma) Phulad Shear Zone, Rajasthan, NW India

et al. 2017

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“…The PSZ is described as a terrane boundary shear zone (Sinha Roy, ) along which the Greater India landmass accreted with the Marwar Craton at ~810 Ma (Chatterjee et al, ). The PSZ is characterized by NE‐SW trend and steep easterly dipping mylonitic foliation that runs for several kilometers (Chatterjee et al, ; Ghosh et al, , ; Golani et al, ; Gupta et al, ; Heron, ; Roy & Jakhar, ; Sen, ; Sengupta & Ghosh, , ; Sinha Roy, ; Sinha‐Roy et al, ; Sinha‐Roy et al, ; Sychanthavong & Desai, ). Structural studies of PSZ indicate that deformation in the shear zone is transpressional with a reverse sense of movement (Ghosh et al, , ; Sengupta & Ghosh, , ).…”

Section: Introductionmentioning

confidence: 99%

Mid‐Neoproterozoic Tectonics of Northwestern India: Evidence of Stitching Pluton along 810 Ma Phulad Shear Zone

et al. 2020

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In northwestern India, Phulad Shear Zone (PSZ,~810 Ma) demarcates the boundary between South Delhi Fold Belt to the east and Marwar craton to the west. This shear zone has regional NE-SW trend with small bends of N-S orientations. PSZ is characterized by steep southeasterly dipping mylonitic foliation with steep oblique stretching lineation. The PSZ has developed in a ductile transpression with top-to-the-NNW reverse sense of movement associated with a component of sinistral-slip movement on horizontal section. The 200 by 6 km porphyritic Phulad granite occurs along and across the PSZ, and it is variably deformed. Phulad granite shows evidence of magmatic foliation with preservation of parallel alignment of euhedral feldspars phenocrysts and microgranitoid enclaves. The feldspar phenocrysts show simple twin interfaces parallel to the direction of elongation. This granite also shows development of solid-state foliation parallel to this magmatic foliation. Detailed study of structural elements suggests that Phulad granite has formed during the regional deformation in the country rock shear zone prior to its complete crystallization. Our data indicate that the releasing bends of N-S orientation within the PSZ have provided the space required for emplacement of Phulad granite in a transpressional regime. EPMA U-Pb-Th monazite and U-Pb LA-ICP-MS zircon ages in Phulad granite indicate a magmatic age of 819.1 ± 4 and 818 ± 18 Ma, respectively. PSZ represents the suture along which Marwar craton accreted with remaining India to form the Greater India landmass. The present study suggests that Phulad granite acted as a stitching pluton during this suturing along PSZ at 810-820 Ma.

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“…In the northwestern Indian shield, the South Delhi Fold Belt (SDFB) consists of NE-SW-trending, multiply folded and polymetamorphosed rocks of Proterozoic age. The SDFB consists mainly of calc-silicate rocks inter-layered with mica schists, granites, and mafic and ultramafic rocks (Heron, 1953;Gupta et al 1980Gupta et al , 1995Gupta et al , 1997Roy & Jakhar, 2002;Chatterjee et al 2016). The western margin of the SDFB is demarcated by a crustal-scale shear zone known as the Phulad Shear Zone (PSZ) (Gupta et al 1980;Sinha-Roy, 1988;Golani et al 1998;Ghosh et al 1999;Chatterjee et al 2017Chatterjee et al , 2020.…”

Section: Geological Backgroundmentioning

confidence: 99%

Petrological implications of element redistribution during metamorphism: insights from meta-granite of the South Delhi Fold Belt, Rajasthan, India

et al. 2022

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Meta-granites of the South Delhi Fold Belt, northwestern India, contain spectacular reaction textures formed during the metamorphic replacement of primary minerals. Textural relationships imply that amphibole was replaced sequentially in two stages. Epidote + titanite + quartz symplectite formed syn-tectonically on amphibole grain boundaries/fractures, followed by post-deformational growth of euhedral garnet overprinting amphibole grains. Besides occurring as symplectite grown during deformation, titanite in this rock also developed as a post-tectonic corona around magnetite. Parent magnetite contains exsolutions of ilmenite and/or ultrafine lamellae of Ti-rich oxide (Ti-oxd). Textures involving coronal titanite suggest their formation through a magnetite + ilmenite(/Ti-oxd) + plagioclase → titanite reaction. Compositional attributes and the calculation of the gain versus loss of components during the reaction suggest that the Mn2+ for garnet (XSpss = 0.23–0.29) that grew replacing amphibole was supplied by ilmenite (Mn2+ is 0.118–0.128 apfu) as it disintegrated to form coronal titanite. The redistribution of components between the metamorphic reaction sites connects the texturally unrelated domains and suggests that these zones were in chemical equilibrium during metamorphism. We estimated the P–T conditions of metamorphism for these post-tectonic assemblages as ∼650–700 °C from pseudosection modelling and conventional thermometry. Zircon data from this study suggest that the granitic rock crystallized at 988.8 ± 8.8 Ma. We propose that the metamorphic phases replaced the primary minerals during the mid Neoproterozoic tectonic activity reported from this terrane. The syn-tectonic symplectitic assemblage formed as the temperature increased during prograde metamorphism, and the post-tectonic minerals developed at peak conditions following the cessation of deformation.

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Reaction enhanced channelised fluid-flux along mid- crustal shear zone: An example from Mesoproterozoic Phulad Shear Zone, Rajasthan, India

Cited by 6 publications

References 26 publications

Significance and dynamics of the Neoproterozoic (810 Ma) Phulad Shear Zone, Rajasthan, NW India

Significance and dynamics of the Neoproterozoic (810 Ma) Phulad Shear Zone, Rajasthan, NW India

Mid‐Neoproterozoic Tectonics of Northwestern India: Evidence of Stitching Pluton along 810 Ma Phulad Shear Zone

Petrological implications of element redistribution during metamorphism: insights from meta-granite of the South Delhi Fold Belt, Rajasthan, India

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