Geodynamic evolution of a Pan-African granitoid of extended Dizo Valley in Karbi Hills, NE India: Evidence from Geochemistry and Isotope Geology

Majumdar, Dilip; Dutta, Pallabi

doi:10.1016/j.jseaes.2015.12.015

Cited by 36 publications

(19 citation statements)

References 36 publications

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“…a). Porphyritic granite plutons dated at 530–480 Ma truncate the sinistral shear‐related faults (Mazumdar, ; Ghosh et al ., , ; Yin et al ., ; Majumdar & Dutta, ). Sinistral shearing in central SMGC may be correlated with re‐metamorphism of the c .…”

Section: Geological Backgroundmentioning

confidence: 99%

“…The basement of the SMGC is composed of amphibolite‐granulite facies gneisses derived from Neoarchean–Palaeoproterozoic gneissic protoliths (Ahmed, ; Nandy, ; Bidyananda & Deomurari, ; Majumdar & Dutta, ). In the northern Garo Hills of Meghalaya and the Goalpara district of Assam (western Shillong‐Meghalaya Plateau, Fig.…”

Section: Geological Backgroundmentioning

confidence: 99%

“…The basement of the SMGC is composed of amphibolite-granulite facies gneisses derived from Neoarchean-Palaeoproterozoic gneissic protoliths (Ahmed, 1983;Nandy, 2001;Bidyananda & Deomurari, 2007;Majumdar & Dutta, 2016 granulites and charnockite (Gogoi, 1963;Mazumdar, 1976;Lal et al, 1978). The metapelites experienced multiple phases of deformation (Bhattacharjee & Baruah, 1973;Lal et al, 1978;Bardoloi et al, 1994;Mazumdar et al, 1999).…”

Section: Geological Bac Kgroundmentioning

confidence: 99%

“…2a). Porphyritic granite plutons dated at 530-480 Ma truncate the sinistral shear-related faults (Mazumdar, 1976;Ghosh et al, 1994Ghosh et al, , 2005Yin et al, 2010;Majumdar & Dutta, 2016). Sinistral shearing in central SMGC may be correlated with re-metamorphism of the c. 1.6 Ga metapelites at c. 500 Ma along a clockwise P-T path with prograde isobaric heating between 635 and 730°C at~5.6 kbar, and retrograde cooling to 595°C at 3.2 kbar (Chatterjee et al, 2011).…”

Section: Geological Bac Kgroundmentioning

confidence: 99%

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Constraints from monazite and xenotime growth modelling in the MnCKFMASH‐PYCe system on the P–T path of a metapelite from Shillong‐Meghalaya Plateau: implications for the Indian shield assembly

Chatterjee

2016

Journal Metamorphic Geology

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The Palaeo‐Mesoproterozoic metapelite granulites from northern Garo Hills, western Shillong‐Meghalaya Gneissic Complex (SMGC), northeast India, consist of resorbed garnet, cordierite and K‐feldspar porphyroblasts in a matrix comprising shape‐preferred aggregates of biotite±sillimanite+quartz that define the penetrative gneissic fabric. An earlier assemblage including biotite and sillimanite occurs as inclusions within the garnet and cordierite porphyroblasts. Staurolite within cordierite in samples without matrix sillimanite is interpreted to have formed by a reaction between the sillimanite inclusion and the host cordierite during retrogression. Accessory monazite occurs as inclusions within garnet as well as in the matrix, whereas accessory xenotime occurs only in the matrix. The monazite inclusions in garnet contain higher Ca, and lower Y and Th/U than the matrix monazite outside resorbed garnet rims. On the other hand, matrix monazite away from garnet contains low Ca and Y, and shows very high Th/U ratios. The low Th/U ratios (<10) of the Y‐poor garnet‐hosted monazite indicate subsolidus formation during an early stage of prograde metamorphism. A calculated P–T pseudosection in the MnCKFMASH‐PYCe system indicates that the garnet‐hosted monazite formed at <3 kbar/600 °C (Stage A). These P–T estimates extend backward the previously inferred prograde P–T path from peak anatectic conditions of 7–8 kbar/850 °C based on major mineral equilibria. Furthermore, the calculated P–T pseudosections indicate that cordierite–staurolite equilibrated at ~5.5 kbar/630 °C during retrograde metamorphism. Thus, the P–T path was counterclockwise. The Y‐rich matrix monazite outside garnet rims formed between ~3.2 kbar/650 °C and ~5 kbar/775 °C (Stage B) during prograde metamorphism. If the effect of bulk composition change due to open system behaviour during anatexis is considered, the P–T conditions may be lower for Stage A (<2 kbar/525 °C) and Stage B (~3 kbar/600 °C to ~3.5 kbar/660 °C). Prograde garnet growth occurred over the entire temperature range (550–850 °C), and Stage‐B monazite was perhaps initially entrapped in garnet. During post‐peak cooling, the Stage‐B monazite grains were released in the matrix by garnet dissolution. Furthermore, new matrix monazite (low Y and very high Th/U ≤80, ~8 kbar/850–800 °C, Stage C), some monazite outside garnet rims (high Y and intermediate Th/U ≤30, ~8 kbar/800–785 °C, Stage D), and matrix xenotime (<785 °C) formed through post‐peak crystallization of melt. Regardless of textural setting, all monazite populations show identical chemical ages (1630–1578 Ma, ±43 Ma). The lithological association (metapelite and mafic granulites), and metamorphic age and P–T path of the northern Garo Hills metapelites and those from the southern domain of the Central Indian Tectonic Zone (CITZ) are similar. The SMGC was initially aligned with the southern parts of CITZ and Chotanagpur Gneissic Complex of central/eastern India in an ENE direction, but was displaced ~350 km northward by sinistral mo...

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Section: Geological Backgroundmentioning

confidence: 99%

Section: Geological Backgroundmentioning

confidence: 99%

Section: Geological Bac Kgroundmentioning

confidence: 99%

Section: Geological Bac Kgroundmentioning

confidence: 99%

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Constraints from monazite and xenotime growth modelling in the MnCKFMASH‐PYCe system on the P–T path of a metapelite from Shillong‐Meghalaya Plateau: implications for the Indian shield assembly

Chatterjee

2016

Journal Metamorphic Geology

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“…Kumar, Rino, et al () suggested that the Palaeozoic granitoids (535‐507 Ma) formed during the late stage of the eastern Gondwana amalgamation during the Pan‐African event (Chatterjee, Bhattacharya, Duarah, & Mazumdar, ). The A2‐type granite (515 Ma) exposed in the Khasi Hills was attributed as a product of extension in the post‐orogenic setting of the Pan‐African event (Majumdar & Dutta, ). Hence, there is a general consensus that the Palaeozoic magmatism in the Indian Craton was generated during the late stage of the Pan‐African event.…”

Section: Discussionmentioning

confidence: 99%

Cambrian magmatism in the Tethys Himalaya and implications for the evolution of the Proto‐Tethys along the northern Gondwana margin: A case study and overview

Zhang

Santosh

et al. 2018

Geological Journal

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The Cuonadong Dome in southern Tibet is a newly discovered gneiss dome in the Tethys Himalaya. Here, we investigate the Late Cambrian augen gneiss (orthogneiss) within the core of this dome to address the controversy surrounding early Palaeozoic tectonic evolution of the northern margin of eastern Gondwana. We report new zircon laser ablation multicollector inductively coupled plasma mass spectrometry (LA‐(MC‐)ICP‐MS) U‐Pb ages, Lu‐Hf isotopes, whole‐rock major and trace element geochemistry, and Sr‐Nd‐Pb data on representative samples from the granitic gneiss. The weighted mean of 116 analyses of zircon grains yields an age of 498.2 ± 1.5 Ma (mean square weighted deviation [MSWD] = 1.2). Forty‐one spots analyses on these grains show consistent εHf (t) values of −2 to +4 (average = +1.1), corresponding to Hf crustal model age (TDM2) of 1.3 to 1.6 Ga (average = 1.39 Ga). The orthogneiss (metagranite) is characterized by high Si and K contents, with low Al, Mg, and Ti, and A/CNK values ranging from 0.87 to 0.98 with an average of 0.92, indicating a metaluminous composition and I‐type granitoid affinity. The granitoid displays significant enrichment in light rare earth elements (LREEs) and relatively flat high rare earth element (HREE) patterns, with strong negative Eu anomalies (Eu/Eu* = 0.26–0.31). The primitive mantle‐normalized trace elements show a relative enrichment in large‐ion lithophile elements, such as Rb, and high‐field strength elements, such as Th, U, Zr, and Hf, with depletion in Ba, Nb, Ta, Sr, P, and Ti. The rocks show high initial 87Sr/86Sr ratios (0.7221–0.7248) and low εNd (t) values (−8.9 to −7.3) with Nd model ages (TDM) of 1.79–1.91 Ga. Their radiogenic Pb isotopic compositions show (206Pb/204Pb)t = 18.804–19.110, (207Pb/204Pb)t = 15.730–15.768, and (208Pb/204Pb)t = 38.409–39.054, indicating an ancient upper middle continental crustal origin. Our study shows that the protolith of the metagranite was most likely derived from the partial melting of upper continental crust with a minor contribution of depleted mantle materials. Through integration of the regional information on early Palaeozoic magmatism and metamorphic events, we contend that the protolith of the Cuonadong granitic gneiss formed in an accretionary setting associated with the early Palaeozoic Proto‐Tethys Oceanic plate subduction beneath the Gondwana continent.

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Geochemistry of Late Palaeoproterozoic (1.69 Ga) A‐type Mayong granitoids in Shillong Plateau, north‐east India: Implication for anorogenic magmatism during Columbia Supercontinent cycle

et al. 2021

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The Late Palaeoproterozoic Mayong granitoids of Assam constitute an important component of the continental crust and the Basement Gneissic Complex in the northern extension of the Shillong Plateau, north‐east India. The basement rocks of Shillong Plateau are considered as a continuation of the Central Indian Tectonic Zone. In this study, emphasis is given on the new zircon U–Pb age, Hf isotopic composition, and the tectonic implication of Late Palaeoproterozoic Mayong granitoids. The Mayong granitoids are essentially composed of quartz—K‐feldspar—plagioclase—biotite—hornblende as major minerals and titanite—zircon—allanite—bastnaesite—apatite—ilmenite as the accessory mineral phase. They show typical geochemical characteristics of A‐type granites, such as high silica (average 71.86 wt%), alkalies (average 8.01 wt%), Rb, Zr, Nb, Ga, and rare earth elements (except Eu); high FeOt/MgO and Ga/Al ratios, and low CaO, MgO, Ba, Sr, P, Eu, and Ti concentrations. Laser ablation inductively coupled plasma mass spectrometry zircon U–Pb dating indicates that they were emplaced at ~1,687 ± 35 Ma during the large‐scale magmatism of Late Palaeoproterozoic to Early Mesoproterozoic periods. Their zircon Hf model (TDM2) ages (1,833–2,257 Ma) in conjunction with trace elemental characteristics suggest that they were generated by the reworking/recycling of Early Palaeoproterozoic crust in an intraplate extensional tectonic environment. Thus, we conclude that these A‐type Late Palaeoproterozoic Mayong granitoids of the Shillong Plateau probably have a close genetic linkage with the magmatic event of the Columbia Supercontinent cycle during 1,687 ± 35 Ma.

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Geodynamic evolution of a Pan-African granitoid of extended Dizo Valley in Karbi Hills, NE India: Evidence from Geochemistry and Isotope Geology

Cited by 36 publications

References 36 publications

Constraints from monazite and xenotime growth modelling in the MnCKFMASH‐PYCe system on the P–T path of a metapelite from Shillong‐Meghalaya Plateau: implications for the Indian shield assembly

Constraints from monazite and xenotime growth modelling in the MnCKFMASH‐PYCe system on the P–T path of a metapelite from Shillong‐Meghalaya Plateau: implications for the Indian shield assembly

Cambrian magmatism in the Tethys Himalaya and implications for the evolution of the Proto‐Tethys along the northern Gondwana margin: A case study and overview

Geochemistry of Late Palaeoproterozoic (1.69 Ga) A‐type Mayong granitoids in Shillong Plateau, north‐east India: Implication for anorogenic magmatism during Columbia Supercontinent cycle

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