The Southern Granulite Terrane, India: The saga of over 2 billion years of Earth's history

Talukdar, Moumita; Sarkar, Tapabrato; Sengupta, P.; Mukhopadhyay, D.

doi:10.1016/j.earscirev.2022.104157

Cited by 12 publications

(8 citation statements)

References 204 publications

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“…SGT is a collage of polydeformed crustal blocks (from north to south named Salem, Madurai, Trivandrum, and Nagercoil blocks) that are separated by crustal-scale shear zones (Figure 1) [1,2,4,6,[8][9][10]. SGT is limited to the north by the Archaean granite-greenstone terranes of the Dharwar craton [11,12], separated by the E-W trending crustal-scale shear zone known as the Moyar Bhavani Cauvery Shear System (MBCS) [4,13].…”

Section: Geology Of the Study Areamentioning

confidence: 99%

“…The Precambrian granulitic terrane of southern India or the Southern Granulite Terrane (SGT) occupies a central position in the Gondwana supercontinent reconstruction models (Figure 1). This vast granulitic terrane has a crustal evolutionary history ranging from the early Archean to Cambrian with imprints of multiple magmatic, metamorphic, and deformation episodes [1][2][3][4][5][6][7]. In this protracted history, the Neoproterozoic assembly of SGT and its counterparts is known for high geotherm prevalence associated with intense crustal reworking and melting during the Himalayan-scale collision orogen referred to as the East African Orogen (EAO; 650-480 Ma; [5] and references therein).…”

Section: Introductionmentioning

confidence: 99%

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Neoproterozoic Mafic Magmatism in Nagercoil Block, Southern India and Its Implications on the Gondwana Collisional Orogeny

et al. 2022

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The Nagercoil block situated at the southernmost tip of India occupies a key position in the East Gondwana collisional tectonic models. The Nagercoil block is dominated by Orosirian I-type charnockite massifs that host numerous gabbroic emplacements. Our present understanding about the crustal architecture of the Nagercoil block is derived mostly from these charnockites, while detailed studies on gabbros are lacking. We present new petrology, geochemistry, and zircon U-Pb/Hf isotopic data of gabbros from the Nagercoil block to understand their petrogenesis and tectonic significance. The results reveal that these are formed by the partial melting of a subduction-modified lithospheric mantle source in a continental arc setting. Zircon U-Pb geochronology results reveal that the gabbros were emplaced between 561 and 531 Ma. Hafnium isotopic studies on zircons argue for a mid-Mesoproterozoic melting source with near-juvenile magmatic signatures. The Hf-TDM ages together with the available data from the terrane point to the involvement of the adjacent Achankovil unit as a possible melting source contributor. The genetic link between the Achankovil unit and Sri Lanka together with the remarkable similarity in ages and isotopic characteristics of mafic rocks from both these terranes point to their coeval formation during the East African Orogeny associated with the final stages of the Gondwana supercontinent assembly.

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Section: Geology Of the Study Areamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Neoproterozoic Mafic Magmatism in Nagercoil Block, Southern India and Its Implications on the Gondwana Collisional Orogeny

et al. 2022

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“…Flanking the Archean Dharwar craton to the north, the Granulite Terrane of Southern India (GTSI) represents one of the largest exposed deep continental crustal sections of the world, consisting of polydeformed and polymetamorphosed high‐grade rocks (reviewed in Brandt et al, 2014; Collins et al, 2014; Talukdar et al, 2022) (Figure 1a). The entire terrane is divided into several crustal blocks (Figure 1a,b) with intervening suture/shear zones (Drury et al, 1984), and retains rock record from Mesoarchean to the Neoproterozoic, covering a time span of c. 2500 Ma (Brandt et al, 2014; Collins et al, 2014; Harris et al, 1994; Santosh et al, 2003).…”

Section: Geological Frameworkmentioning

confidence: 99%

“…The entire terrane is divided into several crustal blocks (Figure 1a,b) with intervening suture/shear zones (Drury et al, 1984), and retains rock record from Mesoarchean to the Neoproterozoic, covering a time span of c. 2500 Ma (Brandt et al, 2014; Collins et al, 2014; Harris et al, 1994; Santosh et al, 2003). The Archean section of the GTSI, which is bounded by the ‘Fermor Line’ to the north and Moyar–Bhawani Shear Zone (MBSZ) to the south has been referred to as ‘Northern Granulite Terrane’ (NGT), which comprises the Salem, Coorg and Madras Block (reviewed in Talukdar et al, 2022) (Figure 1a,b). The vast stretch of the granulite unit (including its retrogressed equivalent) that is exposed to the south of the MBSZ has been referred to as ‘Southern Granulite Terrane’ (SGT).…”

Section: Geological Frameworkmentioning

confidence: 99%

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Long‐lived high‐grade metamorphism in southern India: Constraints from charnockites and sapphirine‐bearing semipelitic granulites from the Madurai Block

Tiwari,

Sarkar,

Karmakar

et al. 2023

Journal Metamorphic Geology

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The Granulite Terrane of Southern India is a collage of Mesoarchean–Neoproterozoic crustal blocks that underwent high‐grade metamorphism associated with the final assembly of the Gondwana supercontinent during late Neoproterozoic–Cambrian. Here, we investigate the charnockites and associated sapphirine‐bearing semipelitic granulites from the eastern part of the Madurai Block (MB). We present new petrographic, mineral chemistry, and geochronological data to constrain the P–T–t evolution of the block and unravel the timescale and source of heat for the ultrahigh‐temperature metamorphism. Both the rock types contain coarse‐grained porphyroblastic garnet and orthopyroxene, yielding peak P–T conditions of 950 ± 30°C at 10.5 ± 0.8 kbar and 970 ± 40°C at 10 ± 0.5 kbar for semipelite and charnockite, respectively, using conventional thermobarometry. Peak ultrahigh temperatures are further supported by high Al content in the orthopyroxene (8.78 wt% Al2O3) coexisting with garnet (XMg: up to 0.57) and feldspar thermometry of the mesoperthites and antiperthites in the semipelite, yielding 950–980°C at 10 kbar. Subsequent decompression has led to the formation of coronal orthopyroxene3 + plagioclase3 in the charnockite and symplectic orthopyroxene3 + cordierite ± sapphirine ± plagioclase3 in the semipelite, yielding P–T range of 950–850°C and 9.5–6.8 kbar for semipelites and 950–820°C and 8–6.5 kbar for charnockite. Based on the obtained P–T estimates, preserved reaction textures, and phase equilibria modelling in the MnNCKFMASHTO system, a clockwise P–T evolution with isothermal decompression followed by cooling is inferred for both the rock types.Texturally constrained in situ monazite dating and rare earth element (REE) patterns show that the core of matrix monazite having low‐Th, Y, and extreme heavy rare earth element (HREE) depletion, yielding weighted mean ages of 582 ± 12 and 590 ± 22 Ma for semipelite and charnockite, respectively, dates the prograde evolution. The mantle of the matrix monazite in semipelite and comparable rim in charnockite, having relative Th‐enrichment compared to the core, yielding weighted mean ages of 552 ± 9 and 557 ± 13 Ma, respectively, dates extensive dissolution–reprecipitation from the melt at the peak stage. The relatively Th‐ and Y‐rich and moderately HREE‐depleted rim of matrix monazite in the semipelite, yielding weighted age of 516 ± 6 Ma, date initial garnet breakdown during post‐peak melt crystallization. By contrast, compositionally homogenous HREE + Y‐enriched monazite in the symplectite and retrograde monazites yielding weighted mean ages of 487 ± 47 Ma for semipelites and 508 ± 19 Ma for charnockites dates extensive garnet breakdown during final stages of melt crystallization and subsequent cooling. Our findings point to collision initiation at ~590 Ma, with the peak conditions attained at ~550 Ma followed by extensional collapse at ~510–490 Ma, resulting in rapid exhumation of lower crustal rocks to mid‐crustal levels under sustained ultrahigh‐temperature (UHT) conditions, followed by cooling to reach a stable geotherm. Our results suggest a long‐lived hot orogeny in the MB, where the UHT conditions were sustained for at least 40 MYr. The UHT conditions were most likely attained in the core of a long‐lived hot orogen by the combined effect of conductive heating through radioactive decay and mantle heat supply, with the former being the primary driver.

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Neoarchean (ca. 2746–2501 Ma) magmatism: Evidence from east coast dykes of northeastern Southern Granulite Terrain, India

Pradhan,

Dash,

Balakrishnan

et al. 2024

J Earth Syst Sci

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The Southern Granulite Terrane, India: The saga of over 2 billion years of Earth's history

Cited by 12 publications

References 204 publications

Neoproterozoic Mafic Magmatism in Nagercoil Block, Southern India and Its Implications on the Gondwana Collisional Orogeny

Neoproterozoic Mafic Magmatism in Nagercoil Block, Southern India and Its Implications on the Gondwana Collisional Orogeny

Long‐lived high‐grade metamorphism in southern India: Constraints from charnockites and sapphirine‐bearing semipelitic granulites from the Madurai Block

Neoarchean (ca. 2746–2501 Ma) magmatism: Evidence from east coast dykes of northeastern Southern Granulite Terrain, India

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