Combined U-Pb/Hf isotopic studies and phase equilibrium modelling of HT-UHT metapelites from Kambam ultrahigh-temperature belt, south India: Constraints on tectonothermal history of the terrane

Dev, J. Amal; Tomson, J.K.; Sorcar, Nilanjana; Nandakumar, V.

doi:10.1016/j.lithos.2021.106531

Cited by 15 publications

(26 citation statements)

References 64 publications

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“…This argument was strictly based on the lack of a 1.9-2.0 Ga magmatic/metamorphic record elsewhere in the south Indian shield. Alternatively, the Nagercoil block was also proposed as a Paleoproterozoic magmatic arc generated with the subduction-collision of crustal fragments within the Columbia supercontinent [37], which is further validated by the increased recognition of 1.9 Ga magmatic/metamorphic episodes from other parts of SGT [22,56]. As contrasting models have been proposed for the tectonic evolution of the Nagercoil block, the present study attempts to address the issue based on the new data generated for gabbros along with available results published so far from the terrane.…”

Section: Geodynamic Significancementioning

confidence: 97%

“…Two major shear zones dissect the Madurai block, namely the Karur-Kambam-Teni-Painavu-Trissur shear zone (KKPTSZ) [9] and Suruli shear zone (SSZ) [18]. This crustal block is also known for the preservation of Ediacaran-Cambrian UHT metamorphic rocks with P-T estimates up to 1100 • C and 12 kbar with clockwise/anticlockwise P-T evolution [3,[19][20][21][22][23]. The Madurai block is separated from the southern Trivandrum and Nagercoil blocks by the Achankovil shear zone (ASZ) [24,25], which is marked by a distinct younger whole-rock Nd model age (1.5-1.2 Ga) [17,[26][27][28] and U-Pb zircon age (1.5-0.95 Ga) [2,29,30].…”

Section: Geology Of the Study Areamentioning

confidence: 99%

“…The major element concentration of six samples was analysed using a Bruker Pioneer S8 Tiger WD-XRF at NCESS following the analytical protocol described in [22]. For trace element determination, these sample powders were dissolved in a reagent grade HF: HNO 3 acid mixture in Savillex screw-top vessels.…”

Section: Major and Trace Element Geochemistrymentioning

confidence: 99%

“…Zircons analysed for U-Pb dating were reanalysed, and spots were positioned close to the previous crater due to spatial limitations. The analytical protocol was according to [22]. 91500 zircon [44] was used as the primary standard, whereas Plesovice [45] was monitored for quality check.…”

Section: Zircon U-pb Ages Trace Element and Hf Isotopesmentioning

confidence: 99%

“…Hf-T DM model ages of the samples range from 1.16 to 1.48 Ga, pointing to a mid-Mesoproterozoic melting source. Available Hf-T DM and Nd-T DM model ages from Madurai and Nagercoil blocks are dominantly Paleoproterozoic [2,17,22,34,37,78], except for the eastern part of central Madurai and southeastern part of Madurai and Trivandrum blocks [2,17,30,31]. Among these, rocks from the eastern part of the central Madurai block are reported with Cryogenian emplacement ages and negative εHf (t) signatures (moderately reworked).…”

Section: Geodynamic Significancementioning

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: Geodynamic Significancementioning

confidence: 97%

Section: Geology Of the Study Areamentioning

confidence: 99%

Section: Major and Trace Element Geochemistrymentioning

confidence: 99%

Section: Zircon U-pb Ages Trace Element and Hf Isotopesmentioning

confidence: 99%

Section: Geodynamic Significancementioning

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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Effectiveness of Ti-in-amphibole thermometry and performance of different thermometers across lower continental crust up to UHT metamorphism

Bartoli,

Carvalho,

Farina

2024

Contrib Mineral Petrol

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Metabasites are important constituents of deep crustal sections and are the favored rock type for studying lower crustal amphibolite to granulite transitions. However, metapelites may develop a larger number of temperature-sensitive mineral assemblages and are particular useful when extreme ultrahigh temperature (UHT) conditions are envisaged. A recent calibration of the Ti-in-amphibole thermometer by Liao et al. (2021) was supposed to make thermometry on metabasites quick and easy to apply. However, their calibration is based on experiments which were not originally designed to investigate in detail the temperature dependence of Ti in amphibole. In addition, a possible effect of aTiO2 and/or pressure on the Ti content of amphibole was not fully taken into account. This resulted in a calibration uncertainty of ± 70 °C (2σ), much higher than that of other single-mineral thermometers. In this study we firstly test the newly calibrated Ti-in-amphibole thermometer across the mid to lower crustal section of the Ivrea–Verbano Zone (IVZ; NW Italy) and compare the performance of different thermometric techniques across the sequence. Ti-in-amphibole thermometry records increasing peak temperatures from amphibolite (600–700 °C), transition (750–800 °C) and granulite (850–950 °C) zones. Titanium content of amphibole may be modified by retrograde fluid influx returning temperatures c. 200–300 °C lower than in non-altered domains. The comparison reveals that Zr-in-rutile thermometer in pelitic granulites seems to be more prone to post-peak resetting than the Ti-in-amphibole thermometry in nearby mafic rocks. This behavior is also confirmed by amphibole analyses from other UHT localities, where the performance of Ti-in-amphibole thermometry is comparable with that of Al-in-orthopyroxene in pelitic granulites. However, Ti-in-amphibole temperatures are underestimated in rutile-bearing samples and this limitation is not solely restricted to rocks containing high H2O contents as previously thought. Derived constraints on the diffusivity of Ti through amphibole demonstrate the robustness of the Ti-in-amphibole thermometer to later thermal disturbances. However, ad-hoc experiments are still necessary to improve the accuracy and precision of calibration and to extend its applicability. This advance will make mafic granulites routine targets for studies devoted to understanding the regional extent of UHT metamorphism.

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Himalayan type strongly peraluminous leucogranite from the western Madurai block, Southern Granulite Terrane, India: Evidence for Tonian crustal reworking

Anto-Francis,

Tomson,

Dev

et al. 2024

J Earth Syst Sci

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Combined U-Pb/Hf isotopic studies and phase equilibrium modelling of HT-UHT metapelites from Kambam ultrahigh-temperature belt, south India: Constraints on tectonothermal history of the terrane

Cited by 15 publications

References 64 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

Effectiveness of Ti-in-amphibole thermometry and performance of different thermometers across lower continental crust up to UHT metamorphism

Himalayan type strongly peraluminous leucogranite from the western Madurai block, Southern Granulite Terrane, India: Evidence for Tonian crustal reworking

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