First Report of Sapphirine+Quartz Assemblage from Southern India: Implications for Ultrahigh-temperature Metamorphism

Sapphirine + quartz assemblage from Ganguvarpatti: diagnostic evidence for ultrahigh-temperature metamorphism in central Madurai Block, southern India

“…The southern granulite terrane (SGT) in India is characterized by the occurrence of Late Neoproterozoic to Early Cambrian (Santosh et al, 2003Collins et al, 2007, and references therein) high -grade metamorphic rocks that underwent T > 900 °C peak metamorphism related to the collisional orogeny during the final stage of assembly of Gondwana supercontinent (Santosh et al, 2009a(Santosh et al, , 2009b and references therein). The peak UHT metamorphism in this terrane is supported by the occurrence of some key mineral assemblages such as orthopyroxene + sillimanite + quartz, spinel + quartz, Al -rich orthopyroxene, and mesoperthite as well as sapphirine + quartz (e.g., Tateishi et al, 2004;Morimoto et al, 2004;Ishii et al, 2006;Tadokoro et al, 2007Tadokoro et al, , 2008Tsunogae et al, 2008a;Shimizu et al, 2009). In spite of the widespread occurrence of UHT metamorphic rocks in southern India, the equilibrium sapphirine + quartz assemblage has been reported only from one locality (Rajapalaiyam in the southern Madurai Block, Tateishi et al, 2004;Santosh, 2006, 2009;Braun et al, 2007).…”

“…The peak UHT metamorphism in this terrane is supported by the occurrence of some key mineral assemblages such as orthopyroxene + sillimanite + quartz, spinel + quartz, Al -rich orthopyroxene, and mesoperthite as well as sapphirine + quartz (e.g., Tateishi et al, 2004;Morimoto et al, 2004;Ishii et al, 2006;Tadokoro et al, 2007Tadokoro et al, , 2008Tsunogae et al, 2008a;Shimizu et al, 2009). In spite of the widespread occurrence of UHT metamorphic rocks in southern India, the equilibrium sapphirine + quartz assemblage has been reported only from one locality (Rajapalaiyam in the southern Madurai Block, Tateishi et al, 2004;Santosh, 2006, 2009;Braun et al, 2007). It is therefore still not known whether the T > 1000 UHT metamorphism is a regional event throughout the SGT, or a local episode possibly related to the infiltration of CO 2 -rich fluids (e.g., Santosh and Omori, 2008;Tsunogae et al, 2008b).…”

Electron microprobe dating of monazites from an ultrahigh-temperature granulite in Southern India: Implications for the timing of Gondwana assembly

“…This block as well as the PalghatCauvery Shear Zone system (PCSZ) at its northern margin have been the focus of several recent studies. Sapphirineand corundum -bearing Mg -Al granulites in this region have provided robust evidence for ultrahigh temperature (UHT) metamorphism at extreme thermal conditions of up to 1100 o C and 12 kbar followed by either simple clock -wise or anticlockwise paths, or a multistage exhumation history (e.g., Raith et al, 1997;Sajeev et al, 2004;Tamashiro et al, 2004;Tateishi et al, 2004;Tsunogae and Santosh, 2006;Santosh and Sajeev, 2006). Recent studies have indicated that the whole of the northern Madurai Granulite Block as well as parts of the Palghat -Cauvery Shear zone system experienced extreme thermal conditions, possibly during a common tectonothermal event (Santosh et al, 2006b).…”

Laser ablation ICP mass spectrometry for zircon U-Pb geochronology of metamorphosed granite from the Salem Block: Implication for Neoarchean crustal evolution in southern India

“…Further, the rocks in several localities have recorded imprints of UHT thermal event (e.g., Brown and Raith, 1996;Morimoto et al, 2004;Tateishi et al, 2004;Tadokoro et al, 2008;Shimizu et al, 2009;Nishimiya et al, 2010). Therefore, the thermal history of the Salem Block which is different from the other blocks in the SGT needs to be addressed in more detail to understand the composite evolution of the terrane.…”