U‐Pb zircon geochronology of granites and charnockite from southern India: implications for magmatic pulses associated with plate tectonic cycles within a Precambrian suture zone

Abstract

The Palghat-Cauvery Suture Zone (PCSZ) in southern India marks the trace along which continental blocks were sutured during the Precambrian. We report here U-Pb geochronological data based on laser ablation ICP mass spectrometry for zircons in two granite plutons and an associated charnockite from within the PCSZ. The weighted mean of 206 Pb/ 238 U ages for a rapakivi granite from the southern part of the PCSZ yields 819 AE 26 Ma (error: 2s; N ¼ 13). On the other hand, a metamorphosed A-type granite and a charnockite from the central part of the PCSZ yield a markedly older upper intercept age of 2468 AE 36 Ma (error: 2s) and a lower intercept age of 588 AE 36 Ma (error: 2s). Our results provide important constraints on the Precambrian crustal evolution in the PCSZ and demonstrate: (1) Neoarchaean to early Palaeoproterozoic magmatism, generating A-type granites which we correlate with a major global crustal formation event; (2) mid Neoproterozoic magmatism, and generation of the rapakivi granite, probably associated with the subduction of the Mozambique Ocean floor; and (3) latest Neoproterozoic high-grade metamorphism (generating the charnockite) associated with the collisional amalgamation of the Gondwana supercontinent. Together with the previous geochronological data from the PCSZ and adjacent crustal blocks, our results provide information on magmatic pulses associated with the Archaean cratonization event, as well as the Neoproterozoic Wilson Cycle of the Mozambique Ocean culminating in continent-continent collision.

Rb–Sr and Sm–Nd study of granite–charnockite association in the Pudukkottai region and the link between metamorphism and magmatism in the Madurai Block

“…Pudukkottai, however, is not the only region to have such charnockite-granite association within the Madurai Block. Similar types of charnockite associated with A-type pink-granite near Ayyermalai from the northern (Sato et al 2011) and near Mottamalai (Rajapalayam) in the southern parts of the Madurai Block (George et al 2015) were reported earlier.…”

“…There have been a few reports of the early-to mid-Neoproterozoic ages now from the Madurai Block (Sato et al 2011;Teale et al 2011;Anderson et al 2012;Brandt et al 2014), since Santosh et al (2009) made the compilation indicating a gap between early-Paleoproterozoic and late-Neoproterozoic (see figure 7 of Santosh et al 2009). The available geochronological dataset indicates significant events during early to mid-Neoproterozoic period within the Madurai Block, though their importance in the broader framework of Wilson cycle, as proposed by Santosh et al (2009) is yet to be established.…”

“…The discoveries of ultrahigh-temperature metamorphism (UHT) during late-Neoproterozoic-Cambrian times, from various locations in the Madurai Block, have highlighted its complex metamorphic history (Bhaskar Rao et al 1996;Raith et al 1997;Sajeev et al 2004Sajeev et al , 2006Sajeev et al , 2009Tateishi et al 2004;Santosh et al 2006Santosh et al , 2009Tsunogae and Santosh 2006;Braun et al 2007;Sato et al 2011). The eastern arm of the KKPT shear zone is in the alignment with the UHT locations (Brandt et al 2014).…”

Precambrian iron formations from the Cauvery Suture Zone, Southern India: Implications for sub-marine hydrothermal origin in Neoarchean and Neoproterozoic convergent margin settings

“…Considering the available age data for the host rocks of the BIFs of the CSZ, it is evident that the majority of the iron formations belong to Neoarchean age Yellappa et al, 2012;Saitoh et al, 2011;Sato et al, 2011b;Noack et al, 2013;Clark et al, 2009;Ghosh et al, 2004. ) with the exception of the Cryogenian rock suite in the MOC Sato et al, 2012;Teale et al, 2011). It is also well established that the Neoarchean as well as Neoproterozoic subduction-accretion events and convergent margin tectonics must have been the hall marks of the CSZ.…”

The Indian Precambrian: correlations and connections

“…Moving to the southern domain of the Indian Precambrian, the Palghat‐Cauvery Shear/Suture Zone marks an important crustal suture that divides the Archaean Dharwar Craton and the Proterozoic collage of crustal blocks. Sato et al () demonstrate major crust building magmatic activities in the Neoarchaean, mid Neoproterozoic magmatism associated with subduction of the Mozambique oceanic crust, followed by latest Neoproterozoic high‐grade metamorphism and magmatism associated with the assembly of Gondwana. This study establishes a protracted magmatic history in this region related to the Wilson Cycle of the Mozambique Ocean.…”