[S-MP24] Supercontinents and Crustal Evolution

[SMP24-P07] Petrography and progressive metamorphism of Chitradurga Schist Belt, Dharwar Craton, southern India

*Tomokazu Hokada^1,2, Madhusoodhan Satish-Kumar³, Yuichiro Ueno⁴, Tsuyoshi Toyoshima³, Kaoru Mishima⁴, Abdulla Nasheeth^4,5, Chiaki Ikawa² (1.National Institute of Polar Research, 2.The Graduate University for Advanced Studies (SOKENDAI), 3.Niigata University, 4.Tokyo Institute of Technology, 5.Osaka City University)

Keywords:Archaean, Dharwar Craton, India, Metamorphism

Dharwar Crton in southern India is typical Archaean granite-greenstone belt, and underwent regional metamorphism at about 2.5 Ga. The progressive change of the regional metamorphic conditions has been summarized by Raase et al. (1986), and they concluded the metamorphic grade increasing from greenschist-facies in the north to granulite-facies in the south. This is based on the change of the metamorphic minerals in mafic rocks either associated with felsic orthogneiss (granite-zone) or metasedimentary sequences (greenstone-zone).

We have investigated metamorphic mineral assemblages of pelitic and psammitic rocks within the greenstone belt of the Chitradurga Schist Belt that is one of well-studied area and located middle of the Dharwar Craton. The sedimentary sequences of this greenstone belt consist of four groups (Sargur, Bababudan, Chitradurga, Hiriyuru Groups from lower to upper structure; e.g., Sreehari and Toyoshima, 2020). Pelitic and psammitic rocks are charactreized by biotite-muscovite asssemblage with minor muscovite/muscovite-chlorite assemblages. Wihtin the schist belt, progressive change of the metamorphic grade is not clear, but muscovite-chlorite assemblage is observed sporadically in central to eastern part (relatively lower structural layer). These observation are not always consistent with the previously summarized south-north metamorphic variation (Raase et al., 1986) estimated from mafic rocks.

We will discuss in this presentation on the petrography and progressive metamorphism of this part of Dharwar Craton and implications on the regional metamorphism of the Archaean greenstone belt.