12:48 PM - 12:51 PM
[SMP09-P05] Nd isotope geochemistry of Archaean BIFs in the Chitradurga Schist Belt, Dharwar Craton, Southern India
The Chitradurga Schist Belt belongs to the Dharwar Supergroup that overlies the basement Peninsular Gneiss (~3.0 Ga) with enclaves of Sargur Group (3.3~3.1 Ga). The Dharwar Supergroup is subdivided into two groups, the Bababudan Group and the Chitradurga Group. Hokada et al., (2013) suggested that the oldest depositional age of Bababudan Group and lower unit of Chitradurga group is around 3.14 Ga and 3.22?2.92 Ga and the youngest depositional age of upper unit of Chitradurga group is between 2.68 Ga and 2.63 Ga. The lower Chitradurga unit is metamorphosed to the biotite-muscovite grade whereas the upper unit is chlorite-muscovite grade. Three major BIF layers occur in the Chitradurga Schist Belt, which belongs to the Bababudan Group, lower Chitradurga unit and upper Chitradurga unit. We compare the geochemical features of these three layers in this presentation.
The Chitradurga BIFs are mostly composed of quartz, magnetite and hematite and rarely contain siderite, pyrite, and carbonate minerals. Bulk rock geochemistry results revealed that the BIFs contain only very less amount of Al2O3 or other oxides than SiO2 and Fe2O3. The majority of lower Chitradurga unit BIFs have low REE contents, LREE
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