Original nature and source of khondalites in the Eastern Ghats Province, India
The khondalites of the Eastern Ghats Province, India represent a sedimentary sequence of shale–greywacke, but the relatively more ferruginous composition can be attributed to some mafic rocks in the provenance. While a high La/Sc ratio and an insignificant Cr-enrichment over V in the majority of samples indicate dominantly granitic source rocks; a low La/Sc ratio and high Cr/V ratio in some samples indicate some mafic source rocks as well. High La/Sc ratio, LREE (light rare earth element)-enrichment, negative Eu anomaly and negative ɛ values, along with evidence of significant weathering and recycling in the provenance, indicate Old Upper Continental Crust-type provenance. Nd-model dates indicate Palaeoproterozoic provenance, which could be the Eastern Dharwar Craton and/or the Napier Complex of East Antarctica. (La/Yb)N ratios are variable and their co-variance with both (La/Sm)N and (Gd/Yb)N are noticeable, and could be attributed to the complexity of possible provenance composition.
Figures & Tables
Palaeoproterozoic of India
The Indian shield represents a vast repository of the Palaeoproterozoic geological record. Built over the four large amalgamated Archaean nuclei (Dharwar, Bastar, Singhbhum and Aravalli–Bundelkhand) the major and minor Palaeoproterozoic sedimentary basins and supracrustal sequences in India are comparable in scale, and perhaps also in development, to those of North America, Africa, Australia and Brazil. The deformation of these supracrustal sequences, attendant metamorphism and emplacement of plutonic bodies hold important clues to their connection with major orogenies. Research in these areas has led to investigations into global correlation, which in turn has had a direct bearing on refining models of Palaeoproterozoic supercontinent assembly and break-up. This book covers various aspects of regional geology as well as broader issues of the Indian Palaeoproterozoic geology and its global context. It is an outcome of the UNESCO-IGCP 509 Palaeoproterozoic Supercontinents and Global Evolution research project.