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(Banerjee et al., 2019) that the paleo-sea was anoxic and ferruginous but not euxinic.
Geochemical analyses also indicate that the Eu-enrichment in the paleo-sea probably evolved
from continental rifting around 1.9–2.0 Ga. The aim of this project is to carry out a detailed
field work and multiproxy geochemical investigation of the next younger Proterozoic
sedimentary basins in India to understand the oxygenation history during that time. To fill in
the knowledge gap here we propose to generate new geochemical data collected from the
marine carbonate rocks of the Mesoproterozoic Indravati and Chattisgarh basins of India that
will not only help us better understand the time dependent oxygenation episode of the
Proterozoic oceans .
8. Description of the problem(Max. 300 words):

The slow buildup of oxygen in the ocean-atmosphere system is arguably the most important
evolutionary process in Earth history and as said earlier occurred in two major episodes at
around 2400-2200 Ma and at 800 – 540 Ma. However, oxygenation was not a simple one-
way process (Lyons et al., 2014) and the details of Precambrian ocean chemistry remain
poorly understood till date. To understand the early oxygenation history of the atmosphere
and ocean during Precambrian, geochemical proxies of the marine carbonates from the
Proterozoic basins around the world must be studied. But a major problem in using carbonates
to monitor Proterozoic seawater chemistry has been the apparent lack of primary marine
precipitates. Hood and Wallace (2014) and Wallace et al. (2017) have recently shown - based
on geochemical (major and trace elements, REEs) and sedimentological/petrographic data -
that unaltered Proterozoic primary dolomites, reefal marine cements and a number of fibrous
calcite and dolomite cements probably can give reliable information about the chemical and
redox structure of the Proterozoic ocean. Similar results have been obtained from recently
completed Palaeoproterozoic Vempalle Formation dolomite (Banerjee et al., 2019). However,
the seawater chemistry of Mesoproterozoic and Palaeoproterozoic marine carbonate rocks
still remains poorly understood and is limited to reports from Australia (Kah et al., 2004),
Brazil (Gilleaudeau et al., 2016), Canada (Fralick et al., 2017), China (Luo et al., 2015),
Mauretania (Gilleaudeau et al., 2016) and Russia (Bartley et al., 2007; Gilleaudeau et al.,
2016). To understand and fill in the gaps of the early oxygenation history of the atmosphere
and ocean during Precambrian history, in this study, we will focus on the Proterozoic Indravati
and Chattisgarh Basins of India (Patranabis-Deb et al., 2016).
9. Objectives:

To understand, compare and contrast the early oxygenation history of the ocean during
Mesoproterozoic using geochemical proxies (iron, molybdenium, calcium, chromium;
carbon, oxygen, and sulphur isotope data, trace element abundances and biomarkers) of the
marine carbonate rocks of the Indravati and Chattisgarh Basins of India.
10. Study Area:
2
The Indravati Basin, covering an area of 900 km in Kanker Baster and Dantewara districts
of Chhattisgarh and Koraput of Orissa, representing good outcrops of the Proterozoic
Indravati Group of sediments, is one of the important Purana basins adjacent to Proterozoic
Chhattisgarh Basin Mainkar et al.(2004) proposed La-ICPMS, U-Pb age 620 + 30 Ma on the
basis of Tokapal and Bhejripadar kimberlite pyroclastics within Kanger limestone Formation.
Mukherjee et al. (2012) did U-Pb isotopic analyses (LA MC-ICPMS) of the zircons from the
Birsaguda tuff, within the Jagdalpur Formation point to closure of the basin at 1001 ± 7 Ma.
A shoreline to shallow shelf depositional environment in a passive margin tectonic set up is
suggested for different lithological variants of the Indravati sequence.

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