• What are Purana Basins?

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Paleobiology and Indian Stratigraphy

Unit 4: Purana Basins of India

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Purana Sedimentary Basins

• What are Purana Basins?

• Purana = ancient

• Purana sedimentary basins

= undeformed & unmetamorphosed sedimentary rocks of

Proterozoic ages

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Purana Basins - summary

• Includes only sedimentary successions of Proterozoic age that occur in numerous basins in the peninsular India

• They are largely unmetamorphosed, undeformed (only

slightly) deformed at basin margins, without body fossils

(any part of the actual animal or plant)

• They are intracratonic basins

• Purana basins in India are Proterozoic in age, filled with

mostly marine, deltaic, and fluvial sediments, with some

alluvial fan deposits in the basin margins

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When did Purana Basins formed?

Major Purana basin formation took place during three (03) main pulses:

1. Paleo-to Mesoproterozoic phase of basin formation (Aravalli – Delhi, Lower Vindhyan, Lower Chhattisgarh and

Cuddapah Basins)

2. Early Neoproterozoic phase of basin formation (Upper Vindhyan, Upper Chhattisgarh Basins)

3. Late Neoproterozoic phase of basin formation (Marwar

basin and the Kurnool Group of the Cuddapah Basin)

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Purana Basins…

• Other basins in India have only poor age constraints though many (Bhima, Kaladgi and Indravati) are

traditionally thought to be Late Neoproterozoic in age

• Three Purana Basins :

Vindhyan Basin, Chhattisgarh Basin, Cuddapah Basin

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Vindhyan Supergroup

• A Purana sedimentary basin

• Sickle-shaped

• Bounded by Aravalli-Bundelkhand cratons in the north and west, Deccan Traps in the south

• Great Boundary Fault (GBF) marks the western limit of this basin

• Composed of several smaller sub-basins: Rajasthan sector,

Son Valley sector, Chitrakoot

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Vindhyan Supergroup: Stratigraphy

Upper Vindhyan Bhander Group

Rewa Group

Kaimur Group

Lower Vindhyan Semri Group

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The maximum thickness of various units (in meters) is given in parentheses

…Stratigraphy

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Lower Vindhyan: Age

• Generally, ages of Purana sedimentary rocks remain a subject of debate

• Age of Lower Vindhyan Supergroup = better constrained = Mesoproterozoic

Sawa Sandstone 1616 Ma (U-Pb detrital zircon) Kajrahat Limestone 1721 Ma (Pb-Pb)

Deonar Porcellanite 1631 Ma (U-Pb zircon) Rampur Shale 1600 Ma (U-Pb zircon) Tirhon Dolostone 1650 Ma (Pb-Pb)

Rohtas Limestone 1600 Ma (Pb-Pb)

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SS: Sandstone LS: Limestone DS: Dolostone PF: Porcellanite Formation

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Upper Vindhyan: Age

• Age of Upper Vindhyan Supergroup = controversial!

Kaimur Sandstone <1172 Ma (U-Pb detrital zircon) Lakheri Limestone 1073±210 Ma (Pb-Pb)

Shikaoda Sandstone <1000 Ma (U-Pb detrital zircon) Balwan Limestone 866±180 Ma (Pb-Pb)

Majhgawan Kimberlite 1070 Ma (Rb-Sr, Ar-Ar) Bhander Limestone 908±72 (Pb-Pb)

Maihar Sandstone <1000 Ma (U-Pb detrital zircon)

• Ediacaran fossils reported from Lakheri and Sirbu Formations (Bhander Group): <635 Ma (Fossil vs. Radiometric ages)

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SS: Sandstone LS: Limestone DS: Dolostone PF: Porcellanite Formation

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Upper Vindhyan: Age

• Majhgawan Lamproite (~1070 Ma) intrudes the Kaimur succession

• Is Ediacaran (635-541 Ma) age of the Upper Vindhyan Supergroup valid?

• Biologic nature and Age of the Ediacaran fossils are questioned (MacGhabann, 2007)

• Upper Vindhyan sedimentation completed by ~1000 Ma

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Chattisgarh Supergroup

• Chhattisgarh basin = Proterozoic (Purana) Sedimentary Basin

• Sandstone-shale-carbonate units varying in thickness from 100-10,000 m

• Deposited alternately with frequent breaks in

sedimentation

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Litho-tectonic map of India

Chhattisgarh basin covers an area of about ~36,000 km²

It is situated on the northern edge of Bastar Craton and bounded by:

-Kotri-Dongargarh Orogen in the West -Satpura Mobile Belt in the North

-Gondwana Graben (Mahanadi) in the NE -Eastern Ghats Mobile Belt in the SE

Chhattisgarh basin extends for about 300 km in the E-W and 200 km in the N- S directions.

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(a) Generalized geological map of central India showing the location of the

Chhattisgarh Basin, basement granitoids, and adjacent litho-units in the Bastar Craton

(b) Geological map of the Chhattisgarh Basin showing the spatial extent of various

lithostratigraphic units (modified after Mukherjee et al. 2014)

Sources of age data:

1: Dasgupta et al. (2013) 2: Mohanty (2015)

3: Manikyamba et al. (2016) 4: Khanna et al. (2019) 5: Bora et al. (2013) 6: Ahmad et al. (2009) 7: Dey et al. (2017) 8: Mukherjee et al. (2017) 9: Bhowmik et al. (2011) 10: Sarangi et al. (2004) 11: Gopalan et al. (2013) 12: George et al. (2018) 13: Amarasinghe et al. (2015) 14: Das et al. (2009)

15: Ratre et al. (2010) 16: Das et al. (2011)

17: Patranabis-Deb et al. (2007) 18: Mukhopadhyay et al. (2010) 19: Renne et al. (2015).

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A generalized geological map of the Chhattisgarh

Supergroup (after George et al., 2019 Mukherjee et al., 2014 Saha and Patranabis-Deb, 2014)

The sediments of the Chhattisgarh Supergroup are deposited in two sub-basins:

Hirri in the west and Bharadwar in the east, separated by the Sonakhan Greenstone Belt (SGB)

And two protobasins in the

southeast: Singhora and Barapahar

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Lithostratigraphy of the Chhattisgarh Supergroup

Lithostratigraphy of Chhattisgarh Supergroup in Hirri (east) and Bharadwar (west) sub-basins

Chhattisgarh Supergroup is divided into four (04) groups:

Kharsiya Group Raipur Group

Chandarpur Group Singhora Group

Data sources: Das et al. (1992) Mukherjee et al.

(2014) Saha and Patranabis-Deb (2014).

Ages: (1) Bickford et al. (2011 a), (2) Patranabis- Deb et al. (2007), (3) Das et al. (2011), (4) Bickford et al. (2011 b), and (5) Das et al. (2017).