Sequence Stratigraphy a Tool for Inter-Basinal Correlation: A Case Study of Paleogene Sediments of Jaisalmer and Barmer Basins
Dhirendra K. Pandey1 and Balram Bhadu2
1Geology, University of Rajasthan, Jaipur, India
2Forward Base, ONGC, Karaikal, India
Paleogene sediments of the Rajasthan Shelf show a variety of depositional history. It ranges from fluvial, lacustrine, deltaic, marginal marine to marine. The obvious reason for assortment is interplay of geo-tectonic setup and location of sedimentary basins with respect to paleo-shoreline, climate, geomorphology, provenance, etc. Of the three sedimentary basins, Bikaner-Nagaur Basin, Jaisalmer Basin and Barmer-Sanchor Basin, recognized on the Rajasthan shelf, the region encompassing northwestern part of the Jaisalmer Basin and eastern part of Bikaner-Nagaur Basin was submerged during Paleogene with marine water, whereas rest of the shelf area of Rajasthan including the Barmer-Sanchor Basin was witnessing non-marine environment.
The lithostratigraphic framework of the Paleocene sediments in all the three basins mentioned above has been quite well conceived, however, due to lack of index/guide fossils from these sediments a comprehensive chronostratigraphic framework has not been possible to develop and this is one of the reasons that we have still not been able to explore the natural reserve to its full extent.
Sequence Stratigraphy is one tool by which genetically linked sedimentary units can be correlated irrespective of its depositional setting and even in the absence of index/guide fossils. Although correlating non-marine with marine sediments is an herculean task, the recent insight of the subject, like relationship of global sea-level and groundwater table in the coastal area, influence of sea-level change on stratigraphic base level, change in rate of inlux of sediments with change in the tectonic settings of the hinterland, etc., has simplified the approach.
With this background present aim to use sequence stratigraphy as a tool for inter-basinal correlation of Paleogene sediments of the Jaisalmer and Barmer basins, which at moment have been proved as best source of hydrocarbons and lignites in Rajasthan.
Lithostratigraphically, Paleogene of the Jaisalmer Basin consists of three formations (Sanu, Khuiala and Bandah formations),whereas in the Barmer Basin these are Fatehgarh, Mataji Ka Dungar, Akli and Kapurdi formations in ascending order.For sequence stratigraphy in all six sections have been measured in both the basins and different parasequences, system tracts and sequence boundaries have been identified. This together with fossil records has been used to correlate contemporary events traced in both the basins.
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