R-mode factor analysis of lithologic variables from cyclically deposited Late Paleozoic Barakar sediments in Singrauli Gondwana sub-basin, Peninsular India

The quantitative relationships between lithological variables from the Late Paleozoic coal bearing cycles have been investigated using factor analysis in an attempt to analyze net subsidence during the deposition of these cycles. The results suggest that there are only two non-zero eigenvalues in varimax matrix which indicate that the hyper ellipsoid enclosing the data points have seven axes of zero length and exists an ordinary two dimensional ellipsoid. The data points can be located with reference to two mutually perpendicular axes. Loading on thickness of sandstones, thickness of shale, number of sandstone beds and number of shale beds are extremely high on RF-I and low on the other factor. This would lead to the interpretation that a balance was maintained throughout the Barakar sedimentation between the rate of deposition and the rate of subsidence. On the other hand, loading on number of coal beds is high on ‘ suggesting that the development of peat swamps (coal beds) is not a normal feature during the Late Paleozoic Barakar sedimentation in this Gondwana sub-basin.

Research highlights
► High loading on sandstone indicate that growing channels bar deposits migrate sideward through the slowly subsiding flood plains.
► An increase in total thickness of strata is due to an increase in the thicknesses and number of constituent clastic lithologies.
► Poor correlation between the total thickness of strata i.e. net subsidence with the total thickness of coal seams imply that the conditions governing the formation of coal swamps and net subsidence are inconsistent.
► Development of peat swamps sub environment apparently not a normal feature during the Late Paleozoic Barakar coal measures in the Singrauli Gondwana sub-basin.