Sedimentary organic matter as a proficient tool for the palaeoenvironmental and palaeodepositional settings on Gondwana coal deposits

Palynofacies is based on the different types of the dispersed/sedimentary organic matter (DOM/SOM) and has been used as a proficient proxy for the palaeoclimatic reconstructions in sedimentary deposits of various time spans. It has also been acknowledged as an effective tool in the different domains like sequence biostratigraphy, palyno-biostratigraphy, palaeodepositional history, identification for depositional processes, oxic–anoxic environment, and variations in the water depth. It has been emerged as an analytical tool in palaeoclimatic reconstruction, which could complement geophysical and geochemical datasets. Since long palynofacies analysis has been exclusively applied in the marine sediments, it has recently dragged the attention of many researchers as a significant parameter for palaeoclimatic interpretation in continental deposits. In the last few decades, more consideration was focused on palynofacies that have become an essential proxy in the biostratigraphic and other non-biostratigraphic fields due to its requirement in the petroleum industries. The present study provides a basic idea of dispersed organic matter characterization, methodology, interpretations, and its application with special emphasis on the Gondwana deposits. The study also includes the summary of the worldwide distribution of the Gondwana sediments, especially for palaeodepositional settings through palynofacies along with other parameters.

DELINEATION OF GEOMETRY AND SPATIAL DISTRIBUTION OF BASIC BODIES USING MAGNETIC AND RESISTIVITY METHODS IN SOHAGPUR COAL FIELD AREA, MADHYA PRADESH

The state of Madhya Pradesh in Central India is known to bear ‘A’ grade coal seams within Gondwana basin. An alluvium-covered area to the north-east of Shahdol was considered to be prospective for the exploration of coal. A number of basic intrusive are encountered in the area and these appear to have played an important role for enhancement of the rank of coal seams. Delineation of the geometry and spatial distribution of these basic bodies has therefore become necessary for exploration of high rank coal seams. Magnetic and resistivity surveys were mainly carried out. Geologically, the alluvium covered area was known to be composed of rocks of different ages such as Precambrian, Gondwana Triassic, Cretaceous (trap) and older alluvium in succession. Gondwana basins are formed over basement depressions or in the downthrown side of the faulted Precambrian. Gondwana sediments lying over such basement sub-basins are prospective areas for the exploration of coal. The magnetic map was vitiated through the presence of high amplitude and small wavelength anomalies due to a thick blanket of basic bodies lying above the Gondwana sediments. Fluctuations in magnetic responses are observed at a few locations which may be due to the presence of basement faults? Low intensity but distinct anomaly patterns are observed in the south-western part of the area possibly indicating subsurface basic intrusive. 2D modeling of the magnetic data has effectively brought out the basement depth varying between 680 m to 1460 m an increasing trend from west to east. Selected resistivity soundings confirm that the overlying high resistivity layer (107-390 Ohm-m) and of thickness (0.7-386.3 m) may possibly indicate the geometry of basic bodies from the surface to depth of 547.5 m. The basement could not be picked up.