Diversity Of The Genus Gangamopteris Mccoy In The Early Permian Sequences Of Singrauli Coalfield, Son-Mahanadi Basin, India

The form genus Gangamopteris, with reticulate venation and midrib less lamina, is an important constituent of the Glossopteris flora and widely distributed in Indian Lower Gondwana sediments. Stratigraphically, its occurrence is generally restricted to the lower Permian sequences namely Talchir, Karharbari and Lower Barakar formations. Barring the sporadic occurrences of this genus in the Upper Barakar Formation, it is altogether absent from the Barren Measures Formation, however, a few occurrences of Gangamopteris have again been recognised in the Upper Permian Raniganj Formation. A diverse Glossopterid assemblage has been recorded from the coal bearing sequence of Block-B colliery, Singrauli Coalfield, belonging to the Barakar Formation. The assemblage includes Gangamopteris, Glossopteris, seeds and equisetalean axes. The genus Gangamopteris comprising five species, viz. G. angustifolia, G. cyclopteroides, G. karharbariensis, G. major and Gangamopteris sp. has been systematically described and discussed in the present study. Gangamopteris cyclopteroides has the maximum occurrence followed by Gangamopteris sp., G. major, G. angustifolia and G. karharbariensis. The leaves of all the Gangamopteris species are quite large and broad that pretend the existence of low light or the shady conditions in and around the vegetated area. The diverse occurrence of Gangamopteris in recovered plant assemblage indicates an Early Permian (Artinskian) age to the studied coal bearing sequence of Block-B colliery. A complete account depicting all the stratigraphical occurrences of various Gangatnopteris species in Indian Gondwana has been provided.