Mahanadi河盆地的冈瓦纳型诸盆地位于印度的近中心地区，呈北西—东南走向分布。Mahanadi主要盆地内的几个重要煤田为Korda煤田，Mand—Raigarh煤田和Ib河煤田。Korda煤田的冈瓦纳系沉积向南东向延伸，经Mand—Raigarh煤田延续至Ib河煤田。Korda和Ib河两个煤田储量巨大，且长期来有小构造活动；而Mand—Raigarh煤田至今很少受到重视，勘探开发晚得多。文中首次对Mand-Raigarh煤田5个钻孔样品作了孢粉研究，以初现面、相对丰度等为特征，划分出7个孢粉组合带，时代从二叠纪最早期(Talchir组)至二叠纪末期(Raniga由组)。填补了东西两个煤田之间的生物地层研究空白。7个孢粉组合带为：i)Parasaccites-Plicatipollenites assemblage zone(相当于Talchir组），ii)Sulcatisporites-Brevitriletes assemblage zone(相当于下Barakar组），iii)Sulcatisporites-Rhizomaspora assemblage zone(少量Densipollenites存在说明其相当于上Barakar组），iv)Densipollenites-Striatopodocarpites assemblage zone(相当于Barren Measures组），v)Striatopodocarpites-Densipollenites assemblage zone(相当于下Raniganj组），vi)Striatopodocarpites-Densipollenites-Sulcatisporites assemblage zone(相当于上Raniganj组）vii)Sriatopodocarpites-Alisporites assemblage zone(相当于Raniganj最上部到Kamthi组最下部），Raniganj组沉积中见到小的皱缩裂隙、植物垂直根和根的印痕，似代表古土壤。

The Gondwana basins of the Mahanadi River basin, located almost at the heart of India, have a regional NW-SE trend. The principal coalfields falling in the Mahanadi master basin are Korba, Mand-Raigarh and Ib-river. The Gondwana sediments of the Korba Coalfield extend south-easterly through the Mand-Raigarh Coalfield and continue to the Ib-river Coalfield. Of these, the Korba and the Ib-river Coalfields have gathered importance because of large reserves of coal and have witnessed the pulse of mining activity since a long time. Compared to this, the Mand-Raigarh Coalfield was the last to attract attention and remained practically neglected - exploration and exploitation starting much later. On the platform of the above-mentioned background, the palynological history of the subsurface coal and associated sediments of Mand-Raigarh Coalfield is yet to be known as per available information. The present work, including samples from five boreholes, not only records miofloral population of the basin for the first time, but also provides with a definite palynostratigraphic frame to the subsurface Gondwana sediments. The palynostratigraphic columns thus erected may serve as reference columns for the recognition and correlation of the disturbed and sliced coal bearing formations in this sub-basin. Seven miofloral assemblage zones have been delineated for the drill core sediments based on parameters such as, first appearance, relative abundance / scarcity of the palynoforms, dating from the earliest Permian (Talchir Formation) up to the close of Permian (Raniganj Formation). i) Parasaccites - Plicatipollenites assemblage zone (corresponding to Talchir Formation), ii) Sulcatisporites - Brevitriletes assemblage zone (corresponding to lower Barakar Formation ), iii) Sulcatisporites - Rhizomaspora assemblage zone (corresponding to upper Barakar Formation due to presence of minor amount of Densipollenites), iv) Densipollenites - Striatopodocarpites assemblage zone (corresponding to Barren Measures Formation), v) Striatopodocarpites - Densipollenites assemblage zone (corresponding to lower Raniganj Formation), vi) Striatopodocarpites - Densipollenites - Sulcatisporites assemblage zone (corresponding to upper Raniganj Formation) and vii) Sriatopodocarpites - Alisporites assemblage zone (corresponding to uppermost Raniganj Formation to lowermost Kamthi Formation). On the basis of the qualitative miofloral composition, earlier workers have compared the coal bearing formations of the Korba and the Ib-river Coalfields. The present work is a necessary step for filling in the gap between these two coalfields on the west and east, respectively, in understanding the regional palynostratigraphy of the Gondwana sediments in the master basin. Surface morphological features, such as microshrinkage cracks, vertical root and root impressions have been observed in sediments of Raniganj Formation, which are suspected to represent a palaeoso).

Q913.84

The hospitality and assistance extended by Shri B.Chakraborti, Geologist, G.S.I., during the course of the field work are gratefully acknowledged，，