Palaeobotany and Stratigraphy of the Coal• Bearing Beds of the Daltongan] Coalfield, Bihar
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PALAEOBOTANY AND STRATIGRAPHY OF THE COAL• BEARING BEDS OF THE DALTONGAN] COALFIELD, BIHAR P. Ie MAITI-IY Birbal Salmi Institute of Palaeobotany. Lucknow Abstract large amount of feldspar. The Barakar The present paper deals with the plant fossils and rocks are sandstones, slightly calcareous, the miospores recovered from the coal-bearing beds more or less yellowish-white in colour. of the Daltonganj Coalfield. On basis of these The river and nala exposes the coal• plant fossil evidences the stratigraphical positions bearing beds at several places. However, of these beds in the Lower Gondwana succession are discussed. from only four shale bands exposures the plant fossils and miospores are recorded. INTRODUCTION The four shale band exposures are located as follows: I. About 2 furlongs east of Amanat- ]injoi HITHERTO,coal-bearing thesedimentaryage of theformationsdifferent river junction, on the North bank of lying above the Talchirs in the Jinjoi river. A shale bed of grey Daltonganj Coalfield is a stratigraphical micaceous shale; 3 feet thick which is problem. Earlier Feistmantel (1886) and overlain by grit. Dip NE. in recent years Lele and Maithy (1966) des• II. From thick shale and sandstone inter• cribed the megafossils from the coal-bearing calations lying in between Rajhara beds of the Daltonganj Coalfield. The plant bottom and Pandwa top seams in the fossils recorded are Equisetalean stems, Rajhara Colliery. The depth of the Phyllotheca, Gangamopteris, Glossopteris, fossil material is about 90 feet from Noeggerathiopsis, Buriadia, Samaropsis and surface. The dip is NE. A major Cordaicarpus. On basis of these evidences fault is present above the Pandwa both Feistmantel (l.c.) and Lele and Maithy Top seam. (l.c.) opined that the coal-bearing beds in III. Beds exposed about 400 yds. north Rajhara Colliery, Daltonganj Coalfield, are of the junction of Sadabaha and Lobjee homotaxially equivalent to the Karharbari rivers on the East bank of Sadabaha Stage of the Giridih Coalfield. To ascertain river. This bed is lying actually above the stratigraphical position of the complete the top Rajhara seam. The sequence succession of the coal-bearing sedimentary of beds is as follows: formation in the Daltonganj Coalfield, the 3. 10' sandstone, fine-grained, bluish• study of the megafossils and miospores has white in colour. been undertaken. The results obtained are 2. 2' coaly shale, dark black in colour, described in the following pages. more or less brittle. The coalfield is about 50 miles west of 1. 20' alternating bands of Carbona• Hazaribagh town and is traversed by North ceous shales and sandstones. Koel river, a tributary of Son. The field is Fossils from both beds NO.1 and NO.2 long irregularly shaped tract, with very have been recorded. tortuous boundaries. It is about 50 miles in IV. Beds exposed on the East bank of the length from East to West and varies in Lobjee river near Rajhara Colliery. breadth from 1 to 8 miles; its total area The bed has ferruginious sandy mica• being 200 square miles. Inside the basin ceous shales. whose boundaries appear natural ones, several inextensive inlier of gneisses occur. DESCRIPTION The only formations represented are the A. MEGAFOSSILS Talchirs, the Karharbaris and the Barakars. In the Talchirs, the usual rocks are sand• Phyllotheca Brongn. stones being more prevalent than shales, Phyllotheca sahnii Saks. emend. Townrow whilst the boulder beds are well developed. The rocks of the Karharbari age are bluish• The collection contain impressions of stems grey sandstones, gritty in nature, contain with and without leaves. Stems ribbed and 265 266 THE PALAEOBOTANIST articulated, 3-4 mm. wide. Jodal and inter• zone they are coherent forming a small cup. nodal zones are distinct. The length of the The major length of the leaves is free. internodal zones varies from 1 to 3 cm. Ribs They spread out at nearly right angle to and furrows are continuous both at the stem. A disc shaped impression shows nodal and internodal zones. Leaf sheaths (PL. 1, FIG. 2) that the leaf segments are closely adpressed to stems, narrow, amplexi• fused at the base forming a very small cup. caul at the base, spreading somewhat above The number of free segments counted are into open saucer-like shape and has 18-22 free 24 in number. Each free segment is linear leaf segments, radiating out more or less at in shape, broader towards base and narrow right angles. Some of the leaf sheaths and at apex. The end is bluntly pointed. Each leaf segments are preserved dorsi ventrally. segment has one prominent median vein They show that the leaf segments are which is persistent along full length of the coherent at the base and somewhat spreading leaf. out in form of saucer. Free leaf segments Adventitious roots emerge from the nodal are linear, 1·5-2·5 cm. long, acute apex. zone of the stem (PL. 1, FIG. 3). The roots Each one of them has one median vein. are 4-5 em. long and 1-2 mm. broad. The The specimens compare well with P. sahnii adventitious roots branch frequently by Saksena (1952) recorded from Ganjra Nalla dichotomy, ultimately they become thin and Beds and Maithy (1965c) recorded from the very short. Some of the roots show a Karharbari beds, Giridih Coalfield. median line in the centre. Probably this represent a vascular bundle. Phyllotheca crassa sp. novo Comparison - Although, a dozen species PI. 1, Figs. 1-3 of Phyllotheca are known from the Southern Hemisphere, but the present species compare Diagnosis - Stem articulated, fairly long; only with P. brookvalensis Townrow (1955) nodal and internodal zones distinct. Inter• to a certain extent. The present form is, nodal zone 1-4·5 cm. long, width 0·5-2·5 cm. however, distinct from P. brookvalensis Surface of stem with alternate ridges and in having leaves broader towards base and grooves, 5-12 in number in the widest part; narrower towards apex. In P. brookvalensis ridges and grooves continuous. Leaves the leaves are uniformly broad. P. ampla emerge from nodal zones, coherent basaly Surange and Kulkarni (1968) differs .in to form a small cup; each leaf is linear, having leaf sheath closely adpressed to stem 3-6 em. long, 2-3 mm. broad, apex blunt. and saucer-shaped cup. The leaves are spreading out from the stem. Each leaf has one median vein, distinct and Sphenopteris Brongn. continuous up to apex. Adventitious roots emerge from the nodal zone of the stems, Sphenopteris polymorpha Feistm. 4-5 em. long and 1-2 mm. broad. Roots branch frequently by dichotomy until they The shales collected from Lobjee and become thin and hair-like. Sadabaha junction exposure contain impres• Syntypes - 33817/833, 33818/833, 33819/ sion of the large number of fronds. The 833 Birbal Sahni Institute of Palaeobotany, fronds are tripinnate. The primary rachis is Lucknow. - incomplete, still it is very long measuring Locality - Lobjee river exposure, near 17 cm. long and 0·4 em broad. It has seve• Rajhara Colliery, Daltonganj Coalfield. ral fine striations. The secondary rachises Description - The zone in which fossils emerge alternately from the main rachis on occur is characterized by overwhelming both the sides. The distance in between the abundance of the impression of stems. emergence of secondary rachises is 1-2·5 em. The stems are fairly long. Jo definite The secondary rachises are fairly long, branching is marked. Stems jointed and 4·8 cm. Each secondary rachis bears pinna ribbed with distinct zones of nodes and rachises alternately at a distance of 0·5• internodes. Internodes are 1 to 4·5 em. 0·8 em. Pinnae 0·5 cm. to 3 em. long. long. Internodal zone 0·2-0·4 em. long. Pinnae lanceolate, pointed (acute) towards Stem width varies from 0·5 to 2·5 cm. Ribs apex. Pinnules deeply lobed, separated from and furrows are continuous at the node and one another and arranged alternately. The internode zones. Leaves emerge from the pinnules are sessile and attached to the nodal region (Pc 1, FIG. 1). At the basal rachis along the full basal width of the MAITHY - PALAEOBOTANY AND STRATIGRAPHY OF COAL-BEARING BEDS 267 pinnule (PL. 1, FIG. 4). Pinnules triangular Glossopteris brownii Brongn. in out~ine, small 2·5 mm. with ± acute apex. Median nerve distinct. Secondary veins Ten incomplete specimens are in the emerge at acute angle, dichotomous and collection. They compare in their venation flexuosus. with G. brownii described by Feistmantel (1881, PL. 29A, FIG. 3). Gangamopteris McCoy Noeggerathiopsis Felstm. emend. Gangamopteris cyclopteroides Feistm. Malthy The collection contains several impressions Noeggerathiopsis hislopi (Bunb.) Feistm. of this type of leaves. Leaves compare well emend. Maithy with the specimens of Feistmantel (1879, PL. 10, FIG. 1) and Maithy (1965d, PL. 1, The collection has a good number of FIG. 1). Some of the incomplete forms are leaf impressions with carbonized crust. very wide, measuring about 10 cm. from the On maceration the crusts do not yield any median region on one side. In these leaves cuticle. The specimens recorded compare the meshes of the median veins are very in its shape and venation with Noeggera• pronounced and big. The meshes are 3-4 thiopsis hislopi described by Maithy (1965b, mm. wide. PL. 1, FIGS.1,2) from the Karharbari Stage, Giridih Coalfield. Gangamopteris mucronata Maithy Buriadia jragilis sp. novo The collection contains about twenty PI. 1, Figs. 5-7 incomplete leaf impressions. Only the middle and the apical portions are preserved. Diagnosis - Shoots irregularly branched, The specimens recorded compare well with thicker shoots leafless or with loosely those of Maithy (1965d, PL. 3, FIGS. 17-19) arranged scattered leaves; penultimate or recorded from the Karharbari Stage, Giridih ultimate branches bear fragile, flat, hetero• Coalfield, both in its shape and venation.