CHAPTER 3 GEOLOGY OF INDRAVATI BASIN

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1 CHAPTER 3 GEOLOGY OF INDRAVATI BASIN

2 CHAPTER3 GEOLOGY OF INDRAVATI BASIN 3.1 GEOLOGY OF THE INDRAVATI BASIN - HISTORICAL ACCOUNT Neoproterozoic intracratonic lndravati basin covers an area of about 9000 sq.km (Figure 3.1 ). It occupies parts of Jagdalpur district of Chhattisgarh and Koraput district of Orissa and rests non-conformably on the Archaean granitic basement of Central Indian craton. It is flanked by Chhattisgarh basin in the North, Eastern Ghat khondalite charnokite complex in the South and West and Pranhita Godawari basin in the Southwest. INORAVATI BASIN Km & estromatolitic Dolomib! Membor Figure Ramakrishnan, 1987) Locality map of the stromatolites occurrence in lndravati Basin (after 16

3 Ball ( 1877) was the first to describe the general configuration and main lithologies of the lndravati basin. He made a reconnaissance survey of Jagdalpur from the Jeypore side. He stated that the quartzites, shales and limestone of the basin were similar as the Chhattisgarh plain which are said to be of Lower Vindhyan. King ( 1881) however reversed Ball's opinion. He noted that sedimentary rocks found near Jagdalpur area are similar to the Kurnool or Cuddapah Formations of the Wardha- Pranhita valley. Walker (1900) suggested tentatively that the high hills of the area belonged to the Cuddapah System and concluded th.at the charnokites were intruded in the older gneisses. Crookshank (1963) proposed an informal stratigraphic division (Table 3.1 ). He divided basin into Lower beds which are mainly arenaceous and Upper beds which are mainly argillaceous with calcareous intercalations. Following lithological succession was proposed: Table 3.1: Classification of lndravati Basin by Crookshank (1963) Upper Beds Limestones, purple shales and slates Lower Beds (c) pale shales, soft sandstones (b) purple shales (a)quartzites, grits, breccia and conglomerate 17

4 Dutt ( 1963) was the first to give a comprehensive account of the basin with segmental map. He proposed the new name "lndravati Series" for the sequence after the name of the river draining the largest area of the formation. He divided lndravati Series into three stages, viz., the Tiratgarh, the Kanger and the Jagdalpur. He also discussed their regional correlation and palaeogeography. The lithological succession proposed by him is given below as Table 3.2 Table 3.2 Classification of lndravati Basin by Dutt (1963) lndravati Series Jagdalpur Stage ( m) Kanger Stage (140m) Purple shale with quartzite intercalations Purple shale with purple limestone Grey and purple limestone and dolomite Purple shale with quartzite and limestone intercalations Grey laminated limestone Tiratgarh Stage (110m) Purple shale with platy quartzite Intercalations Subarkose and orthoquartzite Basal conglomerate Schnitzer (1969) identified four carbonate- 'red bed' (red shale) cyclic sequences in the Kanger and Jagdalpur Stages and separated them from the Tiratgarh Stage by a disconformity. Krupanidhi (1970) divided the Purana Group into the Tiratgarh Formation and the Jagdalpur Formation. The Tiratgarh Formation consists of sandstone (locally conglomeratic) and shale and Jagdalpur Formation comprising white limestone, buff shale, grey limestone intercalated with grey IR

5 shale, dark grey limestone, purple shale with limestone and sandstone intercalations and purple stromatolitic limestone. Sharma (1975) subdivided the Lower Tiratgarh and Upper Jagdalpur Formations into two members and designated them by the same name as the formation such as Tiratgarh orthoquartzite, Tiratgarh shale and Jagdalpur shale. The lithological succession proposed by him is given as Table 3.3. Table 3.3 Classification of lndravati Basin by Sharma (1975) I Upper Member Jagdalpur shale (purple buff N ( m) green) with purple grey D limestone and algal R dolomites. A Jagdalpur Lower Member Kanger Limestone and buff v Formation (120m) shale grading vertically and A laterally to Upper Member. T I Upper Member Tiratgarh shale (purple) with (50 m) arenaceous intercalations. G R 0 Tiratgarh Lower Member Tiratgarh orthoquartzite and u Formation (100m) subarkose with argillaceous p partings. Krupanidhi (1970) and Sharma (1975) clubbed the Kanger Limestone with the Jagdalpur Formation in view of the gradational transition from limestone to shale vertically and laterally. Their classification is broadly similar to the two fold division of Crookshank (1963). Ramakrishnan (1978) redesignated the "lndravati Series" of Dull (1963) as "lndravati Group" and Lower Tiratgarh Stage to 'Tiratgarh Subgroup". He divided Tiratgarh Subgroup into four formations namely the 19

6 Chitrakot Sandstone, the Kapari Shale, the Cherakur Sandstone and the Lohandiguda Formation in the ascending order of succession. Dutta et at. (1983) gave a brief geological outline of the lndravati basin mainly based on aerial photo studies. As mentioned in the above section different workers contributed towards the classification of lndravati basin. The recent classification of lndravati basin was proposed by Ramakrishnan (1987). He classified basin into four formations. The Tiratgarh Formation, the Cherakur Formation, the Kanger Formation and the Jagdalpur Formation. A brief summary is given in Table 3.4 and its Litholostratigraphy is described in Figure 3.2 Table 3.4 Stratigraphic succession of lndravati Group (Chhattisgarh) (after Ramakrishnan, 1987) Geological Units Jagdalpur Formation Lithology Purple shale with purple grey stromatolitic dolomite (Machkot Member) Thickness m Kanger Limestone Formation Purple limestone Grey limestone 150m Cherakur Formation Purple shale with arkose sandstone and chert pebble conglomerate m Tiratgarh Chitrakot Formation Member Mendri Member Quartz Arenite Subarkose and conglomerate m U nco nfo rm ity Archaean Granite and supracrustals. ~---~- ~

7 --~ , JAGDALPUR FORMATION ( M) 400 WITH MACHI<OT OOL.OMITE MEMBER LITHOSTRATIGRAPHY OF INDRAVATI BASIN soor----_ ~." v- " Laminated shale ~!'! with Stromatolitic I.J3 ~ * Bioherms * - -- * <I Ill,.., J ]).. - -c(i]) w Purple limestone &shate KANGER LIMESTONE ( M) Grey limestone I-L-,-...l r-.L--,--L-,-.L~ --t;mestone with pyrite crystals 100~~~--~--~--~~~~ CHERAKUR FORMATION (50-60M) ~o~??~~~~~~~~~ TIRATGARGH FORMATION (50-60Ml ARCHAEAN , ~ + ~..... Sandstone Granite & Supra crustals *Stromatolite sample Sample (R) Reference sample Figure 3.2- Lithostratigraphy of lndravati basin (modified after Ramakrishnan, 1987} 21

8 The under mentioned lithostratigraphic description is based on fields observations and salient features are adopted from mainly Ramakrishnan, Tiratgarh Formation Earlier workers (Dutt, 1957, 1963; Sharma, 1975; Ramakrishnan eta/., 1978) classified the Tiratgrah Formation into two units namely the lower arenaceous unit which consists of subarkose, conglomerate, orthoquartzite and the upper argillaceous cum-arenaceous unit which consists of shale with sandstone/siltstone. The Tiratgarh Formation lies above an unconformity and consists of three distinct rock types viz., basal arkose, oligomict conglomerate and orthoquartzite in ascending order. Tiratgarh Formation is divided into two members - the Mendri Member and the Chitrakot Sandstone Member. The Mendri Member consists of arkose and conglomerate and Chitrakot Sandstone Member consists of orthoquartzite. Mendri Member :- The Mendri Member consists of basal arkose and oligomict conglomerate. Basal arkose is a dark grey, greenish grey, purple or pink, medium grained and indurated rock having variable composition. It occur either as a thin bed on the eroded surface of Archaean granite or as sedimentary dykes within granite or as thin beds within basal conglomerate. The overlying oligomict conglomerate has a clast-supported framework with subrounded quartz pebbles set in an arenaceous base which is locally chloritic or ferruginous. 22

9 Chitrakot Sandstone Member : - The Chitrakot Sandstone Member consists of medium grained sandstone with subangular to subrounded quartz cemented by silica growing over detrital quartz grain with former grain boundaries marked by a ferruginous film. Cross bedding and ripple mark are found in these sandstone. Planar cross-bedding and cross lamination are fairly common. Cherakur Formation The Cherkur Formation conformably overly the Tiratgarh Formation. It mainly consists of arenaceous rocks viz., shales with chert pebble conglomerate, grit, arkosic sandstone and siltstone. The Cherakur Formation is characterized by conspicuous mica (muscovite) content. Mica flacks lie parallel to bedding planes (mostly horizontal) and because of these high mica content bedding planes have become very prominent in this shale. This property of shale is utilized by local villagers for extracting slabs and tiles of shales (which is used for roofing and boundary wall making by villagers). Kanger Limestone Formation The Kanger Limestone Formation lies above the Cherakur Formation. It mainly consists of limestone (Plate 1}. The upper part of this formation gradually becomes argillaceous in nature. The Kanger Limestone is hard and compact and breaks with conchoidal fracture and varies in colour from greyish grey to dark grey. Due to the major fault of Sirisguda, the limestone is greatly affected particularly in thickness and disposition. The major fault passes through the area and as a result of this small sympathetic parallel faults have. also developed which affect the disposition of lithounits and create variance in 23

$Such caves are tourists \ attraction points sites of special interest are stalactite and stalagmite occurrences in Kotomsar and Kailash localities.$

10 PLATE I Figure 1-2 Characteristics of the Kanger Lime stone Formation, Jagdalpur, Chhattisgarh. Figure 1-Kanger Limestone have number of dissolution caves. Such caves are tourists \ attraction points sites of special interest are stalactite and stalagmite occurrences in Kotomsar and Kailash localities. Stalactites hanging from the walls of Kotomsar caves are seen in the picture. In these caves are also found blind fishes in the running water. Figure 2- Fine grained parallel bedding Kanger Limestone exposed as small hillocks. One such exposure noted at Baranji locality. Vertical joints have dismembered the Kanger Limestone in block. These joints are filled with soil. At many places in Kanger Limestone, pyrite crystals are found. 24

11 PLATE II Figure 1. Plate showing burrow structure at Kanger Limestone Formation. 25

12 characters and qualities. Beautiful speleothemes have been developed in Kanger limestones. Petrographic thin section of the Kanger Limestone Formation reveal the presence of burrowing structure (Plate II). Jagdalpur Formation Jagdalpur Formation is the upper most formation lying above the Kanger Limestone Formation. It mainly consists of shale, limestone and dolomite. Stromatolites are restricted to Upper part of the Jagdalpur Formation. The shale is highly susceptible to weathering. It is ferruginous at places but calcareous shale is also common. It is found with and within the Jagdalpur limestone as capping and intercalations. Jagdalpur Limestone is very well exposed near village Bastar, Junaguda, Kerlakonta, Bhursundi, Mundapal, Mongrapal, Ghatlohanga, Mahuguda, Deurgaon, Bhatpal, Manjipara, Pidsiguda, Machkot, Gupteshwar etc (Figure 3.3). Jagdalpur Limestone is hard and compact and stromatolitic in nature as well as in composition. It varies from pinkish to buff in colour. 3.2 AGE OF THE INDRA VATI BASIN Ball (1877), Bose (1900) and Dutt (1963) correlated lndravati Group with Lower Vindhyan or the Kurnool probably on the basis of least structural disturbance and freedom from the basic dykes. King (1881), Walker (1900) and Crookshank (1963) equated them with the Cuddapah. No accurate data about the age of lndravati basin is presently available. But the glauconite from Chopardih Formation of Chhattisgarh basin is correlated with the Chitrakot Sandstone Member of lndravati Group, that has yielded a K-Ar age of

13 750 ma (Kreuzer et a!. 1977). This is correlated by the presence of various stromatolitic groups in the Machkot Dolomite area; this assemblage corresponds to Late Riphean age ( ma) as suggested by Walter (1976). 27

14 Figure 3.3 Geological map showing stromatolite localities. N t [!] Study Area I~!River ~ Stromatolitic Dolomite 0 Jagdalpur Formation ~ Kanger Formatioo - Cberakur Fonnation [3 Tirathgarh Formation G Archaean Basement 0 50KM Scale ~ 28

Practice Test Rocks and Minerals. Name. Page 1

Name Practice Test Rocks and Minerals 1. Which rock would be the best source of the mineral garnet? A) basalt B) limestone C) schist D) slate 2. Which mineral is mined for its iron content? A) hematite