Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

G. Lakshminarayana ¹, S. Bhattacharjee ¹

Affiliations
1 Geological Survey of India, Project: Cuddapah Basin, Operations: Andhra Pradesh, Bandlaguda, Hyderabad 500 068, IN

Abstract

The Gandikota Formation consists of 40 - 45 m thick shale - siltstone - quartzite (lower member) and 140 - 190 m thick quartzite and siltstone (upper member). Vertical profile of the lower member represents a coarsening up sequence of prograding shoreline setting. As many as eight qualtzite sheets of 15 to 25 m thickness each, constitue the upper member. The herringbone, tabular and trough cross stratified quartzite, and ripple bedded quartzite and siltstone constitute major sedimentary lithofacies in the upper member quartzite sheets. Palaeocurrent mean was towards NW and NNE. A shallow marine environment with poorly contined tidal channels is envisioned for the deposition of the upper member quartzite sheets.

Keywords

Sedimentology, Gandikota Formation, Middle Prolelozoic, Cuddapah Basin, Andhra Pradesh.

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G. Lakshminarayana ¹, N. Kutumba Rao ¹

Affiliations
1 Geological Survey of India, Hyderabad 500 001, IN

Abstract

Ptilophyllum flora comprising Ptilophyllum cutchensis Cladophlebis denticulata, Cladophlebis Sp. Araucarites cutchensis, Araucorites Sp. (?) Elatocladus Sp. is reported from the buff siltstones and claystones of Dammapeta area, Chintalapudi sub-basin, Khammam District, Andhra Pradesh. The floral assemblage clearly indicates that the Dammapeta beds' belong to the Upper Gondwana, possibly Gangapur Formation and not Kamthi Formation (Lower Gondwana Group), as hitherto believed.

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G. Lakshminarayana ¹, M. N. Gururaja ¹, N. Kutumba Rao ¹

Affiliations
1 Geological Survey ofIndia, Chandra Vihar, Hyderabad 500001, IN

Abstract

Variegated clay-clast-bearing sandstones and purple claystones containing upper Gondwana plant fossils viz. Cladophlebis cf. denticulata, Ptilophyllum sp., Pterophyllum sp., Elatocladus conferta and Elatocladus cf. plana are recorded for the first time near Chintalapudi from the upper part of the 'Chintalapudi Sandstone' hitherto believed to be of lower Gondwana age. The present study has established that the newly identified upper Gondwana rock units belong to the Kota Formation overlying the 'Chintalapudi Sandstone' (= Karnthi Formation) with an unconformable contact.

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G. Lakshminarayana ¹, K. S. Murti ¹

Affiliations
1 Geological Survey of India, Chandra Vihar, Hyderabad 500 001, IN

Abstract

The Chintalapudi sub-basin, in the southeastern part of the Pranhita-Godavari Valley, was hitherto believed to contain mainly the Kamthi Formation of the Lower Gondwana Group. Recent geological mapping has brought to light the existence of the upper Gondwana sequence consisting of Kota and Gangapur Formations and also the occurrence of new areas of Talchir and Barakar Formations. Revised stratigraphic succession shows, in ascending order, Talchir, Barakar, Kamthi (Lower Gondwana). Kota and Gangapur Formations (Upper Gondwana). The Gondwana sediments are disposed in a NW-SE trending' graben affected by longitudinal and transverse faults. The Barakar Formation is identified over an area of 130sq km in Ayyanapalem-Sattupalli-Pakalagudem area, Khammam district, Andhra Pradesh. Stratigraphic drilling near Sattupalli has established the presence of coal seams with in a depth of 325 m in this newly identified Barakar Formation. The preliminary study of coal seams indicates that the coal is of Class III to Class IV type. The present study has established a new coal belt around Sattupalli in Chintalapudi Subbasins and this find is expected to augment the coal resources of the Godavari Valley considerably.

Keywords

Stratigraphy, Gondwana, Godavari Valley, Andhra Pradesh, Coal.

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G. Lakshminarayana ¹, K. S. Murti ¹, M. Rama Rao ¹

Affiliations
1 Geological Survey of India, Bandlaguda, Hyderabad 500660, IN

Abstract

The Raghavapuram Formation, as demarcated now, consists of shale and micaceous sandstone and contains Early Cretaceous (Neocomian-Aptian age) palynofossil assemblage-represented by Microcachryidites antarcticus, Contignisporites sp., Callialasporites sp, Lycopodiumsporites sp, Impardecispora sp, and Concavissimisporiles sp. The Tirupati Formation consists of conglomerate, ferruginous sandstone and sandstone. The hitherto considered 'Gollapalli sandstone' in Adamilli-Gopalapuram area of West Godavari district forms part of the continental Gondwana sequence (Kota Formation). Therefore, the present study has revealed that there is no stratigraphic unit called Gollapalli Formation in the Upper Gondwana of the Krishna-Godavari coastal tract and the revised stratigraphic succession consists of only two units, namely, the Raghavapuram and Tirupati Formations.

Keywords

Stratigraphy, Gondwana, Krishna-Godavari, Andhra Pradesh.

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G. Lakshminarayana ¹

Affiliations
1 Geological Survey of India, CHQ, Monitoring Division, 27, J.N. Road. Calcutta - 700 016, IN

Abstract

A 3000 m thick Gondwana lithic fill consisting of multifacies associations were preserved in a NW-SE oriented intracratonic Chintalapudi sub-basin set across the Eastern Ghat Complex (EGC). Sedimentation commenced with the deposition of diamictite-rhythmite sequence of the Talchir Formation in glacio-lacustrine environment. The succeeding sandstone-coal cyclothems of the Barakar Formation were formed in fluvial-coal swamp complex. The fluvial streams flowed across the EGC, originating somewhere in the southeast beyond the East Coast of India. Phase-wise upliftment of the EGC during Mesozoic imparted changes to the Permian intercontinental drainage system which started supplying increased aJll'lOunt of detritus to the basin. Basin marginal faults were first formed at the beginning of Triassic. Alluvial fans originated in the east and southeast and northwesterly flowing braided streams deposited the conglomerate-sandstone sequence of the Kamthi Formation. The Early Jurassic uplift of the Mailaram high in the north imparted westerly shift to the braided rivers during the Kola sedimentation . Due to prominence of Kamavarapukota ridge in the south by Early Cretaceous, the drainage pattern became centripetal and short-lived high sinuous rivers debouched into the basin. The silting up of the Chintalapudi sub-basin with tbe sandstoneclaystone sequence of the Gangapur Formation marks the culmination of the Gondwana sedimentation, perhaps, coinciding with the breakup of India from the Gondwanaland.

Keywords

Gondwana, Sedimentation, Chintalapudi Sub-Basin, Godavari Valley, Andhra Pradesh.

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G. Lakshminarayana ¹

Affiliations
1 Geologist (Sr), Geological Survey of India, Bandlaguda, S.R. Hyderabad-500068, IN

Abstract

The east coast Cretaceous Sedimentary basins namely the Krishna-Godavari Basin (K-G Basin) in north and the Palar Basin in south are located towards the tapering ends of the crescent shaped 'Cuddapah Basin'. Cretaceous stratigraphic succession in ascending order is Raghavapuram and Tirupati formations in the K-G Basin and Sriperambattur and Satyavedu formations in the Palar Basin. The Raghavapuram and Sriperambattur formations consist of mainly shale and siltstone deposited in prodelta/shallow marine environments. Sedimentological studies on sandstone and conglomerate revealed that in the Tirupati Formation coarse clastic detritus was derived from the Archaean crystallines and Proterozoic Cuddapah and Kurnool Groups of rocks by braided streams flowing towards east. Alluvial fans and the associated braided streams originated in the southern part of the 'Cuddapah Basin' were fed by mainly 'Nagri Quartzite' to deposit the bouldery conglomerate, conglomerate and sandstone sequence of the Satyavedu Formation. The Cretaceous sedimentary outcrops located east of 'Cuddapah Basin' i.e. Guntur, Ongole and Nellore areas show evidence for deposition in fluvial and fluviomarine settings. The Early Cretaceous tectonic disturbances coinciding with the break up of India from east Gondwanaland reactivated the eastern margin of the 'Cuddapah Basin' thereby enabling it to supply increased amount of detritus to the coastal sedimentary basins. However, the central part of the 'Cuddapah Basin' and the adjacent shield area located between Lat. 14° and 16° acted as a water divide to the Cretaceous drainage.

Keywords

Sedimentology, Cretaceous, Cuddapah Basin.

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G. Lakshminarayana ¹

Affiliations
1 Sandhyagiri Apartments, F.304, Kalyannagar, Gaddiannaram, Hyderabad - 500 060, IN

Abstract

Sedimentary facies in the Cumbum and the Bairenkonda type sections include banded slate, graded rhythmite. quartzite and dolomite (Cumburn Formation), quartzite-slate, massive quartzite, parallel stratified quartzite and medium to thick bedded quartzite (Bairenkonda Formation). The quartzite-slate facies marks the gradational contact between the Cumburn and the Bairenkonda Formations. Stratigraphic disposition of sedimentary facies between these two type sections is identical and correlatable. These sediments are deformed into NNE-SSW trending tight to open folds and NW-SE to E-W trending cross folds. It is now indicated that the Cumbum Formation is stratigraphically older than the Bairenkonda Formation and the resultant succession is at variance to the hitherto held stratigraphic framework. The argillite-dominated Cumbum sedimentary facies indicates deep-water depositional setting, whereas the arenite - dominated Bairenkonda facies represents shallow water environment, thereby pointing to the shallowing up of the basin during Nallamalai sedimentation.

Keywords

Sedimentary facies, Stratigraphy, Cumbum Formation, Bairenkonda Formation, Nallamalai fold belt, Cuddapah basin.

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K. V. S. Reddy ¹, G. Lakshminarayana ²

Affiliations
1 Geological Survey of India, Southern Region, Bandalaguda, Hyderabad - 500 068, IN
2 F-304, Kalyan Nagar, Gaddiannaram, P&T Colony (P.O.), Hyderabad - 500 060, IN

Abstract

No Abstract.

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G. Lakshminarayana ¹, C. Manikyamba ², Tarun C. Khanna ², Prachiti P. Kanakdande ², K. Rajub ³

Affiliations
1 Geological Survey of India, Bandlaguda, Hyderabad - 500 068, IN
2 National Geophysical Research Institute (Council of Scientific and Industrial Research), Uppal Road, Hyderabad - 500 606, IN
3 National Geophysical Research Institute (Council of Scientific and Industrial Research), Uppal Road, Hyderabad - 500 606, IN

Abstract

The Rajahmundry Traps of the Krishna Godavari Basin (K-G Basin) consist of three distinct basalt flows interbedded with two intertrappean sedimentary horizons, which in turn are underlain by the late Cretaceous fossiliferous limestone bed (infratrappean) and overlain by the Cenozoic Rajahmundry Formation (Conglomerate/Sandstone). Among the three, the lower flow is characterized by the presence of the physical volcanological features such as ischolar_mainless cones, tumuli and dyke like forms along with single to multitier columnar and radial jointing. The middle and upper flows are simple, massive and vesicular and exhibit spheroidal weathering. Physical volcanological features and lithological attributes indicate that the lower flow was formed by an explosive volcanic activity in hydrous environment, followed by sub aerial eruption to form the middle and upper flows. The fossiliferous limestone bed is a representative horizon for the K-T boundary mass extinction caused due to intense volcanism. Intertrappean sediments exhibit weathered soil profiles (palaeosols) with limestone beds denoting a distinct time gap during various phases of lava eruption. Evaluation of the palaeogeographic scenario of the Krishna and Godavari Rivers does not provide any evidence for the existence of Cretaceous palaeovalley which would have provided pathway for lava transportation from the Deccan volcanic province of western India to the K-G Basin situated along the east coast. The present study opens up an alternative approach to explain the origin of basalt flows at Rajahmundry. In all probability the lavas could be intrabasinal. NW-SE and NESW faults or their intersection zones are probable pathways for lava eruption in the K-G Basin.

Keywords

Rajahmundry Traps, Intertrappeans, Infratrappeans, K/T Boundary, Krishna-Godavari Basin.

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G. Lakshminarayana ¹, S. Bhattacharjee ¹, Ajit Kumar ¹

Affiliations
1 Geological Survey of India, Operations, Andhra Pradesh, Project: Cuddapah Basin, Bandlaguda, Hyderabad 500068, IN

Abstract

Palaeocurrents of the diamondiferous Banganapalle Formation show convergence towards Nandyal depression in the Kurnool Sub-basin. Localised depocentres, separated by E-W trending ridges, are identified near Kurnool, Paniam, Uppalapadu and Proddatur. These ridges pass through Gani, Banganapalle and Gandikota and have influenced sediment dispersal pattern in the Banganapalle Formation. Provenance for the Banganapalle Formation was mainly the intrabasinal tract occupied by lower Cuddapah sediments, igneous intrusives and the basement located to the west. Deposition commenced in an alluvial environment followed by intertidal setting.

Keywords

Sedimentology, Palaeocurrents, Banganapalle Formation, Diamond, Kurnool Sub-Basin, Cuddapah Basin, Andhra Pradesh.

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