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

Surendra Prasad ¹

Affiliations
1 Geological Survey of India, Jaipur, IN

Abstract

The golden oolitic limestone (lower part of the Jumara Formation) was earlier considered to be the oldest rock unit in the Middle Jurassic stratigraphic succession of Keera dome, Kachchh district. Gujarat. The author has, however, recorded a 12 meter thick succession comprising shale with marl, siltstone, shale with ironstone, and ferruginous calcareoue sandstone underlying the golden oolitic limestone. These rock units contain ammonite fossils similar to those in the golden oolitic limestone, viz., Macrocephalites madagascariensis and M. formosus (Sowerby) ♀ morph formosus. The unit has been assigned Lower Callovian age on the basis of aforesaid fauna.

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G. N. Dwivedi ¹, S. K. Sharma ¹, Surendra Prasad ¹, R. P. Rai ¹

Affiliations
1 Geological Survey of India, Lucknow-226020, IN

Abstract

The Quaternary sediments of the Indogangetic plain in eastern part of Uttar Pradesh, can broadly be subdivided into two groups lithostratigraphically, viz. the Older Alluvium and the Newer Alluvium. The former is subdivided into basal Banda Older Alluvium (BOA) comprising of variegated clays and clastic sediments of Chitrakoot Formation encountered in the boreholes in the southern part and its equivalent Upper Siwalik in the northern part and an upper Varanasi Older Alluvium (VOA) and Palaeo Bhur deposits. The Newer Alluvium includes Bhat Alluvium, GhagharalRapti/GandakiChhoti GandaklChhoti Sarju Terrace Alluvium and their Recent Alluvia. The lithounits correspond to two broad geomorphic units, viz. an upland - the Bhangar surface and a low lying area demarcating the flood plains - the Khadar surface. The former consists of a piedmont zone of alluvial fans and an alluvial plain. while the later consists of terraced valley. The evolutionary history of Quaternary sedimentation commenced with a change in the configuration of Middle Siwalik basin converting it into much wider one by transgressing southward further over Bundelkhand gneissic complex and Vindhyan basement probably, during Upper PliocenelLower Pleistocene with sediment supply in the southern part from the Peninsular provenance constituting the Banda Older Alluvium and with sediments derived from Himalaya in northern part of the basin to constitute the Upper Siwalik. This was followed by a break in sedimentation caused due to upliftment during Middle Pleistocene resulting in a new basin formation superimposed over previous one, with sediment influx from the north, to the deposition of Varanasi Older Alluvium. The Upper Pleistocene glaciation brought an end to this sedimentation phase. The gradual warming up and retreat of glaciers accompanied with a large amount of sediment supply led to the formation of Bhat Alluvium in piedmont zone. A number of fluvial regimes, namely Ghaghara, Rapti, Gandak etc. carved out their new, narrow basins with warming up and increased precipitation during Holocene represented by their terraces. The ongoing phase of sedimentation is restricted to within the present active flood plain in response to reduced discharge and sediment supply.

Keywords

Quaternary, Indo-Gangetic Plain, Geomorphology, Uttar Pradesh.

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Surendra Prasad ¹, R. L. Jain ¹, M. S. Srivastava ¹

Affiliations
1 Geological Survey of India, Western Region, Jaipur, IN

Abstract

A single specimen of Middle Jurassic (Bathonian) Ammonite Genus Clydoniceras BLAKE has been collected from the sandy limestone of the base of Bada Bag Member of jaisalmer Formation of Charu area of jaisalmer District, Western Rajasthan. This specimen is described and figured in the present text to update the stratigraphy of rocks of pre-Kuldhar Member of the jaisalmer Formation.

Keywords

Mesozoic (Bathonian), Ammonite, Clydoniceras, Shell Anatomy, Jaisalmer Formation, Rajasthan.

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D. K. Bhatt ¹, Surendra Prasad ², R. L. Jain ², A. K. Mathur ²

Affiliations
1 57, Clay Square, Lucknow - 226 001, IN
2 Geological Survey of India, Palaeontology Division, Jaipur - 302 004, IN

Abstract

Based on the present detailed field observations on the physiographic setting and the lithological nature of the Pokran Boulder Bed (PBB), the authors conclude that it is a consolidated sedimentary bed, apparently in the nature of a glacial drift and not a tillite (like Talchir Formation of Gondwana Supergroup). The denuded upper surface of bouldery hummocks of the PBB on the ground invariably shows presence of loose boulders. The consolidated horizons lie buried within the hummocks, wherever thicker horizons of PBB are still preserved. The weathered top of the PBB, forming rolling, hummocky topography is reminiscent of continental glaciated areas. It is likely that the PBB represents remnant of the Well-Known global Precambrian (Vendian) Ice Age. It rests directly over the rhyolitic (Malani Rhyolite) basement.

The field observations also lead to the conclusion that the thick succession of sandstones of the Jodhpur Group (sometimes referred as 'Jodhpur sandstone') of Marwar Supergroup (MSG) only occasionally overlie the PBB and always with a marked unconformity, such as at Gaphur Khan ki Dhani and elsewhere. Clearly the PBB does not form part of the stratigraphy of Marwar Supergroup.

Keywords

Pokaran Boulder Bed, Genesis, Stratigraphical Status, Marwar Supergroup, Rajasthan.

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Surendra Prasad ¹, E. A. Khan ²

Affiliations
1 Geological Survey of India, Sector-E Aliganj, Lucknow - 226 024, IN
2 5/573, Vikas Nagar, Lucknow - 226 022, IN

Abstract

Gandak fan, is a large lobate feature trending in NW-SE direction, restricted between the fluvial regimes of Little Gandak in the west and Burhi Gandak in the east, in parts of eastern Uttar Pradesh and north Bihar. It is characterised by distinct geomorphology, manifested by clusters of tals, palaeochannels, oxbow lakes and spill over channels left out by a past history of river migration and flash floods of Gandak and its predecessors. The terrain is characterised by wide spread drapes of newer altuvium sediments locally known as Bhat Alluvium forming a calcareous, fine sandy to silty soil. Granulometric properties of the sand sequence associated with ths unit indicate dominance of very fine grained sand with median value of 3.0 phi. The clay mineral study of this soil unit indicates preponderance of calcite mineral (30%) besides illite, chlorite and muscovite.

Based on the analysis and synthesis of data, an attempt has been made to interpret the morphology of Gandak fan and the genesis of widespread occurrences of BhatAlluvium of this region. The model envisaged for the formation of the fan dwells on possible cataclasmic neotectonic events related to Gandak Tear and other structures in the vicinity. The neotectonic event triggered widespread river migration/avulsion and cascades of mud flows released from breach and spill over of some large lacustrine bodies formed earlier by damming of the river course in the Jhawani Valley in upstream of Gandak catchment area in Nepal. In addition, the geological and geomorphological set up of Gandak Fan has also relevance to environmental scenario of the area especially to the perpetual floods in large tracts of north Bihar.

It is also surmised that the cascades of mudflows related in the formation of fan and rampant floods in the area might be the causative factors for burial of many important temples and monasteries of Buddhist period, such as Kushinagar, Vaishali, Lauria, etc.

Keywords

Quaternary Geology, River metamorphosis, Basement Configuration,Bhat Alluvium, Gandak fan, Uttar Pradesh and Bihar.

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B. S. Paliwal ¹, D. K. Bhatt ², Surendra Prasad ², R. L. Jain ², A. K. Mathur ²

Affiliations
1 Office of the Dean, New Campus, Jai Narain Vyas University, Jodhpur - 342 00 1, IN
2 57, Clay Square, Lucknow - 226 001, IN

Abstract

No Abstract.

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R. L. Jain ¹, Surendra Prasad ¹, A. K. Mathur ¹

Affiliations
1 Geological Survey of India, Jhalanadungari, Jaipur -302 004, IN

Abstract

Recent geological mapping has shown that Khichan Conglomerate marks the hiatus between the Nagaur Formation of Marwar Supergroup (Eocambrian ?) and the Permo-Carboniferous Badhaura Formation in Rajasthan.

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Surendra Prasad ¹

Affiliations
1 Geological Survey of India, Jaipur, IN

Abstract

A more refined ammonite biostratigraphy than hitherto proposed for the Middle to Late Jurassic sediments of Keera and Jara domes, Kachchh district, Gujarat is presented in this paper. Ammonite based six biozones (Triangularis, Formosus, Anceps, Athleta, Maya and Helenae) and thirteen subzones (Madagascariensis, Diadematus, Semilaevis, Anceps, Eucyclum, Singulare, Kleidos, Athleta, Lalandeanum, Semirugosus, Maya, Helenae and Kranaus) are distinguished in ascending oder for Pre-Callovian-Oxfordian rocks of Kachchh. The Triangularis Biozone is assigned to Pre-Callovian/Late Bathonian, the Formosus to Early Callovian, the Anceps to Middle Callovian, the Athleta to Late Callovian, the Maya to Early Oxfordian and the Helenae to Middle Oxfordian.

Keywords

Palaeontology, Jurassic, Ammonite, Gujarat.

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D. K. Bhatt ¹, Surendra Prasad ¹, R. L. Jain ¹, D. S. Chauhan ²

Affiliations
1 Palaeontology Division, Geological Survey of India,W.R., 15- 16, Jhalana Instt. Area, Jaipur-302 004, IN
2 Jai Narain Vyas University, Jodhpur, IN

Abstract

No Abstract.

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