Browsing by Author "M.N. Mehrotra"

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Graphite, its occurrence and production
(1955) M.N. Mehrotra
[No abstract available]
Physico-chemical behaviour of the carbonate rocks of Western Son Valley Region, India
(Kluwer Academic Publishers, 1975) M.N. Mehrotra; R.A.K. Srivastava; P.K. Sinhamahapatra
The techniques of DTA and TG were employed to study the thermal characteristics of unfossiliferous carbonate litho-units, viz. Fawn dolomitic limestone (microdolsparite) and Rohtas limestone (micrite) belonging to the Vindhyan Supergroup (PreCambrian) of India. The DTA of Fawn dolomitic limestone displayed two successive endothermic peaks at 725° and 860° whereas only one endothermic change at 910° was recorded in the DTA curve of Rohtas limestone. It was confirmed by chemical analyses, TG, IR and X-ray diffraction studies that the two peaks in the first case are due to dissociation of CO2 from magnesium and calcium lattice positions, while the sole peak in the second case is due to complete decarbonation. A tentative correlation between the thermal characteristics and structural changes of these carbonate rocks at various transition temperatures is presented. © 1975 Wiley Heyden Ltd., Chichester and Akadémiai Kiadó, Budapest.
Study of pollution of the river ganga in the Mirzapur Region (India) and its impact on sediments
(1993) Ajai Srivastava; M.N. Mehrotra; R.N. Tiwari
The paper presents the various sources of pollution in the Mirzapur region, an industralized town in eastern Uttar Pradesh, which lies on the right bank of the river Ganga (Ganges). Municipal and industrial effluents affect the sediment and water of the river. An analysis of the bank sediments revealed the presence of toxic metals, some of them present in greater concentration than those recorded in average shale. The maximum concentrations of Cu, Pb, Ni and Zn in the region, 931, 226, 24 and 717 ppm, respectively, were recorded near the Oliar ghat (landing steps), whereas 138 ppm of Cr was found at the same ghat. Likewise, the maximum value of Co (20 ppm) occurs opposite to the Fathua ghat. These metals present no direct danger to the ecosystem as long as they are tightly bound to the sediments. However, due to a change in the physico-chemical conditions, viz. pH, salinity, redox condition, etc., of the aquatic milieu, these metals from the sediments may pass into the water phase and thus may cause a health hazard. © 1993, Taylor & Francis Group, LLC. All rights reserved.
The Son porcellanite formation: an example of volcaniclastic sedimentation in India.
(1985) M.N. Mehrotra; R. Banerjee; R.K. Dalela; P. Lal
This Lower Vindhyan (1100-1400 m.y.) formation represents the oldest volcaniclastic formation in India. It lies conformably over the Kayrahat limestone formation and is underlain by the Olive shale formation. The Son formation stretches E-W for approx 380 km and has a varying thickness of 90 to > 300 m. The rocks have been subjected to folding and occasional faulting, the folding axis running generally in the strike direction. On field appearance the formation can be classified into conglomeratic, banded and massive porcellanites. The two latter types occur on a regional scale while the conglomeratic type is of a local nature. Apart from the conglomeratic, the porcellanites are fine-grained, consisting of quartz, chert, feldspars, micas, pumice fragments, shards and iron oxides.-J.M.H.