Mineralogical Characteristics and Mineral Economics of Sanu and Gotan SMS Grade Limestone Deposits of Rajasthan

Transcription

1 JOURNAL GEOLOGICAL SOCIETY O INDIA Vol.75, May 2010, pp Mineralogical Characteristics and Mineral Economics of Sanu and Gotan SMS Grade Limestone Deposits of Rajasthan M. S. SHEKHAWAT 1 and G. PRABHULINGAIAH 2 1 Department of Geology, M. L. Sukhadia University, Udaipur , India 2 Wharton Overseas.Z.E., Azman, UAE shekhawatgeol@yahoo.com Abstract: Two large, chemically similar, SMS grade limestone deposits occur in Sanu area of Jaisalmer and Gotan area of Nagaur, Rajasthan. The Sanu deposit belongs to Khuiala ormation of Tertiary sequence of lower Eocene age, while Gotan deposit belongs to Bilara Group of Marwar Supergroup of late Neoproterozoic to early Cambrian. These deposits are being developed and utilised as flux in the steel plants of India. The Sanu limestone of Jaisalmer is more suitable compared to Gotan and other limestone deposits of the country due to its superior and favourable physical properties. Mineralogically, it consists of fine-grained, sub-rounded to rounded grains of calcite mainly replacing tests of the larger foraminifera. While, the Gotan limestone is composed of fine to coarse-grained, angular to sub-rounded grains of calcite. In Sanu area, about 54% of the limestone produced is being generated as -30 mm grit during the process of sizing for SMS grade. This lower size of limestone is suitable for making cement but due to non-avaibility of rail transport facility from Sanu to Jaisalmer for a distance of about 60 km, it remains unutilised as mineral reject. Keywords: SMS grade limestone, Mineralogy, Mineral economics, Jaisalmer, Rajasthan. INTRODUCTION A number of large limestone deposits of different grades occur in association with rocks of Precambrian to Quaternary age in Rajasthan. These deposits are being developed and utilised mainly for making cement, lime and as decorative and dimensional stones over the past several decades. The Sanu limestone of Jaisalmer and Gotan limestone of Nagaur which are located in western and central Rajasthan respectively (igs.1a and b) have achieved immense economic importance due to their Steel Melting Shop (SMS) properties. The Sanu limestone represents the largest high grade SMS limestone of the country. It belongs to Khuiala ormation of the Tertiary sequence (ig. 1a), (Pareek, 1984; GSI, 1999; Singh, 2008), while Gotan limestone belongs to Bilara Group of the Marwar Supergroup (ig. 1b), (Pareek, 1984; Dasgupta et al. 1988; Sinha-Roy et al. 1998; GSI, 1999). The initial preliminary studies on Sanu limestone were carried out by Pareek (1977, 1981) and Laul (1980). But, the suitability and significance of Sanu limestone as the superior SMS grade limestone resource of the country was first identified by M/s Steel Authority of India Limited (SAIL) in 1987 following closure of mining activities of Dehradun limestone, which was till then the main source of this grade of limestone in the country. Subsequently, the Jaisalmer deposits were developed and mined by the Rajasthan State Mines and Minerals Limited (RSMML) and Rajasthan State Minerals Development Corporation (RSMDC) and was subsequently merged with the former company. The SMS grade Gotan limestone is also being developed and quarried at small-scale mainly by RSMML and few private companies. The physical and chemical properties of limestone of Sanu and Gotan deposits have been studied in detail by Prabhulingaiah et al. (2006), Sen et al. (2006), Prabhulingaiah et al. (2007a, b) to understand their suitability for SMS use. In the present study, an attempt has been made to understand mineralogical characteristics of both Sanu and Gotan limestones for their comparison and suitability for SMS use. GEOLOGICAL SETTING AND IELD CHARCTERISTICS The Tertiary rocks of Jaisalmer Basin of western Rajasthan are represented by Sanu, Khuiala and Bandah ormations of Paleocene to middle Eocene (ig. 1a), these rocks overlie the Habur ormation of Mesozoic sequence and are underlain by Shumar ormation of Quaternary / /$ 1.00 GEOL. SOC. INDIA

2 740 M. S. SHEKHAWAT AND G. PRABULINGAIAH Jaisalmer Nagaur N 28 I N D I A 28 T A R A J A S T H A N S P A K I 72 N Khuiala 27 Sanu 27 INDEX Jaisalmer Quaternary Wind blown sand Shumar ormation Tertiary Bandah ormation Khuiala ormation Sanu ormation Mesozoic (Cretaceous) a Badesar ormation 40 km Mesozoic (Jurassic) 70 Abur ormation Parihar ormation Baisakhi ormation Jaisalmer ormation 74 N Nagaur km Gotan INDEX Wind blown sand Tertiary Palana ormation Marwar Supergroup Jodhpur Luni River Quaternary Intrusive b 74 Malani Igneous Suite Erinpura Granite & Gneiss Bilara Group Jodhpur Group Bilara 26 Nagaur Group Delhi Supergroup Punagarh Group ig.1. Geological map of (a) Sanu area, Jaisalmer and (b) Gotan area, Nagaur, Rajasthan (based on GSI, 1999). JOUR.GEOL.SOC.INDIA, VOL.75, MAY 2010

3 MINERAL ECONOMICS O SANU AND GOTAN SMS GRADE LIMESTONE DEPOSITS, RAJASTHAN 741 (Pareek, 1984 and Singh 1996). A detailed geological and lithostratigraphic account of the Tertiary rocks of Jaisalmer Basin has been given by Narayan (1964), Khosla (1971, 1973), Dasgupta (1975), Pareek (1981, 1984), Singh (1996, 2008). The SMS grade limestone is well exposed around the village Sanu (N 27º15' : E 70º39') about 60 km northwest of Jaisalmer city (ig. 1a). It belongs to Khuiala ormation of early Eocene age. The limestone deposit occurs over a large stretch of about 100 km length and 4 km width. It is exposed in nearly a flat terrain partially covered with aeolian sand and comprising two distinct beds. The upper surfacial bed of 1 to 1.5 m thickness is fragmental to nodular bouldery form, yellowish colour and contains loose argillaceous impurities as matrix. The lower bed is represented by a massive and compact limestone with a thickness varying from 2.5 m to 3.5 m (ig. 2a). The limestone is fine-grained and mostly white to pale-yellow colour with pinkish tint. Underlying this bed, a thick fossiliferous chalky limestone occurs with a thickness of about 10 to 15 m. The chalky limestone is pinkish-white to buff colour, moderately compact to soft and porous in its physical form and found suitable for making cement. The general strike of the limestone beds is NNW-SSE and these are nearly horizontal. However, at places, they show low dips up to 5 towards the northwest. The chalky limestone of Sanu area is comparatively soft and porous than a common limestone and hence, resemble with chalk. But chemically, it contains 44 to 50% CaO, 5 to 18% SiO 2 and less than 1% MgO (DMG, 1998) and differs from the well known Upper Cretaceous chalk deposits of Britain, Denmark and other parts of Europe which are mainly composed of tests (coccoliths) of single celled, calcareous, marine algae (John, 2009). The chalk of these deposits is soft, white, and porous and represents the purest form of limestone having about 98% CaCO 3. Thus, the term chalky has been used as an adjective instead of its lithological significance. In India, chalk deposits occur only in Gujarat in association with miliolitic limestone of Quaternary age. The workable deposits are located in Porbandar area of Junagarh district with small occurrences in Bhavnagar, Kachchh and Jamnagar districts (Merh, 1995; GSI, 2001). The chalk is white to yellowish colour, soft and porous and extensively used for making whiting powder over the past five decades. The high grade Gotan (N 26º39'30" : E 73º43'00") limestone deposits occurring in central Rajasthan belongs to Bilara Group of Marwar Supergroup (Pareek, 1984; Dasgupta et al. 1988; Dasgupta, 1996; Sinha-Roy et al. 1998; GSI, 1999). The Bilara Group is represented by rocks of Depth (m) msl Depth (m) msl S INDEX S Distance (m) ragmental, nodular - bouldery SMS grade limestone Compact, massive SMS grade limestone Chalky limestone Distance (m) INDEX Alluvium Siliceous dolomitic limestone Clay and kankar SMS grade limestone Clay and chert Low grade limestone ig.2. Generalised geological sections of (a) Sanu limestone deposit and (b) Gotan limestone deposit. calcareous facies of sedimentation in the Bikaner-Nagaur Basin lying unconformably over arenaceous sequence of the Jodhpur Group and underlain by arenaceous-argilaceous rocks of the Nagaur Group of the Marwar Supergroup (Sogani and Khan, 1974; Pareek, 1984) (ig. 1b). The age of Marwar Supergroup ranges from late Neoproterozoic to early Cambrian (Kumar et al. 1997; Chauhan et al. 2004). The Bilara Group is further sub-divided into lower Dhanapa, middle Gotan and upper Pondlo ormations. Khilnani (1964, 1968) has recorded presence of algal stromatolitic structures in the lower and upper formations while, Babu et al (in Pandey and Tej Bahadur, 2009) has cited the presence of several micro-phytofossils from the chert specks of middle Gotan ormation of the Bilara Group. However, notable absence of index-fossils or other invertebrate body-fossils in the rocks of Marwar Supergroup has been inferred by Pandey and Tej Bahadur (2009) due to either high influx of siliciclastic sediments or incompatible prevalent water N b N a

4 742 M. S. SHEKHAWAT AND G. PRABULINGAIAH chemistry. The Bilara limestone constitutes a prominent N- S trending belt in central Rajasthan that extends for about 150 km in length and 2 to 6 km in width. It is being developed and used for making lime since past five decades. The Bilara Group represents a marine environment of deposition. Pandit et al. (2001) and Maheshwari et al. (2003) inferred cold and subsequent warmer conditions for the Bilara carbonate sediments. Recently, Pandey and Tej Bahadur (2009) suggested warm and arid climatic conditions for these sediments on the basis of dominance of carbonates, presence of algal stromatolites, absence of primary sedimentary structures, sharp bedding surfaces and depleted value of δ 13 C in the carbonates. The Gotan SMS grade limestone deposits are located mainly in central part of the Bilara limestone belt (ig. 1b) and exposed as flat topped, low altitude, isolated ridges extending mostly from 200 m to 500 m in length, few of them extends up to 2 km. The deposits have also been proved between these ridges in low-lying areas blanketed with wind blown sand cover. The SMS grade limestone deposits are mostly capped with a thin bed of siliceous dolomitic limestone and at places with a thin veneer of alluvium (ig.2b). Thickness of this upper bed varies from 0.5 to 2 m and it forms overburden. It is separated from underlying SMS grade limestone beds by a thin band of clay having disseminations of kankar. The SMS grade limestone deposits occur as two to three distinct beds with cumulative thickness of about 5 m. These beds are separated from each other by thin bands of clay and chert having a thickness of about 0.5 m. The limestone is mostly light to dark grey, fine to coarse-grained and massive to laminated. The beds show rolling low dips mostly varying from 1 to 5. The lower bed of SMS grade limestone gradually passes to low grade limestone. XRD Data MINERALOGICAL CHARACTERISTICS Two representative samples of SMS grade limestone collected one each from Sanu and Gotan mines were prepared for X-ray diffraction (XRD) study at the University Department of Physics, M. L. Sukhadia University, Udaipur. The diffractograms were obtained on a Rigaku Miniflex tabletop diffractometer using Ni-filtered, Cukα radiation at 2 kv and 15 na with scanning speed of 2 /min. The diffractograms and XRD data of these samples are given in ig.3 and Table 1 respectively. The values of d-spacing obtained for these samples were compared with those of standard samples of calcite and dolomite. They correspond closely with those of calcite (JCPDS Card No ), Table 1. XRD data of SMS grade limestone from Sanu area and Gotan area Sanu limestone Gotan limestone JCPDS Card No θ d(å) 2θ d(å) 2θ d(å ) with absence of dolomite, a common constituent present in Aravalli limestones of Rajasthan. Petrography A number of thin sections of the SMS grade limestone samples collected from working quarries from Sanu and Gotan areas have been studied under polarizing microscope. The study indicates that nearly 80% to 90% of the Sanu SMS grade limestone is composed of micro-fossils (ig. 4a) and rest of 10% to 20% consists of fine-grained calcite with minor amounts of iron-oxides, present as fine-grained impurities which may probably imparted light-yellow to pinkish colour to the limestone. The tests of micro-fossils are well preserved within the fine-grained matrix of calcite with their distinct shape and are completely replaced by carbonate material. Three distinct types of test forms have been identified on the basis of their shape and structure. These are: (i) tubular worm-like form, (ii) coral-type form and (iii) oval-shaped form. The worm-like forms are predominant over the other two types and make major part of the limestone. In longitudinal-sections, they appear tubular, straight to curvilinear and have clearly visible closely spaced cross rib-like structure giving them segmented outline (ig. 4a). Their cross-sections are perfectly circular in outline with two closely spaced outer and inner rings. The coraltype test forms are mostly sub-rounded to irregular in their shape and variable in size with diffused outline (ig. 4a). Their cell structures are clearly visible and under high magnification, they appear circular to hexagonal in shape. The oval-shaped test forms are rarely observed. They show distinct outline and are characterised by presence of three to four thick layers with a small nuclear part (ig. 4a). The occurrence of several species of larger benthic and planktic foraminifera notably Assilina granulossa, Assilina deviesi, Assilina lacunata etc. of lower Eocene age have

5 MINERAL ECONOMICS O SANU AND GOTAN SMS GRADE LIMESTONE DEPOSITS, RAJASTHAN 743 ig.3. X-ray diffractograms of SMS grade limestone (a) Sanu and (b) Gotan. been reported by Sigal et al. (1971), Singh (1976, 1984, 1996, 2008) from various exposed and subsurface litho-units of the Khuiala ormation of Tertiary sequence of Jaisalmer Basin. Based on litho-association and larger foraminifera, an inner-neretic environment of deposition of the sediments has been concluded for the basin (Singh, 2008). The Gotan limestone consists of fine to coarse-grained calcite with minor impurities of iron-oxides. On the basis of thin section study, two types of limestone have been identified. One type consists of fine to medium-grained calcite and characterised by presence of fine laminations (ig. 4b). These laminations are mostly traversed by fractures which are filled with secondary cryptocrystalline carbonates. Another type is composed of sub-rounded to angular medium-grained calcite without any laminations (ig. 4c). In several thin sections, fine to medium- grained calcite occurs in the form of sub-rounded to rounded aggregates with their diffused boundaries and the space between them is occupied by cryptocrystalline secondary calcite. SEM Studies To understand grain morphology, two representative samples of the SMS grade limestone one each from Sanu and Gotan area and their corresponding calcined samples were scanned through electron microscope (LEO 430, CAMBRIDGE) at University Department of Geology, Udaipur. The images reveal that Sanu limestone is composed of more or less uniform, fine and sub-rounded to rounded grains (ig. 5A), while Gotan limestone comprises uneven, comparatively larger and angular to sub-rounded grains of calcite (ig. 5B). The images of their corresponding samples reveal that after calcination, the Sanu limestone does not show development of any significant cracks and remains massive (ig. 6A) while, in Gotan limestone cracks have developed (ig. 6B) which results in increase of fines (-15 mm). Chemical Analyses Seven representative and fresh samples of the SMS grade limestone from Sanu and six from Gotan were collected from

6 744 M. S. SHEKHAWAT AND G. PRABULINGAIAH a A b B ig.5. SEM photomicrographs of natural samples showing (A) fine-grained, sub-rounded to rounded grains of calcite in Sanu limestone, (B) medium to coarse-grained, angular to sub-rounded grains of calcite in Gotan limestone. c ig.4. Photomicrographs showing (a) abundance of larger three types of foraminifera tests composed of fine-grained calcite in Sanu limestone (Bar = 0.28 mm), (b) presence of fine laminations in Gotan limestone consisting of fine to medium-grained calcite (Bar = 0.28 mm), (c) non-laminated massive type Gotan limestone consisting of mediumgrained calcite (Bar = 0.28 mm). working quarries and analysed by using conventional method at the Chemical Laboratory of RSMML, Jhamarkotra, Udaipur. The analytical results presented in Table 2 shows that both Sanu and Gotan limestones are nearly similar in their chemical composition. They contain to 54.88% and to 55.10% CaO, 0.30 to 1.00% and 0.30 to 1.2% MgO, 0.70 to 1.54% and 0.38 to 1.66% SiO2, 0.23 to 0.86% and 0.14 to 0.52% Al2O3, and 0.12 to 0.26% and 0.06 to 0.12% e2o3 respectively. The chemical composition of limestone from both the areas meets the specifications required for SMS use (IBM, 2008). MINERAL ECONOMICS In India SMS grade limestone deposits occur in several states but large and superior grade deposits occur only in Jaisalmer area of western Rajasthan with total estimated reserves of about million tonnes (DMG, 2009a). These figures will certainly increase to many-folds on detailed exploration of large soil covered deposits as indicated by Pareek (1977) and Laul (1980). In steel industries, it is used as a flux after calcination. The limestone for SMS use should contain +53.5% CaO, <2% MgO and <1.5% SiO2 (IBM, 2008). The size of limestone should be JOUR.GEOL.SOC.INDIA, VOL.75, MAY 2010

7 MINERAL ECONOMICS O SANU AND GOTAN SMS GRADE LIMESTONE DEPOSITS, RAJASTHAN 745 Table 2. Chemical analysis of SMS grade limestone of Sanu area and Gotan area Sample No. SL-1 SL-2 SL-3 SL-4 SL-5 SL-6 SL-7 GL-1 GL-2 GL-3 GL-4 GL-5 GL-6 CaO MgO SiO Al 2 O e 2 O LOI Total SL-1 to 7: Sanu SMS grade limestone, GL-1 to 6: Gotan SMS grade limestone in the range of 80 mm to +40 mm and in certain specific cases 50 mm to +30 mm. More importantly, it should be compact and be able to withstand size reduction during the handling operations (loading, transportation and unloading). Similarly, the lime produced should also contain ig.6. SEM photomicrographs of calcined samples (A) Sanu limestone (5A) showing massive nature without development of any visible cracks after calcination (B) Gotan limestone (5B) showing development of cracks after calcination. A B minimum 15 mm size because this size is not suitable to feed Linz Donawitz (LD) Converters. The chemical analyses presented in Table 2 shows that limestone of both Sanu and Gotan areas are nearly similar in chemical composition and meet the specifications required for SMS use (IBM, 2008). However, Sanu limestone of Jaisalmer area has superior physical properties than limestone of Gotan and other areas of the country and hence, it has even replaced use of imported limestone by major steel plants of India (Prabhulingaiah et al. 2007b). Such superior physical properties and chemical purity of the Sanu limestone may be attributed to micro-biological activities, which played an important role in its formation as indicated by abundance of tests of larger foraminifera, which constitute about 80% to 90% of its volume. After the better results achieved in initial study carried out by SAIL in for the suitability of Sanu limestone to the steel plants, its production was started in by the then RSMDCL at small-scale. But, on realisation of the resource as a national asset in 1991 by the Government of India and consequent conversion of meter-gauge to broad-gauge railway line from Jodhpur to Jaisalmer over a distance of about 325 km in , this resource is being developed on large-scale through fully-mechanised mining by RSMML. The current production is about 2.19 million tonnes valued at about Rs million (Table 3) that meets the requirements of high grade SMS limestone for the Indian steel plants. After required sizing, the resource is being road-transported to Jaisalmer Railway Station for a distance of about 60 km for its dispatch. It results in additional cost of loading, unloading and loss of the resource in terms of size reduction. The resource produced is being consumed by major steel plants of the country located mainly at Rourkela, Bokaro, Bhilai, Durgapur, Burnpur, Jamshedpur, Toranagallu, Vizag etc. It is also a major source of income (Rs. 250 million in ) to the Western Railways. Moreover, during the process of sizing (crushing and screening), about 54% of the run of mines (ROM) is

8 746 M. S. SHEKHAWAT AND G. PRABULINGAIAH Table 3. Production and sale value of SMS grade limestone from Sanu area during to Years Production Sale value Revenue (tonnes) (Rs. million) (Rs. 000) Source: DMG (2009b) generated as -30 mm size limestone annually. This large quantity of high grade -30 mm size limestone is considered as a reject and is disposed continuously in mined-out pits for their reclamation. It is a nature s gift and valuable national asset that should be utilised appropriately instead of using as back-filled material. Chemically (Table 2), it is quite suitable for making cement where size specifications are not required. Besides, a large deposit of chalky limestone occurring at the base of SMS grade limestone deposit is also suitable for making cement, which could be developed without any additional cost by utilising upper beds of the SMS grade limestone. ortunately, other raw material required for manufacturing cement like coal/lignite, gypsum, clay and water (Indira Gandhi Canal) are easily available at reasonable distance in the area. The only constraint for setting up of cement plants is absence of rail transport from Sanu area to Jaisalmer city for a distance of only 60 km and power requirement. Efforts should be made to develop these facilities. SUMMARY AND CONCLUSIONS Sanu and Gotan SMS grade limestone deposits occur as nearly horizontal beds with total thickness of about 5 to 6 m each. The Sanu limestone is massive, compact and exposed directly on the ground surface while, Gotan limestone is also compact in nature but mostly well laminated and covered with a thin bed of siliceous-dolomitic limestone and at places thin layer of wind blown sand. The chemical analyses presented in Table 2 shows that Sanu and Gotan limestones are nearly similar in chemical composition and meet the specifications required for SMS grade limestone (IBM, 2008). The mineralogical studies carried out also show that Sanu and Gotan limestones are composed mainly of calcite as confirmed by XRD analyses (Table 1). However, petrographic study reveals that Sanu limestone has a distinct and unique composition. It is fossiliferous and composed of fine-grained calcite occurring mainly in the form of tests of larger foraminifera, while Gotan limestone consists of fine to coarse-grained calcite mostly showing microscopic laminations and is not fossiliferous. Thus, on the basis of mineralogical composition, it has been concluded that Gotan limestone formed by inorganic process, whereas, for the Sanu limestone, micro-biological process has played an important role and it is mainly responsible for its superior physical properties. The grain morphology reflected by SEM images reveals that Sanu limestone consists of rounded to sub-rounded nearly uniform fine-grained calcite with their better packing giving it high resistance to size reduction. While, Gotan limestone mainly comprises angular to sub-rounded, uneven, fine to coarsegrained calcite offering it less resistance to its size reduction. Similarly, the SEM images of calcined samples show that Sanu limestone does not show development of cracks after its calcination but, the Gotan limestone displays development of cracks which results in increase of higher quantity of -15 mm size of lime which is not found suitable for use in LD converters. Production data given in Table 3 shows that about 2.19 million tonnes of SMS grade limestone (+30 mm size) which is nearly 46% of the ROM is being produced annually from Sanu area to meet the requirements of Indian steel plants. The rest of 54% high grade limestone (-30 mm size) generated during the process of sizing, which is chemically suitable for making cement, is being disposed of continuously as reject. Similarly, the vast reserves of chalky limestone, which are chemically suitable for making cement and occurring at the base of SMS grade limestone which could be developed without any additional cost, are buried again through back-filling of the pits. Therefore, it is suggested that to utilise these high grade produced-and-developed resources economically through manufacturing cement, the Ministry of Steel and Mines, Railways, the State Government and RSMML should jointly take a positive step to develop broad-gague railway transport facility from Jaisalmer city to Sanu area for a distance of just 60 km. It will significantly help in economic development of the Thar region of western Rajasthan, and lowering of the present transport cost of SMS grade limestone, there by enhancing revenue to the railways and the State Government. Acknowledgements: The authors are grateful to the Managing Director, RSMM Ltd, Udaipur for providing required facilities for the work. They are thankful to Dr.

9 MINERAL ECONOMICS O SANU AND GOTAN SMS GRADE LIMESTONE DEPOSITS, RAJASTHAN 747 D. M. R. Sekhar, former Group General Manager, Gypsum Division, RSMM Ltd., Bikaner for useful discussion and his valuable suggestions. Dr. N. Laxmi, Department of Physics, is thankfully acknowledged for her help in XRD analyses. The Heads, Department of Geology, M. L. Sukhadia University, Udaipur are gratefully acknowledged for providing required facilities for completing this work. We also wish to thank Shri Arjun Singh Rathore, JR, Department of Geology, M. L. Sukhadia University, Udaipur for his help in graphics. References CHAUHAN, D.S., BHANWARA RAM and NARAYAN RAM, (2004) Jodhpur sandstone: A gift of ancient beaches to Western Rajasthan. Jour. Geol. Soc. India, v.64, pp DASGUPTA, S.K. (1975) Revision of the Mesozoic-Tertiary stratigraphy of the Jaisalmer basin, Rajasthan. Indian Jour. Earth Science, v.2(1), pp DASGUPTA, S.K., KUMAR, V., CHANDRA, R. and JAIRAM, M.S. (1988) A framework of the Nagaur-Shriganganagar evaporate basin. Indian Minerals, v.42, pp DASGUPTA, S.K. (1996) Marwar Supergroup evaporates, Rajasthan. In: Ajit Bhattacharyya (Ed.), Recent advances in Vindhyan Geology. Mem. Geol. Soc. India, no.36, pp DMG (1998) Limestone deposits of Rajasthan. Department of Mines and Geology, Govt. of Rajasthan, Udaipur, pp DMG (2009a) Metallic.aspx, September DMG (2009b) Unpublished Records of limestone. Department of Mines and Geology, Govt. of Rajasthan, Udaipur. GSI (1999) Geological and Mineral Map of Rajasthan. Geol. Surv. India, Hyderabad. GSI (2001) Geology and Mineral Resources of Gujarat, Daman and Diu. Misc. Publ., No.30. Pt. XIV, pp IBM (2008) Indian Minerals Yearbook 2007, Nagpur. Pt.II, p.(53)21. JOHN D. MATTHEWS (2009) Chalk and Upper Cretaceous Deposits are part of the Noachain lood. November KHILNANI, B.V. (1964) A note on the occurrence of algal stromatolites in Vindhyan Limestone from Bilara area, district Jodhpur, Rajasthan. Curr. Sci., v.33(24), pp KHILNANI, B.V. (1968) Stromatolites of Vindhyan limestone from Bilara, district Jodhpur, Rajasthan. Quart. Jour. Geol. Min. Met. Soc. India, v.xl(1), pp.1-6. KHOSLA, S.C. (1971) Classification of the Lower Tertiary beds of Rajasthan. Bull. Ind. Geol. Assoc., v.4(3,4), pp KHOSLA, S.C. (1973) Stratigraphy and Micro-fauna of the Eocene beds of Rajasthan. Jour. Geol. Soc. India, v.14, pp KUMAR, G., SHANKAR, R., MAITHY, P.K., MATHUR, V.K., BHATTACHARYA, S.K. and JAIN, R.A. (1997) Terminal Proterozoic-Cambrian sequences in India: A review with special reference to Precambrian-Cambrian boundary. Palaeobotanist, v.46(1,2), pp LAUL, V.P. (1980) Prospects of industrial grade limestone in Khuiala ormation (Lower Eocene), Jaisalmer district, Rajasthan. Indian Minerals, v.33(4), pp MAHESHWARI, A., SIAL, A.N. and MATHUR, S.C. (2003) Carbon and Oxygen isotope profiles from the Terminal Pre-Cambrian Marwar Supergroup, Rajasthan, India. Carbonates and Evaporites, v.18(1), pp MERH, S.S. (1995) Geology of Gujarat. Geol. Soc. India, Bangalore, p.117. NARAYAN, K. (1964) Stratigraphy of Rajasthan Shelf. Proc. Symp. Problems of Indian Arid Zone, Jodhpur. Govt. of India Publ., New Delhi, pp PANDEY, D.K. and TEJ BAHADUR (2009) A review of the Stratigraphy of Marwar Supergroup of Western-central Rajasthan. Jour. Geol. Soc. India, v.73, pp PANDIT, M.K., SIAL, A.N., JAMRANI, S.S. and ERREIRA, V.P. (2001) Carbon isotopic profile across Bilara Group rocks of Trans- Aravalli Marwar Supergroup in western India: implications for Neoproterozoic-Cambrian transition. Gondwana Res., v.4, pp PAREEK, H.S. (1977) Limestone deposits of northwestern Rajasthan. Indian Minerals, v.31(4), pp PAREEK, H.S. (1981) Basin configuration and sedimentary stratigraphy of western Rajasthan. Jour. Geol. Soc. India, v.22(11), pp PAREEK, H.S. (1984) Pre-Quaternary Geology and Mineral Resources of northwestern Rajasthan. Mem. Geol. Surv. India, v.115, 99p. PRABHULINGAIAH, G., GHOSH JOYEE, SEN PRASENJIT and SEKHAR, D.M.R. (2006) Test for Steel Melting Shop grade limestone. Trans. Indian Inst. Met., v.59(1), pp PRABHULINGAIAH, G., JAKHAR, S.R., SHEKHAWAT, M.S., RANAWAT, P.S. and SEKHAR, D.M.R., (2007a) Resistance of limestone to size reduction. Indian Chemical Engineer, v.49(2), pp PRABHULINGAIAH, G., SHEKHAWAT, M.S., ACHARYA, D.S., JAISWAL, A.K. and RAMA SHANKAR (2007b) Limestone for Steel Making. MGMI, Transactions, v.103(1,2), pp SEN, P., GHOSH, J., PRABHULINGAIAH, G. and SEKHAR, D.M.R. (2006) Internal morphology of SMS grade limestone samples. Mineral Processing and Extractive Metallurgy (Trans. Inst. Min. Metall. C.), v.115(3), pp SIGAL, J., SINGH, N.P. and LYS, M. (1971) The Paleocene-Lower Eocene boundary in Jaisalmer area, India. Jour. oraminiferal Res., v.1(4), pp SINGH, N.P. (1976) Micropaleontological control in subsurface Tertiary sequence of Jaisalmer basin, West Rajasthan, India. IV Indian Colloquium Micropalaeology Stratigraghy, pp SINGH, N.P. (1984) Addition to the Tertiary biostratigraphy of

10 748 M. S. SHEKHAWAT AND G. PRABULINGAIAH Jaisalmer basin. Petroleum Asia Journal, v.ii(1), pp SINGH, N.P. (1996) Mesozoic-Tertiary biostratigraphy and biogeochronological datum planes in Jaisalmer basin, Rajasthan. In: J. Pandey et al. (Eds.), Contrib. XV Indian Colloquium on Micropalaeontology and Stratigraphy. K.D. M.I.P.E., ONGC, Dehradun, pp SINGH, N.P. (2008) Cenozoic lithostratigraphy of the Jaisalmer basin, Rajasthan. Jour. Palaeontological Soc. India, v.52(2), pp SINHA-ROY, S., MALHOTRA, G. and MOHANTY, M. (1998) Geology of Rajasthan. Geol. Soc. India, Banglore, 278p. SOGANI, P.C. and KHAN, E.A. (1974) A note on high grade limestone in Sojat-Gotan-Mundwa Limestone belt in Rajasthan. Indian Minerals, v.28(4), pp (Received: 19 September 2009; Revised form accepted: 23 December 2009)