- V. P. Mishra
- S. K. Basu
- I. R. Kirmani
- Appah Amrit Bhasker
- Utpal Bose
- M. S. Reddy
- P. Gupta
- K. Mukhopadhyay
- J. Bhattacharjer
- S. S. Jain
- Shabbir Hussain
- S. Raju
- B. Dayal
- U. Bose
- B. L. Srivastava
- A. B. Reddy
- J. Bhattacharjee
- M. A. Shankara
- B. Basavalingu
- A. S. Janardhan
- R. H. Sawkar
- K. S. Misra
- M. R. Hammond
- Anant V. Phadke
- Fiona Plows
- U. S. N. Reddy
- I. V. Reddy
- G . Parthasarathy
- C. R. M. Rao
- B. N. Gohain
- Dinesh Gupta
- Suresh Kharkhanis
- G. Parthasarathy
- Sambhunath Ghosh
- S. Viswanathan
- M. S. Rao
- N. C. Pant
- S. Neogi
- U. P. Singh
- N. S. Venkatesh
- K. S. Godhavari
- R. Gopalkrishnan
- Susmita Gupta
- P. R. Golani
- Suresh Chander
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z All
Fareeduddin,
- Kimberlites, Lamproites and Lamprophyres of India: A Petrographic Atlas
Authors
1 Geological Survey of India, AMSE Wing, Vasudha Bhavan, Kumaraswamy Layout, Bangalore - 560 078, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 69, No Spl Iss 3 (2007), Pagination: 467-504Abstract
A pictorial display of some of the kimberlites, lamproites and lamprophyres of India, is given in this work. This would give an idea about the texture and mineralogy of these rocks from different cratonic regions of the Indian shield.Keywords
Kimberlites, Lamproites, Lamprophyres, Petrography, Atlas.
- Geochemistry of Differentiated Lamprophyre Dyke, South Delhi Fold Belt, Pipela Area, District Sirohi, Rajasthan
Authors
1 Geological Survey of India, Western Region, Jhalana Dungari, Jaipur - 302 004, IN
2 Geological Survey of India, AMSE Wing, Vasudha Bhavan, K.S.Layout, Bangalore - 560 078, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 56, No 6 (2000), Pagination: 615-623Abstract
A dyke of lamprophyric composition intrudes the meta-volcanic rocks of Ajabgarh Group of the Delhi Supergroup near Pipela, Sirohi district, Rajasthan. It exhibits well-defined compositional and textural layering in the form of chilled margin, sparsely porphyritic zone, aphyric zone and central porphyritic zone. Geochemical studies of this lamprophyric rock have led to the following interpretations: (i) the lamprophyric melt was derived from a less metasomatised mantle, (ii) crustal contamination took place during ascent and/or emplacement (iii) there was sufficient time for the lamprophyric body to differentiate into well-defined layers, and (iv) there was post-emplacement hydrothermal alteration.Keywords
Lamprophyre, Dyke, Differentiation, Geochemistry, South Delhi Fold Belt, Rajasthan.- Sedimentation and Deformation Analysis of Gurusiddapura Conglomerate, Chitradurga Schist Belt
Authors
1 INSA Project, Department of Mines and Geology, Bangalore 560001, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 22, No 6 (1981), Pagination: 258-265Abstract
The Gurusiddapura and Hoskere conglomerates of Chitradurga schist belt belong to one continllolls stratigraphic unit. Deformational analysis indicates that the pebbles in both the conglomerates belong to one single population. Graded bedding and occurrence of pebbly and non-pebbly zones indicate turbidite environment of deposition in an unstable geosyncline. Since the conglomerates are interbedded with chlorite schist they do not mark any unconformity.- Polymodal Volcanism in Parts of the South Delhi Fold Belt, Rajasthan
Authors
1 Geological Survey of India, Regional Geology Division II (Operation: Rajasthan), Jhalana Dungri, Jaipur 302 004, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 36, No 3 (1990), Pagination: 263-276Abstract
The Proterozoic South Delhi Fold Belt (SDFB) is known to have a dominant volcanic component along the western flank of the Aravalli Range. Earlier studies have indicated both bimodal and unimodal characters of these volcanics in different parts of the SDFB. The Shyopura-Narpura area in north-central part of the Aravalli Range has, on the other hand, volcanics of intermediate and ultrabasic composition, interlayered with basic and felsic volcanics. This polymodal suite of secondary greenstone character is interpreted to have erupted in a rifted back-arc setting.Keywords
Geochemistry, Delhi Fold Belt, Volcanism, Rajasthan.- Tectono-Stratigraphic Framework and Volcanic Geology of the South Delhi Fold Belt in Central Rajasthan
Authors
1 Geological Survey of India, Jaipur 302004, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 37, No 5 (1991), Pagination: 431-441Abstract
The Delhi rocks are deposited in two sub-basins separated by a median inlier of Pre·Delhi rocks. The Barotiya and Sendra Fonnations occupying the western sub-basin contain significant basic flows and tuffs with associated felsic volcanics. The eastern sub-basin recording a diachronous evolutionary history is the repository of the Rajgarh and Bhim sediments.
Striking similarities are noted in respect of lithology, structure and metamorphism amongst the gneisses and schists of the Pre-Delhi rocks flanking the Delhi Supergroup and also of the median inlier. Structural imprints and contact relationship indicate that these gneisses and schists fonn the basement for the Delhi sediments. Migmatization related to orogeny suggests reactivation of a sialic basement, which along with the tectonic emplacement of basement slices in the Delhi stratigraphy argue in favour of an intra-cratonic development of the Delhi basin.
The western sub-basin shows bimodal volcanism and the various geochemical discriminants suggest an IATor MORB setting, but fail to make a choice between the two. Bimodal volcanism in association with shallow clastic sediments signify ensialic origin in a rifted mobile belt. Structural studies indicate large-scale dextral vergence with steep 'S' surfaces which are characteristic of oblique shear transpressive mobile belt.
Keywords
Delhi Fold Belt, Tectona-Stratigraphy, Rajasthan, Aravalli.- Tectonic Setting, Petrochemistry and Tungsten Metallogeny of the Sewariya Granite in the South Delhi Fold Belt, Rajasthan
Authors
1 Geological Survey of India, Jhalana Dungri, Jaipur, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 42, No 1 (1993), Pagination: 3-16Abstract
The Scwariya granite, 'largest of the Erinpura granite intrusions' occurs along the western margin of the Middle-Late Proterozoic Soulh Delhi Fold Bell. Synkincmalic with the Delhi orogeny, the granite body intrudes a rifled back arc type basin (Barotiya Formation) and hosts W ± Sn ± Li mincralization in pneumatolytic quartz veins. Innumcrable metasedimentary enclaves occur which are traversed by syn-to post-tectonic ductile shear zones. Geochemistry of Ihe granite suggests it to be a well differntiated, calc-alkliline, S-typc metallogcnetically specialised orogenic massif. The nature of the granite and the host supracrustals and Ihe tectonic discriminant diagrams indicate that it may have evoled in an arc-related environment. W ± Sn ± Li mineralization in this granite, Pb-Zn-Cu and Zn-Cu mineralization in the contiguous units of Barotiya and Sendra formations respectively suggests a conspicuous metallogenic zoning.The Sewariya granite forms a central link to the major Sn-W hosted granite rocks in Rajasthan Haryana sector that lie along a 500 km long NNE-SSW trending lineament. Although associated with felsic plutonic suites of contrasting geotectonic environments, W -Sn mineralizalion along this belt defines a single metallogenic province, a large part of which is unexplored.
Keywords
Tectonics, Geochemistry, Economic Geology, Tungsten, Rajasthan.- Petrochemistry and Tectonic Setting of the Champawat Granite Suite of Lesser Himalaya, Pithoragarh District Uttar Pradesh
Authors
1 Geological Survey of India, Jhalana Dungri, Jaipur, IN
2 Geological Survey of India, Aliganj, Lucknow, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 44, No 1 (1994), Pagination: 17-25Abstract
The concordantly emplaced polyphase granite suite exposed in the Champawat area of Pithoragarh district of Uttar Pradesh represents a part of the southernmost granitoid belt of Himalayan region. In the field it can be divided into four successive mappable phases, viz. biotite granite, grey granite, leucogranite and microgranite. Mineralogically the biotite granite and grey granite are classified as "granodiorite" while the leucogranite and microgranite are classified as "granite". All these varieties of granite show xenoliths of country rocks. Champawat granite suite is a well differentiated, polyphase, calc-alkaline, peraluminous, S-type granitoid batholith that ranges in composition from granite to granodiorite- adamellite and trondhjemite. It is interpreted to be the product of anatexis of supracrustals at middle to lower crustal levels. The geochemical discriminant diagrams of the Champawat granite suite suggest that it is an orogenic granite showing characters of continental collision environment.Keywords
Igneous Petrology. Granite, Champawat, Himalayas, Uttar Pradesh.- Reappraisal of the Delhi Stratigraphy in the Ajmer-Sambhar Sector, North-Central Rajasthan
Authors
1 Geological Survey of India, Jhalana Dungari, Jaipur-302004, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 45, No 6 (1995), Pagination: 667-679Abstract
The supracrustals occurring in the northern sector of the South Delhi Fold Belt (SDFB; main Delhi Synclinorium of Heron, 1953) between Ajmer-Pushkar valley and Sarnbhar Lake in north-central Rajasthan are classified into Anasagar migmatites and the overlying Ajmer Formation comprising Taragarh quartzites and Kalyanipura arkose-pelite-greywacke sequence. The Anasagar migmatites and paragneisses are intruded by Iatero genic granite(1600 Ma) and post orogenic ultramafic and alkaline rocks. Four folding and two shearing movements characterize these rocks. Three metamorphic zones could be identified in these supracrustals with grade increasing towards west: staurolite-kyanite grade (middle arnphibolite facies) in the eastern sector, sillimanite-muscovite grade (upper amphibolite facies) in the central sector, and orthopyroxene-plagioclase and orthopyroxene-sillimanite grade (granulite facies) in the western sector.
The Anasagar and Ajmer supracrustals are deposited in an Early Proterozoic ensialic basin in the Archaean BGC (Banded Gneissic Complex) protocontinent and differ from the other tectono-stratigraphic units of the SDFB in respect of lithological organisation, metamorphism and magmatism besides the latter being decisively of Upper Proterozoic age. The authors, therefore suggest a separate and older stratigraphic status to these supracrustals and delink from the rest of the SDFB stratigraphy.
Keywords
Stratigraphy, Delhi Supergroup, Ajmer, Sambhar, Rajasthan.- Lamprophyre Dykes in the South Delhi Fold Belt Near Pipela, District Sirohi, Rajasthan
Authors
1 Geological Survey of India, Jhalana Dungari, Jaipur - 302 004, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 46, No 3 (1995), Pagination: 255-261Abstract
Lamprophyre dykes are reported from the southern part of the South Delhi Fold Belt (SDFB), near Pipela, about 3 km SE of Sarupganj in Sirohi district of Rajasthan. They occur as sub-volcanic intrusives in the Ajabgarh supracrustals and follow a WNW -ESE to E-W trends. They show porphyritic and panidiomorphic textures with biotite and magnetite occurring as euhedrru phenocrysts ina cryptocrystalline matrix. One large Jamprophyre body shows acompositionallayering. Widespread alteration (chloritisation of biotite and potash depletion) suggests that they are not cogenetic with the post-Cretaceous, fresh lamprophyres of the Mundwara area. Probably these dykes are emplaced during the waning stage of the Late Proterozoic tectonomagmatic cycle of the South Delhi Fold Belt.Keywords
Lamprophyres, Delhi Fold Belt, Rajasthan.- P-T Conditions of Pelitic Granulites and Associated Charnockites of Chinwali Area, West of Delhi Fold Belt, Rajasthan
Authors
1 H.408, Ramesh marg, C Scheme, Jaipur 302 001, IN
2 Department of Geology, Univeisity of Mysore, Manasagangotri, Mysore-570 006, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 43, No 2 (1994), Pagination: 169-178Abstract
A brief account of the petrology and structure of medium grade pelitic granulites and associated charnockites occurring as slivers in the Anasagar migmatitic gneiss is given. These granulite slivers have been traced along strike up to 40 km and may cover a much wider area. Cordierite bearing pelitic granulites associated with charnockites around Chinwali were chosen for estimating metamorphic P-T conditions. The pelitic granulites are represented by the assenlblage opx-cord-gt-bio--silli-plag-k felds- qtz. Biotite-fibrolite intergrowths grow on cordierite which has opx inclusions. Garnet is often smeared with graphite. Metamorphic conditions of petite show peak pressures of 7.5 kb at 640°C. Charnockites generally record retrogressive pressure conditions of 5.7 - 4.0 kb. The mineralogy of the Chinwali granulites and P-T condition compare well with that of Sandmata granulites. The presence of these granulites, north of Ajmer, in basement migmatitic gneisses suggest the presence of an older deep crustal fragment (ca. 1.7 Ga) along the northwestern margin of the Aravalli Delhi Mobile Belt (ADMB) and belies the prevailing concepts of eastward crustal thickening and westward age polarity in the western Indian shield.Keywords
Granulite, Charnockite, Petrology, Ajmer, Chinwali, Rajasthan.- Wall Rock Alteration in Cu-Zn-Au Bearing Volcanogenic Massive Sulphide Deposit at Danva, District Sirohi, Rajasthan
Authors
1 Geological Survey of India, Jhalana Dungri, Jaipur - 302 004, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 52, No 4 (1998), Pagination: 391-402Abstract
The Upper Proterozoic mafic volcanic suite of the Delhi Supergroup between Nanna and Deri sectors of Rajasthan host several volcanogenic massive sulphide prospects. The massive sulphide ore body at Danva is enveloped by hydrothermally altered volcanic rocks containing sulphide-bearing stock work mineralization. Geochemistry of the unaltered metavolcanics indicate that they are basalts with calc-alkaline affinity. The main types of hydrothermillly altered rocks are quartz-biotite schist, quartz-biotite-sericite schist and quartz-sericite schist.Mass balance studies indicate marginal and significant gains of SiO2, H2O and K2O during the processes of biotitization and sericitization. Na and Ca show strong depletion. The iron oxides, in general, record marginal to heavy depletion whereas sulphur is significantly added during the hydrothermal activity. It is suggested that Au has largely been mobilized during sulphidation process.
Keywords
Economic Geology, Volcanogenic Massive Sulphide, Cu-Zn-Au, Wall Rock Alteration, Delhi Supergroup, Rajasthan.- The Ninth International Kimberlite Conference, Frankfurt, Germany
Authors
1 Geological Society of India, Bangalore, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 72, No 6 (2008), Pagination: 837-840Abstract
No abstract.Full Text
- Igneous Petrology: 21st Century Perspective
Authors
1 AMSE Wing, Geological Survey of India, Bangalore, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 72, No 4 (2008), Pagination: 574-575Abstract
No Abstract.Full Text
- Training in Diamond Exploration
Authors
1 Bangalore, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 71, No 4 (2008), Pagination: 453-458Abstract
No Abstract.Full Text
- Occurrence of Fullerene Bearing Shungite Suite Rock in Mangampeta Area, Cuddapah District, Andhra Pradesh
Authors
1 Geological Survey of India, Seminary Hills, Nagpur, IN
2 Stanford University, San Fransisco, US
3 Pune University, Pune, IN
4 Cihergen Biosystesms, San Fransisco, US
5 Geological Survey of India, Hyderabad, IN
6 Geological Survey of India, AMSE Wing, Bangalore, IN
7 National Geophysical Research Institute, Hyderabad - 500007, IN
8 Seminary Hills, Nagpur, IN
9 Geological Survey of India, Jaipur, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 69, No 1 (2007), Pagination: 25-28Abstract
The black carbonaceous slates, interbedded within the Proterozoic volcano-Sedimentary sequence of Cuddapah Supergroup in the vicinity of Mangampeta are found to the fullerene bearing and belonging to the shungite suite of rocks. Presence of fullerene in powdered rock samples is identified from the characteristic spectra obtained by laser desorption/Ionization spectrometry. This is further confirmed by making soxhlet extract using toluene and exposing it to different laser powers to avoid any possibility of it being analytical artifact. Both carbon allotrope fullerene C60 and C70 are identified within these rocks. Two geological samples collected from the prominent rock units within this thick sequence of black carbonaceous unit belonging to the shungite suite of rock are found to have fullerenes. This reporting of fullerene is first of its kind from any geological material from India. The only other occurrence of fullerenes in geological samples is recorded from the Shunga locality of the Karelean province of Russia.Keywords
Fullerenes, Shungite, Carbonaceous Slate, Barite, Mangampeta, Cuddapah District, Andhra Pradesh.- Occurrence of Fullerene Bearing Shungite Suite in Mangampeta Area, Cuddapah District, Andhra Pradesh
Authors
1 Analytical Research Laboratory, Department of Polymer and Petroleum Engineering, MIT Engineering College, Kothrud, Pune - 411 038, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 71, No 4 (2008), Pagination: 590-591Abstract
No Abstract.Full Text
- Dehradun-2006: Proceedings of the Annual General meeting - 2005-2006
Authors
1 Geological Society of India, Bangalore - 560 019, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 69, No 1 (2007), Pagination: 183-191Abstract
No Abstract.- Chondritic Features in a Diamondiferous Rock, Ma Jhgawan, Central India: Implications for Diamond Genesis
Authors
1 Director, Geological Survey of India, Petrology Division, Eastern Regions, DK-6, Sector II, Salt Lake City, Kolkata - 700 091, IN
2 Geological Survey of India, PPOD Division, AMSE Wing, Bangalore - 560 078, IN
3 503/23-C MHADA Complex, Hiranandani, Powai, Mumbai - 400 076
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 69, No 4 (2007), Pagination: 863-864Abstract
No Abstract.Full Text
- Group Discussion on Kimberlites and Related Rocks of India
Authors
1 Bangalore, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 67, No 1 (2006), Pagination: 120-122Abstract
No Abstract.Full Text
- Petrology of the Kodomali Diatreme, Mainpur Area, Chhattisgarh, Central India: Implications for a Palaeozoic Orangeite Field
Authors
1 Geological Survey of India, PPOD Division, A M S E Wing, Bangalore - 560 078, IN
2 Geological Survey of India, EPMA Lab , Op P, H & HP, Faridabad - 12 1 001, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 68, No 1 (2006), Pagination: 19-34Abstract
Thc Kodomali body is one among the six pipes, reportedly of kimberlitic composition in Mainpur area, district Raipur, Chhattisgarh. It occurs within the Bundelt granitoid that is emplaced in the lower part of the Khariar/Pairi group of rocks. Recent age determinations have indicated that the Kodomali has intruded into Bundeli granitoids at about 500 Ma. The Kodomali diatreme exhibits a distinct macro crystal texture with coarse olivine occurring in a very fine grained groundmass made of diopside, phlogopite, spinel and secondary serpentine. Two generations of olivine occur in the rock. Macrocrystal olivine is distinctly xenocrystic whereas microphenocrystic olivine, which is zoned with more forsteritic cores than their margins, show chemical parameters suggestive of crystallization from a melt Fe-poor diopside and T1-rich, Al and Cr-Poor phlogopite constitute the bulk of the groundmass. Phlogopite cores are I richer in T1 and Al compared to rims and show crystallisation trends typical of orangaeites. Spinel group minerals (Magnesio-Chromite) occur as (1) coarse xenocrystic zoned grains with T1 poor, Al and Mg rich cores relative to the rims and (11) as line size grains in groundmass. Some coarse spinel group mineral grains are enveloped by corona of sphene against macrocrystic perovskite, inferred to result from low temperature hydrothermal alteration through interaction with Si-Bearing fluids. Groundmass spinel, also represented by magnesian chromite, is sparse, has no perceptible zoning and exhibits T1- magnetite crystallization trend that is charactenstic of orangeites. The petro-Mineralogical attributes of the Kodomali diatreme show close affinities with the South African orangeites. Recent studies on another diatreme in the area is also suggestive of an orangeitic affinity for the rock. These studies imply that the Mainpur area represents an orangeitc field of Palaeozoic age.Keywords
Kimberlite, Orangeite, Petrography, Mineral Chemistry, Khariar, Pairi, Kodomali, Mainpur, Chhatisgarh.- Proposed Group discussion on Kimberlites and Related Rocks of India
Authors
1 Geological Society of India Bangalore - 560 019, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 65, No 2 (2005), Pagination: 252-253Abstract
No Abstract.Full Text
- Lamprophyre Dykes in Chotanagpur Gneissic Comlex, Near Simdega, Gumla District, Jharkhand
Authors
1 Geological Survey of India, Central Zone, AMSE Wing, Ranchi, IN
2 Geological Survey of India, AMSE Wing, 40th Cross, Eshwar Nagar, Bangalore - 560 078, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 63, No 6 (2004), Pagination: 655-658Abstract
Lamprophyre dykes are reported from the Precambrian metamorphites of the Chotanagpur Gneissic Complex near Simdega, Gumla district, Jharkhand. Petrological and petrochemical studies indicate that they are calc-Alkaline lamprophyres. The economic significance of these lamprophyres is discussed in light of their proximity to (i) the gold prospects in its strike continuity and (ii) reported occurrences of diamonds in the major drainage basins of the region.Full Text
- Auriferous Formations and Gold Exploration
Authors
1 AMSE Wing, GSI, Bangalore, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 64, No 5 (2004), Pagination: 708-709Abstract
No Abstract.Full Text
- Applied Geochemistry in the coming Decades
Authors
1 AMSE Wing Geological Survey of India Bangalore, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 61, No 4 (2003), Pagination: 500-501Abstract
No Abstract.Full Text
- Explanatory Booklet on the Geological Map of the Limpopo Belt and its Environs (1:500,000)
Authors
1 AMSE Wing, Geological Survey of India, Bangalore, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 59, No 6 (2002), Pagination: 586-587Abstract
No Abstract.Full Text
- Chondritic Features in a Diamondiferous Rock, Majhgawan, Central India: Implications for Diamond Genesis
Authors
1 Geological Survey of India, AMSE Wing, Vasudha Bhavan, K S layout, Bangalore - 560 078, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 68, No 5 (2006), Pagination: 743-760Abstract
Majhgawan, on the southeastern margin of the arc shaped Bundelkhand craton and within the Mesoproterozoic Vindhyan basin in Central India hosts the only diamond producing mine in India. Variously classifieds ultramafite, agglomeratic tuff, kimberlite, lamproite, orangeite, serpentine rock, a transitional rock etc the host rock for diamond, comprising mainly ultramafic breccia, and exposed in an elliptical outcrop pattern, shows significant differences in bulk chemistry and mineral compositions with other known kimberlites and related rocks of India. It shows textural features suggestive of crater facies volcanic eruption.Several distinctive and hitherto unreported features of shock metamorphism in olivine such as parallel fractures, planar deformational features (PDFs), shock mosaicism, arrested mineral melts, veinlets of rock melts, mixed melts, spherules and darkened silicates have been documented, recording up to S6 stage of shock metamorphism and shock pressures > 45 Gpa. These shock metamorphic imprints as well as the presence of variety of features bearing starting resemblance to the chondrites suggest that the Majhgawan ultramafic breccia contains traces of chondritic components in it. Though it is Interpreted here that the Majhgawan body is a result of a billion year old, impact triggered eruption of mantle material, which has incorporated the surface remains of the chondritic matter, clearly much more study is called for on these lines to understand the textural and mineralogical complexities exhibited by the Majhgawan rocks. It is argued that the difficulty in providing a descriptive classification for this rock within the framework of the IUGS schemes for terrestrial rocks is attributed mainly to its identifications simple rock akin to the known diamondiferous primary sources. Some new thoughts on the genesis of the diamonds In the light of these findings are also touched upon.
Keywords
Shock Metamorphism, Kimberlites, Lamproites, Chondrules, Meteorite, Diamonds, Vindhyans, Majhgawan, Panna, Madhya Pradesh.- Evolution of Continental Lithosphere - A Bottom-Up View
Authors
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 72, No 3 (2008), Pagination: 439-440Abstract
No Abstract.Full Text
- Journal of Asian Earth Sciences-Special Issue on Alkaline and Carbonatitic Magmatism and Associated Mineralization, Part II
Authors
1 AMSE Wing, Geological Survey of India Bangalore - 560 078, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 60, No 2 (2002), Pagination: 233-234Abstract
No Abstract.Full Text
- Economic Mineralization
Authors
1 Geological Survey of India, AMSE Wing, Bangalore - 560 078, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 75, No 2 (2010), Pagination: 439-440Abstract
No Abstract.Full Text
- Tourmaline as Metallogenic Indicator: Examples from Paleo-Proterozoic Pb-Zn and Cu-Au Deposits of Rajasthan
Authors
1 Geological Survey of India, PPOD Division, RSAS Wing, Kumaraswamy Layout, Bangalore - 560 078, IN
2 Geological Survey of India, Training Institute, Jaipur, IN
3 Geological Survey of India, Operations Rajasthan, Jaipur, IN
4 Geological Survey of India, WZ, RSAS, Jaipur, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 76, No 3 (2010), Pagination: 215-243Abstract
Petrology and mineral chemistry of ten types of tourmalines from Pb-Zn bearing strata-bound exhalative deposits and Cu-Au-Fe deposits, presumably of IOCG-type, from Rajasthan are presented. The Pb-Zn deposits studied include Agucha, Kayar and Dariba areas in central Rajasthan, each of which is widely separated in space and occurs in isolated but coeval basins within the Archaean basement. The Cu-Au deposits include Ghagri, Bada Talav, Dugocha and Bhukia areas in southeast Rajasthan. The syngenetic Pb-Zn type and the epigenetic Cu-Au-Fe type of deposits are formed during the initial phase of Paleoproterozoic Aravalli Basin evolution with dominant deposition of shelf facies pelite-carbonate sequence of Debari Group. The post-depositional tectono-metamorphic history of the host rocks of Pb- Zn type and Cu-Au type deposits differ significantly with the former deposits showing higher metamorphic impress (amphibolite to lower granulite facies) than the latter (green schist facies).
This study suggests that tourmalines on individual deposit scale exhibit both similarities and differences in optical and chemical features that are in accordance to their bulk host mineral assemblages. But on individual belt-scale, despite significant differences in the post-depositional metamorphic alterations, there is an overall chemical similarity of tourmalines that suggests prevalence of similar hydrothermal conditions during the formation of the tourmalines of individual deposits in each of the Pb-Zn and Cu-Au belts. In many of the discriminant diagrams using the critical elements, the tourmalines of these two belts maintain a distinct identity and assert their role as metal-type indicator in contemporaneous (Paleoproterozoic) deposits formed in different hydrothermal conditions.
This study also tests the reported role of tetrahedral alumina (Aliv) and X-site vacancies (X£) in the tourmaline in indicating the grade of metamorphism of the host rocks. Whereas this study confirms the assertions regarding the covariance of Aliv with respect to the grade of metamorphism in calcareous and metapelitic sediments, the same assertions could not be made in respect of X£ for the tourmalines from different ore deposits of Rajasthan. The latter is attributed to the diffusion of Na in the tourmaline structure from the abundantly available Na+-rich host rocks (albitites) in a postore formation event.
Keywords
Tourmaline, Pb-Zn Ore Deposit, Cu-Au Ore Deposit, Stratabound, Evaporitic, Paleoproterozoic, Aravalli, Rajasthan.- Geology 0f Rajasthan (Northwest India) Precambrian to Recent
Authors
1 No. 1532, 14th Main Kumaraswamy Layout Bangalore - 560 075, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 60, No 6 (2002), Pagination: 718-719Abstract
No Abstract.Full Text
- Petrology, Geochemistry and Fluid Inclusion Studies of Cu-Au Mineralization in Paleoproterozoic Salumber-Ghatol Belt, Aravalli Supergroup, Rajasthan
Authors
1 Geological Survey of India, PPOD Division, SR, 40th Cross Eshwar Nagar, Bangalore - 560 082, IN
2 Geological Survey of India, Western Region, Jhalana Dungari, Jaipur - 302 004, IN
3 Geological Survey of India, AMSE Wing, West Zone, Jhanalana Dungari, Jaipur - 302004, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 80, No 1 (2012), Pagination: 5-38Abstract
The Salumber-Ghatol belt in Rajasthan, India, situated along southern margin of the Aravalli Craton, hosts a cluster of Cu-Au deposits in calcitic and dolomitic marbles that belong to Debari Group of the Paleo-mesoproterozoic Aravalli Supergroup. The Fe-Mn rich dolomitic marble of the Delwara Formation hosts Cu-Au-Fe-oxide mineralization at Ghagri and associated distal K-Fe-Mg rich altered rocks (cryptocrystalline microcline + magnesioriebeckite + magnetite + phlogopite) and proximal feldspathised carbonate rocks (medium grained albite + microcline + dolomite + magnetite). The calcitic marble of Mukandpura Formation hosts Dugocha Cu-Au deposit with development of distal graphite-tourmaline-bearing albitites and proximal albite-microcline-magnetite rocks. Calcite and dolomite carbonates of Bhukia region with development of albite-actinolite-bearing alteration assemblages host the largest of the Cu-Au deposits in this belt. The second generation folds and associated ductile-brittle shear zones of the multiply deformed events constitute conduits for the mineralizing fluids at all locations in this belt.
Carbon isotope data for the dolomitic marbles of Ghagri area suggest mixed isotopic signatures: (i) normal marine values close to zero per mil (mean= -0.269 ‰) and (ii) enriched positive values (mean= +4.04 ‰) akin to the 1.9 Ga global event of positive excursion. The calcitic marbles of Dugocha area have significantly depleted δ13C values that are interpreted to be the result of pervasive inter-mixing of isotopically distinct carbon derived from primary depositional carbonates, hydrothermally exchanged carbonates, with significant influence of the organic carbon. The petrographic distinction of calcitic and dolomitic marbles of Bhukia area is corroborated by δ13C values that show a bimodal distribution of near 0 per mil and depleted values of -3 per mil. Fluid inclusion studies suggest predominance of saline brines in the ore fluids. The δ13S values for all the three deposits are narrowly constrained between 10.4 and 15.1 ‰, which suggests a common metasedimentary source for sulfur.
Identical chondrite-normalized REE patterns and primitive mantle-normalized multi-element patterns suggest a common Na- and/or K-source for the formation of Ghagri and Dugocha-Bhukia feldspathic rocks. Based on mineralization styles and attendant alteration patterns, it is argued that the mineral deposits of Salumber-Ghatol belt in the Aravalli Supergroup (i) represent sedimentary carbonate-hosted Cu-Au deposits belonging to the wider class of Proterozoic Iron-Ore-copper-Gold type (IOCG-like) mineral deposits; (ii) the fluids responsible for the mineralization are generated from common sub-crustal source and (iii) during mineralization, the influx of Na-K-rich fluids is so intense that it created 'artificial' hyper-saline conditions in the normal depositional basin that facilitated crystallization of scapolite, brucite, spadaite, povondraite and phlogopite bearing mineral assemblage.
Keywords
Petrology, Carbonates, Copper, Gold, IOCG, Mineralization, Stable Isotopes, Salumber, Ghatol, Aravalli Supergroup, Paleoproterozoic, Rajasthan.References
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