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Roonwal, G. S.
- 10th International Geochemical Exploration Symposium and Third Symposium on Methods of Geochemical Prospecting
Abstract Views :274 |
PDF Views:133
Authors
Affiliations
1 Department of Geology, University of Delhi, IN
1 Department of Geology, University of Delhi, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 25, No 5 (1984), Pagination: 318-322Abstract
No Abstract.Full Text
- Geochemical Indicators for Concealed Cu-Zn-Pb Mineralization in Rajpura, Udaipur, Rajasthan
Abstract Views :155 |
PDF Views:93
Authors
G. S. Roonwal
1,
Aneel Kumar
1
Affiliations
1 Department of Geology, University of Delhi, Delhi, IN
1 Department of Geology, University of Delhi, Delhi, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 29, No 3 (1987), Pagination: 358-361Abstract
Geochemical analysis of 73 rock samples collected from Rajpura 'B' and 'C' blocks has been carried out for 6 major (Fe, Mn, Mg, Ca, Na and K) and 8 minor (Cu, Zn, Pb, Ni, Ag, Cr, Co and Ti) elements. The results indicate anomalous geochemical patterns. Majority of the samples collected from gossan unit show more than 1000 ppm concentration for Pb, Zn and 500 ppm Cu. In calc-silicate-bearing-dolomite (CSD) and recrystallized-siliceous-dolomite (RSD), Pb-Zn-Cu values seldom reach 1000 ppm but they are of importance due to high mutual correlation. The correlation between different trace elements indicates that there exists a positive correlation between elements Cu-Zn-Pb-Ni-Co and antipathetic relationship between these elements and Ag and Cr. The elemental dispersal is controlled by their relative mobilities in an environment which is secondary, acidic and oxidizing.
The study shows that CSD and RSD are suitable lithounits for mineralization with former being favourable for Cu-Zn and latter for Pb and Zn. Mineralization in graphite-mica-schist (GMS) unit is likely to be confined to weak fracture zones.
Full Text
- Observations on Some Manganese Nodules from the Central Pacific
Abstract Views :173 |
PDF Views:2
Authors
Affiliations
1 Department of Geology, University of Delhi, Delhi 110007, IN
1 Department of Geology, University of Delhi, Delhi 110007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 30, No 3 (1987), Pagination: 227-235Abstract
Manganese nodules have been studied under the microscope with the use of reflected light and scanning electron microscope. Around the nucleus accretion of the diagenetically derived material is seen to take place giving rise to columnar or dendritic texture. Away from the nucleus textural variation and abrupt discontinuity in the nodule growth is observed indicating changes in depositional characteristics of ferromanganese oxides as the nodule grew. The intermingling of manganese oxides and silicate minerals, and sometimes iron oxides is common, generating discontinuities within the nodule texture. Scanning electron microscopic observations indicate that the material deposited on the surface is crystalline, non-crystalline, inorganic. organic or detrital in nature giving rise to different surface features such as botryoidal, consolidated compact layering or unconsolidated porous surface appearance.
- 'Pahar' - (In Hindi)
Abstract Views :239 |
PDF Views:129
Authors
Affiliations
1 Department of Geology, University of Delhi, Delhi 110 007, IN
1 Department of Geology, University of Delhi, Delhi 110 007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 31, No 1 (1988), Pagination: 180-180Abstract
No Abstract.Full Text
- Notes
Abstract Views :172 |
PDF Views:123
Authors
Affiliations
1 Department of Geology, Delhi University, Delhi, IN
1 Department of Geology, Delhi University, Delhi, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 32, No 2 (1988), Pagination: 153-155Abstract
No Abstract.Full Text
- Hot Vents and Massive Sulphide Bodies on the Southern Parts of the East Pacific Rise (EPR) Seafloor Spreading Centres: Geometep-4
Abstract Views :161 |
PDF Views:2
Authors
Affiliations
1 Department of Geology, University of Delhi, Delhi 110007, IN
1 Department of Geology, University of Delhi, Delhi 110007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 33, No 5 (1989), Pagination: 419-428Abstract
New ore bodies of sulphide on the diverging plate boundaries on the East Pacific Rise were discovered during the German Expedition Geometep-4 in the South Pacific. The marine sulphides occurring along the rift system are attributed to large-scale hydrothermal circulation through the fractured volcanic rocks on the seafloor. Such hydrothermal plumes in contact with basalt, result in leaching of metals and their subsequent reconcentration and deposition. Certain transition metals such as Cu Zn Fe get concentrated in the form of disseminated, stockwork particulate deposits that may hold commercial value. The occurrence of these deposits on the seafloor can be traced by certain geological, geophysical and biological tools.- In-Situ growth of Authigenic Minerals and Micronodules in Some Pelagic Sediments from the Central Pacific
Abstract Views :185 |
PDF Views:2
Authors
Affiliations
1 Department of Geology, University of Delhi, Delhi 110007, IN
1 Department of Geology, University of Delhi, Delhi 110007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 34, No 6 (1989), Pagination: 647-650Abstract
Sediment samples from NS Transect in the Central Pecific Ocean, comprising the Areas C. D. F and G investigated with the help of scanning electron microscopy reveal in-situ formation of several authigenic minerals within pelagic sediments, which affect their surface texture and morphology. Zeolite crystals developed in-situ are noted in the siliceous ooze in the north equatorial Pacific (Area C). Micronodules with well developed initial growth lines, formed authigenically are commonly observed in the siliceous debris-rich calcareous ooze of south equatorial Peciflc (Area F). Quartz and feldspars of detrital origin are also found in the sediment. Dissolution of biogenic debris is noted in them. However. undissolved radiolarian oozes are common particularly in the sediments from south Pacific. Authigenic phillipsite needles are identified in the sediments from Area G which falls within the Marquesas Fracture Zone.- Clay Mineralogy of the Pelagic Sediments: Along a West-East Transect in the Indian Ocean
Abstract Views :236 |
PDF Views:1
Authors
Affiliations
1 Department of Geology, University of Delhi, Delhi 110 007, IN
1 Department of Geology, University of Delhi, Delhi 110 007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 38, No 1 (1991), Pagination: 37-54Abstract
The clay fraction of the sediments contain illite, chlorite, kaolinite, montmorillonite and iron-smectite with minor amounts of goethite. The siliceous sediments contain both montmorillonite and iron-smectite, while the calcareous sediments show only montmorillonite. This suggests that montmorillonite is formed by the alterations of ridge basalts, palagonite and volcanic glass. Iron-smectite is probably formed during low temperature diagenesis by the chemical combination of iron and silicon. High biogenic sedimentation in the calcareous sediments inhibited the formation of iron-smectite.Keywords
Clay Mineralogy, Pelagic Sediments, Indian Ocean.- Environmental Management of Indian Eez
Abstract Views :168 |
PDF Views:137
Authors
John Yates
1,
G. S. Roonwal
2
Affiliations
1 University of Manchester, GB
2 University of Delhi, Delhi, IN
1 University of Manchester, GB
2 University of Delhi, Delhi, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 44, No 6 (1994), Pagination: 694-694Abstract
No Abstract.Full Text
- B. L. Dhar (1946-2007)
Abstract Views :172 |
PDF Views:155
Authors
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 71, No 2 (2008), Pagination: 300-300Abstract
No Abstract.Full Text
- Marine Minerals in the Indian Ocean
Abstract Views :164 |
PDF Views:3
Authors
Affiliations
1 Department of Geology, University of Delhi, Delhi 110 007, IN
1 Department of Geology, University of Delhi, Delhi 110 007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 34, No 2 (1989), Pagination: 182-191Abstract
It is apparent that while knowledge of distribution of marine mineral resources. in the Indian Ocean has increased substantially over the last decade, actual production is restricted to placer, precious stones and aggregates, as well as to salt and chemicals. from seawater. The anticipated development of deep-sea minerals such as manganese nodules has not taken place and is unlikely to do so in the forseable future. One reaSOD is the lack of information for the proper evaluation of marine minerals. There is considerable scope for the systematic survey of both the EEZ as well as the deeper parts of the ocean to make a realistic assessment of the mineral resources and the development of technology for their eventual recovery.- Petrography and Mineral Chemistry of Neovolcanics Occurring Between Pacific and Nazca Plate Boundaries
Abstract Views :187 |
PDF Views:0
Authors
Affiliations
1 Department of Geology, University of Delhi, Delhi - 110 007, IN
1 Department of Geology, University of Delhi, Delhi - 110 007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 74, No 5 (2009), Pagination: 559-572Abstract
Mid-Oceanic Ridge Basalt (MORB) samples collected from southern East Pacific Rise (SEPR) have been investigated. These highly phyric plagioclase basalts (HPPB) and moderately phyric plagioclase basalts (MOPB) show rare cumulate and vitrophyric textures with plagioclase (>10% as phenocryst) and abundant glass (>72%). Electron Probe Micro Analysis (EPMA) showed large compositional variations in the megacrysts as well as microcrysts of plagioclase (An62 to An82), olivine (Fo78 to Fo87), pyroxene (ferroaugite to augite) and iron oxides, mostly titaniferous magnetite. Olivine grains show high Mg# (>80%) and distinctly low in NiO (0.01-0.2%). Ferroan trevorite (NiO = 16.22 and FeO(t) = 83.06) a characteristic meteoritic mineral has been identified from the olivine megacrysts of MORB, possibly attributed to Ni-enrichment, resulted from heterogeneity of the lower mantle. Wide range of An composition in plagioclase is indicative of large pressure range of crystal nucleation under decompression at a depth of ∼70 km (An82) up to the ocean spreading centre. Absence of zoning observed in all the minerals present in the MORB samples, possibly attributed to unmixing and dominant fractionation process.Keywords
Mid Ocean Ridge Basalt, Magmatism, Megacrysts and Microcryst, Ferroan Trevorite.References
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