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
Som, S. K.
- Ground Water Geochemistry of Recent Weathering at Panchpatmali Bauxite-Bearing Plateau, Koraput District, Orissa
Authors
1 Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur 721302, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 40, No 5 (1992), Pagination: 453-461Abstract
Recent weathering of Panchpatmali bauxite-bearing terrain, Koraput district, Orissa has been discussed in terms of groundwater geochemistry. pH and Eh are in favour of Fe (OHh development, whereas Na+ : Ca2+ vs. HCO3 : SiO2, HCO3 : SiO2 vs. ppm HCO) and pH -pNa, 2pH -pCa, pK-pH vs. -log [H4 Si04] are all in favour of kaolinite development with a minor amount of gibbsite. These observations have been confirmed by X.R.D., I.R., and S.E.M. of the recent weathered samples of the area. The condition of development of these mineral phases with respect to C02 has also been discussed.Keywords
Ground Water Geochemistry, Weathering, Bauxite, Koraput, Orissa.- Mineralogy of Panchpatrnali Bauxite Deposit Based on XRD, IR, DTA and SEM Studies
Authors
1 Geological Survey of India, Unit: VIII : Nayapalli, Bhubaneswar - 751 012, IN
2 Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur - 721 302, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 45, No 4 (1995), Pagination: 427-437Abstract
Mineralogy of bauxite profile, after khondalite parentage, at Panchpatmdi area, Koraput district, Orissa is studied by XRD, JR, DTA and Optical/electron microscopy. XRD shows thedominance of kaolinite in saprolite, whereas IR and DTA results confirm its presence in the entire profile. All the above studies confirm the strongly disordered nature of kaolinite. Gibbsite, geothite, hematite, diaspore and allophane are present in the entire profile with the intermittent occurrence of boehrnite, anatase, and futile. Microscopic investigation reveals poIycyclic crystalisation of gibbsite and ultimately resilicated to kaolinitevia dlophane. Transformation of alurninious parent minerals to gibbsite is direct without the intermediate kaolinite stage. Evidences are presented to show that gibbsites are later transformed to kaolinite due to ground water activities.Keywords
Bauxite, Mineralogy, Panchpatmali, Orissa.- Morphotectonic Evolution of the Laterite Profiles over Sukinda Ultramafics, Jaipur District, Orissa
Authors
1 Geological Survey of India, Opn.WB-S-A&N, 4, Chowringhee Lane, Calcutta 16, IN
2 Geological Survey of India, Unit:8, Nayapalli, Bhubaneswar 12, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 52, No 4 (1998), Pagination: 449-456Abstract
Sukinda ultramafic field of Jajpur district, Orissa is capped by thick lateritic duricrust. Two generations of laterite are inferred in the studied area. The older laterite (in situ) is capped by transported laterite (younger). The entire area is divided into two subareas (A1 and A2) Physiographically, three terraces are identified in A1 area, of which, the oldest one (T3) comprises of insitu lateritic hard crust. The other two terraces (T2 and T1) are made up of valley fill deposits, which are later lateritised. The area A2 shows the lateral continuity of T3 terrace of A1 area along with valley fill deposit of T1 terrace and the absence of T2 terrace. Drainage analysis show the A1 area is structurally more disturbed than A2 area. Correlation of geomorphological evolution and lateritisation indicates three stages of development in the A1 area. Lateritisation was initiated on a comparatively flat ground (T3 terrace) and subsequent destabilisation of the area developed the younger terraces (T2 and T1) with the modification of older laterite profile.Keywords
Geomorphology, Laterite, Morphometric Evolution, Sukinda, Orissa.- Geochemistry of Groundwater Over Sukinda Ultrabasic - Basic Rocks, Jajpur District, Orissa
Authors
1 Geological Survey of India, Opn. WB-S-A&N, 4, Chowringhee Lane, Calcutta 700 016, IN
2 Geological Survey of India, Opn. Orissa, Unit: 8; Nayapalli, Bhubaneswar 751012, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 54, No 1 (1999), Pagination: 73-81Abstract
The geochemistry of groundwater over Sukinda ultrabasic - basic rocks, Orissa, covering an areat extent of about 50 km2, has been investigated to understand the hydrogeology of the area. The dominant geochemical processes were interpreted from geochemical data and mass balance calculations. The entire study area contains two broad lithounits comprising ultrabasic rock at the centre and metabasics at eastern and western flanks, with a general groundwater flow pattern from east to west. The groundwater in the area is fresh, meteoric in origin with high Na, Kover metabasics as well as the northern part of the ultrabasic rock, and high Mg, HCO3- and TDS over the remaining ultrabasic rock. Mineral solubility study of Mg- phases present in the system shows that the present day geochemical conditions are not suitable for Mg2+ precipitation and most likely, serpentine is the dominant Mg2+ contributer in the system. Mass balance calculations based on mixing ratio along the E-W flow path show that K and to some extent Na behave conservatively in the evolution of groundwater. The conservative mixing model presented here evaluates the formation of secondary mineral phases along the flow path.Keywords
Geochemistry, Groundwater, Mass Balance Calculation, Sukinda, Orissa.- U, Th Enrichment in Cesium Bearing Aplitic Pegmatite of Belamu (North) Area, Purulia District, West Bengal with Special Reference to Monazite Group of Minerals
Authors
1 Earthquake Geology Division, Geological Survey of India, Eastern Region, DK Block, Sector-II, Salt Lake City, Kolkata-700091, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 71, No 2 (2008), Pagination: 229-238Abstract
Celsium bearing aplitic pegmatites ot Chhotanagpur Gneissic complcx Purulia district. West Bengal show enrichment in U and Th through at least one phase of lanthanide actinide rich hydrothermal activity. Monazite group of minerals with Th and REE are hosted by the aplitic pegmatites with varying texture and composition. Monazite(Ce) occurs as inclusions within quartz and feldspar with evolutionary trcnd from huttonitic monazite at core to monazite (Ce) at rim Ce/Sm ratio varies from 8 11 to 25 67 representing a wider evolutionary trend of the melt from which monazite crystallized. Principal component analysis shows different subsitution phenomenon in monazite. Chemical variations indicate the huttonitic monazite to be a primitive component which was transformed to monazite (Ce) by interaction with LREE P-rich fluid.Keywords
Aplitic Pegmatite, Cesium REE, Cheralite, Monazite, Chhotanagpur, Gneissic complex, Belamu Purulia, District West Bengal.- Macroseismic Survey of Sikkim Earthquake, 14th February, 2006
Authors
1 Earthquake Geology Division, Geological Survey of India, Eastern Region, DK-Block, Sector-II, Salt Lake City, Kolkata - 700 095, IN
2 Earthquake Geology Division, Map Division, Geological Survey of India, Eastern Region, DK-Block, Sector-II, Salt Lake City, Kolkata - 700 095, IN
3 Earthquake Geology Division, TC-1 Division, Geological Survey of India, Eastern Region, DK-Block, Sector-II, Salt Lake City, Kolkata - 700 095, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 71, No 4 (2008), Pagination: 541-550Abstract
A moderate earthquake struck the Sikkim Himalaya on Tuesday, February 14, 2006 at 6.25 am. The earthquake was felt in North Bengal, Sikkim,nepal and Bhutan. Macroseismic survey was carried out for the accessible regions of Sikkim and the northern portion of West Bengal to assesses the intensity of ground motion, the damage caused by the earthquake and also to ascertain the possible source and its orientation.
The survey results show that the MSK (Medvedev-Sponheuer-Karnik) intensity varies between III to VII. The maximum intensity is found in Gangtok-Deorali-Tadonga areas, which are far from the instrumental epicenters identified by USGS and IMD. Statistical procedure has been adopted for numerical weighted intensity calculation to quantify the MSK intensity and for deducing the isoseismal lines more logically. Separate macroseismc epicenter is calculated from the high MSK- intensity sites, which falls in between Deoralt and Tadong. The probable orientation of the source (fault) is found to be E-W that passes through Makha village, north of Gangtok area. The damages to constructions on the terraces is much less than those constructed on other topographic forms, like slopes, ridges and low zones. Within the most damaged Gangtok-Deorail Tadong areas, most of the buildings are located along the ridge top or along the ridge axis.
Keywords
Earthquake, Macroseismic Survey, Sikkim.- Cesium Enrichment and Resource Evaluation in Aplite and Pegmatite at the Southern Slope of Belamu Hill, Purulia District, West Bengal
Authors
1 Earthquake Geology Division, Eastern Region, DK-Block, Sector-11, Salt lake City, Kolkata - 700 091, IN
2 H R D Division, 27, J L Neheru Road, Kolkata - 700 016, IN
3 Ranchi Institute, Ranchi Centre, 433 A, Road No 5 , Ashoknagar, Ranchi - 834 002, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 70, No 2 (2007), Pagination: 273-281Abstract
The cesium bearing aplite and pegmatite in the southern slope of Belamu hill occur in association with calc-Silicate and granite gneiss country rocks of Chhotanagpur Gneissic Complex (CGC). The hydrothermal units are highly peraluminous and tectonically disturbed in which, cesium is mainly incorporated within pollucite and Li-Muscovite Rb/Sr shows sympathetic relationship with cesium having a strong correlation towards the higher end for both aplite and pegmatite. Cesium resource evaluation by ground survey and shallow drilling has been done for aplite and pegmatite. Reserves and grades established for both aplite and pegmatite have shown concoidance with the statistical laws of distribution, suggestive of productive output.Keywords
Cesium, Aplite, Pegmatite, Chhotanagpur Gneissic Complex, Belamu, West Bengal.- Ni-Enrichment and Mass Balance in Sukinda Laterites, Jajpur District, Orissa
Authors
1 Geological Survey of India, Op. WB-S-A&N, GSI Office Complex, DK-Block, Sector II, Salt Lake City, Kolkata -700 091, IN
2 Geological Survey of India, Op. U.P., Vasundhara, Sector-E, Aligunj, Lucknow - 226 024, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 62, No 2 (2003), Pagination: 169-180Abstract
Weathering of serpentinite from Sukinda area, Orissa is studied from a series of lateritic profiles to understand the behaviour of nickel concentration at different parts of the regolith column. The area shows development of laterite profile of variable thickness. Fresh parent rock (serpentinite) is not exposed. Petro-chemical studies show that Ni is concentrated within nepouite and kerolite in partially altered serpentinite, whereas it is mainly in goethite and partly in Mn- oxides within saprolite horizon and negligible in top in situ laterite. Volumetrically, Ni-substituted goethite is more significant for exploration than Ni-substituted Mn-oxides. In the absence of fresh parent rock, methods such as normalization of chemical elements and calculation of mass balance relations between density and chemical elements are adopted, based on the mean element content of the profile. Application of these methods with studied samples clearly discriminate the residual and supergene behaviour of Ni in laterite column.Keywords
Chemical Weathering, Laterite, Mass Balance, Ni-Concentration, Sukinda, Orissa.- GPS Derived Co-Seismic and Post-Seismic Effects of Recent Earthquakes on Peninsular Indian Shield and its Tectonic Implications
Authors
1 Earthquake Geology Division, Geological Survey of India, Salt Lake City, Kolkata - 700 091, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 76, No 5 (2010), Pagination: 485-492Abstract
Several major earthquakes affected the stable continental Indian peninsular shield in recent past due to the activity of fault movements. This necessitates identifying the active faults in the region for future monitoring. The far field co-seismic and post-seismic effects of recent major earthquakes occurred at Sumatra, 2004, Pakistan, 2007 and Indonesia, 2007 on HYDE and IISc IGS GPS stations were studied by small span GPS analysis. Different type of movement pattern on displacement components ensure the reactivation of existing fault planes signifying an integral relationship between GPS displacement vectors and geological structure of the region.Keywords
GPS, Active Fault, Earthquake, Peninsular India.- Li-Cs-Rb Mineralisation in Proterozoic Zoned Pegmatites of Beku, West Bengal
Authors
1 Geological Survey of India, Op. WB-S-A&N, GSI Office Complex, DK-Block, Sector 11, Salt Lake City, Kolkata -700 091, IN
2 Geological Survey of India, Zorem building, Nongrim Hills, Shillong - 793 003, IN