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
Singh, S. L.
- Seismic Survey for Delineation of Shallow Structures in the 2001 Earthquake-Affected Areas of Anjar and Bhuj, Gujarat
Authors
1 Geological Survey of India, Western Region, Jaipur - 302004, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 70, No 5 (2007), Pagination: 824-828Abstract
Shallow seismic refraction survey (Hammer source) was carried out by Geological Survey of India in Kutch distinct Gujarat after the devastating i e earthquake of 26thJanuary 2001. The aim of the investigation was to delineate different lithological units based on their P-wave velocities In earthquake-Affected areas of Anjar and Bhuj. The seismic survey camed out over 17 locations in township areas of Anjar and Bhuj has reflected two to three layer structures. In both areas, the P-wave velocity of first layer vanes from 476 m/s 1067 m/s while the velocity of second layer vanes from 1091 m/s to 1892 m/s. The third layer exhibits the velocity ranging from 1818 m/s to 4865 m/s. The first layer corresponds to loose soil, second layer to compact soil/weathered rock and third layer to weathered/bedrock.The depths given by two boreholes drilled in both areas of study are in excellent agreement with those obtained by seismic survey conducted at borehole locations. This lends additional credence to geophysical results obtained in the area. According to layer parameters deduced from shallow seismic survey, the foundation of houses in earthquake affected areas should be below first interface/or in second layer i e compact soil/weathered rock to be safer.
Keywords
Seismic Surveys, Shallow Structures, Layer Parameters, Anjar And Bhuj, Gujarat.
- Mise-A-La-Masse Technique in Planning the Exploratory Drilling for Basemetal Exploration in Sawar Belt, Ajmer District, Rajasthan
Authors
1 Geological Survey of India, Northern Region, Lucknow - 226 024, IN
2 Geological Survey of India, Western Region, Jaipur - 302 004, IN
3 Geological Survey of India, A M S E Wing, Bangalore - 560 078, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 67, No 1 (2006), Pagination: 83-91Abstract
A small deposit of lead and zinc was established in southern part of Sawar metasedimentary belt during third phase of drilling. The Mise-A-La-Masse survey, a post discovery geophysical method carried out in the boreholes of this belt has yielded significant results. This method has been useful in delineating the subsurface disposition of mineralised zones and their lateral extension. This technique is also successful in the area in establishing correlation between different parts of an ore body with varying sulphide percentage, which are located distantly but are in electrical continuity. Hence the Mise-La-Masse method has been of immense help in planning the boreholes thereby optimizing drilling cost in the Sawar Belt. The composite map of equipotential line and chargeability contour has indicated that the contour pattern and disposition of anomaly axes are similar in both the cases.Keywords
Mise-A-La-Masse Survey, Pb-Zn Mineralised Zone, Composite Map, Sawar Metasedimentary Belt, Ajmer District, Rajasthan.- Induced Polarisation in Search of Lead-Zinc Mineralisation in Sawar Belt, Ajmer District, Rajasthan
Authors
1 Geological Survey of India, Northern Region, Lucknow - 226 020, IN
2 Department of Geophysics, Banaras Hindu University, Varanasi - 221 005, IN
3 Geological Survey of India AMSE Wing, Bangalore - 560 078, IN
4 Geological Survey of India Western Region, Jaipur - 302 004, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 68, No 2 (2006), Pagination: 213-224Abstract
Lead-zinc mineralisation in Sawar metasedimentary belt is essentially sediment-hosted type it is of Proterozoic age and occurs in the two-carbonate members of Sawar group lnduced Polansation cum resistivity survey has delineated 22 anomaly zones located in lower marble, lower schist and upper marble and at the mutual contacts formed by these different litho-units of Sawar group Out of these, eight zones have been drill tested proving mineralisation and the remaining 14 zones in the area are yet to be tested Drilllng results in the area have clearly indicated that there is a fair correlation between induced polarisation cum resistivity anomalies and mineralised zones intersected in the different boreholes.
Induced Polarisation cum resistivity pseudo depth sections constructed in few zones located over different rock units have established depth persistence of inferred shallow conductors The resistivity survey has demarcated the contact of different litho-units of Sawar group occuring in the area even under soil cover The lithocontacts inferred from resistivity data coincide fairly accurate with extrapolated geological contacts The Interpretation of induced polarisation and resistivity pseudo sechons by inversion technique has brought the model and its geometry, whch compares well wlth the subsurface geology The resistivity model correlates the measured and calculated apparent resistivity pseudo sections The chargeability model also corroborates these inferences.