[en] Abnormally radioactive granitoids are targets of uranium exploration because they can be the source for uranium deposits as well as the hosts. Significant uranium mineralization is known to occur northwest of Suryamalai granite batholith at Kullampatti situated 40 km southwest of Salem. This paper embodies the geophysical exploration for uranium, using results of magnetic and radiometric methods. The investigations revealed that uranium mineralization is structurally controlled and such structures have magnetic expression. Incidentally, correlation of anomalous content of W with U is also brought to light. (author)

[en] In this paper the results of airborne gamma ray spectrometric surveys over 1100 sq. km of area (Survey of India toposheet nos. 64 D/10 and 14) in Rajnandgaon District of Madhya Pradesh, India are presented. The area surveyed forms part of Dongargarh Super Group. Bodal and Bhandaritola uranium prospects are located within this area. Uranium mineralisation in these prospects occurs in metabasics, metarhyolites and/or quartz porphyry and is practically free from thorium. As per the analysis of some rock samples from Bodal area thorium values are elevated compared to uranium values in all rock types with the exception of mineralised amphibolites. The airborne spectrometric data is presented in the form of total radioactivity anomalies plotted on the flight path indicating for each anomaly the respective half-width, intensity in counts/sec. of total channel and contribution from uranium, thorium and potassium qualitatively estimated from the flight data. Narrow belt of about 20 km x 2.5 km having predominantly uranium anomalies has been delineated from the airborne data in contrast to the thoriferous anomalies in the rest of the area as recorded in these surveys. This well defined belt comprising of granite, metarhyolite and pegmatites is considered to be a good target for uranium exploration, which is trending NW-SE and is located about 5∼7 km southwest and south of Bhandaritola-Bodal axis. (author). 1 table, 11 refs

[en] Geophysics is an integral part of most uranium exploration programmes. In India, the induced polarisation technique is being widely employed to locate buried uranium bearing horizons which are associated with sulphides. The inherent drawback with this method has been its inability to demarcate the target occurring in adverse topographic conditions. In this paper, a case is chosen from Arbail, India to explain the importance of dynamic parameters computed from the IP transient decay curves to define the ore bearing horizons precisely. (author). 8 refs., 6 figs

[en] Natural Thermoluminescence (NTL) study of whole-rock samples from a bore hole at Jublatola, Singhbhum, Bihar, revealed that different rock types such as quartzite and schist give glow peaks at markedly different temperatures, a feature which can be made use of for a broad classification of rock types. Even in the same major rock type like schist, sub-classification based on variation in the content of different constituent minerals is possible due to distinct differences in the glow peak temperature. In a given rock type, the intensity of NTL shows a marked increase over a known radioactive horizon, and a similar increase may be taken as an aid in the location of radioactive ore bodies. Such significant observation from an unknown is interpreted as due to nearby potential sources not intercepted by the bore hole, thus emphasizing the meaningful role of the technique in uranium exploration. (Auth.)

[en] In India, Madhya Pradesh is one of the important provinces known for uranium and other poly-metal occurrences. In this paper a comprehensive study of airborne magnetic and gamma-ray spectrometric results over parts of Madhya Pradesh and contiguous areas in Maharashtra is attempted with an aim to refine the known geological information and to suggest promising areas for uranium exploration. Tectonically the area under study assumes great significance as it has undergone several orogenies covering a wide chronological spectrum and is marked by the trans-Chhatisgarh Aeromagnetic Lineament characterising a cryptic suture zone. Anomalous concentration of radioactive minerals along the eastern contact of Sakoli rocks which is tectonised, zones of varying levels in the radioactive minerals over the Dongargarh granite, major magnetic lineaments sub-parallel to the trans-Chhatisgarh Aeromagnetic Lineament are the salient features of this terrain. 24 refs., 5 figures. (author)

[en] The application of non-radiometric geophysical methods like magnetic, electrical resistivity, induced polarisation, electromagnetic and seismic for uranium exploration has been discussed by many workers. In thispaper it has been demonstrated that the self-potential technique which is simple, fast and cheap can also be effectively and meaningfully employed. For this purpose, a case study from Arbail (Lat 14⁰, 50' 40'', Long 74⁰ 38' 25''), India where uranium mineralisation is known to occur in association with sulphides, is presented. The method of downward continuation is used to estimate the depth to the top of the target and the results thus obtained are correlated with the data obtained from subsequent borehole drilling. (author)

[en] Studies have shown the induced polarization (IP) technique to be among those geophysical methods which have yielded the most consistent results in identifying favourable localities for uranium mineralization. A case history is presented of a time-domain IP survey that was carried out at Arbail (latitude 15⁰ 50' 40'' north, longitude 74⁰ 38' 25'' east), near Belgaum, northern Karnataka, India, where uranium mineralization has been reported to occur with pyrite in meta-arenites. (author)