November, 2025 || Volume 29 No.06
Volume 29(6) (2025)6-6
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1
Appraisal of potential mineralization in the Wajrakarur kimberlite field, India: New insights from recent geophysical studies
R. B. Singh1*, S. Bangaru Babu1 and Birendra Pratap2
1Geological Survey of India, Hyderabad, India- 500 068
2Department of Geophysics, Banaras Hindu University, Varanasi- 221005, India.
https://doi.org/10.71122/JIGU.29(6)2025.0035
ABSTRACT
The study investigates the Bouguer Gravity (BGA) and magnetic anomalies (MA) in the Wajrakarur kimberlite field (WKF), located in Anantapur, Andhra Pradesh, India, an area well known for kimberlite exploration in the South Indian Kimberlite Province. The WKF is characterized by distinct gravity highs and lows between the Closepet Granites (CG) and the adjacently located Cuddapah Basin (CB). Notable gold-mineralized zones are found in the Ramagiri- Penakacherla Greenstone Belt (RPGB) and the Jonnagiri Greenstone Belt (JGB). The study primarily focused on identifying shallow geological features, such as granite, mafic intrusive and fault/shear zones, that occur at a depth of around 3 to 4 km. Additionally, magnetic data indicates the presence of lineaments, oriented along NW-SE, NE-SW, and E-W directions, which align with geological structures, that may imply kimberlite intrusions. The gold mineralization is primarily found in the gravity high zones of RPGB, JGB, apart from a delineated gravity high zone GH3, and along the lineaments. Furthermore, concentrations of Rare Earth Elements (REE) are noted between two gravity highs along the eastern margin of the Closepet granite.
2
Comparison of seismic displacement, velocity and acceleration for discriminating landslides from earthquakes and background noise
Mahesh Yezarla1, 2, Rajesh Rekapalli1, 2*, Raviteja Kethavarapu1
1 CSIR-National Geophysical Research Institute, Hyderabad- 500007, India
2 Academy of Scientific and Innovative Research (AcSIR), Ghaziabad- 201002, India
https://doi.org/10.71122/JIGU.29(6)2025.0036
ABSTRACT
Seismic signals from landslides, earthquakes, and background noise exhibit distinct spectral characteristics that enable effective event classification. This study presents a comparison of the Power Spectral Density (PSD) of seismic displacement, velocity, and acceleration. We analyzed frequency power distribution and power decay rates using PSDs, estimated from all three ground motion measurements. The seismic displacement signals of landslides are characterized by gradual amplitude evolution and dominant low-frequency content, whereas earthquakes show impulsive energy release with broader frequency bandwidths. Our results demonstrate that the landslides exhibit distinct spectral trends that are more pronounced in the PSD of acceleration data, compared to earthquake and ambient noise. Additionally, background noise displays a more stable and less structured spectral profile. Furthermore, we have achieved 98% accuracy in the detection of landslides using PSD features from displacement, velocity, and acceleration domains when using a frequency range of 1–10 Hz. The study suggests that the analysis of seismic waveform PSD is a robust and region-independent method for seismic event characterization, particularly for rapid landslide detection and geohazard monitoring.
3
Gravity and magnetic studies for mapping of subsurface structural features and mineralized zones in the Proterozoic Cuddapah Basin, Eastern Dharwar Craton (India)
Linga Swamy Jogu* and Udaya Laxmi, G
Centre of Exploration Geophysics, Osmania University, Hyderabad-500 007, India.
https://doi.org/10.71122/JIGU.29(6)2025.0037
ABSTRACT
The present study focuses on the integrated analysis of gravity and magnetic data to map subsurface structural features and identify potential mineralized zones within the Proterozoic Cuddapah Basin, situated in the Eastern Dharwar Craton. The study area encompasses the northern segment of the Peninsular Gneissic Complex (PGC) and the northwestern margin of the Cuddapah Basin. It is drained by tributaries of the Krishna River and comprises rock assemblages, PGC, Cuddapah Supergroup, and Kurnool Group. Basic and ultramafic intrusions occur within the both PGC and Cuddapah litho-units. Bouguer gravity and magnetic anomaly maps were interpreted to delineate deep-seated structural frameworks, utilizing contrasts in rock density and magnetic susceptibility. The northern part of the study area features biotite granite, intruded by a prominent NW–SE trending body, well expressed in geophysical data. Structural analysis reveals multiple lineament trends NW–SE, NE–SW, E–W, and N–S, suggesting significant tectonic disturbances that could favour the emplacement of kimberlite and lamproite bodies. Spectral analysis of gravity and magnetic data sets identifies three major depth interfaces, supported by Euler 3D solutions. Two-dimensional gravity-magnetic modeling across the Bollaram and Kollapur clusters, highlights the intrusive bodies and their structural configurations. The study identifies prominent structural trends (NW–SE, NE–SW), subsurface depth interfaces at 0.75 km, 1.46 km, and 3.0 km, and possible potential kimberlite zones, based on gravity-magnetic closures. A comprehensive structural map compiled from geophysical and geological data confirms the presence of previously reported kimberlite and lamproite occurrences, emphasizing the region's mineral exploration potential.
4
Evaluation of preferential sub surface flow through an inferred lineament – A case study in fluoride infested Nalgonda district, Telangana, India
Rangarajan, R.1*, Rolland Andrade2 and Muralidharan, D.1
1CSIR-National Geophysical Research Institute, Hyderabad-500007, India
2Central Water and Power Research Station, Pune-411024, India
https://doi.org/10.71122/JIGU.29(6)2025.0038
ABSTRACT
Remote sensing data inferred two major WNW-ESE trending lineaments with a spatial extent of about 3 km parallel to a stream course in Halia watershed located in the Nalgonda district, Telangana state of India. The watershed in semiarid zone is located in granite terrain, covered by red soils with a mean annual rainfall of 636 mm. Integrated study comprising hydrological, hydrogeological, geophysical, drilling, hydrochemical and tracer tests, were carried out during the period 2005 to 2006, to investigate groundwater movement through one of the two inferred lineaments. The observations on rainfall, groundwater level, natural recharge rate, groundwater flow velocity, streaming potential data and fluoride concentration of groundwater indicated that the inferred lineament does exists at deeper depth and in this, preferential flow is the dominant groundwater movement process with the flow velocity of about 14.9 m/d, considering effective porosity of granite/gneiss as 3%.
5
Are there no kimberlitic rocks in Southern Granulite Terrane, India?
Formerly, CSIR-National Geophysical Research Institute Hyderabad-50 00 07 (India)
https://doi.org/10.71122/JIGU.29(6)2025.0039
ABSTRACT
Recent discoveries of kimberlites and lamproites in Proterozoic orogenic belts adjacent to Achean cratons, such as those in South Africa, North-western Australia and George Creek (USA), mark a significant breakthrough in kimberlite exploration. These findings challenge the long-established Clifford’s Rule, which traditionally links kimberlite occurrences to Archean cratons. Inspired by this shift, an intriguing question arises, why have kimberlites not been found in the Southern Granulite Terrane of India? This question invites further scientific discussion and exploration.
6
Effect of the valley on fluxes associated with internal gravity waves excited by the Assam-Burma hills in India
Department of Mathematics, Ramananda College, Bishnupur, Bankura-722122,W.B., India.
https://doi.org/10.71122/JIGU.29(6)2025.0040
ABSTRACT
Assam-Burma hills (ABH) is situated in the northeastern region of India. ABH is synthesized by two ridges and they are separated by the valley. In this paper, we develop a three-dimensional (3-D) model of the effect of this valley on momentum flux and energy flux associated with the internal gravity waves excited by the ABH. To prepare this model, a 3-D adiabatic, non rotational, laminar, Boussinesq and inviscid moist air is considered, where both stability wind of the prevailing flow remain changing with height. The primary objective of this study is to investigate the impact of gradually increasing valley distance on the magnitude of momentum flux and energy flux. Finally, the outcomes of momentum and energy fluxes are examined in the light of previous studies.