September, 2026 || Volume 30 No.05
Volume 30(5) Sept 2026 (5-6)
Click Here to open this PDF
1
Crustal reworking and magmatic evolution in the northeastern Dharwar craton: evidence from geochemistry and zircon U-Pb geochronology of Ghanapur granitoids
Namrata Khadkea,b*, Sarbajit Dasha, T. Vijaya Kumara,b, E.V.S.S.K. Babua,b and Y.J. Bhaskar Raoa
aCSIR-National Geophysical Research Institute, Hyderabad, 500007, India
bAcademy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
https:doi.org/10.71122/JIGU.30(5)2026.0034
ABSTRACT
The widespread occurrence of granitoids in Precambrian terranes provides crucial insights into crustal processes and geochemical evolution within cratonic blocks. The Eastern Dharwar Craton (EDC) of southern India, records extensive granitic magmatism during the late Archean, a transformative period in Earth's history marked by significant geological and geochemical shifts. This study presents a comprehensive, first-hand investigation of granitoids from the Ghanapur area in the underexplored north-eastern EDC, using integrated fieldwork, petrography, geochemistry, and zircon U-Pb geochronology, to provide new insights into the evolutionary history of granitic crust. The granitoids of Ghanapur are categorized into three suites: granitic gneisses, granodiorite gneisses and leucogranites. Zircon U-Pb dating reveals two distinct magmatic episodes: granitic gneisses at ca. 2697– 2607 Ma, while granodiorite gneisses formed at ca. 2560–2545 Ma. Granitic gneisses are silica rich, weakly metaluminous to slightly peraluminous, and show high-K calc-alkaline to shoshonitic affinity, with magnesian character. They show variable Eu anomaly and REE fractionation. Their ages and geochemistry together suggest repeated crustal reworking and mixed origin. The granodioritic gneisses are weakly peraluminous and moderately silicic, with elevated Mg# and enriched in incompatible elements. They resemble Archean sanukitoids and suggest their origin from a metasomatized mantle wedge. These rocks record a two-stage evolutionary history: initial sanukitoid magmatism driven by partial melting of the enriched mantle wedge, followed by a younger migmatitic episode, resulting in their preservation as mesosome within the migmatitic complex. Leucogranites are garnetor magnetite- bearing, silica-rich, peraluminous to strongly peraluminous, high-K calc-alkaline, ferroan rocks, likely reflecting the waning stages of late Archean crustal thickening. Taken together, the geochemistry and geochronology suggest progressive crustal reworking and differentiation over a period of at least 150 Ma during the late Archean in the Ghanapur region.
2
Pressure dynamics controlling crude oil migration for reservoir management and exploration in Niger Delta, Nigeria
Abigail T. Olaoluwa*1, Olusegun O. Alabi1, Bosede T. Ojo2, Enock O. Oladimeji1 and Samuel O. Sedara3
1Physics Department, Osun State University, Osogbo, Osun State, Nigeria
2Applied Geophysics Department, Federal University of Technology, Akure, Ondo State, Nigeria
3Physics and Electronics Department, Adekunle Ajasin University, Akungba-Akoko, Ondo State, Nigeria
https:doi.org/10.71122/JIGU.30(5)2026.0035
ABSTRACT
Pressure conditions are required in reservoir operations management. This is essential in the adjustment of migration and production strategies. The study investigates the relationship between fluid flux and static pressure across multiple wells in a Niger Delta reservoir using well log and pressure data. Fluid flux and pressure gradients were obtained from modified Darcy’s Law, and these were used to generate plots for oil, gas, and oil/water phases. A threshold pressure of approximately 4,899 psi was identified beyond which fluid flux increased sharply, reaching a maximum of 1,400 ft3/day. Below this threshold pressure, fluid mobility was minimal, which indicates an insufficient energy to overcome capillary barriers. The optimal pressure suggests enhanced bulk fluid transmissibility, where both metrics exhibited a sharp decline, stabilizing at lower positive values until approximately 4800 psi. A critical pressure range of 4800 psi to 5050 psi was identified as a pressure range for optimal fluid flux. The major fluid encountered across the entire pressure spectrum was identified as oil, with isolated occurrences of gas and oil/water mixtures. In the present work, we observed that there is existence of a pressure-controlled migration regime and emphasize the importance of maintaining reservoir pressure above threshold values to enhance the oil production. The results obtained would provide insights for designing enhanced oil recovery (EOR) strategies and maintaining long-term reservoir performance above the present traditional concepts of oil production.
3
Petrology and mineral chemistry of Mesoproterozoic granitoids from the southwestern Chhotanagpur Granite Gneiss Complex (CGGC), Central India: Physico-chemical conditions of crystallization
Mohammad Qasim1,2, Satya Narayana Mahapatro3, Aparajita Tripathi4 and M. Ram Mohan1,2
1CSIR-National Geophysical Research Institute, Hyderabad - 500007, India
2Academy of Scientific and Innovative Research (AcSIR), Ghaziabad - 201002, India
3Geological Survey of India, Southern Region, Hyderabad - 500068, India
4Department of Geology, Centre for Advanced Study, Institute of Science, Banaras Hindu University, Varanasi - 221005, India
https:doi.org/10.71122/JIGU.30(5)2026.0036
ABSTRACT
We present field relationships, petrographic features, and mineral chemistry of feldspar, biotite, and amphibole for the Mesoproterozoic granitoids from the southwestern part of the Chhotanagpur Granite Gneiss Complex (CGGC) in central India. Based on field and petrographic observations, the granitoids in the study area are characterized as porphyritic granite and equigranular granite. The P-T-ƒO2 conditions and physico-chemical environment during the emplacement of these granitoids have been established based on mineral compositions of amphibole and biotite. The estimated temperatures from amphibole and biotite thermometry are similar with ranges of 738-769 ? for porphyritic granite and 723-798 ? for equigranular granite, respectively. The calculated barometry based on amphibole and biotite shows pressures ranging from 3.2 to 4 kbar for porphyritic granite, from 2 to 2.8 kbar for equigranular granite, and attaining up to 5.7 kbar for the equigranular granite. The estimated barometric conditions suggest the crystallization of porphyritic granite at a depth of ~13 km, and the equigranular granite, at ~14 km, corresponding to the upper-crustal crystallization conditions. The amphibole composition indicates that the granite crystallized from a volatile-rich magma under high oxygen fugacity conditions. Biotite and amphibole thermobarometric conditions of equigranular granite, indicate that these rocks crystallized under a high-oxidizing environment buffered in NNO (nickel-nickel-oxygen) to HM (hematitemagnetite) conditions. Biotite compositions indicate these granitoids to have been derived from a crustal source due to alkaline A-type parental magma in an anorogenic tectonic environment.
4
Behaviour of surface temperature during high-magnitude earthquakes (M ? 6.0)
Pooja Sharma1, Ananna Bardhan1, D. K. Sharma1 and Rajkumari2
1Department of Sciences, Manav Rachna University, Faridabad-121004, Haryana, India
2Department of Physics, DAV Centenary College, Faridabad-121001, Haryana, India
https:doi.org/10.71122/JIGU.30(5)2026.0037
ABSTRACT
As the Earth prepares itself before an earthquake, different anomalous signs in the atmospheric parameters, such as surface temperature, are generally observed. A thorough examination of these anomalous signs assists us in understanding the earthquake mechanisms and seismic predictions. In the present work, the surface thermal parameter - surface temperature (ST) during the twelve recent earthquakes of high magnitude (M? 6.0) are studied. All the earthquakes considered in the study originated on land. The data of surface temperature have been retrieved from the NCEP/NCAR website re-analysis. The value of ST considered is one month pre- and post- to the earthquakes. It is observed that all the earthquakes show an anomaly during the seismicaffected periods (pre- and post). Most of the earthquakes considered show a maximum anomalous surge in ST within ~ 1–9 days prior to the mainshock. Also, post-seismic anomalies are observed during most of the events. In some of the events, the maximum anomalies occurred on the day of the earthquake. The anomalous behaviour of normalised ST varied from ~ 6.15% to 116.6% as compared to background noise during the pre-seismic period of the considered earthquakes. During the post-seismic period, this variation spans from ~ 17.69% to 83.95% compared to the background noise.
5
Reanalysis dataset-driven assessment of super cyclonic storm Fani and extremely severe cyclonic storm Amphan over the Bay of Bengal, India
Arun Kumar1, Sushil Kumar2*, Nagendra Kumar3, Nitin Lohan4 and Reena Nupur5
1,3Department of Mathematics, M.M.H. College, Ghaziabad 201001, India
1,2,4Deparment of Applied Mathematics, Gautam Buddha University, Greater Noida 201312, India
4Department of Applied Sciences and Humanities, G.L. Bajaj Institute of Technology and Management, Greater Noida 201306, India
5SVKM’S NMIMS Anil Surendra Modi School of Commerce, Mumbai- 400056, India
https:doi.org/10.71122/JIGU.30(5)2026.0038
ABSTRACT
This study uses European centre for medium-range weather forecasts (ECMWF) reanalysis 5 (ERA5) and Indian monsoon data assimilation and analysis (IMDAA) reanalysis datasets, to examine the characteristics and evolution of extremely severe cyclonic storm Fani and super cyclonic storm Amphan over the Bay of Bengal. Key parameters analysed include track, track error, mean sea level pressure, maximum sustained wind, potential vorticity and wind vector. For Amphan, all the parameters are assessed, while for the Fani, potential vorticity, and wind vector are not included. Results from both reanalysis datasets are compared with IMD observations. The comparison reveals that IMDAA provides better representation of most dynamical and structural features such as landfall-time track, mean sea level pressure, maximum sustained wind, potential vorticity, and wind fields particularly for Amphan. Conversely, ERA5 performs slightly better in estimating track errors for both cyclones. Overall, IMDAA dataset emerges as more reliable for analysing the tropical cyclones over the Bay of Bengal.