C MANIKYAMBA
Articles written in Journal of Earth System Science
Volume 129 All articles Published: 1 January 2020 Article ID 0032 Research Article
ARIJIT PAHARI P PRASANTH DEVLEENA M TIWARI C MANIKYAMBA K S V SUBRAMANYAM
The granite batholiths of eastern Dharwar Craton, which are showing intrusive relationship with TTGs, exposed in the eastern part of Telangana state at University of Hyderabad, Gachibowli ($9.30 \rm{km}^{2}$), are studied for their petrographic and geochemical characteristics compared with their counterparts in EDC and evaluated their petrogenesis. These are predominantly microcline and quartz with subordinate plagioclase, exhibiting intergranular and perthitic textures. Geochemically, they are strongly peraluminous to slightly metaluminous in nature with high Alumina Saturation Index (ASI) ranging from 0.86 to 1.11 indicating the role of plagioclase in their genesis. Their alkali-calcic to alkalic nature, narrow range of Modified Alkali-Lime Index ($\rm{MALI; Na_{2}O+K_{2}O -CaO}$), and low Fe-number reflect their similarities with the I-type Cordilleran granites. Prominent negative Europium anomalies, high Sr, Rb, Rb/Sr and low Sr/Y ratios indicate moderate to low pressure partial melting of pre-existing TTG with residual plagioclase in the source. We suggest, the melting of older TTGs through crustal anataxis process formed these granites and the sanukitoid melts supplied the required heat for the melting of TTG to evolve into granites. The genesis of these granites supports reworking of older crust, crustal differentiation during syn-collisional stage and marks the stabilization of continental crust in the Dharwar Craton during the Neoarchean time.
Volume 129 All articles Published: 10 January 2020 Article ID 0044 Research Article
TAUFIQUE WARSI V SATISH KUMAR DEWASHISH KUMAR M J NANDAN GEORGE BISWAS DINESH KUMAR SAHADEVAN C MANIKYAMBA T VINODA RAO R RANGARAJAN SHAKEEL AHMED V CHANDRASEKHAR
A comprehensive geophysical and petrological study was carried out at Giddalur area in Prakasam district, Andhra Pradesh, which is geologically a highly deformed area and is difficult to delineate the aquifer zone(s). The task was to find out the exact rock type in which aquifer is concealed as well as to delineate the aquifer zone, which can yield sufficient quantity of water. The resistivity models derived from geophysical dataset were interpreted in terms of hydrogeology and the results revealed substantial resistivity contrast of the geological formations within the study area. We have delineated two major groundwater potential zones based on this study. These zones were tapped at different depths in diverse rock types. Drilled hand specimens (rock cuttings) were not adequate, so these specimens were petrographically studied to reveal the exact contact zones of the rock type. On integration of the geophysical and the petrographic results, it was illustrated that two aquifer zones were struck at a depth of 92 and 122 m between shale-phyllite and phyllite-quartzite, respectively. These findings were correlated, which matched with the lithology of the drilled borehole. This integrated approach will be helpful in strategy for groundwater assessment as well as prospecting groundwater resources in different geological terrain.
Volume 130 All articles Published: 16 August 2021 Article ID 0168 Research article
ARIJIT PAHARI TH DHANAKUMAR SINGH C MANIKYAMBA K S V SUBRAMANYAM
The Meso-Neoarchean Kudremukh greenstone belt (KGB) of Western Dharwar craton comprises predominant metabasalts associated with banded iron formations (BIFs). The metabasalts are characterized by moderate MgO (7.23–8.97 wt.%), Ni (48–374 ppm), Cr (33–188 ppm) with a wide variation in $\Sigma$PGE (21.8–215.7 ppb) contents with 15.8–115.9 ppb Pd, 3.7–105.2 ppb Pt and 0.7–8.5 ppb Rh. Among IPGE group, Iridium, Osmium and Ruthenium range from 0.2–5.9, 1.4–7 and 1.8–7.8 ppb, respectively. These metabasalts are relatively enriched in $\Sigma$PPGE (21.8–215.7 ppb) than $\Sigma$IPGE contents (3.6–18.6 ppb). Their Pd/Ir (7.6–100.7) and Pd/Pt (0.8–5.5) ratios correspond to moderate to lower degree of melting. The abundance of PGEs in Kudremukh metabasalts is dominantly controlled by sulphide and chromite fractionation trend of the parent magma. Sulphur undersaturated nature of the parent magma is evidenced through the relationship of Pd
$\bf{Highlights}$
$\bullet$ PGE systematics on the metabasalts from Kudremukh greenstone belt, western Dharwar Craton, India.
$\bullet$ The KGB metabasalts are characterised by low- moderate degrees of partial melting and high degrees of sulphide fractionation.
$\bullet$ PGE geochemistry of the KGB metabasalts infers the early sulphur undersaturated nature of magmas.
Volume 132, 2023
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