KSV Subramanyam - Academia.edu (original) (raw)

Papers by KSV Subramanyam

Geological Magazine, 2022

We report a new zircon U–Pb age of 1257 ± 6 Ma for the Punugodu granite (PG) pluton in the Easter... more We report a new zircon U–Pb age of 1257 ± 6 Ma for the Punugodu granite (PG) pluton in the Eastern Dharwar Craton (EDC), Southern India. The Mesoproterozoic PG is alkali feldspar hypersolvus granite emplaced at shallow crustal level, as evident from the presence of rhyodacite xenoliths and hornfelsic texture developed in the metavolcanic country rocks of the Neoarchaean Nellore Schist Belt (NSB). Geochemically, the PG is metaluminous, ferroan and alkali-calcic, and is characterized by high SiO2 and Na2O + K2O, Ga/Al ratios >2.6, high-field-strength elements and rare earth element (REE) contents with low CaO, MgO and Sr, indicating its similarity to anorogenic, alkali (A-type) granite. The highly fractionated REE patterns with negative europium anomalies of PG reflect its evolved nature and feldspar fractionation. Mafic (MME) to hybrid (HME) microgranular enclaves represent distinct batches of mantle-derived magmas that interacted, mingled and undercooled within the partly crystal...

Journal of Earth System Science, 2021

Journal of Applied Geochemistry, 2015

Mafic dykes are a kind of minor intrusions usually occurring within granitic plutons commonly exe... more Mafic dykes are a kind of minor intrusions usually occurring within granitic plutons commonly exemplified by the Chittoor dyke cluster, south of Cuddapah Basin, Eastern Dharwar Craton. A number of mafic dykes having two distinct geological and geochemical characteristics are identified in the Chittoor dyke cluster, the origin of these dykes has been studied here through detailed petrographic and geochemical investigations. The analytical results suggest that the mafic dykes in the Chittoor cluster are subalkaline to dolerite, derived from a continental arc source. The mafic dyke samples contain 5.7 wt% MgO; exhibit negative Ba, Nb, Sr, Zr and Ti-anomalies and are enriched in Cs, Rb, U, K, Nd and Sm. It is suggested that these mafic dykes were subduction related and contaminated during their emplacement. After reviewing the existing basic data of the Proterozoic geology and geochemistry in Chittoor dyke cluster south of Cuddapah Basin, as well as the geochemistry of the mafic dykes i...

International journal of Earth Sciences and Engineering, 2017

Punugodu Granite Pluton (PGP) is one among the many granitic plutons hosted by Nellore Schist Bel... more Punugodu Granite Pluton (PGP) is one among the many granitic plutons hosted by Nellore Schist Belt (NSB) and considered as post collisional A-type Granite. It consists a variety of enclaves; they are seen as Xenoliths, Mafic magmatic enclaves (MME), Felsic magmatic enclaves (FME) and Basic Microgranular Enclaves (BME) which are having a distinct field, petrographic, and geochemical characteristics. They are subalkaline tholitic to alkaline and magnesian to ferroan in nature. Chondrite normalized REE patterns of MME, FME and xenoliths show fractionation, relative LREE enrichment and HREE depletion with negative-Eu anomalies. When compared among these enclaves, BME show slightly less fractionated REE patterns without Eu-anomalies, which is transitional between tholitic-alkaline basalts, and akin to oceanic-continental tectonic settings. BME of OIB signatures which are early formed and assimilated into granitic melts or late stage chemical exchange/equilibration of coeval melts at high...

It is observed that a significant number of reactions are stoichiometrically unbalanced in the ex... more It is observed that a significant number of reactions are stoichiometrically unbalanced in the existing databases (e.g. MetaCyc), even in curated databases like RiceCyc. To obtain a valid model, reactions should be mass balanced. Here, we propose a systematic algorithm based on generalized inverse matrix – to search all the reactions where mass is not conserved and to calculate the appropriate balancing coefficients of reactants and products, wherever possible (feasible reactions). Using this algorithm we have identified the set of reactions which cannot be stoichiometrically balanced with the present set of substrates and products (infeasible reactions). We have also suggested names of filler metabolites to turn infeasible reactions into feasible reactions.

Pt, Pd and Rh emitted into the air through the exhausts of cars and trucks collected from Bangalo... more Pt, Pd and Rh emitted into the air through the exhausts of cars and trucks collected from Bangalore, Hyderabad and Visakhapatnam cities of south India were assessed in the context of their accumulation and resultant risks on human health and ecology. Apart from road dusts, respirable suspended particulate matter (RSPM) samples from these three cities were collected and studied. Road dust and top soil samples from road junctions and traffic signals with heavy and erratic traffic flow showed higher PGE levels than those from roads with low and free flow traffic suggesting that traffic flow conditions greatly influenced emissions of PGE from the auto-catalysts. Further studies on the exposure levels from Hyderabad, showed higher amounts of Pt, Pd and Rh in the blood samples of older people (for example, traffic police) who are exposed to extreme traffic conditions. Owing to the adverse health and ecological risk potential of PGE on humans, monitoring their levels, understanding the tra...

The petrological studies and geochemical analysis carried out on the basalts of Mandla Lobe (MB),... more The petrological studies and geochemical analysis carried out on the basalts of Mandla Lobe (MB), Madhya Pradesh of eastern Deccan Volcanic Province (EDVP) to evaluate their petrogenetic and tectonic evolution. A variety of lavas such as columnar, vesicular, amygdaloidal, inflated pahoehoe flows and red bole interflow horizons around the study areas Chutka, Mandla and Jabalpur-Niwas sectors of Mandla lobe are found. These basalts are fine to medium grained porphyritic and non-porphyritic composed of calcic plagioclase (An36 Ab61 Or3 to An74 Ab25 Or1; labradorite to bytonite), clinopyroxene (Wo24–42, En30–52, Fs15–43; augite-ferroaugite), altered olivine, chlorophaeite, opaque and glass usually show a variety of intersertal (seriate, ophitic and subophitic), intergranular (porphyritic, glomeroporphyritic, poikilitic) textures indicating variable cooling histories and melt replenishment in a magma chamber. The MB samples exhibit tholeiitic trends evidenced by iron enrichment on AFM di...

MAPAN, 2020

Inductively coupled plasma mass spectrometry (ICP-MS) has become inevitable for quantitative dete... more Inductively coupled plasma mass spectrometry (ICP-MS) has become inevitable for quantitative determination of trace and ultra-trace elements in geological samples. Inferences derived from ICP-MS data sets and other supportive evidence have revolutionized theories on geology/geodynamics. In this scenario, validation through interlaboratory studies plays an important role in assuring the quality of measurements, along with the performance and accreditation programs of the laboratory. The Geological Survey of India (GSI) initiated an interlaboratory testing program on soil and stream sediment testing in which about fifteen laboratories, including our geochemical laboratory participated. Trace and rare-earth elements (REE) determined on the reference material PKS-1 by high-resolution ICP-MS and validated with the certified values for PKS-1 provided by GSI after compilation. The fitness of acquired data for either “pure geochemistry” or “applied geochemistry” was determined based on the Z-scores. The data for most of the analytes fell within the -2 < Z < + 2 range, which included the majority of the trace and REE used in petrogenetic and provenance studies. These results help to review the analytical mismatches observed in the data, optimize necessary aspects and minimize the interference effects caused during analysis.

Journal of Earth System Science, 2019

The granite batholiths of eastern Dharwar Craton, which are showing intrusive relationship with T... more 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 km2), 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 (MALI; Na2O+K2O −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.

Geological Journal, 2016

The Nagaland–Manipur ophiolites (NMO) of Northeast India forms a part of the Tethyan ophiolites a... more The Nagaland–Manipur ophiolites (NMO) of Northeast India forms a part of the Tethyan ophiolites and comprises a suite of tectonite peridotites and cumulate mafic–ultramafic sequence with mafic extrusive–intrusive rocks, felsic intrusives and oceanic pelagic sediments along with minor podiform chromitites. However, sheeted dykes, which are considered as a significant component of ophiolites, are absent in the NMO. The tectonite peridotites are distinguished from the cumulate pyroxenites by the presence of pyroxene lineation, deformed bands and strained extinction in olivine, kink twin lamellae in pyroxene. Both the tectonite peridotites and cumulate pyroxenites contain aluminous spinel with Cr number [Cr# = Cr/(Cr + Al)] in the range of 0.14 to 0.29 and 0.27 to 0.48, respectively. Mg number [Mg# = Mg/(Mg + Fe2+)] in Cr-spinel is higher in tectonite peridotites (0.71–0.76) than cumulate pyroxenites (0.44–0.53). Chondrite-normalized rare earth elements (REE) patterns of cumulate pyroxenites exhibit depleted at light REEE (LREE) (LaN/SmN = 0.380–0.759) but flat middle REE (MREE) to heavy REE (HREE) (SmN/YbN = 0.622–0.756). However, the tectonite peridotites show gradual decrease in concentrations from HREE to MREE (SmN/YbN = 0.285–0.460) and slight increase in LREE (LaN/SmN = 0.721–2.201). The cumulate pyroxenites show strong enriched PPGE patterns and higher PGE concentrations (∑PGE = 85.8–163.5 ppb) compared with the tectonite peridotites (∑PGE = 34.8–113.0 ppb). The estimated equilibration temperature ranges from 890 to 931 °C for cumulate pyroxenites and 971 to 1156 °C for tectonite peridotites. The olivine–spinel equilibrium along with Cr-spinel chemistry and PGE data suggests that the tectonite peridotites represent the residual mantle left after limited extraction of basaltic melts by low-degree partial melting (<15%). Conversely, the presence of highly magnesian orthopyroxene and clinopyroxene in the cumulate pyroxenites in conjunction with their geothermometry suggests that they were formed at high pressure and temperature by magmatic fractionation from the basaltic melt. The geochemical data together with field and petrographical evidences indicate that both the tectonite peridotites and cumulate pyroxenites are essentially spinel-bearing and devoid of plagioclase, suggesting their derivation in the mantle beyond the stability limit of plagioclase in a mid-oceanic ridge tectonic setting. We conclude that the ultramafic sequence of the NMO was initially generated at a mid-oceanic ridge tectonic setting close to the eastern boundary of the Indian passive margin and then thrust over the continental margin of the Indian Plate towards the west during its collisional and subduction process with/beneath the Myanmar Plate. Copyright © 2016 John Wiley & Sons, Ltd.

Proceedings of the IODP, 2016

This data report focuses on Holes U1394B, U1395B, and U1396C located offshore Montserrat. These h... more This data report focuses on Holes U1394B, U1395B, and U1396C located offshore Montserrat. These holes were drilled during Integrated Ocean Drilling Program Expedition 340 and contain deposits associated with the growth and decay of the volcanic island of Montserrat. Hole U1394B dates to ~353 ka and is composed of 17 bioclastic turbidites, 24 mixed turbidites, 55 volcaniclastic turbidites, and 32 tephra fall layers within a background stratigraphy of hemipelagic marine mud. Hole U1395B dates to older than 1 Ma and contains 18 bioclastic turbidites, 27 mixed turbidites, 43 volcaniclastic turbidites, and 52 tephra fall layers. The uppermost 7 m of Hole U1396C covers ~1 My of stratigraphy and contains 1 bioclastic turbidite, 1 mixed turbidite, 9 volcaniclastic turbidites, and 13 tephra fall layers. Tephra fall and some volcaniclastic deposits are associated with episodes of island building, whereas bioclastic turbidites, mixed turbidites, and some volcaniclastic turbidites are associated with large landslide events from Montserrat. During the Expedition a total of nine sites were drilled offshore Montserrat, Martinique, and Dominica in the Lesser Antilles (Expedition 340 Scientists, 2012) (Fig. F1).

Proceedings of the IODP, 2013

Integrated Ocean Drilling Program Preliminary Report, 2012

Dynamics of the Earth System: Evolution, Processes and Interactions, 2020

Journal of Geophysical Research: Solid Earth, 2015

Ortho Magmatic Ore Deposits, 2014

Boggulakonda gabbroic complex (BKGC) (E 80º00'30", N 15º44'04") in the Prakasam Igneous Province ... more Boggulakonda gabbroic complex (BKGC) (E 80º00'30", N 15º44'04") in the Prakasam Igneous Province (PIP) (southern India) is studied in detail using major, trace, REE and PGE geochemistry to understand its geochemical evolution. It shows sharp contact relationships with the Precambrian quartzofeldspathic mica schist and granite gneisses. It is one among the several gabbroic complexes, occurring to the east of Cuddapah basin, along the eastern margin of Nellore schist belt. It is predominantly composed of gabbro and gabbronorite with melanocratic to leucocratic variations.

Environmental monitoring and assessment, 2014

Recently introduced microwave plasma-atomic emission spectroscopy (MP-AES) represents yet another... more Recently introduced microwave plasma-atomic emission spectroscopy (MP-AES) represents yet another and very important addition to the existing array of modern instrumental analytical techniques. In this study, an attempt is made to summarize the performance characteristics of MP-AES and its potential as an analytical tool for environmental studies with some practical examples from Patancheru and Uppal industrial sectors of Hyderabad city. A range of soil, sediment, water reference materials, particulate matter, and real-life samples were chosen to evaluate the performance of this new analytical technique. Analytical wavelengths were selected considering the interference effects of other concomitant elements present in different sample solutions. The detection limits for several elements were found to be in the range from 0.05 to 5 ng/g. The trace metals analyzed in both the sectors followed the topography with more pollution in the low-lying sites. The metal contents were found to be...