Kanchan Pande

• Indian Institute of Technology Bombay

This study focuses on compositional diversity and origin of green clays within the Late Cretaceous volcaniclastic horizons (green boles) in Deccan volcanics based on petrographical, mineralogical and geochemical investigation on outcrop samples. Green boles, showing either sharp or gradational contacts with the underlying basalt, were comprised of...

The eruptive history of the Malwa Plateau Subprovince of the Deccan Traps is addressed by dating 21 lavas spanning the exposed stratigraphic extent, using the ⁴⁰Ar/³⁹Ar method applied to plagioclase separates. Major, minor, and trace element geochemistry was determined for each of the dated lavas and four additional ones. Dating results indicate th...

The Western Ghats sections of the Deccan Volcanic Province (DVP) are considered the ‘type area’ for most of the established models of its eruptive history and age. The prevailing chemostratigraphy and lithostratigraphy of the Western DVP based on the study of these sections are largely comparable but have subtle conceptual and practical differences...

We investigate the shallow plumbing system of the Deccan Traps Large Igneous Province using rock and mineral data from Giant Plagioclase Basalt (GPB) lava flows from around the entire province, but with a focus on the Saurashtra Peninsula, the Malwa plateau, and the base and top of the Western Ghats lava pile. GPB lavas in the Western Ghats typical...

Green authigenic mica, i.e., celadonite, is commonly associated with submarine alteration of basic igneous rock. However, very few studies have reported the formation of celadonite under nonmarine conditions. An integrated study involving field investigation, petrography, mineralogy, and mineral chemistry highlighted the origin of celadonite in two...

Rapidly expanding geochronological, paleomagnetic and volcanological data of the Deccan Volcanic Province (DVP) has given new insights to the expansive knowledge on it that had been built up through the preceding decades. Precursory Late Cretaceous (80 – 68 Ma) magmatic activity across the Indian subcontinent preceded the main event of volcanism. T...

The Bhetkheda-Mohana Lineament is traced as a continuous lineament across nearly 100 km in the Central Narmada valley across the Deccan Trap basalts and their basement of Proterozoic sediments. While a major length of this lineament is occupied by a basaltic dyke, there are segments where the dyke is completely absent, and the lineament is represen...

The Siang antiform which forms the southern portion of the Eastern Himalayan Syntaxis is a massive subaerial duplex comprised of Paleogene rocks. The specifics of growth and deformation of the Siang duplex remain ambiguous due to limited studies in the region. Using multi-thermochronometry and Raman spectroscopy of carbonaceous matter (RSCM), this...

Mud volcanoes at convergent margins are important pathways through which clay minerals and fluids, collectively known as mud breccia, originating from deep within forearcs, are ejected at the surface, opening an important window to shallow level processes in subduction zones. Although the mud breccia is the only detachable part of a subducting slab...

This study presents physical, petrographical and mineralogical investigation of interbasaltic red boleRed bole within the late CretaceousCretaceous Deccan lava flows in Pune and Mahabaleshwar areas (India) to understand depositional and weathering conditions. The micromorphological study of red bolesRed bole reveals two genetic types characterized...

The comments by Dr. Misra on our work are appreciated, although barring the opening para, he makes no reference to our work.

Deccan Traps flood basalt volcanism affected ecosystems spanning the end‐Cretaceous mass extinction, with the most significant environmental effects hypothesized to be a consequence of the largest eruptions. The Rajahmundry Traps are the farthest exposures (~1,000 km) of Deccan basalt from the putative eruptive centers in the Western Ghats and henc...

We welcome the comments by Dr. Sudha Vaddadi on our paper "Emplacement history and evolution of the Deccan Volcanic Province, India" and respond to the points raised by her.

p. 598, Table 1: The subgroups “Kalsubai” and “Khandala” under the Western Subprovince need to be interchanged. The corrected table is below with these names shown in red. See PDF file for details.

We describe the distribution and characters of a megaporphyritic basalt that was arguably the earliest described ‘giant phenocryst basalt’ (GPB) from the Deccan Volcanic Province (DVP). It is a marker horizon exposed in a[30,000 km2 area below the Mahabaleshwar Formation in the western DVP. Its presence, distribution and stratigraphic importance as...

A review of the existing knowledge on the Deccan Volcanic Province of India shows that it has a significant geographic bias towards the western parts, while the rest of the province is not as well constrained. Emerging data on its structure, geochronology and volcanology in the last decade suggests that many existing concepts and models of this lar...

A review of the existing knowledge on the Deccan Volcanic Province of India shows that it has a significant geographic bias towards the western parts, while the rest of the province is not as well constrained. Emerging data on its structure, geochronology and volcanology in the last decade suggests that many existing concepts and models of this lar...

The Andaman ophiolite forms part of the ophiolite chain that encircles the northern and eastern boundaries of the Indian plate. Unlike its northern counterparts, it occurs on an accretionary prism, located at the convergent margin of Indian and Burma plates. It not only forms part of the basement of the accretionary complex but also occurs as thrus...

The India-Eurasia convergence continued forming the Himalaya since the last ca. 60-50 Ma. Previously, researchers proposed that the bounding Main Central thrust (MCT), and the South Tibetan Detachment system (STDS) played the major role in evolution of the Himalayan Metamorphic Core (HMC). They proposed different models like mid-crustal channel flo...

The legendary river Saraswati of Indian mythology has often been hypothesized to be an ancient perennial channel of the seasonal river Ghaggar that flowed through the heartland of the Bronze Age Harappan civilization in north-western India. Despite the discovery of abundant settlements along a major paleo-channel of the Ghaggar, many believed that...

The Greater Himalayan Sequence (GHS), bounded by the South Tibetan detachment system, and the Main Central thrust (MCT), constitutes majority of the Himalayan Metamorphic Core. Recent studies identified several shear zones within the GHS, which played significant role in its evolution. Here, we report the presence of a major shear zone, the Chungth...

A review of existing knowledge, new geochronology and volcanological perspective is presented to suggest a revised model for the evolution of the DVP.

A detailed investigation of a glauconite bed within the Late Cretaceous Bryozoan Limestone Formation of the Bagh Group in central India, as well as the study of existing records, reveals the existence of a ‘glauconitic sea’ along the margins of the Palaeo-Tethys Ocean during the Late Cretaceous Epoch. The authigenic green mineral formed abundantly...

The Deccan Volcanic Province (DVP) is significant for its eruption close to Cretaceous–Paleogene (K-Pg) boundary. Chemostratigraphy established in its western parts is the foundation of postulated long distance correlations across the province and consequential models of its eruptive history. A critical review of diagnostic parameters used to chara...

Elephanta Island, located near Mumbai in the western Deccan Traps, is composed of subaerially erupted tholeiitic lava flows and dykes, with no evolved or pyroclastic rocks. In contrast, Deccan volcanism in Mumbai includes subaerial and subaqueous lava flows, intrusions, and pyroclastics, of highly varied composition. The Mumbai and Elephanta sequen...

Two timelines for extinction The Cretaceous-Paleogene extinction that wiped out the nonavian dinosaurs 66 million years ago was correlated with two extreme events: The Chicxulub impact occurred at roughly the same time that massive amounts of lava were erupting from the Deccan Traps (see the Perspective by Burgess). Sprain et al. used argon-argon d...

Most continental flood basalt (CFB) provinces of the world contain silicic (granitic and rhyolitic) rocks, which are of significant petrogenetic interest. These rocks can form by advanced fractional crystallization of basaltic magmas, crustal assimilation with fractional crystallization, partial melting of hydrothermally altered basaltic lava flows...

The Spongtang ophiolite (Ladakh, NW India) constrains the nature of oceanic lithosphere before Indo-Asia collision and key stages in the development of the Himalayas. We report whole-rock ⁴⁰ Ar/ ³⁹ Ar and in situ zircon ²³⁸ U– ²⁰⁶ Pb ages from its crustal and upper and lower mantle sequences. Major and trace elements from harzburgite minerals sugge...

Obtaining constraints on the timing of orogenic gold mineralization hosted in shear zones in greenstone belts is often difficult because of the lack of easily datable minerals and problems of overprinting of earlier events of mineralization by later hydrothermal events. In the orogenic Hutti gold deposit the U-Pb SHRIMP date obtained from a monazit...

This study presents ⁴⁰Ar/³⁹Ar ages of autochthonous glauconites from the lower segment of the onshore Karai Shale Formation of the Cauvery Basin that constrain its age from 100.3 ± 0.7 to 92.6 ± 0.6 Ma. The ⁴⁰Ar/³⁹Ar plateau ages of the 3 glauconite samples are consistent with the existing biostratigraphic age of Late Albian to Middle Turonian of t...

This study presents geochemical characteristics of glauconites in estuarine deposits within the Maastrichtian Lameta Formation in central India. Resting conformably over the Bagh Group, the Lameta Formation consists of ~4 to 5 m thick arenaceous, argillaceous and calcareous green sandstones underlying the Deccan Traps. The sandstone is friable, med...

This study presents geochemical characteristics of glauconites in estuarine deposits within the Maastrichtian Lameta Formation in central India. Resting conformably over the Bagh Group, the Lameta Formation consists of ~4e5 m thick arenaceous, argillaceous and calcareous green sandstones underlying the Deccan Traps. The sandstone is friable, medium...

Reassessment of the geochronological, paleomagnetic and volcanological data from the Deccan Volcanic Province (DVP) indicates a hitherto unrecognised zonation of its eruptive history. Each of these sub-provinces appear to have an (interlinked, but) independent eruptive history. The thickest pile in the western part (that hosts the best studied seq...

The presence of large inter-species and seasonal variability in trace elemental composition of foraminifera demands the species-specific Mg/Ca and temperature calibration. The temperature is only one of the possibly several factors influencing the incorporation of Mg and Sr in foraminiferal calcite. The lack of correlation of Mg/Ca and Sr/Ca with t...

Mumbai, located on the western Indian continental margin, exposes Danian-age Deccan magmatic units of diverse compositions, dipping seaward due to the Panvel flexure. TheGhatkopar- Powai tholeiitic sequence contains seaward-dipping (thus pre-flexure) flows and subvertical (thus post-flexure) dykes. We present new ⁴⁰Ar/³⁹Ar ages of 62.4 ± 0.7 and 62...

The Lower Lesser Himalayan Sequence (L-LHS) in Darjeeling- Sikkim Himalaya (DSH) displays intensely deformed, low-grade metasedimentary rocks, frequently intervened by granite intrusives of varied scales. The principal motivation of our present study is to constrain the timing of this granitic event. Using 40Ar/39Ar geochronology, we dated muscovit...

An integrated study involving sedimentology, mineral chemistry and spectroscopy highlights a distinctive compositional evolution of Cretaceous glauconite within the Ukra Hill Member. Glauconite occurs at the top part of transgressive systems tract deposits built on a marine shelf. The concentration of glauconite steadily increases towards the maxim...

The Kaladgi Basin on the northern edge of the Dharwar craton has characters diverse from the other epicratonic Purana Basins of Peninsular India. Sedimentological studies in the basin have established the presence of three cycles of flooding separated by an event of intra-basinal deformation accompanied by low grade incipient metamorphism. The over...

The Goriganga river valley in the west-central Indian Himalayas represents one of the very few spectacular sections where the extensional South Tibetan Detachment System (STDS) is exposed with a NNW-SSE transport-parallel trend, having an approximate thickness of 6-7 km. The mapping and micro-textural analysis within mylonitic metapelites, indica...

The reports of inter-species variability to intra-test heterogeneity in Mg/Ca in several species of foraminifera have raised question about its use in estimation of seawater temperatures and necessitate field and culture studies to verify it for species from different habitats. In this study, we attempt to investigate if Mg/Ca in larger benthic for...

A detailed mineral chemical investigation of glauconite within the condensed section deposits of the Cretaceous Karai Shale Formation, Cauvery Basin, India reflects a wide spectrum in chemical composition related to origin and evolution in different substrates, stratigraphic condensation, and post-depositional alteration. Fe- and Mg-rich glauconite...

Bolide impact and flood volcanism compete as leading candidates for the cause of terminal-Cretaceous mass extinctions. High-precision 40Ar/39Ar data indicate that these two mechanisms may be genetically related, and neither can be considered in isolation. The existing Deccan Traps magmatic system underwent a state shift approximately coincident wit...

Little was known about the nature and origin of the deep crust beneath the Andaman Island Arc in spite of the fact that it formed part of the highly active Indonesian volcanic arc system, one of the important continental crust forming regions in Southeast Asia. This arc, formed as a result of subduction of the Indian Plate beneath the Burma Micropl...

The Mile Tilek Tuff is one of several consolidated volcanic ash deposits in the Andaman and Nicobar Islands that has preserved evidence of a large-scale volcanic eruption in Southeast Asia. Assumed to be of Mio–Pliocene age (25–2 Ma), the tuff was thought to have been generated by the Andaman–Indonesia volcanic arc. Little was known about its sourc...

Mafic dykes constitute an important component of the Deccan Volcanic Province. The duration of Deccan volcanism was from 69 to 63 Ma with apeak at 65  1 Ma. The thickness of the lava flows is much reduced and intensity of dyke occurrence is much less in the eastern part of the province compared to the west-ern part. Here we report new 39 Ar–...

Dominant dip-slip faulting along the Himalayan orogen changes to strike-slip tectonics in the vicinity of the eastern syntaxial zone. The study area lies within this transition zone, to the southwest of the Namche Barwa antiform. Rapid exhumation and erosion in the syntaxial region to the north and a disparately slow exhuming Siang window to the...

The Newania carbonatite complex of India is one of the few dolomite-dominated carbonatites of the world. Intruding into Archean basement gneisses, the rocks of the complex have undergone limited diversification and are not associated with any alkaline silicate rock. Although the magmatic nature of the complex was generally accep- ted, its age of em...

Optically Stimulated Luminescence (OSL) of quartz, with closure temperatures of 30–35°C in conjunction with Apatite Fission Track (AFT; closure temp. ∼120°C) and 40Ar-39Ar (biotite closure temperature ∼350°C), were used to obtain cooling ages from Higher Himalayan crystalline rocks of Western Arunachal Himalaya (WAH). Cooling age data based on OSL,...

The Sindreth Group exposed near Sirohi in southern Rajasthan, western India, is a volcanosedimentary sequence. Zircons from Sindreth rhyolite lavas and tuffs have yielded U–Pb crystallization ages of ∼768–761 Ma, suggesting that the Sindreth Group is a part of the Malani magmatic event. Earlier 40Ar–39Ar studies of other Malani volcanic and plutoni...

The existence of E–W extensional features from northeast (NE) Himalaya is poorly documented. Our investigation in the western part of Arunachal Himalaya provides evidences of active Quaternary E–W arc-parallel extensional features in the Higher and Lesser Himalayas. They are represented by arc-perpendicular normal faults and arc-parallel sinistral...

Determination of the peak thermal condition is vital in order to understand tectono-thermal evolution of the Himalayan belt. The Lesser Himalayan Sequence (LHS) in the Western Arunachal Pradesh, being rich in carbonaceous material (CM), facilitates the determination of peak metamorphic temperature based on Raman spectroscopy of carbonaceous materia...

Barren Island of Andaman Sea is the only active vol- cano in the Indian subcontinent. While the volcano has erupted sporadically many times over the last ~70 ka, it is not known when it formed and breached the sea surface. To provide estimates for the timing of these events, we dated two tephra (ash) layers older than 42 ka and generated by this vo...

The Sindreth Group exposed near Sirohi in southern Rajasthan, western India, is a volcanosedimen-tary sequence. Zircons from Sindreth rhyolite lavas and tuffs have yielded U–Pb crystallization ages of ∼768–761 Ma, suggesting that the Sindreth Group is a part of the Malani magmatic event. Earlier 40 Ar– 39 Ar studies of other Malani volcanic and plu...

The Tavidar volcanic suite in western Rajasthan, India, comprises a group of lava flows (and subordinate pyroclastic deposits) of highly diverse compositions ranging from basalt through trachyte to rhyolite. We have dated five samples of the Tavidar volcanic rocks by the 40 Ar– 39 Ar incremental heating technique. One trachyte and two rhyolite samp...

The Tavidar volcanic suite in western Rajasthan, India, comprises a group of lava flows (and subordinate pyroclastic deposits) of highly diverse compositions ranging from basalt through trachyte to rhyolite. We have dated five samples of the Tavidar volcanic rocks by the 40 Ar– 39 Ar incremental heating technique. One trachyte and two rhyolite samp...

Fourteen elements (Al, B, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Sr, and Zn) in 56 tea samples from different geographical regions of India (Assam, Darjeel- ing, Munnar, and Kangra) were quantitatively determined using inductively coupled plasma opti- cal emission spectrometry (ICP- OES) after microwave digestion. Validation of the analytical metho...

The Amba Dongar carbonatite-alkaline complex is one of several alkaline complexes present within the Chhota Udaipur subprovince of the Deccan flood basalt province, western India. Despite previous geochronological studies, the evolutionary history of this complex had remained uncertain due to lack of precise age data for the tholeiitic basalts that...

Thermal infrared spectroscopy is a powerful technique for the compositional analysis of geological materials. The spectral feature in the mid-IR region is diagnostic of the mineralogy and spectral signatures of mixtures of minerals that add linearly, and therefore, can be used as an important tool to determine the mineralogy of rocks in the laborat...

40Ar–39Ar geochronological studies carried out on the Khardung volcanics of Ladakh, India and our earlier Ar–Ar results from the volcanics of the Shyok suture along with the available geological and geochemical data provide good constraints for post-collision evolution of the Shyok suture zone. Whole-rock samples from the Shyok volcanics yielded di...

In the compressional regime related to India-Asia convergence, the plane of decoupling of easily yielding sedimentary pile of the Tethys basin from its rigid basement of the Vaikrita crystalline complex behaved differently at different point of time in northern Kumaun (Uttarakhand) Himalaya. The terrain-defining Trans-Himadri Detachment Fault (T-HD...

We report for the first time 40Ar-39Ar plateau ages for the Sylhet Traps of eastern India. Our results provide concordant ages for two samples, vertically separated by ∼200 m, from a tholeiite lava flow sequence. The ages are indistinguishable at 2σ confidence level indicating a rapid emplacement of these lavas. The weighted mean of the plateau age...

Rates of chemical and silicate weathering of the Deccan Trap basalts, India, have been determined through major ion measurements in the headwaters of the Krishna and the Bhima rivers, their tributaries, and the west flowing streams of the Western Ghats, all of which flow almost entirely through the Deccan basalts.Samples (n = 63) for this study wer...

New40Ar-39Ar thermochronological results from the Ladakh region in the India-Asia collision zone provide a tectono-thermal evolutionary scenario. The characteristic granodiorite of the Ladakh batholith near Leh yielded a plateau age of 46.3 ± 0.6 Ma (2σ). Biotite from the same rock yielded a plateau age of 44.6 ± 0.3 Ma (2σ). The youngest phase of...

We report here a40Ar-39Ar age of 66.0 ± 0.9 Ma (2σ) for a reversely magnetised tholeiitic lava flow from the Bhimashankar Formation (Fm.), Giravali Ghat, western Deccan province, India. This age is consistent with the view that the 1.8–2 km thick bottom part of the exposed basalt flow sequence in the Western Ghats was extruded very close to 67.4 Ma...

Rootless cones, also (erroneously) called pseudocraters, form due to explosions that ensue when a lava flow enters a surface water body, ice, or wet ground. They do not represent primary vents connected by vertical conduits to a subsurface magma source. Rootless cones in Iceland are well studied. Cones on Mars, morphologically very similar to Icela...

It is now an accepted view that the Rajmahal-Bengal flood basalts of eastern India belong to the Kerguelen plume generated Large Igneous Province (LIP) that encompasses the Bunbury-Naturaliste Plateau basalts of western Australia, volcanism on the southern and central Kerguelen Plateau, Elan Blank, and Broken Ridge in the Indian Ocean (e.g., Kent e...

Shyok volcanics, from the Shyok suture zone in northern Ladakh, ranging from basalts to andesites are analysed for 40Ar-39Ar isotopic systematics by step heating experiment. All samples, collected along the Nubra river, in the vicinity of Karakoram fault zone, yielded disturbed age spectra, reflecting subsequent tectono-thermal events. However, con...

A review of the available radiometric and paleomagnetic data from the Deccan Flood Basalt Province (DFBP) suggests that the volcanism was episodic in nature and probably continued over an extended duration from 69 Ma to 63 Ma between 31R and 28N. It is likely that the most intense pulse of volcanism at 66.9 ± 0.2 Ma preceded the Cretaceous Tertiary...

The felsic volcanics (rhyolites and rhyodacites) of the St. Mary’s Islands (SMI), southern India (∼13°N), were originally interpreted as a distant outlier of the ∼65 Ma Deccan volcanic province of west–central India, comprising dominantly flood basalts. Later the SMI volcanics were dated at ∼93 Ma by the K–Ar technique. However, this K–Ar ‘age’ was...

We present 40Ar-39Ar ages of 60.4+/-0.6Ma and 61.8+/-0.6Ma(2sigma) for Deccan Trap trachytes from Manori and Saki Naka, Bombay, situated in the tectonized Panvel flexure zone along the western Indian rifted continental margin. These ages provide clear evidence that (i) these trachytes are of Palaeocene age and therefore substantially younger than t...

40Ar-39Ar analyses of one alkali pyroxenite whole rock and two phlogopite separates of calcite carbonatites from the Sung Valley carbonatite-alkaline complex, which is believed to be a part of the Rajmahal-Bengal-Sylhet (RBS) flood basalt province, yielded indistinguishable plateau ages of 108.8 ± 2.0Ma, 106.4 ± 1.3Ma and 107.5 ± 1.4Ma, respectivel...

Two late Cretaceous mafic dykes with an ENE strike that is orthogonal to the west coast of India and located nearly 200 km inland around Huliyardurga, Karnataka state, yield 40Ar-39Ar plateau ages of 90.0±1.0 and 87.5±0.9 Ma. These Fe-Ti-enriched tholeiites are essentially co-eval with at least four other igneous suites widely scattered in southern...

The Deccan Trap geology of Bombay (Mumbai) differs from the main Deccan flood basalt province in several ways. Very few geological, geochemical and geochronological studies exist on the Deccan geology of Bombay. The basalt of Gilbert Hill, Andheri occupies a special place in Bombay geology on account of its spectacular columnar jointing, more than...