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We thank Patil Pillai et al. for preparing a critique on our article (Joy et al., 2018). Patil Pillai et al. contest the analytical procedure utilized for the carbonates and "geological information" documented in our research article and raise concerns on our conclusions. We hereby provide our reply to each of their comments. [ABSTRACT FROM AUTHOR]

The present paper addresses petrography, geochemistry and Ar‐Ar geochronology of a significant number of mafic dykes from the Paleo‐ to Neoarchean Bundelkhand Craton in central India. The majority of the dykes are NW‐SE oriented (with a few NE‐SW and ENE‐WSW) with tholeiitic, sub‐alkaline and basalt to basaltic andesite composition. The trace element geochemistry of these dykes indicates an island arc setting during emplacement. The Ar‐Ar mineral dating (plagioclase) of three representative dykes reveals an emplacement age between 1.53 and 1.46 Ga. This finding and earlier reports (2.1–1.73 Ga) point to sustained mafic magmatism throughout the Bundelkhand Craton in a preferred structural orientation between 2.1 and 1.46 Ga. Mafic magmatism was episodic and can be linked to the perpetual subduction accretion processes between the central Indian Archean continents during the development of the Columbia supercontinent. The mafic dykes were emplaced at 45° to the maximum compression direction (E‐W), that is, along the line of no finite longitudinal strain. This time equivalent widespread NW‐SE and NE‐SW trending mafic dyke system is also relatable along the adjacent continents (Singhbhum, Bastar) and thus opened up a new paradigm for the dyke's emplacement across the Indian cratons. [ABSTRACT FROM AUTHOR]

The establishment, development and abandonment and/or destruction of ancient civilizations were catalytically controlled by geomorphic features such as lakes and rivers and the climate. This paper examined the possible influence of tectonism and climate on six habitations of the ancient Vaigai River Basin civilization in South India, using multiple proxies such as grain size, geochronology and geochemistry of the sedimentary archives. The tectonic setting of the basin changed between the active margin and passive margin; the discriminant diagrams suggested varying provenance and changing climatic conditions over the mid‐ and‐late Holocene. Tectonic activism and quiescence, base‐level change in the channel morphology led to the burial/marooning of the first habitation surface. Overall, arid conditions were punctuated with catastrophic flooding and peak discharge (flood) destroyed the second, third and fourth habitation sites. These flooding events were characterized by moderate weathering (CIA) and high values of Al, Fe and Rb/Sr and low Ca/Mg in the sediment records. The abandonment/destruction of the fifth habitation also occurred during an arid interval (droughts), possibly caused by weak monsoon. Along with the interactions between tectono‐climatic and fluvial geomorphic factors, the new results provided avenues to (a) check and recognize the archives for 8.2 and 4.2 ka‐like events in this part of the world, and (b) the utility of integrated analyses to constrain on the civilizational histories of the mankind. [ABSTRACT FROM AUTHOR]

Among several devastating natural hazards, flooding is a common and serious threat to society causing huge loss of lives, properties, and infrastructure throughout the world. The intensity and frequency of this extreme weather event are expected to increase due to significant changes in the present‐day climate and land use and land cover (LULC) pattern. India has a very systematic and organized structural program and policies but lacks proper implementations, and adverse effect of climate change and the extreme event goes on in society. This paper is an analysis of floods in India and hazards due to climate change and LULC change patterns. Three models, namely "Eco‐biogeography‐based optimization (EBO), Random forest (RF), and Support vector machine (SVM)" were used to obtain the final output to prepare a "Flood susceptibility map". The result was validated through the "Receiver operating characteristics (ROC)" with "Area under curve (AUC)" values. The future rainfall scenario has been estimated by considering the "General circulation models" through different "shared socioeconomic pathways (SSPs)". The values of AUC are 0.915 (EBO), 0.887 (RF), and 0.869 (SVM), respectively. After consideration of different SSPs, the result shows that there is an increasing tendency of flood hazards in the projected period. Among all the employed modelling approaches, the EBO model has notable potential in delineating the possible flood‐prone regions for effective flood planning and management. Decision‐makers can benefit from country‐specific information and regional planner to implement sustainable and long‐term measures to overcome this type of hazardous situation. [ABSTRACT FROM AUTHOR]

The paper presents data on the U–Pb chronology of detrital zircon grains and radiogenic isotopic composition (87Sr/86Sr, ɛNd) from the Proterozoic clastic successions of the Garhwal‐Kumaon Lesser Himalaya representing the extended northern Indian cratonic margin, NW India. The Proterozoic Lesser Himalayan Basin in Garhwal‐Kumaon Himalaya is divided into two sectors, namely, Inner Lesser Himalaya (ILH) and Outer Lesser Himalaya (OLH) by a tectonic boundary, namely the Tons Thrust (TT). Age distribution from inner and outer sectors of the Lesser Himalaya shows that the U–Pb chronology of most of these zircons provides Palaeoproterozoic (between 1.6 and 1.8 Ga) to Neoproterozoic (800 Ma) ages. The age data suggest sedimentation of the Rautgara Formation (Damtha Group) of ILH continued till the Neoproterozoic (~850 Ma), which was earlier regarded as ≤1.6 Ga. Tracking the detrital U–Pb zircon ages in the near adjacent cratonic parts point towards Aravalli Orogen as the major source region. Whole‐rock ƐNd(0) values for ILH rocks range from −37.6 to −14.6 and for OLH it ranges from −19.6 to −6.7. More negative ƐNd values along with dominance of Neoarchean‐Palaeoproterozoic ages in ILH indicates supply from more evolved protolith or recycled sources and less negative ƐNd values with major Neoproterozic zircon ages from OLH supports for less evolved source rock. The change from more negative ƐNd to less negative ƐNd values progressively upward the stratigraphy can be due to a shift in source with time. Both U–Pb zircon and ƐNd supports for a continuous sedimentation model, rule out the presence of ~500 Ma unconformity within the LH and argues for separate evolution of the Lesser Himalayan Basin on the trailing edge of the extended north Indian craton in "Columbia" configuration. [ABSTRACT FROM AUTHOR]

This paper discusses the porphyry copper mineralization in A‐type granitoids from the Precambrian shield of the Karbi Hills (Mikir Hills), NE India. The prospective zone lies in the Kuthori‐Bagori of Kaziranga locality of the north Karbi Hills. The host granitoids are characterized by intermediate to high SiO2 (66.30–72.97 wt.%), Na2O (up to 4.90 wt.%), Ba (up to 1,943 ppm), Zr (up to 410 ppm), Y (up to 70 ppm) and Al2O3 (up to 14.77 wt.%) with low concentrations of CaO (up to 1.53 wt.%), and Cu (up to 32.41 ppm) which suggest a consistent granodiorite‐monzogranite host composition, an intraplate emplacement, A‐type chemistry, shoshonitic to high‐K calc‐alkaline and a predominant metaluminous character. Minerals in the investigated granitoids show hypogene alteration features similar to ideal porphyry style mineralization. Remnants of early chalcopyrite‐bornite‐magnetite (Magnetite‐I) veins have been preserved in the distant propylitic zone. The central core zone of potassic alteration shows the dominance of pyrite‐chalcopyrite‐magnetite (Magnetite‐II) assemblages. Mineral chemistry confirms the presence of two types of magnetites: magmatic (Mag‐I) and hydrothermal (Mag‐II). Mag‐I is octahedral, less commonly cubic, or irregular. It has a porous core with trellis‐type ilmenite exsolution lamellae. Mag‐II is non‐porous, devoid of ilmenite exsolution lamellae, has irregular to distinctly octahedral crystal habit and contains micro‐inclusions of pyrite, chalcopyrite, aluminosilicates, manganite and apatite. The progressive chemical purification of igneous magnetite, exacerbated by hydrothermal re‐equilibration, has resulted in a significant reduction in trace element contents such as Ti, Al, Mg, Zn and Cr, and a significant increase in iron content from 89 to ~94 wt.%. A combination of [Ni/(Cr + Mn) vs. Ti + V], and [(Ca + Al + Mn) vs. Ti + V] variation diagrams and upper threshold concentrations for the Kuthori‐Bagori ore effectively separates Mag‐I and Mag‐II. Our field, petrographic and geochemical data indicate that the Kuthori‐Bagori of Kaziranga granitoid of the Karbi Hills (Mikir Hills) in NE India is an ideal location for porphyry copper mineralization. [ABSTRACT FROM AUTHOR]

Studying granitoids can provide important knowledge on the composition of continental crust and the geodynamic processes of continental growth. Nevertheless, the mechanisms of granitoids formation during continental collision remain uncertain. In this paper, we present new zircon U–Pb–Hf isotope and whole‐rock Sr–Nd isotope compositions, and major‐ and trace‐element data for granitoids from the Chacangka area of the central Lhasa Terrane, southern Tibet. The Chacangka quartz monzonites crystallized at ca. 61 Ma, whereas the monzonites and granites were emplaced at ca. 51 Ma. The quartz monzonites are peraluminous and have high 87Sr/86Sri ratios (0.7129–0.7131), and their low εNd(t) (−7.65 to −7.10) and zircon εHf(t) (−9.3 to −7.5) values are more depleted than those of ancient crustal basement beneath the central Lhasa Terrane, which suggests that they originated from a mixed source of juvenile and ancient lower crust. Compared with the quartz monzonites, the monzonites have much higher contents of MgO (2.34–3.62 wt%) and values of Mg# (42.3–46.3) and zircon εHf(t) (−6.9 to 1.9) and show more depleted Sr–Nd isotopes, indicating that more juvenile materials were involved in their source. The granites have Sr–Nd isotope compositions that are similar to those of the coeval monzonites but have higher SiO2 contents, lower CaO and MgO contents, and lower values of Mg#, suggesting that they were differentiates of the monzonites. The elemental and isotopic compositions of the Chacangka granitoids exhibit a marked transformation from 61 to 51 Ma, probably indicating breakoff of the Neo‐Tethyan oceanic slab. The Neo‐Tethyan slab breakoff not only induced the upwelling of deep material and eruption of magma but also caused re‐melting and destruction of ancient crustal basement of the central Lhasa Terrane. [ABSTRACT FROM AUTHOR]

The Mahanadi river basin (MRB) is one of the eight major fluvial basins of India. This paper presents a very first systematic study of geochemical characteristics, including rare earth elements of surface sediments collected from the riverbed at different parts of this basin to infer the chemical weathering, provenance, and tectonic settings. Lower mean values of major elements (except for SiO2 and K2O) are observed compared with that of the upper continental crust (UCC). It is attributed to the dominance of quartz and orthoclase in sediments and removal of mobile elements from the sediment during the transportation. The concentrations of Rb, Ba, Cu, Th, and Pb are elevated with respect to the UCC. The higher concentration of K2O and Rb, the ratio of Al2O3 to TiO2, and other bivariant plots indicate that the sediments are derived mostly from acidic to intermediate igneous rock. Majority of the sediments have geochemical similarity with the arkose and litharenite sandstones. The chemical index of alteration (CIA) values of the MRB sediments varies between 52 and 69 with most of the samples having CIA < 60 suggesting the lower degree of weathering which is further supported by the mineralogy. The eroded sediments have compositional maturity comparable to sediments deposited under semi‐arid climatic conditions. Sediments show both positive and negative Eu anomalies based on the source rock. Based on the commonly used discrimination diagrams, it is concluded that the MRB has a tectonic setting similar to the passive continental margin. [ABSTRACT FROM AUTHOR]

The Singhbhum cratonic block, eastern India, unlike other Indian cratonic blocks, bears a continuous geological record from the Palaeoarchaean to Mesoproterozoic. The Palaeoarchaean Iron Ore Group of rocks are exposed along three distinct belts (the eastern, western, and southern) encircling the Singhbhum granitoids. The economic geological aspects of the BIF and the gold mineralization aspects of the quartz‐pebble conglomerates of the Eastern Iron Ore Group (EIOG) have been discussed by a number of authors. Komatiites and basalts of the EIOG have been studied by earlier authors. However, no effort has yet been made to infer the volcano‐sedimentary processes in the Eastern Iron Ore belt. This paper presents a brief overview of the sedimentation and magmatic processes in the EIOG belt. The EIOG sedimentary succession is characterized by a basal terrestrial to shallow marine deposits that progressively became deeper up section. The EIOG clastics bear carbonaceous matter. The basal terrestrial deposits (conglomerate‐sandstone association) of the EIOG provide a rare opportunity to undertake fluvial architectural analysis and may enable us to unlock the peculiarities of Palaeoarchaean fluvial systems. [ABSTRACT FROM AUTHOR]

The spatial and temporal association between lamprophyres and kimberlites provides unique opportunities to explore their genetic relationships. This paper explores such a relationship by detailing mineralogical and geochemical aspects of Korakkodu lamprophyre dykes located within the well‐known Mesoproterozoic diamondiferous Wajrakarur Kimberlite field (WKF), towards the south‐western margin of Paleo–Mesoproterozoic Cuddapah Basin, Eastern Dharwar Craton, southern India. Mineralogy reveals that these dykes belong to calc‐alkaline variety of lamprophyres, but their geochemistry display mixed signals of both alkaline and calc‐alkaline lamprophyres. These lamprophyres are highly potassic, and their high Al2O3 and low‐TiO2 content implies a shoshonitic character. Low Mg#, Ni, and Cr concentration highlight their evolved nature. High (La/Yb)N and (Gd/Yb)N content is consistent with their derivation from low degrees of partial melting, whereas highly fractionated nature suggests the presence of garnet in their source. Absence of prominent Nb‐Ta anomaly implies to the dilution of lithospheric mantle source by melts rich in HFSEs and low La/Nb ratio compared to those of the calc‐alkaline island arc volcanics and suggests an asthenospheric overprint on lithospheric mantle source. Carbonatite metasomatism in the source region of these lamprophyres is apparent from conspicuously high‐Zr/Hf ratio, and the HFSE budget of these lamprophyres are principally controlled by the presence of phlogopite veins in their lithospheric source. An extremely heterogeneous and layered lithospheric mantle beneath Eastern Dharwar Craton has been inferred from the divergent genetic history of Mesoproterozoic lamprophyres and kimberlites in the Wajrakarur field. [ABSTRACT FROM AUTHOR]

The Bangong–Nujiang Suture Zone (BNSZ) is one of the main suture zones in the Tibetan Plateau and indicates the existence of the Bangong–Nujiang Neo‐Tethys Ocean (BNO). It was formed by the collision between the Qiangtang and Lhasa blocks after the closure of the BNO. However, its evolutionary processes and subduction polarity remain controversial. Research on the BNSZ is of great significance for exploring plate tectonic evolution and ocean–continent connection. The scarcity of the BNSZ structural data is one of the most important reasons for the debate of the BNO tectonic evolution. Based on structural analysis in the field and combined with previous petrology and palaeomagnetic data, this paper has determined that the closure time of the BNO is progressive and scissor‐like, from Middle Jurassic in the east to Early Cretaceous in the middle and late Early Cretaceous to early Late Cretaceous in the west. There was a three‐stage deformation in the BNSZ: (a) N–S‐directed compression induced by the initial collision; (b) WNW–directed transpression related to the stress adjustment; and (c) NE–SW‐directed compression caused by the low‐angle NE‐directed subduction of the Indus–Yarlung Zangbo Ocean. The different structural pattern along the eastern segment of the BNSZ may have resulted from orogenic bending due to the later Himalayan Orocline caused by the India–Eurasia collision in the Cenozoic. [ABSTRACT FROM AUTHOR]

This paper presents the sedimentological analysis of about 1.3 km succession of Neogene Siwalik Group exposed in the Gish River section, Darjeeling foothills. Contrary to the existing alluvial fan‐braided stream depositional model, the facies analysis shows that the succession accumulated in a shallow marine deltaic setting. Nine facies identified represent deposition from various processes related to unidirectional and oscillatory current, suspension settlement in quiet water and also to processes related to soil formation. Abundant trace fossils of marine affinity occur throughout the succession and include Cylindrichnus, Rosselia, Teichichnus, Rhizocorallium, Chondrites and Zoophycos. The studied succession has been subdivided into seven facies associations that can be interpreted in terms of the different sub‐environments of a river‐dominated delta. The lower ~550 m of the succession comprises sand–mud alternation of delta front, delta mouth and delta plain deposits (FA3, 4, 5 and 6), organized in stacked, 10–30 m coarsening‐upward units, and is inferred to represent progradation of the delta lobes. The overlying 300 m mud‐dominated interval is dominated by prodelta to open marine bay‐fill succession (FA1 and 2); the pebbly sandstones and conglomerates of the uppermost ~500 m represent a braidplain delta environment. A kilometre‐scale coarsening‐upward trend of the Siwalik deposits of this section is attributable to southward propagation of the thrust front related to the activity of the Main Boundary Thrust (MBT). The sedimentological analysis shows that a marine embayment existed in the Eastern Himalaya during the Siwalik time and the deltaic succession reported here provides the link between the upland transverse drainages recorded from Western Himalaya and the deep marine Bengal Fan succession. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Detailed facies architecture study of the Late Cretaceous (Cenomanian) Nimar Sandstone (Bagh Group), from Son-Narmada rift valley, Central India, reveals deposition in a fluvial-marine environment. The lower part of the Nimar Sandstone succession depicts deposition in predominantly fluvial setting, whereas the middle-upper part of the succession manifests sedimentation under a tide-dominated estuarine to a tide-wave influenced shoreface environment. Retrogradational nature of the successions in the upper part and lateral facies change from west to east signifies an eastwardly decreasing marine influence. This attests to a sustained event of marine transgression from the west affecting the Son-Narmada rift valley during the Late Cretaceous time. Beds with various soft-sediment deformation structures (SSDS), viz., convolute laminae, load and flame structures, pseudonodules, contorted beddings, syn-sedimentary faults, and sand/silt dykes, occur in distinct stratigraphic levels within the middle part of the succession. These beds are separated by thick successions of undeformed beds. This paper reports these beds as seismites for the first time from the Son-Narmada rift valley. The seismites signify instantaneous liquefaction and fluidization of unconsolidated sediments triggered by passage of repetitive earthquake shock waves during sedimentation in fault-bound rift basin. These seismites are important as they mark a new phase of reactivation of the Son-Narmada South Fault within the Son-Narmada rift valley during the Cenomanian time. This reactivation of the Son-Narmada South Fault led to basinal subsidence under prevalent extensional tectonism, which controlled the sedimentation during the Late Cretaceous time. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]