Browsing by Author "Birendra Pratap Singh"

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Early Evolution of Basal Angiosperms: Insights From the Fossil Pollen and Phylogenetics of Myristicaceae
(John Wiley and Sons Inc, 2025) Shalini Parmar; Mahi Bansal; Kadukothanahally Nagaraju Shivaprakash; Robert J. Morley; Shreya Mishra; Omer Babiker Abdelrahim; Shaaeldin Hasan; Srinivasan Prasad; Krishnamurthy Anupama; Harsanti P. Morley; Rajeev Patnaik; Birendra Pratap Singh; Vandana Prasad
Aim: The early evolution of basal angiosperms and the diversification of flowering plants remain unclear due to fragmentary fossil records and unresolved deep phylogenetic relationships. This study focuses on Myristicaceae, an early diverging lineage of flowering plants, to clarify its evolutionary history and broader implications on determining the timing and drivers of basal angiosperm diversification. Location: Tropics. Taxon: Myristicaceae. Methods: We integrated pollen morphology of Myristicaceae fossils from the Maastrichtian of Africa as well as India and early Paleogene of India, and extant species along with molecular sequences of 127 living species to reconstruct a dated phylogeny of Myristicaceae using BEAST2. To assess paleobiogeographic patterns, we applied BIOGEOBEARS in R, and diversification trends were assessed using Lineage-Through-Time (LTT) curve analysis. Further, we conducted mega-analysis optimised with deliberately assessed 44 calibration points including the revised crown age of Myristicaceae to construct a dated megaphylogeny of angiosperms. Results: Our analysis suggests that the crown lineage of Myristicaceae originated ~130 Ma in western Gondwana, and diversified into Myristicoid, Pycnanthoid, and Mauloutchioid clades likely driven by the South America–Africa separation (~120 Ma). The LTT plot shows that Myristicaceae diversification accelerated ~72 Ma, coinciding with the spread of wet tropical climates, and continued post K-Pg extinction (~65 Ma), indicating resilience to mass extinction events. Further, the revised angiosperm megaphylogeny supports a pre-Cretaceous origin for basal angiosperms. Main Conclusions: Myristicaceae likely originated in western Gondwana during the Early Cretaceous and diversified across palaeotropics ensuing deep-time Plate tectonism, climate change, and vicariance. The study also proposes a pre-Cretaceous origin of basal angiosperms in the localised wet-highland habitats of mid- to low paleolatitudes. Overlapping pollen traits between Myristicaceae and earliest angiosperm fossils across Africa and northern mid-latitudes further suggest a boreotropical expansion of basal angiosperms under wet tropical climates of Cretaceous–Paleogene. © 2025 John Wiley & Sons Ltd.
Formation of the associating high-Al and high-Cr chromitites in the Nagaland-Manipur Ophiolites in northeast India
(Taylor and Francis Ltd., 2025) Monika Chaubey; Athokpam Krishnakanta Singh; Sashimeren Imtisunep; Ibrahim Uysal; Birendra Pratap Singh; Manavalan Satyanarayanan; Bendangtola Longchar; Shoraisam Khogenkumar
The Nagaland-Manipur ophiolites (NMO), part of the Phanerozoic (538.8–0 Ma) Tethyan ophiolites, occur in the NNE-SSW trending Indo-Myanmar Orogenic Belt (IMOB), northeast India. The NMO hosts both high-Al (0.46 < Cr# < 0.53) and high-Cr chromitites (0.71 < Cr# < 0.79). These chromitite bodies are hosted in lherzolite, harzburgite, and dunite and show various textures, including massive, disseminated, nodular, and granular. The high-Al chromitite compositions in conjunction with the calculated Al2O3[melt] (15.66–16.39 wt.%), TiO2[melt] (0.65–0.94 wt.%), and FeO/MgO[melt] (0.65–0.83 wt.%) values indicate that they were derived from the tholeiitic melt that formed at the mid-ocean ridge centre through low-degree partial melting. In contrast, the high-Cr chromitites, coupled with the Al2O3[melt] (11.24–12.99 wt.%), TiO2[melt] (0.21–0.33 wt.%), and FeO/MgO[melt] (0.58–1.54) values show similar geochemical affinities to those derived from boninitic melts produced by partial melting of already depleted mantle due to the subduction of oceanic plate in a supra-subduction zone environment. The total platinum group element (PGE) contents (60–190 ppb) of high-Al chromitites are lower than the total PGE contents (118–2341 ppb) in high-Cr chromitites. Chondrite-normalized PGE patterns in high-Al chromitites are flat from Os to Rh and negatively sloping from Rh to Pd, whereas high-Cr chromitites show strongly fractionated chondrite-normalized PGE patterns. Total PGE contents and low Pd/Ir ratios (0.02–0.64) of chromitites are consistent with typical ophiolitic chromitites. Mineral chemistry and PGE systematics suggest that NMO chromitites were generated in two separate tectonic settings. Thus, we argue that the upper mantle of the NMO of the IMOB has been modified by a substantial amount of supra-subduction zone components after initially being formed in a mid-ocean ridge tectonic environment. © 2024 Informa UK Limited, trading as Taylor & Francis Group.
Garnet-Staurolite-Mica Schist from Southern Sonbhadra District, U.P.: Constraints from Geothermobarometry and P-T Pseudosection Modelling
(Geological Society of India, 2024) Ankita Anand Singh; Divya Prakash; Birendra Pratap Singh; Chandra Kant Singh; Rajeev Kumar Pandey
The area around Renukoot town shows the exposure of garnet-staurolite-mica schist belonging to the Chhotanagpur Granite Gneiss Complex (CGGC). The characteristic mineral assemblage present in the rock are garnet–biotite–staurolite–quartz along with minor opaque minerals like rutile, ilmenite and hematite. For the constituent minerals, the calculated XMg value decreases in the order: chlorite>biotite>staurolite>garnet. The metamorphic conditions of the garnet-staurolite-mica schist were determined using the winTWQ and Perple_X programmes, and the peak pressure-temperature conditions for the rock are estimated to be 5.3 kbar and 570°C. The metamorphic episode in the CGGC during Mesoproterozoic time may be attributed to the global level Columbian Super-continental accretionary orogeny. © 2024, Geological Society of India. All rights reserved.
India–Ladakh arc collision during Early Eocene (~ 55 Ma): evidence from the Shimla hills, India
(Indian Academy of Sciences, 2025) Birendra Pratap Singh; Aditi Mishra
[No abstract available]
Petrogenesis and tectonic implications of the Late Cretaceous to Paleogene calc-alkaline volcanic rocks, Ladakh Himalaya
(Elsevier Ltd, 2023) Nongmaithem Lakhan Singh; Salim Akhtar; Athokpam Krishnakanta Singh; Birendra Pratap Singh; Ashima Saikia; Syed Hamim Jeelani
One of the most widespread volcanic suites exposed in the northwest Himalaya is the Khardung volcanic suite sandwiched between the Ladakh Batholith in the south and the Karakoram Batholith in the north. These volcanic rocks show a transition from andesite, dacite to more evolved rhyolite and have a calc-alkaline affinity. They display large ion lithophile elements (Rb, Sr, Ba, U, Pb) enrichment and depletion of high field strength elements (Nb, Ta, Hf, Ti) with increasing Eu negative anomaly from andesite to rhyolite. Bulk-rock Liquid Line of Descent (LLD) modelling shows that fractional crystallization played a dominant role in their petrogenesis. The calculated zircon saturation temperature (TZr) in andesitic magma (745 °C) is higher than the dacitic and rhyolitic magmas (682 °C). Andesites have zircon ages of 69–68 Ma, whereas more evolved dacite and rhyolite yield younger ages (59–64 Ma) that are consistent with their generation in the last stage of magmatism in an active continental marginal setting. Geochemical and geochronological findings of this study demonstrate that Khardung volcanic rocks were derived through two major magmatic events. These events occurred during the Late Cretaceous to the Paleocene Epoch due to the subduction of the Neo-Tethyan oceanic slab underneath the Eurasian plate boundary before the main collision between India and Eurasia. © 2023 Elsevier Ltd
Provenance of the Lower Cambrian Khewra Sandstone: Implications for Pan-African Orogeny
(Elsevier B.V., 2022) Shoukat Husain Khan; Ying-Ming Sheng; Muhammad Saleem Mughal; Birendra Pratap Singh; Muhammad Rustam Khan; Chengjun Zhang
This study describes the sedimentological aspects of the Lower Cambrian Khewra Sandstone, along with its lithostratigraphic correlation of globally distributed coeval red sandstones to decipher the imprints of Pan-African Orogeny. Despite the economic significance of Khewra Sandstone, the understanding of its environment of deposition, provenance and lower contact with the suite of igneous body namely Khewrite is poor. The Khewra Sandstone is an allostratigraphic unit bounded by unconformities. The upward coarsening sequence with abundant sedimentary structures and varying sedimentological properties of the topmost bed suggest that the Khewra Sandstone is tempestites deposited under fluvio-deltaic depositional environment. This sandstone is dominated by subarkoses, feldspathic litharenites and sublitharenites which were derived from the craton interior to recycled orogen provenance during the Pan-African orogeny under humid to semi-humid paleoclimatic conditions. The plutonic to metamorphic characteristics of framework grains suggest that the Bundlekhand Craton, Delhi Fold Belt and Aravalli Orogen rocks were the primary provenances. The lower and middle parts of the Khewra Sandstone are significantly affected by diagenesis while the diagenetic action in upper part is negligible and it acts as a potential hydrocarbon reservoir rock. The lithostratigraphic correlation suggests a worldwide series of rifting events before the deposition of Khewra Sandstone and the presence of Khewrite at lower contact marks a similar rifting event on the Indian plate. © 2022 Elsevier B.V.
Provenance, weathering, and paleoclimatic records of the Pliocene-Pleistocene sequences of the Himalayan foreland basin, NW Himalaya
(Springer Science and Business Media Deutschland GmbH, 2021) Sajid Ali; Binita Phartiyal; Ajay Taloor; Mohammad Arif; Birendra Pratap Singh
We present major oxides, trace element compositions, rare earth elements (REEs), clay mineral assemblages, and magnetic mineral parameters data for the siliciclastic fraction from the Upper Siwalik Subgroup (Parmandal, Nagrota, and Boulder Conglomerate formations) in the Tawi sub-basin of the Himalayan foreland basin, NW Himalaya in order to identify source rock compositions, continental weathering, and paleoclimate over the past 5.6 million years. The trace elemental ratios of Th/Co, Th/Sc, La/Sc, and Cr/Th suggest Upper Siwalik Subgroup sediments initially originated from a stable felsic source, which is possibly in the High Himalayan crystalline and Lesser Himalayan source regions. The REE patterns of the studied sediments with prominent negative Eu anomalies also suggest a felsic source for the Upper Siwalik Subgroup sediments deposited in the basin. The chemical index of alteration (CIA), plagioclase index of alteration (PIA), Rb/Sr ratio, and clay mineral assemblages as well as mineral magnetic parameters demonstrate the variable intensity of weathering and environmental conditions during the deposition of Parmandal, Nagrota, and Boulder Conglomerate formations between 5.6 and 0.6 Ma. The weathering proxy records of Parmandal (5.6 to 3.9 Ma) and Boulder Conglomerate (1.7 to 0.2 Ma) formations indicate relatively strong chemical weathering associated with the warm and wet climates in the source region. On the other hand, a decrease in chemical weathering intensity and change in environmental conditions during the formation of Nagrota formation (3.9–1.7 Ma) suggest a dry and cold climate in the source region. © 2021, Saudi Society for Geosciences.
Seismic origin of the soft-sediment deformation structures in the upper Palaeo-Mesoproterozoic Semri Group, Vindhyan Supergroup, Central India
(John Wiley and Sons Ltd, 2020) Birendra Pratap Singh; Krishna Mondal; Akanksha Singh; Preeti Mittal; Rohit Kumar Singh; Shyam Kanhaiya
Soft-sediment deformation (SSD) structures are the syn-sedimentary structures that can form by seismic as well as non-seismic processes. The SSD structures commonly occur in the Semri Group of the Vindhyan Supergroup in the Kajrahat Limestone, Chopan Porcellanite and Rohtas Limestone formations, and the Glauconitic Sandstone Member. The SSD structures include, slump folds, kink bands, chevron folds, convolute beddings, contorted cross-beds, flame structures, pinch-and-swell structures, breccias, sagging structures, water-escape structures, and dykes of varying dimensions. The lagoonal and tidal depositional environments of the Kajarahat Limestone Formation (not the continental slope environment) lead to suggest that the SSD structures formed as a result of the seismic activities in them. The SSD structures of the Chopan Porcellanite Formation associated with rhyolite might have originated as a result of volcanic activities or seismicity, while those occurring in the Glauconitic Sandstone Member (Kheinjua Formation) adjacent to the Son Lineament might have formed as a tectonics-related seismicity. The convolute bedding with large lateral extent in the Rohtas Limestone Formation looks related to seismicity in the light of its deposition along the shelf. Thus, the upper Palaeo-Mesoproterozoic Semri Group, Vindhyan Supergroup represents varieties of the SSD structures formed mostly by seismic processes. These imply that the Central India was unstable and was a place for tectonically controlled seismic events during the upper Palaeo-Mesoproterozoic (1,700–1,600 Ma). © 2020 John Wiley & Sons Ltd
Textural analysis and statistical synthesis to interpret depositional environments in the palaeochannel of the Assi River in the Central Ganga Plain, India
(Springer Nature, 2025) Mallikarjun Mishra; Shyam Kanhaiya; Birendra Pratap Singh; Koppella N. Prudhvi Raju
The current study is aimed to characterize the facies based on grain-size composition and textural parameters along the palaeo-course of the Assi River in Central Ganga Plain, India. Grain size fractions are expressed in terms of ratios of sand, silt and clay and plotted in ternary diagrams, while grain-size variations are used to explain the sediment transport mechanism, depositional history and energy levels during sedimentation. The palaeochannel deposits of the river in study largely consist of silty sandy mud with sand silt clay in various proportions. The occurrence of minor proportions of fine sands and silts in clay suggests successive stream episodes/floods in the recent past. The palaeochannel sediments show mean size ranges from 3.83 to 7.02 phi (average = 5.38 phi), indicating coarse to very fine silt, and sorting ranges from 0.81 to 2.49 phi (average = 1.87 phi), indicating moderately to very poor sorted sediments. Skewness varies from − 0.01 to 0.81(average = 0.28), indicating near-symmetrical to very fine-skewed sediment distributions and kurtosis ranges from 0.85 to 1.89 (average = 1.21) suggest that the majority of the sediments are mesokurtic to very leptokurtic in nature. The bivariate plot of mean grain size versus sorting shows that the bulk of the sediments were deposited in quiet-water environment under episodic fluvial regimes. The C–M pattern of the sediments in the palaeochannel suggests that sediments were transported in graded to uniform suspension before they are deposited. © Indian National Science Academy 2025.
Zircon U–Pb geochronology, mineral and whole-rock geochemistry of the Khardung volcanics, Ladakh Himalaya, India: Implications for Late Cretaceous to Palaeogene continental arc magmatism
(John Wiley and Sons Ltd, 2020) Nongmaithem Lakhan; Athokpam Krishnakanta Singh; Birendra Pratap Singh; Koushik Sen; Mutum Rajanikanta Singh; Shoraisam Khogenkumar; Saurabh Singhal; Govind Oinam
In this study, we present new mineral and whole-rock geochemical data with zircon U–Pb ages of the Khardung volcanics (KV) from the western Himalaya and discuss their tectono-magmatic evolution. These volcanics are sandwiched between the Ladakh batholith and Karakoram batholith and classified as intermediate volcanics (basaltic andesite-andesite) and felsic volcanics (dacite-rhyolite). The intermediate volcanics are marked by low SiO2 (52.80–61.31 wt.%), enriched LREEs, and depleted HFSEs (Nb, Ti, Zr), whereas more evolved felsic volcanics exhibit quartz, K-feldspar, and plagioclase as dominant mineral phases and felsic compositions are characterized by high SiO2 (64.52–79.19 wt.%) content with pronounced negative Eu anomalies, enriched LREEs, and depleted HREEs and HFSEs (Nb, Ti). New zircon U–Pb ages of intermediate volcanics (andesite) yield 69.71 Ma, whereas felsic volcanics (rhyolites) range between 62.49 and 66.55 Ma, indicating that the Khardung magmatism overlaps with the last phase of the Ladakh batholith magmatism. Geochemical characteristics indicate that the KV were generated from a same parental magma source through fractional crystallization along with crustal assimilation from an older crust, and they show genetic affinity with the adjacent Ladakh batholith. Therefore, the KV and Ladakh batholith could be considered as a product of the mature stage arc magmatism generated during subduction of the Neo-Tethyan oceanic crust prior to the main collision between the Indian and Eurasian continents. © 2019 John Wiley & Sons, Ltd.