Physical Research Laboratory

In many drylands globally, badlands (coalesced gully networks) have developed in colluvial (e.g. hillslope, pediment) and alluvial (e.g. river terrace, floodplain) landforms. Badland development can have serious on-site and off-site impacts including soil loss and reservoir sedimentation but can also create striking visual scenery that may have aesthetic appeal and geoheritage potential. Vigorous debate surrounds the relative importance of human and natural factors in badland development, with some researchers attributing their development mainly to human causes such as poor land management, while others have argued for natural causes, including decadal-scale climatic fluctuations, susceptible soil characteristics, and/or breaching of hard rock barriers along river beds. Intrinsic land surface adjustments may also account for some gullies, such as valley floor oversteepening that leads to erosion and slope adjustment. In short, is badland development dominantly a human-induced problem, a natural part of landscape development, or some combination of both factors? The answer has implications not only for advancing our understanding of Earth surface dynamics and human–nature interactions, but also for the targeting of the limited resources aimed at erosion control, sustainable land management, and geoheritage promotion. The Chambal Badlands in semiarid, north-central India exemplify these issues. The ~4800 km2 badlands are some of the largest in the world and present striking development challenges: soil erosion threatens food and water security but the deeply dissected terrain provides opportunities for geoheritage promotion. The region faces intertwined socio-economic and environmental challenges: marginal agriculture, limited alternative livelihoods, and widespread soil loss. In places, the badlands are heavily degraded by poorly controlled agricultural developments. Attempts to infill gullies and level the land for cultivation often fail within years as the soil simply re-erodes, trapping farmers in never-ending cycles of nutrient, water and soil carbon loss. At the same time, the badlands and associated bedrock channels, potholes, waterfalls and gorges of the Chambal and other nearby rivers illustrate landform combinations rarely present elsewhere on Earth, and certainly not at the same scale, and their promotion as geoheritage could enhance geoeducation (e.g. for local schools) and geotourism (e.g. for domestic/international markets). We report here on the initial findings from a UK-India collaborative project that is combining field data, laboratory analyses and science communication to address key questions, including: i) when and why did the badlands form?; ii) do modern agricultural practices enhance badland growth?; iii) how can we best use this information to address the development challenges? Geomorphological perspectives are a crucial element of the project, which hopes to develop a scientific, practical, and social blueprint for transforming the fragile badlands into productive and culturally-valued, resilient landscapes.

Plagiogranites are the felsic plutonic rocks occurring amidst a suite of predominantly mafic and ultramafic rocks. Their occurrence ranges from newly formed oceanic crust to Archean ophiolites, and they are usually associated with the crustal section, i.e., gabbros and sheeted dykes. Sometimes, they have been observed in the mantle sections as well. The Andaman ophiolite (AO) is a dismembered ophiolite suite located on the forearc of the Andaman subduction zone, where the Indian plate obliquely subducts beneath the Burma microplate. Plagiogranites of the AO are found to be intruding into gabbros and serpentinized mantle peridotites. They have been dated to 98-93Ma, and are contemporaneous with the other rocks of the ophiolite. Earlier studies propose that these have been generated by crystal fractionation or an immiscible separation from a parental basaltic magma. In this study, we utilize new whole-rock geochemical data and Sr-Nd isotopic ratios of these rocks to constrain their petrogenesis. Geochemically, these rocks are classified as diorites to tonalites-trondhjemites, characterized by plagioclase+amphibole+quartz assemblage. Petrographic observations reveal that euhedral plagioclase and amphiboles were the early crystallizing phases, while anhedral quartz crystallized later in the sequence. The plagiogranites exhibit LREE-enriched patterns on chondrite-normalized plots and negative Nb-Ta and Zr-Hf anomalies on primitive mantle-normalized plots, suggesting derivation from a metasomatized source. Sr-Nd isotopic compositions strongly overlap with other rocks of the ophiolite suite, pointing to a common mantle parentage. Low TiO2 contents, overlapping trace element patterns with the mafic rocks of the AO, and REE-SiO2 systematics negate the possibility of plagiogranite formation by fractional crystallization from a basaltic magma. The occurrence of amphiboles in the plagiogranites suggests that the parent magma was hydrous, implying that liquid immiscibility was not the genetic mechanism. Therefore, we explore the possibility that they are crystallized products of a high-magnesian andesitic magma (HMA) derived by the partial melting of a metasomatized mantle source at low pressure, followed by fractional crystallization of plagioclase±amphibole, to explain their genesis and the observed compositional variation. We demonstrate, using the results of alphaMELTS simulations, that compositional variation and the mineral assemblages observed in the plagiogranites of the AO can be explained by this model and suggest that derivation from HMAs is a viable mechanism for the genesis of plagiogranites in similar settings. We propose that the plagiogranites of AO have formed during the initiation of an intra-oceanic subduction, which can explain their geochemical features and geochronological results.

Abstract Complex organic molecules (COMs) in starless cores provide critical insights into the early stages of star formation and prebiotic chemistry. We present a chemical survey of 16 starless cores (including five prestellar cores) in the Orion A and B molecular clouds, targeting CH 3 OH, N 2 H + , CCS, and c-C 3 HD, using the Atacama Compact Array (ACA) and the Yebes 40 m telescope. CH 3 OH was detected toward all targets, confirming its ubiquity in starless cores, consistent with previous surveys in Taurus and Perseus. ACA imaging shows that CH 3 OH, CCS, and c-C 3 HD generally trace the outer layers of the dense cores outlined by N 2 H + , each exhibiting distinct spatial distributions. Meanwhile, comparison with Yebes data reveals an extended, flattened CH 3 OH component. CCS and c-C 3 HD tend to be detected or nondetected together across cores, while cores near dust-rich regions on a large scale often lack both, suggesting environmental influences linked to the interstellar radiation field. Within individual cores, CCS typically resides in an outer layer relative to c-C 3 HD. Our findings underscore the importance of high-resolution studies for understanding the origins and spatial differentiation of COMs and carbon-chain molecules in cold, quiescent environments.

Abstract We report the discovery of 45 compact hub-filament systems (HFSs; median size ∼2.4 pc) in infrared-dark clouds (IRDCs) in the W33 complex, located at the junction of the Scutum and Norma spiral arms. Using Spitzer 8 and 24 µ m, and unWISE 12 μ m images, HFSs are identified as regions where three or more filaments converge onto a central hub, appearing as absorption features toward IRDCs. In each IRDC, HFSs mainly lie at the intersections of elongated substructures, associated with groups of protostars and lacking radio continuum emission. Minimum Spanning Tree (MST) analysis shows that protostars are closely associated with the HFSs, with protostellar core separations of ≤0.7 pc, indicating strong clustering within fragmented structures. The HFSs form two main groupings spanning 10–15 pc, with member separations of 1–3.3 pc. Around 65% are tightly clustered (<2 pc), exhibiting rich small-scale structures and emphasizing the uniqueness of the complex. MST analysis of ALMAGAL 1.38 mm continuum cores—predominantly low-mass and embedded in 10 HFSs—reveals a median core separation of ∼0.03 pc. The protostellar spacing (∼0.7 pc) significantly exceeds the thermal Jeans length (∼0.08 pc for temperature ∼18 K and density ∼10 5 cm −3 ), whereas the core spacing is smaller than the Jeans length, suggesting that thermal fragmentation may influence core formation but alone cannot explain the larger-scale protostellar distribution. All these findings together support a picture in which fragments of clouds/filaments form clumps hosting compact HFSs that facilitate efficient and clustered star formation, often yielding massive stars.

Abstract Picophytoplankton are drivers of biogeochemical cycling and serve as key indicators of seafood productivity, ocean health, and climate change. The Arabian Sea and the Bay of Bengal—two basins of the northern Indian Ocean that support the livelihoods of over a billion people—share similar climatic conditions but differ in their hydrographic and ecological characteristics. However, the environmental factors governing picophytoplankton abundance and their implications on carbon biomass in these regions remain poorly understood. This study investigated the abundance, carbon biomass, and environmental relationships of three groups of picophytoplankton: Prochlorococcus , Synechococcus , and picoeukaryotes. We observed Synechococcus dominating the surface waters (47% in the Arabian Sea and 63% in the Bay of Bengal), while Prochlorococcus showed the highest abundance and variability in the water column between basins. Picoeukaryotes contributed more to the total picophytoplankton carbon biomass in both basins. In particular, picophytoplankton carbon biomass contribution to particulate organic carbon were not substantially distinct between the two basins. The estimated picophytoplankton carbon stock was 1.05 Tg C in the Arabian Sea and 0.5 Tg C in the Bay of Bengal. Furthermore, we determined key environmental factors—temperature, salinity, light, dissolved inorganic phosphorus (DIP), and dissolved inorganic silicate (DSi)—that shape picophytoplankton dynamics in the region. Temperature and salinity primarily influenced picophytoplankton distribution in the Arabian Sea, while nutrients were critical in the Bay of Bengal. Overall, we underscore the role of physicochemical dynamics in carbon cycling by presenting the contribution of picophytoplankton carbon biomass to the region's particulate organic carbon pool.

Abstract. In India, land ownership disputes remain a major source of litigation, often resulting from fragmented records, lack of transparency, and outdated administrative processes. This study explores the potential of geospatially enabled blockchain technology to transform land administration into a secure, efficient, and trust based system. By combining the immutability and decentralization of blockchain with the spatial precision of geospatial data, the research proposes a digital framework that enhances the integrity of land transactions and builds stakeholder confidence. The methodology follows a modular system development approach using both software and database life cycle models. Through fact finding, stakeholder interviews, prototyping, and interface development, the system was designed to accommodate various users buyers, sellers, inspectors, and administrators. Key features include cryptographic public private key generation and secure hashing algorithms for transaction protection. A functional prototype was developed using Java and MySQL, integrating GIS capabilities and smart contracts to automate processes and ensure spatial traceability. The system’s performance was assessed based on its completeness, usability, and security. Results showed that the blockchain ledger enabled real time synchronization and minimized the risk of fraud, tampering, or duplication. Incorporating spatial data allowed for visual verification of land parcels and ownership histories, improving reliability for both citizens and government agencies. This research demonstrates how integrating geospatial intelligence with blockchain can modernize land governance, reduce bureaucratic delays, and foster a more transparent and citizen centric system. It presents a promising direction for high performance, scalable digital infrastructure in rapidly developing regions.