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The Pur‐Banera belt of metasedimentary rocks, in the Bhilwara region of the Aravalli Craton, northwestern India, constitutes a Mesoproterozoic rift‐related supracrustal sequence. The Pur‐Banera belt, while containing psammitic, calcareous, and ferruginous metasediments, is dominated by garnet–staurolite–kyanite‐bearing metapelites. Here we integrate data on outcrop‐ and microscopic‐scale deformation structures with pseudosection modelling and zircon–monazite geochronology to decipher the P–T–t–d evolution of these metapelites. The metapelites record three distinct deformation events. The first two (D1–D2) produced a composite S1//S2 foliation, and a younger event of dextral shearing (D3) produced crenulations superimposed on the foliation. Textural and compositional data indicate two stages of growth of garnet, whose core compositions were significantly altered during peak metamorphism. The textures combined with pseudosection modelling and conventional thermobarometry reveal that the garnet cores continued to grow up to staurolite‐grade prograde metamorphism, followed by a second stage of garnet growth (syn‐D2; 7.3–7.9 kbar and 665–690°C) during kyanite‐grade peak metamorphism. Fibrolite grew in the matrix during post‐peak readjustments due to uplift and decompression, whereas fluid‐induced retrograde metamorphism (480–540°C) resulted in the formation of euhedral staurolite prisms and narrow rims around garnet porphyroblasts. Detrital zircons of magmatic origin yield a weighted mean 207Pb/206Pb age of 1,827 ± 7 Ma (95% confidence) indicating a Palaeoproterozoic igneous source rock for the sediments, consistent with a Mesoproterozoic (1.6–1.3 Ga) age of deposition as inferred in previous work on the Pur‐Banera quartzofeldspathic gneisses. Monazite U–Th–(total) Pb ages indicate the timing of commencement of prograde metamorphism at c. 1.3 Ga, peak metamorphism at c. 1.2–1.1 Ga, and fluid‐induced retrograde metamorphism at c. 0.85–0.75 Ga. Our combined results indicate that the metapelites experienced two deformation events (D1 and D2) during the closure of the Pur‐Banera basin and the consequent burial of the sediments to lower crustal depths. These were followed by post‐collisional uplift and exhumation, and fluid‐induced retrograde metamorphism during D3 shearing. Southwestward tilting of the rocks during the D3 event, and subsequent erosion, have exposed rock units in the western, central, and southeastern parts of the belt which were buried deeper than those in the southwestern parts. This explains the observed northeastward increase in the metamorphic field gradient along the NE–SW strike of the belt. These new insights into the Meso‐ to Neoproterozoic tectonometamorphic evolution of the Pur‐Banera belt help relate it to the amalgamation and fragmentation of the supercontinent Rodinia. [ABSTRACT FROM AUTHOR]

As a rapidly accelerating expression of global change, plastics now occur extensively in freshwater ecosystems, yet there is barely any evidence of their transfer through food webs. Following previous observations that plastics occur widely in their prey, we used a field study of free‐living Eurasian dippers (Cinclus cinclus), to test the hypotheses that (1) plastics are transferred from prey to predators in rivers, (2) plastics contained in prey are transferred by adults to altricial offspring during provisioning and (3) plastic concentrations in faecal and regurgitated pellets from dippers increase with urbanization. Plastic occurred in 50% of regurgitates (n = 74) and 45% of faecal samples (n = 92) collected non‐invasively from adult and nestling dippers at 15 sites across South Wales (UK). Over 95% of particles were fibres, and concentrations in samples increased with urban land cover. Fourier transform infrared spectroscopy identified multiple polymers, including polyester, polypropylene, polyvinyl chloride and vinyl chloride copolymers. Although characterized by uncertainty, steady‐state models using energetic data along with plastic concentration in prey and excreta suggest that around 200 plastic particles are ingested daily by dippers, but also excreted at rates that suggest transitory throughput. As some of the first evidence revealing that plastic is now being transferred through freshwater food webs, and between adult passerines and their offspring, these data emphasize the need to appraise the potential ecotoxicological consequences of increasing plastic pollution. [ABSTRACT FROM AUTHOR]

The Banded Gneissic Complex (BGC) of the Aravalli Craton (Rajasthan, northwestern India) is considered to have evolved through the amalgamation of several crustal terranes. The BGC has been previously divided into an older, Archaean, BGC-I (exposed south of Nathdwara and roughly equivalent to Mewar Gneiss) and a younger, Proterozoic, BGC-II (exposed north of Nathdwara). However, the poorly documented deformation history and insufficient geochronological work limit our understanding of BGC evolution. To understand this, we combine detailed structural analysis of basement gneisses (traditionally considered to be BGC-II) and a metasedimentary cover sequence (the Pur-Banera belt) exposed in the Bhilwara region, with U–Pb zircon and U–Th–total Pb monazite geochronology. Resorbed zircon cores from the basement gneisses yield a 207Pb–206Pb age of 3159 ± 8 Ma (1σ). This oldest analysed population, giving a minimum crystallization age, is hitherto unreported from BGC-II. The basement gneisses experienced four phases of deformation, D1 through D4, each of which developed a tectonic fabric. Textural evidence and U–Pb zircon ages indicate the D1 deformation to be 2.9 Ga in age. A NNW–SSE-directed shortening event (D2) at 2.5 Ga formed upright folds on early gneissic foliation (S0//S1), with syn-tectonic granite emplacement. Subsequent NNE–SSW-directed deformation (D3) at 1.8 Ga produced NW–SE-trending vertical folds. Asymmetrical folds developed due to N–S-trending dextral shearing at 1.3 Ga constitute the last phase of deformation (D4) in the basement gneisses. The Pur-Banera sequence shows NNE–SSW-directed shortening on primary foliation, forming S1 foliation along WNW–ESE direction. These metapelitic supracrustals also show tight crenulations on S1 foliation, with pervasive axial planar fabric (S2), typically observed in high-strain zones formed at 1.3 Ga. This suggests that the two deformation events experienced by the Pur-Banera sequence correspond to the D3 and D4 deformation events affecting the basement gneisses. The ubiquitous record of older age populations (3.2–1.3 Ga) in zircon grains, with younger age populations (1.3–0.8 Ga) mostly preserved in monazite grains, indicates that monazite growth was associated with younger tectonic events that reworked large parts of the basement gneisses and supracrustal rocks. Our results demonstrate that BGC-I and BGC-II, with Mesoarchaean ages and known similar geochemical signatures, are not different. The BGC thus represents a coherent crustal entity formed during the Archaean and reworked several times during the Proterozoic.Keywords: Aravalli Craton, Rajasthan, Banded Gneissic Complex, Geochronology, Crustal evolution [ABSTRACT FROM AUTHOR]