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Continuous multiproxy data were generated to understand the mid-late Holocene palaeoenvironmental history of the Kashmir Valley and the biogeochemistry of Wular Lake, India. For this purpose, geochemical and stable isotopic analyses were carried out on sediment samples retrieved from a 160 cm long trench excavated on the eastern bank of Wular Lake located in the Union Territory of Jammu and Kashmir, India. The chronology of the sediment strata developed using 14C dating by accelerator mass spectrometry covered the last ~5600 yr BP. Our results indicated the occurrence of an extended dry climate phase from 4600 to 3800 yr BP, which coincided with the widely recognised Meghalayan Stage, when major civilisations like the Harappa and the Akkadian were known to collapse. The lake biogeochemistry revealed dominance of the emergent macrophytes during this stage. Another dry phase was observed between 3100 and 2200 yr BP. This dry phase peaked at around 2900 yr BP, coinciding with Bond Event 2. Wular Lake faced nutrient limitation due to low runoff around 2500 yr BP caused by the persistent dry and cold climate. Geochemical signatures revealed that anthropogenic activities during the last two millennia might have significantly influenced erosion in the catchment area. [ABSTRACT FROM AUTHOR]

The loess-paleosol proxy records from mid-latitude Asia have been instrumental in the reconstruction of regional paleoclimate evolution and its relationship with global climatic changes. The present study explores the discrete occurrence of a loess and paleosol sequence (LPS) in the Southern Zanskar Range (SZR), NW Himalaya. Stratigraphic variations in sediment texture, supplemented with geochemical, organic and magnetic proxies, indicate two broad phases of loess accretion (L-1) and paleosol formation (PS-1). The older phase of loess accretion (L-1) is dated between 2.5 ± 0.3 ka and >2.0 ka, whereas the L-2, which fully transformed into the modern soil (MS) probably deposited during the Little Ice Age (LIA) phase. The textural attributes (high sand content) of loess indicate source proximal deposition, whereas the geochemical and magnetic proxies point towards the pre-depositional weathering (in the source area). The PS-1 dated to 2189 ± 296 cal yr BP indicates improved moisture conditions, whereas the MS is assigned to post LIA warm phase. These findings provide an important step towards better understanding the sensitivity of loess accretion and paleosol formation in the SZR linked to late Holocene climate variability. [ABSTRACT FROM AUTHOR]

Freshwater lakes and sediments need to be monitored continuously for environmental assessment and geochemical explorations. Lake sediments are major sinks for organic matter and for all geochemical elements. In the present study, total organic matter (TOC), nitrogen (TN), and geochemical analysis of major oxides was carried out on Yercaud Lake surface sediments, located at a higher elevation in South India to infer sediment distribution pattern and source for organic matter. Particle size distribution of lake surface sediments suggests that the sediments are predominantly silty sand and sandy silt, poorly to very poorly sorted and symmetrically skewed. TOC/TN ratio (6.54–12.65) reveal that the organic matter (OM) is derived from the in situ lake sources particularly from the vascular plants and lake biota accumulation. Weathering indices that fall from [chemical index of alteration (CIA)] 88.59–93.08 values and A‐CN‐K plot reflects intense chemical weathering of the bedrock exposures in the source area, which was accelerated under warmer and humid climate conditions in the sub‐tropical regions. Al2O3/TiO2 ratio (6.94–26.62) indicates weathering particularly of the exposed charnockite rocks around the lake basin. [ABSTRACT FROM AUTHOR]

Integrating multiproxy results (geochemistry, mineral magnetism, grain size, and C/N ratio variability supported by 14C AMS dating), obtained from a 1.4-m sediment core retrieved from high-altitude Anchar Lake, Kashmir Valley, NW Himalaya, we present a 6000-years record of paleoenvironmental and paleolimnological shifts. Phase 1 (6000–4700 cal. yr BP) revealed a wetter climate with a significant terrestrial input corresponding to the gradual strengthening of the westerlies. Phase 2 (4700–3900 cal. yr BP) reflects an overall improved westerly precipitation and autochthonous sources of organic matter (OM). Magnetic parameters also indicate higher lake levels and reducing conditions during this phase. Phase 2 was followed by a gradual diminishing pattern of the westerlies as also represented by phase 3 (3900–2500 cal. yr BP) and phase 4 (2500–1600 cal. yr BP) indicating moderate precipitation conditions, catchment stability, and temperate and/or cold-dry climatic conditions. Phase 5 (1600–500 cal. yr BP) revealed the prevalence of moderately cold/dry and further subdued westerly precipitation. Phase 6 (500 cal. yr BP to present) is represented by reduced westerly precipitation, shrinking lake margins, and significant terrestrial/anthropogenic controls over the lake basin. Mineral magnetic parameters indicate reducing lake bottom water conditions and eutrophication during this phase due to anthropogenic activities. These paleoenvironmental shifts reveal near synchronous changes (within dating uncertainties) with other regional paleoclimate records close to the present Anchar Lake location and reflect the gradual late-Holocene diminishment of the amount of winter/early summer moisture provided by the mid-latitude westerlies. [ABSTRACT FROM AUTHOR]