AMS and upcoming geochronology facility at Inter University Accelerator Centre (IUAC), New Delhi, India

Sharma, Rajveer; Umapathy, G.R.; Kumar, Pankaj; Ojha, Sunil; Gargari, S.; Joshi, R.; Chopra, Sundeep; Kanjilal, D.

doi:10.1016/j.nimb.2018.07.002

Cited by 52 publications

(18 citation statements)

References 19 publications

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“…The chronology for the trench was generated by dating organic carbon from eight bulk sediment samples by 14 C dating using Accelerator Mass Spectrometer at the Inter University Accelerator Centre (IUAC), New Delhi, following methodology by Sharma et al (2018; Table 1). 14 C ages were calibrated using IntCal 13 atmospheric curves (Reimer et al, 2013) in OxCal v 4.3.2 (Ramsey, 2017) without any reservoir corrections and the modelled ages were generated using a Poisson deposition model.…”

Section: Methodsmentioning

confidence: 99%

Holocene palaeoenvironmental records from the high-altitude Wular Lake, Western Himalayas

et al. 2020

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We present a comprehensive record of Holocene (11,590–628 cal. yr BP) climate and hydrographic changes around the Wular Lake located in Kashmir Valley, India. Based on the multi-proxy investigations, we have identified three phases of wet climate conditions that prevailed from the commencement of the Holocene Epoch – 9000 cal. yr BP, 8100–6650 cal. yr BP and 6350–5000 cal. yr BP, whereas periods of dry climate were observed during 9000–8100 cal. yr BP, 6650–6350 cal. yr BP and ~5000 to 4000 cal. yr BP. The results also suggested that the lake widened and deepened significantly around 6350–5000 cal. yr BP. The results indicated desiccation and the exposure of the lake margin around 5000–4500 cal. yr BP. The sedimentation rate since 4500–628 cal. yr BP was quite low for detailed paleoclimate interpretations. Oscillations in lake extension and deepening appear to be due to changing intensity of westerly moisture in the region, and we correlate several of the low lake-level phases to the Bond events caused by North Atlantic ice rafting events.

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Section: Methodsmentioning

confidence: 99%

Holocene palaeoenvironmental records from the high-altitude Wular Lake, Western Himalayas

et al. 2020

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“…For 14 C AMS dating, all the sediment samples were first visually cleaned under a stereo-zoom microscope to remove extraneous material to the possible extent followed by washing in de-ionized type-1 water (resistivity = 18.2 Ω ·cm). Furthermore, the samples were subjected to acid (HCl), base (NaOH), and acid (HCl) cycle (Brock et al, 2010; Sharma et al, 2019). The samples were immersed in the solvent at 60°C for about 5 h and the residue was removed.…”

Section: Methodsmentioning

confidence: 99%

Paleoenvironmental shifts spanning the last ~6000 years and recent anthropogenic controls inferred from a high-altitude temperate lake: Anchar Lake, NW Himalaya

et al. 2019

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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.

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“…Accelerated Mass Spectrometry (AMS) radiocarbon dating of seven peat samples after standard Acid Alkali Acid (AAA) pre-treatment (Nakamura et al, 2003) was carried out at the Inter-University Accelerator Centre (IUAC), New Delhi (Table 1). Blank sample prepared along with the peat samples was used for background correction, while standard sample OXII (oxalic acid II) was used for normalization (Sharma et al, 2019). Data quality was monitored with a secondary standard (IAEA-C7); the consensus value (pMC = 49.53±0.12) was within the error limits of the experimental result (pMC= 49.48±0.12).…”

Section: Methodsmentioning

confidence: 99%

Climate change and the migration of a pastoralist people c.3500 cal. years BP inferred from palaeofire and lipid biomarker records in the montane Western Ghats, India

Kavil¹,

Bala²,

Kumar

et al. 2020

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Human migration in response to climate change during the Holocene has been recorded in many regions of the world. The Todas are a pastoralist people who are believed to have colonized the higher elevations (>2000 m asl) of the Nilgiris in the Western Ghats, India, not earlier than about 2000 cal. yr BP. Vegetation shifts in response to changing climate in tropical montane forest-grassland mosaic of the Ghats have been well documented using stable carbon isotopes and pollen profiles; however, there have been no corresponding investigations of human presence and activity at the highest elevations. We used a number of other proxies to infer the human ecology of this montane region. Radiocarbon dated (~22,000 cal. BP to the present) peat samples from the Sandynallah basin (2200m asl, Nilgiri hills, Tamil Nadu State) were used to reconstruct fire history, animal abundance, and human presence since the Last Glacial Maximum (LGM). While the macro-charcoal record indicates fires at the LGM, macro- and micro-charcoal counts indicate intense fire at ~3500 cal. yr BP, coprophilous fungal spores indicate a large population of herbivorous mammals, and steroid biomarkers indicate human faecal remains for the first time. This period is also characterized by dry arid conditions and dominant grassy vegetation as inferred from n-alkane signatures. We thus infer that a pastoralist people, most likely the Todas, migrated to the highest elevations of the Western Ghats along with their buffalo herds in response to prolonged or abrupt climate change in peninsular India, about 3500 cal. yr BP or at least 1500 years prior to what historical accounts assume.

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AMS and upcoming geochronology facility at Inter University Accelerator Centre (IUAC), New Delhi, India

Cited by 52 publications

References 19 publications

Holocene palaeoenvironmental records from the high-altitude Wular Lake, Western Himalayas

Holocene palaeoenvironmental records from the high-altitude Wular Lake, Western Himalayas

Paleoenvironmental shifts spanning the last ~6000 years and recent anthropogenic controls inferred from a high-altitude temperate lake: Anchar Lake, NW Himalaya

Climate change and the migration of a pastoralist people c.3500 cal. years BP inferred from palaeofire and lipid biomarker records in the montane Western Ghats, India

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