Tracing Indian Summer Monsoon (ISM) variability from the Mid-Holocene to the present in Uttarakhand, India using X-ray fluorescence (XRF)

Authors: Emily Alyssa Niederman*, Dept. of Geography, University of Georgia, USA, David Porinchu, Dept. of Geography, University of Georgia, USA, Jeff Speakman, Center for Applied Isotopes Studies, University of Georgia, USA, Bahadur Kotlia, Dept. of Geology, Kumaun University, India
Topics: Paleoenvironmental Change, Anthropocene, Asia
Keywords: Indian Summer Monsoon, Palaeoclimatology, Lake Sediment, X-ray fluorescence, India, Abrupt Climate Change, 4.2 ka event
Session Type: Paper
Day: 4/4/2019
Start / End Time: 3:05 PM / 4:45 PM
Room: Coolidge, Marriott, Mezzanine Level
Presentation File: No File Uploaded

The Indian Summer Monsoon (ISM) provides approximately 80% of the total annual rainfall in India, impacting India’s agricultural productivity and substantial population. Reconstructions detailing the long-term variability of the ISM over millennial timescales during the mid- to late-Holocene, an interval which includes the Little Ice Age (LIA), Medieval Climate Anomaly (MCA), and 4.2 ka event, are relatively limited for this region. Of particular interest is the potential link between abrupt climate change at 4.2 ka and the onset of a step-wise decline of the Harappa—a complex, highly urbanized, and centralized society.

High-resolution analysis of a lake sediment core, recovered from Deorital, a mid-elevation lake (located at 2393 m asl in the Garhwal Himalaya of Uttarakhand) was undertaken to document how long-term and abrupt climatic fluctuations influenced the intensity and timing of the ISM during the Holocene. A robust chronology, based on eleven AMS 14C dates obtained from water chestnut seed cases, indicates that the Deorital core extends into the mid-Holocene. Non-destructive imaging approaches, such as X-ray fluorescence (XRF), X-ray, and CT scans are being used to assess the response of the lake system to changing hydroclimatic conditions. The preliminary results of the XRF analysis suggest that there are two environmental regimes for the lake over the entire study period with climatic anomalies the corresponding to the timeframe for the MCA in Europe and three events of interest around the time of the Harappan Civilization for 3000, 4100, and 4800 cal yr BP.

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