Loktak C18

Published: 23 August 2026| Version 1 | DOI: 10.17632/td9xh7gpj3.1
Contributors:
Aubrey Hillman, Choudhurimayum Sharma, Yengkhom Singh, Bronwen Konecky, Josilyn Bouffard, Abigail Santis, Jack Hutchings, Hailey Sinon, Matthew Finkenbinder, Mark Abbott

Description

The Bay of Bengal branch of the Indian Summer Monsoon (ISM) dominates the hydroclimate of the Indian subcontinent. There are several terrestrial Holocene-scale records of the ISM from the Indian mainland, but fewer well-dated records from northeastern India where instrumental climate trends are distinct. Loktak Lake is an ideal system for study because of its geographic location and its annual increase in water level of >3 m that floods the surrounding wetlands, doubling the lake area during the summer monsoon season. This study is based on a chronologically robust, multi-proxy analysis of sediment cores from Loktak that span the last 2800 years. Over this period there is a trend toward a weaker ISM which decreases the level and magnitude of annual flooding, albeit with considerable variability on multi-centennial timescales. There are three distinct sedimentary units from 2800 to 1600, 1600 to 500, and 500 cal yr BP to present. These units are defined by changes in the sediment flux, clastic and organic matter content, density, scanning XRF counts, and C/N ratio. We interpret these millennial- to multi-centennial changes in sediment supply and content as representing distinct stages in an overall decreasing trend in the magnitude, depth, and duration of annual flooding associated with the ISM. This dynamic ISM record exhibits a strong connection to the seasonal distribution of insolation, the Indian Ocean Dipole, and the El Niño Southern Oscillation as well as known periods of climate change such as the Little Ice Age.

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Lake Sediment, India, Paleoclimate, Elemental Geochemistry, Holocene, Monsoon

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