Kuhnt, W., Holbourn, A.E., Jöhnck, J. and Lübbers J., (2020). Miocene to Pleistocene Palaeoceanography of the Andaman Region: Evolution of the Indian Monsoon on a Warmer-Than-Present Earth

The Andaman Sea is ideally situated to assess the sensitivity of the Indian Monsoon to insolation forcing and to changes in climate boundary conditions such as global ice volume and greenhouse gas concentrations on a warmer-than-present Earth. Sediment archives from this region record the monsoonal discharge of water and sediment from mountainous areas at the southern slope of the Eastern Himalayas, the western slopes of the Arakan Mountains and Indo-Burman Ranges and from the catchment of the Irrawaddy, Sittang and Salween Rivers. New sediment cores recovered during International Ocean Discovery Program (IODP) Expedition 353 (iMonsoon) provide the first complete millennial-scale resolution record of the Indian Monsoon over the late Neogene, when major changes in the Indian and East-Asian monsoonal subsystems occurred. Initial results from sediment natural gamma ray core-logging and foraminiferal stable isotope analyses indicate that a long-term increase in physical weathering and erosion coincided with a prolonged late Miocene cooling trend between ~7 and 5.5 Ma. Monsoonal erosion remained intense during the subsequent warming episode between 5.5 and 5.3 Ma, probably associated with a northward shift of the monsoonal rain belt. Ocean mixed layer oxygen isotope records indicate freshening of the Andaman Sea during late Miocene warm isotope stages as during Pleistocene interglacials. Knowledge of this past evolution of freshwater and sediment discharge from one of the core areas of Indian Monsoon precipitation is essential to better predict trends and consequences of monsoonal spatial variability with future climate change.


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