Decoding the Indian monsoon evolution during the last glacial abrupt climate transitions in interannual resolution: Applying congruent imaging techniques on Northeastern Arabian Sea sediment

• Applicant: Dr. Igor Obreht
• Subject Area: Palaeontology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 542517899

The Indian monsoon is one of the most important large-scale coupled land-ocean-atmosphere phenomena in the low latitudes. However, the forcing mechanisms of the decadal-scale monsoon variability are not well understood because knowledge of short-term climate oscillations is mostly limited to instrumental era. Understanding of the short-scale climate evolution in the more distant past is hampered by the small number of records that preserve undisturbed signals and by methodological limitations to obtain highly resolved records. However, recent developments that interrogate laminated sediments with novel imaging techniques showed great potential to overcome these limitations. In order to reveal the interannual paleoclimate evolution of the Indian monsoon region, I propose to apply biomarker and elemental imaging on laminated sediment sections from the Arabian Sea deposited between 50000 and 35000 years BP. The goal of this project is to explore the interplay of the Intertropical Convergence Zone (ITCZ), Indian monsoon intensity, and related environmental responses at interannual resolution during climate period characterized by multiple abrupt climate transitions in order to better comprehend monsoon response to major changes in the climate system. Sediment core SO130-289KL from the Arabian Sea preserves an undisturbed, laminated record over the major part of the core, providing an excellent archive for high-resolution studies. I propose to apply mass spectrometry imaging, a novel technique in paleoclimate research, and combine it with congruent µXRF data from sediments deposited between 50000 and 35000 years BP. The aim is to combine independent biomarker proxies for sea-surface temperature (SST) in 200 µm resolution and relate this data to elemental ratios indicative of environmental conditions acquired at 50 µm resolution. Obtained near annually resolved biomarker and elemental records will reveal previously inaccessible information on monsoon intensity and its relation to ITCZ in different climate states between 50000-35000 years BP, as well as precisely establish monsoon forcing on the environment by detecting leads and lags in the responses of the ocean (reconstructed by SST-proxies) and environment (reconstructed by elemental composition) to abrupt climate change in an unprecedented level of details. An important objective of this proposal is to address the limitations associated with the lack of independent chronology at the site by applying cosmogonic 10Be for synchronization of the marine sediment records directly to ice cores. Applying this method to Arabian Sea sediment will provide us with the opportunity to more precisely compare the reconstructed environmental changes in the Arabian Sea, Greenland and Antarctica and address their coupling and feedbacks. Building on this improved chronology, I will more precisely constrain the SST rate of change and cyclicity under different stages of climate state between 50000-35000 years BP.

• DFG Programme: Research Grants