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Jing Lyu

Institution: University of Bremen
Office: GEO, room 3160
Phone: +49 421 218 - 65990
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Other webpage(s): Jing's MARUM web page

 

Jing Lyu

PhD Project

Tracing Tasman Leakage since the middle Miocene

The global ocean circulation connects Earth’s ocean basins at different latitudes and different water depths. Thereby, water and heat are transported from one ocean basin into another. For instance, the Indonesian Throughflow connects the Pacific and Indian Oceans at surface depth north of Australia (~300 m). South of Australia, an additional pathway connects the Pacific and Indian Oceans at intermediate water depth (~1100m). Oceanographers started describing this second inter-basin connection as recently as 2001, and they named it Tasman Leakage (TL). Once TL reaches the Indian Ocean, it flows in a north-westerly direction, towards the African continent, at a water depth between 300 – 1100 m. Thereby, it passes over Broken Ridge, which is an oceanic plateau in the central Indian Ocean. Broken Ridge rises up to ~1000 meters below the sea surface and therefore bathes in TL waters. This implies that sediments accumulating on Broken Ridge have the potential to record TL temporal dynamics. This potential, however, has not yet been explored by sedimentologists and paleoceanographers. Indeed, the geologic history and TL variability has not yet been documented by means of sedimentary archives.  

To pinpoint the onset of TL in geologic time and to understand its dynamics, I will use previously-drilled sediment cores from Broken Ridge. These cores consist of carbonate-rich sediments that allow for different geochemical and geophysical proxies to be measured. These proxies will provide us with information on environmental changes on Broken Ridge throughout the last 13 million years (middle Miocene to recent), and will thus be key to constructing the first geologic history for TL. Specifically, I will generate a 4-cm spaced carbon and oxygen stable isotope record from benthic foraminifera (unicellular fossils that lived on the seafloor and in the sediment) at Broken Ridge. Additionally, I will use clumped isotope thermometry to reconstruct bottom-water temperature throughout the studied interval. Besides constraining the onset of TL, I also anticipate to understand TL dynamics on astronomical time-scales (10 000 – 100 000 years) and to evaluate the role of TL in the global circulation of water and heat throughout the oceans.

Thesis Committee

Prof. Dr. Heiko Pälike University of Bremen
Dr. David De Vleeschouwer University of Bremen
Dr. Mahyar Mohtadi University of Bremen
Dr. Julie Meilland University of Bremen
Dr. Henning Kuhnert University of Bremen