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E345: Carbon transfer in the Himalaya by chemical weathering in the wake of the April 2015 Nepal Earthquake (Lead Supervisor: Ed Tipper, Earth Sciences)

Supervisor: Ed Tipper (Earth Sciences)

Importance of the area of research:

Chemical weathering regulates Earth’s carbon cycle and hence global climate over geological timescales. Ca and Mg from silicate minerals are released to the solute phase during chemical weathering. This solute Ca and Mg subsequently gets buried as Ca and Mg carbonates in ocean basins transferring carbon from the atmosphere to the carbonate rock reservoir. This simple reaction acts as a key climate feedback in regions where weatherable material is in ready supply such as active origins.    In the Himalaya, weatherable material is mainly supplied by landslides.  Thousands of landslides were triggered by the 2015 earthquakes and this research seeks to understand the role of tectonics in controlling carbon transfer at an orogenic scale.  We collected samples in the aftermath of the earthquakes and continue to collect water and sediment samples.

Project summary:

The 2015 earthquakes in Nepal last year triggered thousands of landslides which are causing major perturbations to sediment and chemical loads carried by Himalayan rivers. The objective of this project is to quantify the impact of this ∼100 year event on inorganic and organic carbon fluxes exported from this part of Nepal. This will determine the impact of such major events on the chemical fluxes thought to moderate long-term climate change.  The key weathering negative climate feedback is largely controlled by such catchments where the supply of material outpaces it’s weatherability, making these areas important for the long-term carbon cycle.

What the student will do:

The project will involve both lab and field components.  The student will initially work on samples collected in the two monsoon seasons following the earthquakes.  A key part of the lab work will be detailed chemical and petrological analysis of the suspended sediments to interpret changes in chemical weathering. With a clearer view of the existing sample set fieldwork will be planned, likely to take place close to the end of year 1 of the project.  The new data will be compared to existing data collected prior to the earthquakes.  In particular we will be trying to identify the weatherability of reactive phases such as pyrite and carbonate, which commonly may have already have weathered out of sediments, but in fresh material delivered by landslides, play a fundamental part in carbon transfer from mountain belts.

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

Jin et al, Controls on fluvial evacuation of sediment from earthquake-triggered landslides Geology, 43, 115-118 (2015).

Jin et al, Seismically enhanced solute fluxes in the Yangtze River headwaters following the A.D. 2008 Wenchuan earthquake, Geology, 44, 47-50 (2015)

Lupker, M. et al., Increasing chemical weathering in the Himalayan system since the Last Glacial Maximum, EPSL, 365, 243-252.

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