NERC Studentship: Understanding Climatic versus Tectonic Controls on
Continental Erosion in the Mekong River Basin
Supervisor: Peter Clift, David Macdonald (Aberdeen) and Andrew Carter
(UCL-Birkbeck)
Debate continues as to the relative importance of climate versus solid Earth
tectonic forces in controlling the erosion of the continental crust.
Understanding what controls erosion is important to quantifying the rates of
crustal destruction and recycling back in the mantle, as well as determining
long term sealevels and feedbacks to climate via chemical weathering of
eroded material. This project is designed to make a sediment budget for the
Mekong River system using a combination of geochemical provenance tools and
sedimentary volumes estimated by seismic stratigraphic methods.
The Mekong River has its headwaters in SE Tibet and flows through Indochina
to the South China Sea. Sediment is derived from eastern Tibet where active
rock uplift is occurring, from the stable core of Indochina and from the
Vietnamese Central Highlands, uplifted in the Miocene and now the location
of heavy monsoon summer rains. The student will be required to sample modern
river sands throughout the Mekong basin and visit core stores in Vietnam,
Japan and Europe to take samples of paleo-delta sediments. The provenance of
the sediments will be constrained through application of Nd and Sr bulk
sediment isotope measurements, together with U-Pb dating of zircon grains at
UCL-Birkbeck and Ar-Ar dating of micas at SUERC, East Kilbride. The student
will also be trained in basic petrographic microscopy, quantitative clay
mineralogy by XRD methods and major element chemistry to assess the
intensity of chemical weathering in different parts of the river system.
Seismic data from the Mekong delta mouth will be interpreted on a computer
workstation in order to estimate total volumes of sediment reaching the
ocean and a mass balance will be attempted between source and sink. Key
objectives will include determining the speed of transport of different
mineral grains through the river and assessing how much sediment is stored
in terraces or flood plains and what causes this sediment to be stored or
released. By doing so the project will determine how the deep sea sediment
record can be used as a recorder of erosion in Tibet and whether the river
has ever been involved in large scale headwater capture events.
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Plan on attending the AGU Chapman meeting on climate change and society in
March 2011
http://www.abdn.ac.uk/~wpg008/AGUClimateSocietyChapman.html
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Peter D. Clift
Department of Geology & Petroleum Geology
University of Aberdeen
Meston Building, Kings College
Aberdeen, AB24 3UE
United Kingdom
Tel: +44 (0) 1224 273456; Fax +44 (0) 1224 272785: E-mail:
[log in to unmask]
http://www.abdn.ac.uk/~wpg008/PChomepage.html
The University of Aberdeen is a charity registered in Scotland, No SC013683.
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