Drastic environmental
changes are expected in the next tens to hundreds of years when atmospheric
CO2 will attain levels that were last reached during the warm
Paleogene period, 65.5 to 23 Myr ago. To understand major climate changes
like global warming, it is crucial to know how and when our world changed
from the Greenhouse state of the Paleogene into the Icehouse state of today.
The prevailing hypothesis assumes that global cooling was caused by uplift
of the Tibetan Plateau, following the onset of the Indo-Asia continental
collision.
However,
proving this far-sighted theory is upsetting the geosciences community
because of the inability to establish unequivocal relationships between
tectonism, global climate and major environmental changes in Asia.
The most fundamental
boundary condition to solve the problem is the age of the collision itself,
but despite previous attempts to constrain it, this age is still highly
controversial with estimates ranging from 70 to 35 Myr ago. The aim of
this PhD project is to date the Indo-Asia collision accurately, and quantify
associated continental deformation.
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Wentao
overlooking the geology of the southern Tarim basin at Aertashi (left)
and drilling Oligocene red beds (above).
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Using state-of-the-art
paleomagnetic methods on well-targeted and crucial areas, our results will
allow reconstructing the positions of continents in unprecedented detail
in place and time. Our reconstructions will be independently constrained
by tomography, and will constitute the building blocks for regional tectonic
models (collision, exhumation, crustal deformation, basin formation) and
their environmental response (sea retreat, aridification, cooling, monsoon
intensification, biotic events).
In addition to providing
the boundary conditions for tectonic modelling of continental collision,
our long awaited results are essential for global circulation modelling
of the peculiar Paleogene climate events.
This project is embedded
with an ongoing VIDI project from NWO: "Is the India-Asia collision responsible
for global climatic cooling?" of G.
Dupont-Nivet. This projects fits excellently with ongoing and future
research of The Netherlands Research Centre for Integrated Solid Earth
Science (ISES).
This work is done in
collaboration with the University of Arizona. With this group and within
a Continental Dynamic project of the National Science Foundation we will
combine a very large array of expertise including: geologic and basin analysis
thermo-chronology and geochemistry stable-isotope paleoaltimetry as well
as modelling of lithospheric collision.
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