DETRITAL-ZIRCON GEOCHRONOLOGY OF THE SOUTHERNMOST
ANDES
Working as a part of the illustrious
Team Barbeau (Tectonics
and Sedimentation Laboratory at the University of South
Carolina) I have been part of a project using
detrital-zircon ages to better understand the history of
orogenesis and basin development in the Southernmost
Andes. We are particularly interested in the timing of
the development of the Patagonian Orocline and the
implications for the opening of the Drake Passage and
the glaciation of Antarctica. U-Pb age data from
detrital zircons collected from the Magallanes foreland
basin show a distinct provenance shift at the end of the
middle Eocene between the time when there is evidence
for Pacific waters first entering the Atlantic and the
major Oi1 glaciation of Antartica. We interpret this
shift as resulting from a peak in tectonic activity that
caused out-of-sequence thrusting and the development of
a structural blockage that prevented zircons from the
Fuegian batholith from reaching the basin. A manuscript
detailing these results was submitted to Earth and
Planetary Science Letters in December, 2008.
Work continues on this project as members of Team Barbeau
venture across the Drake Passage seeking provenance and
thermochronological constraints from equivalent rocks on
the Antarctic Peninsula. Find out about this ongoing, and
very exciting, work at: IPY:
SCOTIA.