Download Professor Bruce Watson

DEPARTMENT OF PHYSICS,
APPLIED PHYSICS AND
ASTRONOMY
Department of Physics, Applied Physics & Astronomy
Colloquium
March 11, 2015
CII 3051, 4:00PM - 5:00PM
Host: Professor Toh-Ming Lu
Professor Bruce Watson
Department of Earth & Environmental Sciences
Rensselaer Polytechnic Institute
“The Environment of Earliest Earth: Decoding the Oldest Crystals”
Abstract:
The first 700 million years of Earth’s existence (the Hadean Eon) are widely regarded as the
most geodynamically vigorous period in the history of our planet. It has been variously inferred
that during this time the Earth: 1) collided with a Mars-sized-object; 2) formed a deep magma
ocean; 3) grew the first continents; 4) suffered withering bombardment; and 5) witnessed the
emergence of life. In terms of ‘hard’ geochemical evidence, however, the record from these
earliest times is limited, and our understanding of Hadean events is rudimentary at best. The
oldest firmly dated terrestrial rock is only 4.06 billion years (Gyr) old, so there is no rock record
to inform us about processes that occurred during the prior 500 Myr of Earth history. Prof.
Watson will provide a summary of the evidence gleaned over the past ten years -- much of it at
RPI -- from 4+ Gyr-old zirconium silicate crystals (zircons) from Western Australia supporting
the view that continental crust was already fully developed, that the gases emanating from
ancient volcanoes into the Hadean atmosphere were much like those of today, and liquid water
was present at or near the Earth’s surface.
NOTE: The complete list of colloquia and seminars is posted on the department web site,
http://www.rpi.edu/dept/phys/calendar.html and also on the Institute Calendar of Events,
http://events.rpi.edu/main/showMain.rdo;jsessionid=8589F4957B89E6751705AC48D37C96A4.
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