MAIN ACHIEVMENTS – (1) Developed the concept
of ribbon continents; (2) Introduced “oroclinal orogeny”
as a process explaining bends of mountain belts; (3) Provided the first
comprehensive tectonic model of the Cordillera of North America explaining
geological and paleomagnetic data; (4) Originated Velocity Net Plots
as a means of constraining paleogeographic reconstructions
RESEARCH STATEMENT - The Paleogeographic evolution
of Earth through deep time provides a first order constraint for understanding
Plate Tectonics and the role played by tectonics in the evolution of
the Earth’s atmosphere, biosphere and continental lithosphere
and deep mantle. Unfortunately, the oldest intact oceanic lithosphere,
which provides the only direct record of plate motions, formed as recently
as 180 Ma; the bulk of Earth’s oceanic lithosphere formed more
recently than 100 Ma. Hence reconstructing Earth’s paleogeography
requires that we make use of the highly imperfect continental record
of plate motion.
Orogenic belts develop at and record interactions along continental
plate margins. It has, therefore, been in modern mountain systems and
the eroded roots of ancient orogens that most of the constraints on
Earth paleogeography have been and continue to be mined. But while we
generally agree on the geological and geophysical data generated in
the study of orogens, the same cannot be said regarding interpretations
of such data. It is in the disparate readings of the continental record
of plate motions and interactions that most all current controversies
and conundrums in geodynamics and geology lay, and it is along these
fault lines that I have focused my research.
My research is rooted in field-based geological mapping of key parts
of mountain belts, both modern and ancient. Multidisciplinary studies,
including geophyscial investigations (paleomagnetism, geodetic surveys
and reflection seismic studies), and geochemical and geochronological
analyses are utilized to further constrain the geometry and evolution
of mountain belts. Models of development and evolution of ancient orogens
are tested against (1) tectonically active modern analogues, including
the Apennines of southern Italy, and the Melanesian region of the southwest
Pacific, and (2) geodynamic, geometric, climate and thermal models.
It is through this two-pronged approach field- and laboratory-based
approach that I have addressed questions such as: (1) How do map-view
bends of mountain belts originate, and are they important? (they are!!)
(2) To what extent does paleogeography control climate, and was it responsible
for Earth having descended into a Snowball state in the Neoproterozoic?
and (3) Why is it that in numerous orogenic belts, ranging from the
modern day Melanesian region, through the Neogene of southern Europe,
the Mesozoic Cordillera of western North America, and the Paleozoic
Appalachian-Variscan orogen that lay at the heart of Pangea, that paleomagnetic
data is commonly held to be irreconcilable with abundant geological
data? My hope is that in asking and answering these questions, we will
improve our understanding of Earth history, and in doing so, help insure
our continued evolution as part of the Earth system.
See me interviewed by David Suzuki here.
Go on a Geologic
Journey through the Rocky Mountains.
Listen to Quirks
and Quarks interviews about my research: 1
or 2.
In addition to my own research, I also edit the journal GSA
Today and am the secretary and director of the Canadian
Geological Foundation.
Key Words: Plate Tectonics, Structural Geology, Orogenesis, Convergent
Margin Orogens, Oroclines, Paleomagnetism.
