Abstract View

Volume 30 Issue 7 (July 2020)

GSA Today

Article, pp. 36–37 | Full Text | PDF


Assembling Laurentia—Integrated Theme Sessions on Tectonic Turning Points

Michael L. Williams

Dept. of Geosciences, University of Massachusetts, Amherst, Massachusetts 01003, USA, mlw@geo.umass.edu

Dawn A. Kellett

Geological Survey of Canada–Atlantic Division, Natural Resources Canada/Government of Canada, 1 Challenger Drive, Dartmouth, Nova Scotia B2Y 4A2, Canada, dawn.kellett@canada.ca

Basil Tikoff*

Dept. of Geoscience, University of Wisconsin–Madison, 1215 W. Dayton Street, Madison, Wisconsin 53706, USA, basil@geology.wisc.edu

Steven J. Whitmeyer

Dept. of Geology and Environmental Science, James Madison University, 801 Carrier Drive, MSC 6903, Harrisonburg, Virginia 22807, USA, whitmesj@jmu.edu


The North American continent records the evolution of tectonic processes and tectonic environments from the earliest Archean to modern times. The continent hosts a rich Archean (and possibly Hadean) record, at least three great Proterozoic orogenic belts, and a wide range of Phanerozoic tectonic, sedimentary, and paleobiologic environments, including active plate boundaries. In many ways, Laurentia (ancestral North America) might be thought of as the prototypical continent, with a little—if not a lot—of everything. With its long record of changing tectonic settings, supercontinent cycles, and geologic outcomes, one question persists: Does Laurentia preserve a record of fundamental, relatively short duration changes in tectonic processes on Earth, or rather, a gradually changing configuration of continents in a slowly evolving plate tectonic system? The resolution of this question requires a continent-wide perspective on tectonics through time, and it requires the integration of many fields of geoscience. One way to approach the question is to ask (1) what is the holistic geological character of Laurentia at particular times in Earth history?; and (2) what are the apparent controlling factors at those times, from mantle dynamics to plate interactions, to surface weathering, to biological evolution?

* Corresponding author.

Manuscript received 3 Apr. 2020. Revised manuscript received 15 Apr. 2020. Manuscript accepted 24 Apr. 2020. Posted 22 May 2020.

© 2020, The Geological Society of America. CC-BY-NC.