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The AAPG/Datapages Combined Publications Database

Earth Science Bulletin (WGA)


Earth Science Bulletin
Vol. 17 (1984), No. 1. (Annual), Page 105b

Abstract: Did the Basement Fold During the Laramide Orogeny in the Rocky Mountain Foreland Province?

Vincent Matthews1

What is meant by structural basement? Did structural basement fold or fault during the Laramide orogeny? What difference does it make? How much of this long-standing debate is based on hard data and how much is based on interpretation only?

Geologic models of folded basement and faulted basement are both compatible with subsurface borehole data and seismic data. However, observations of surface exposures and subsurface mine exposures reveal only brittle deformation of the basement. The observed brittle deformation is consistent with the way that theoretical and experimental data indicate that the basement should have deformed under confining pressures and thermal gradients existing during the Laramide in the Foreland Province.

Only seismic data and subsurface borehole data are compatible with the notion that the structural basement folded during the Laramide. Theoretical analysis, experimental results, surface and subsurface exposures, seismic data and borehole data are all consistent with the idea that structural basement deformed in a brittle manner during the Laramide Orogeny. Therefore, it appears reasonable to conclude that the basement did not fold during the Laramide.

Acknowledgments and Associated Footnotes

1 Vincent Matthews: Lear Petroleum Exploration

© Wyoming Geological Association, 2015