Laramide tectonics

The Laramide orogeny is the mountain-building event that produced the Rocky Mountains. We have been studying Laramide structures in both the northern and southern Rockies: the Sierra Nacimiento and adjacent San Juan Basin in New Mexico and the Beartooth Mountains in Montana.

         
Slump folds in Cretaceous sandstone, San Juan Basin, New Mexico
Beartooth Mountains, southwestern Montana
 

Sierra Nacimiento and San Juan Basin

The Sierra Nacimiento is a Laramide fault-block mountain range that is bordered by the San Juan Basin, a part of the Colorado Plateau. There is an ongoing controversy regarding the amount of northward movement of the San Juan Basin relative to the Nacimiento and the timing. We have been able to show that the movement is likely no more than ~ 3 km and the movement began in the Late Cretaceous. Click here for a poster we presented at the 2002 GSA meeting in Denver that describes our results.

 
The mapping page shows some of the geologic maps that we have produced during our work in this area.
 
The paleoseismology page contains a description of seismically induced liquefaction features from the San Juan Basin.
 
 
 
 

Beartooth Mountains, Montana

Our work in Montana is focused on the record of paleoseismic activity (ancient earthquakes) within the Clarks Fork Basin. As the Beartooth mountains were rising, earthquakes along the Beartooth fault liquefied the nearby Paleocene sediments. Heather Ballantyne is working on this project along with Jerry Bartholomew from the University of Memphis.

 
 
Copyright © 2003 Kevin G. Stewart
page last modified: August 12, 2003