ABSTRACT

In northwestern Wyoming the northern part of the Green River basin was overridden first by the Hoback Range from the west and later by the Gros Ventre Mountains from the northeast. The fault plane underlying the Hoback Range dips 10-30° westward and southwestward; that under the Gros Ventre Mountains, where observed, dips north and northeast about 45°. Eastward displacement of the rocks in the Hoback Range was of such magnitude that it brought markedly contrasting facies within 2 to 4 miles of one another at the northern end of the Green River basin.

Major folding and faulting of most basin margins occurred during Paleocene and earliest Eocene time, but major deformation of the Gros Ventre Mountains was post-early Eocene. Magnitudes and types of movement are interpreted as follows.

Subsidence (in feet)UpliftHeave along basin margin fault (in miles)
Wind River basin (north-central) 16,000 Owl Creek Mtns. 17,500 
Wind River basin (northeastern) 16,000 Bighorn Mtns. (south, margin) 16,000 
Wind River basin (central-eastern) 14,000 Casper arch 7,500 
Great Divide basin (northeastern) 12,000 Granite Mtns. 20,000 
Great Divide basin (northwestern) 11,000 Wind River Mtns. (southern margin) 18,000 3? 
Green River basin (north-N.E. margin) 17,000 Gros Ventre Mtns. (southeast end) 18,000 
Green River basin (N.W. margin) 15,000 Gros Ventre Mtns. (west-S.W. margin) 20,000 
Green River basin (N.W. margin) 15,000 Hoback Range (northeast end) 15,000 15 ± 
Subsidence (in feet)UpliftHeave along basin margin fault (in miles)
Wind River basin (north-central) 16,000 Owl Creek Mtns. 17,500 
Wind River basin (northeastern) 16,000 Bighorn Mtns. (south, margin) 16,000 
Wind River basin (central-eastern) 14,000 Casper arch 7,500 
Great Divide basin (northeastern) 12,000 Granite Mtns. 20,000 
Great Divide basin (northwestern) 11,000 Wind River Mtns. (southern margin) 18,000 3? 
Green River basin (north-N.E. margin) 17,000 Gros Ventre Mtns. (southeast end) 18,000 
Green River basin (N.W. margin) 15,000 Gros Ventre Mtns. (west-S.W. margin) 20,000 
Green River basin (N.W. margin) 15,000 Hoback Range (northeast end) 15,000 15 ± 

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