- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
The Anderson Ridge quadrangle was mapped on a reconnaissance scale while 10 sq mi in the western part of the quadrangle were mapped in detail. In the detailed area, Palmer Draw, a peraluminous granite stock and related pegmatites have been emplaced in pelitic and quartzo-feldspathic metasediments. The metasediments are mainly quartz-biotite-plagioclase and quartz-biotite-plagioclase-paragonite porphyroblastic "peanut" schists with a contact zone surrounding the granite stock. The metasediments of the Palmer Draw area have been complexly folded and faulted and their field relations and geometry indicated 3 episodes of deformation. The area was divided into 2 fields of approximate structural homogeneity for analysis. The fabric of field 1 indicates flexural folding of S, a well-defined foliation parallel to the original bedding around a nearly horizontal fold axis B s 1 . This is thought to represent the first episode of deformation. In field 2 the fabric of S and L 2 lineations, minor fold axes, indicate flexural folding of S around a nearly vertical fold axis B s 2 . This episode of folding affected primarily the steep limbs of the previous B s 1 folds. Field relations and the projection pattern of the L 3 lineations, biotite traces, suggest a penetrative surface S'. S' is planar through the B s 2 minor folds which they transect at various angles. This and other evidence indicates that S' is later than the B s 2 folds and is superimposed on the B s 2 folds. The last episode of deformation then involve faulting and passive folding by movements on S'. It is thought that the granitic emplacements preceded the B s 2 folding. This is consistent with evidence of a thermal metamorphism preceding a regional metamorphism. The B s 1 and B s 2 folds are thought to be Precambrian in age. S' may be Laramide in age and related to the overthrusting of the western slope of the Wind River Range.