Earth and Planetary Sciences ETDs

Publication Date



The Cimarron Range forms a southeastern extension of the southern Sangre de Cristo Mountains. The area mapped in this study lies mainly between Eagle Nest and Ute Park, New Mexico, and is centered around Cimarron Canyon.

Rocks ranging from Precambrian to Quaternary in age are exposed• - in the central Cimarron Range. Precambrian rocks in the core of the range consist mainly of moderately foliated, low- to medium-grade metamorphics intruded by faintly foliated bodies of meta-granodiorite and meta-diabase.

Approximately 4000 feet of sedimentary rocks ranging from the Sangre de Cristo Formation of Pennsylvanian-Permian age through the Poison Canyon Formation of Paleocene age are exposed in the area. Over­lying the predominantly piedmont alluvial deposits of the Sangre de Cristo Formation is about 700 feet of continental, interior-basin deposits consisting of the Dockum Group, of Triassic age, Entrada Sandstone, of Jurassic age, and the Morrison Formation, also of Jurassic age. Almost 2000 feet of Cretaceous rocks include the marginal marine sediments of the Dakota Sandstone and the marine sediments of the following formations, listed in ascending stratigraphic order: Graneros Shale, Greenhorn Limestone, Carlile Shale, Niobrara Formation, and Pierre Shale. The Poison Canyon Formation of Paleocene age and younger Tertiary rocks lie to the north and east of the mapped area. Tertiary and Quaternary gravels floor Moreno Valley on the west, and various surficial deposits of Quaternary age are exposed in the area.

At least three major laccolithic bodies of mid-Tertiary age are exposed in the northern and eastern parts of the central Cimarron Range. The laccoliths are composed of stacks of granodiorite porphyry sills, which intrude or replace, to varying degrees, every exposed sedimentary formation of pre-Tertiary age. Late Tertiary quartz porphyry and minor hornblende andesite intrusions are exposed in the western and northeastern parts of the area, respectively.

Laramide deformation in the Cimarron Range was expressed mainly by vertical uplift of the Precambrian basement. Continued uplift resulted in the formation of the Fowler Pass fault, an upthrust which steepens at depth. The Fowler Pass fault tapped a magma chamber and may have served as the main feeder for the granodiorite prophyry laccoliths. Anisotropic features in the Precambrian basement and the position of the late Paleozoic Cimarron arch were probably determinants in the location and trend of the Fowler Pass fault.

Deformation of late Tertiary age is represented by high-angle faults which developed in tensional response to the uplift of the Cimarron Range. This deformation was probably an eastward extension of tectonism related to the formation of the Rio Grande rift.

Degree Name

Earth and Planetary Sciences

Level of Degree


Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Lee A. Woodward

Second Committee Member

Gary Perrin Landis

Third Committee Member

Charles Troy Siemers

Fourth Committee Member

Jonathan Ferris Callender

Fifth Committee Member

J. Paul Fitzsimmons



Document Type


Included in

Geology Commons