Earth and Planetary Sciences ETDs

Publication Date

5-1976

Abstract

The Caballo uplift, along the east side of the southern end of the Rio Grande depression, is comprised of rocks which range in age from Precambrian to Recent. The northern Caballo Mountains do not contain rocks of Silurian, Devonian, Mississippian, Triassic, Jurassic, or Lower Cretaceous ages. The Precambrian rocks consist mainly of granite which encloses small rounded bodies (possibly roof pendants) of biotite-hornblende gneiss and schist, granitic gneiss, and metasediments. The Lower Paleozoic is comprised of the Cambro-Ordovician Bliss Formation, the Ordovician El Paso Group, and the Ordovician Montoya Group. These marine sediments are overlain unconformably by the Pennsylvanian Magdalena Group. The relief on this unconformity locally may be several hundred feet. The Pennsylvanian is overlain by the Permian Abo Formation, which contains terrestrial plant fossils and animal tracks. The marine Yeso and San Andres Formation, also of Permian age, are superimposed on the Abo. The Upper Cretaceous includes the Dakota, Mancos, and Mesaverde Formations. The Mesaverde contains silicified wood and argillaceous coal. The lower Tertiary is not represented in the map-area; the Santa Fe Group of late Cenozoic age is exposed along the west side of the uplift. A set of basalt dikes, dated as Pliocene, strikes about N. 50◦ W. across the northeast corner of the map. The Quaternary units consist of basalt flows of two ages, pediment deposits, talus, stream terraces, spring deposits, sand dunes, and recent alluvium.

The Caballo area has been subjected to numerous deformations: Precambrian, lower Paleozoic, Pennsylvanian, Permian, Late Cretaceous-early Tertiary (Laramide), and late Cenozoic. Based on a study of foliations, joints, veins, dikes, folds, and faults, the principal stress axis for the northern Caballo area seems to have been about east-west through most of the last 1.5 billion years of geologic time. The Laramide and late Cenozoic deformations are responsible for much of the present configuration of the Caballo Mountains.

Although the area has been intensively prospected, and has yielded ore minerals; mining has not been important in the map-area in the last 30 years. The Jornada del Muerto along the east side of the uplift may have potential for petroleum.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Lee A. Woodward

Second Committee Member

J. Paul Fitzsimmons

Third Committee Member

Albert Masakiyo Kudo

Language

English

Document Type

Thesis

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