Earth and Planetary Sciences ETDs

Publication Date



Precambrian metamorphic rocks in a part of the North Manzano Mountains, New Mexico, underwent regional synkinematic greenschist facies metamorphism. Abundant green hornblende in greenstones and muscovite, chlorite, and biotite in metapelites tentatively suggest p4 kb and TC during metamorphism. The greenstones were probably derived from basic volcanic rocks; the metapelites were probably derived from shales, siltstones, clay-rich sandstones, cherts (7), and mature quartz sandstones.

The oldest exposed rocks are the Moyos metasediments, a sequence of phyllites and schistose grits that is lithologically transitional to a younger greenstone complex of mostly aphanitic greenstone with intercalated phyllites and metasiltstones and intrusive metadiorite. The greenstone sequence is lithologically transitional to the Bosque metasediments, an inferred younger sequence of phyllites and mecaquartzites with rare interbedded greenstones. The Bosque metasediments, appear to be unconformably overlain by a metamorphosed mature quartz sandstone, the Sais Metaquartzite. Intruding the Bosque metasediments and probably younger than all the regional metamorphic rocks is a sill of quartz gabbro that is correlated with a larger isolated mass of quartz gabbro, quartz diorite, and olivine gabbro; these rocks may be differentiated products of a fractionally crystallized magma. The main mass of gabbro-quartz diorite is intruded by and essentially isolated by massive leucocratic quartz monzonite of the Ojito stock; dynamic metamorphism of the stock formed foliated zones that are considered to be protoclastic. Basaltic and diabasic dikes that intrude these rocks are considered to be the youngest Precambrian rocks.

Tight folds overturned to the north were formed by apparent north-south compression during Precambrian time. Laramide deformation probably formed a west-dipping high-angle reverse fault with Precambrian rocks juxtaposed against steeply inclined Pennsylvanian strata. North- to northeast-trending high-angle normal faults are probably associated with formation of the Rio Grande rift during the late Cenozoic.

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

George Roger Jiracek

Third Committee Member

J. Paul Fitzsimmons



Document Type


Included in

Geology Commons