Most of the pre-Cambrian metamorphic rocks of the northern end of the Sandia Mountains crop out on and adjacent to a prominent spur, called the Rincon, which lies to the west of the main mountain mass. These metamorphic rocks which consist of quartzite, schist, and greenstone are considered to be the result of moderate regional metamorphism of clastic sedimentary rocks and possibly some basic flows and stills. These rocks are here tentatively named the Juan Tabo sequence and are Archeozoic or early Proterozoic age. The Sandia granite, which lies to the east and south of the Juan Tabo sequence, was intruded into that sequence on Proterozoic time. Associated with the granite are aplite and lamprophyre segregations and numerous pegmatite dikes and sills. The granite associated dike and sill rocks are primarily igneous in origin, but there are indications of granitization in the border facies.
Faults of pre-Cambrian and Tertiary age are recognized in the area. At least two period of pre-Cambrian faulting and jointing are recognized, one which took place prior to or during the folding and regional metamorphism of the rocks, and another which took place during intrusion of the Sandia granite. The fractures produced by the intrusion contain most of the pegmatite dikes. Two normal faults of Tertiary age, which are largely responsible for the present altitude of the Sandia Mountains, cross the area. Several smaller normal faults in the normal part of the area are related to the larger Tertiary faults.
There is little prospect of mineral exploitation in the area.
Earth and Planetary Sciences
Level of Degree
Department of Earth and Planetary Sciences
First Committee Member (Chair)
Second Committee Member
Carl W. Beck
Third Committee Member
J. Paul Fitzsimmons
Sandia Mountains, Sandia Granite, Ricon, Sandia Ricon, Economic Geology
Hayes, Philip T.. "Geology of the Pre-Cambrian Rocks of the Northern End of the Sandia Mountains, Bernalillo and Sandoval Counties, New Mexico." (1951). https://digitalrepository.unm.edu/eps_etds/181