Structure Section Between Ojo Caliente and La Madera Mountains: Supplement 2 from "Petrology of the Hopewell Series in the Ojo Caliente of New Mexico" (Thesis)

Description

The Hopewell series is a group of pre-Cambrian metamorphic rocks exposed in the Picuris, Petaca, and Ojo Caliente districts of northern New Mexico. In the Ojo Caliente district these and other pre-Cambrian rocks are exposed in an elongate inlier in the surrounding Tertiary strata. This inlier represents a low mountain or monadnock on an early Tertiary erosion surface. The Hopewell series has been divided into two phases, the Picuris basalt and a series of metasedimentary rocks. Both general rock types show a well defined sequence of metamorphic degree, but the variation of metamorphic degree is roughly bedding controled. The highest degree of metamorphism noted in the area is correlative with the sillimanite zone. In type, the metamorphic processes involved could be classed as normal regional metamorphism, which includes a certain amount of metasomatism. From the evidence in the Ojo Caliente district it seems probable that the processes of normal regional metamorphism were carried out in large part under the influence of hydrothermal solutions.

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