Geologic and tectonic evolution of the Manzano Peak Quadrangle, central New Mexico
The Sandia and Manzano Mountains in central New Mexico are a N-S-striking, Precambrian-cored, uplift that forms the east flank of the Albuquerque Basin of the Rio Grande Rift. During the Paleoproterozoic, the Precambrian rocks exposed in the range were accreted onto the "southward" growing Laurentian craton (southward by current day coordinates). Regional plutonism occurred during accretion (ca. 1.65 Ga) and also in the Mesoproterozoic between 1.45 and 1.35 Ga; both sets of plutons intrude the older Proterozoic rocks. Within the Manzano Mountains, it is controversial whether the present fabrics and foliations record the older accretion-related event, or the Mesoproterozoic (ca. 1.4 Ga) pluton-related event. The focus of the study was to improve the understanding of the Proterozoic stratigraphy of the mountain belt, and document the style and timing of tectonic events. Major structures within the Precambrian core of the Manzano Peak Quadrangle include 1) the Monte Largo shear zone in the northwestern area of the quadrangle, 2) the Manzano Peak synclinorium; a regional fold interpreted as a second generation fold that refolds the stratigraphic section; and 3) the Estadio antiform, a third generation structure that refolds the western limb of the Manzano Peak synclinorium. Syn- or post-pluton shear zones in Estadio Canyon show both west and east side up shear, suggesting conjugate shear bands related to east-west shortening during Priest pluton emplacement. The new structural interpretation provides a refined understanding of the Paleoproterozoic stratigraphy. The supracrustal succession consists of the Sevilleta Metarhyolite at the base, overlain by the Abajo Formation (new name) of metalithic arenite and schist. The Abajo Formation grades upward into the White Ridge Quartzite and has a distinctive aluminous horizon at its top. The White Ridge Quartzite is overlain by the Estadio Schist (new name), then the Sais Quartzite. The youngest part of the succession consists of interbedded quartzites, schists and metarhyolite of the Blue Springs Formation.
Tectonics, Tectonic Evolution, Manzano Peak Quadrangle, Manzano Peak
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