New Mexico Geological Society Annual Spring Meeting — Abstracts

Uplift of the Manzano Mountains is constrained by stratigraphic studies and ⁴⁰Ar/³⁹Ar dating, allowing partial reconstruction of the tectonic history of a part of the eastern margin of the Albuquerque Basin. Proterozoic schist, quartzite, and granite, and Pennsylvanian conglomerate and limestone are exposed along the rugged footwall escarpment. The eastern dip-slope exposes reddish-brown Permian sandstone. A 12-37? west-dipping succession of volcanic-bearing sandstone and conglomerate near Trigo Canyon, ~0.75 km west of the frontal fault, was previously correlated to the pre-rift Datil Fm and early rift Popotosa Fm (Santa Fe Group). Groundmass concentrate from an interbedded basalt flow in this succession yielded a whole-rock plateau age of 26.60±0.18 Ma (NMGRL#51633). A fluvial recycled tuff cobble, stratigraphically below the basalt, yielded a laser-fusion ago on sanidine of 27.83±0.27 Ma (NMGRL#51625). This cobble is similar in age and composition of the pre-rift Lemitar Tuff, found 30-60 km to the south. These ages and a potential southern detrital source suggest correlation to the Mongollon-Datil Groups.

The 504-m deep Aguayo-Comanche#1 well (Sec. 31, T6N, R5E), drilled 3.4 km NNE of Trigo Canyon and <1.5 km west of the mountain front, encountered 158 m of schist-bearing detritus derived from the Manzano Mountains, herein assigned to the Santa Fe Group. The lower 115 m of this upper interval contains sparse volcanic detritus. At least 346 m of volcanic-bearing lithic arkose and feldspathic litharenite, herein assigned to the Mongollon-Datil Groups, underlie this upper interval. The proximity of thick volcanic-bearing deposits in this well relative to the mountain front suggests that these recycled volcanic-sourced deposits once covered at least part of this range. This is supported by the presence of sparse volcanic detritus within Santa Fe Group sediments in this well and by fission-track thermochronology (Behr, 1999). Exposures near Tio Bartolo Canyon, ~5 km southwest of Trigo Canyon, contain abundant limestone, sandstone, with subordinate to sparse chert, quartzite, granitic, and volcanic clasts that may record a phase of unroofing of the southern Manzano Mountains.