New Mexico Geological Society Annual Spring Meeting — Abstracts

The Canada quadrangle is located at the boundary between the Jemez volcanic field and Santo Domingo Basin. The northern 2/3rds of the quadrangle is Keres Group volcanic rocks and Bandelier Tuff, and the southern 1/3rd is volcaniclastic basin-fill sediments and pediment gravels of the Santa Fe Group. The oldest volcanic unit is a 12.4 Ma Canovas Canyon Rhyolite flow. Intercalated andesite and dacite flows, domes, and volcaniclastic deposits of the Paliza Canyon Formation (11-7 Ma) are widespread. Bearhead Rhyolite lava flows, domes, and the associated pyroclastic and sedimentary strata of the Peralta Tuff Member erupted 7-6 MA. An intrusive center that was coeval with Keres Group volcanism is exposed in uplifted blocks north of Bearhead Peak, where Bearhead Rhyolite dikes and stocks intrude Paliza Canyon Formation hypabyssal rocks. The Cochiti Formation gradationally overlies the Peralta Tuff and consists of volcaniclastic sediment eroded from Keres Group rocks after the cessation of most or all Keres Group volcanism.

Normal faults in the quadrangle trend N-S or NE-SW and dip 65 degrees – 80 degrees to the east. Displacement in Keres Group rocks is at least 300 m. Several faults offset upper Pliocene pediment gravels, and a few displace the 1.22 Ma Bandelier Tuff. The Pajarito fault cuts a middle Pleistocene terrace gravel and displaces the Bandelier Tuff by 80 m. The Medio Dia and Peralta fault zones define the Bearhead basin, which accommodates a 500 m think section of Peralta Tuff that is absent east and west of the basin, indicating deposition during basin subsidence.