Tertiary Geology of the Abiquiu Quadrangle, New Mexico

Stratigraphic nomenclature of volcanic rocks in the Jemez Mountains, New Mexico

“…These sediments constitute most of the alluvial fill of the Rio Grande graben and were initially called the "Santa Fe marl" (Hayden, 1869) and later the Santa Fe Formation (Bryan, 1938;Smith, 1938;Denny, 1940;Galusha, 1966). Spiegel and Baldwin (1963) proposed that the Santa Fe be raised to group status and separated it into the Tesuque and Ancha Formations in the vicinity of Santa Fe.…”

“…Because of uncertainties in the correlation of the Tesuque and Ancha Formations with other Santa Fe beds in and adjacent to the Jemez Mountains, however, the term Santa Fe Formation, as used by Denny, Smith, and Galusha, is used in this paper. In the northern Jemez Mountains, the Santa Fe Formation includes the sediments above the Abiquiu Tuff of Smith (1938) and below the Lobato Basalt (new name, this paper). East of the Jemez Mountains, the Santa Fe Formation includes the sediments exposed below the Puye Formation and below the basalts of Cerros del Rio, although it is recognized that the uppermost of these beds east of the Kio Grande belongs to the Ancha Formation.…”

“…The Polvadera Group unconformably overlies the Abiquiu Tuff of Smith (1938) The name Lobato Basalt is proposed for the basaltic lavas that form the high-level mesas fringing the northern and northeastern sides of the Jemez Mountains. The formation includes the basalts of Clara Peak, Lobato Mesa, Polvadera Mesa, and Escoba Mesa in the Abiquiu quadrangle and of Cerro Pedernal and La Grulla Plateau in the Youngsville quadrangle.…”

“…H. T. U. Smith (1938) briefly referred to the basalts on Lobato Mesa as the "Lobato basaltic lavas" but did not y describe them or formally name them.…”

“…Smith (1938), but no definition or description of the formation appeared in print until Griggs (1964) published the results of his mapping in the Los Alamos ^ area. Griggs separated the Puye into two members the Totavi Lentil, a basal river gravel, consisting mainly of Precambrian quartzites and crystalline rock types; and a f anglomerate member, consisting mainly *> of volcanic rocks derived from the Jemez Mountains.…”