Bidahochi Formation: An interpretative summary
David W. Love
The upper Ternary Bidahochi Formation covers over 16.000 km2 in eastern Arizona and western New Mexico. The depositional "basin" consisted of paleovalleys and interfluves sloping southwest and west from Black Mesa, Defiance and Zuni uplifts, anti north from the White Mountains toward the ancestral Little Colorado River. Facies are generally alluvial, lacustrine, eolian, monchiquitic eruptives, travertine and other spring deposits and silicic ash. After initial erosion of valleys through tilted older Cenozic, Mesozoic and upper Paleozoic rocks, deposition of the Bidahochi Formation began by at least 9 my. Lower parts tit the Bidahochi Formation in Arizona may be lateral age equivalents of the upper Fence Lake Formation in western New Mexico. Eruptions of basaltic and monchiquitic lavas and tephra from diatremes influenced the formation of lakes in the Hopi Buttes area between 8.5 and 6 my and again between 4.5 and 4 my. tip to 240 in of Bidahochi Formation accumulated in some paleovalleys on the flanks of uplifts, possibly by longitudinal and Lateral progradation of alluvial facies. Major episodes of valley-scale cuts-and-tills may occur within the formation. Aggradation of alluvial and eolian facies of the Bidahochi Format ion had ceased at least locally by 4 my. and erosion beveled the upper part of the Bidahochi prior to eruptions in the Springerville volcanic bold less than 4 my. Episodic incision and terrace formation have subsequently incurred along all major drainages cutting the Bidahochi. Depositional facies and age of the Bidahochi Formation me similar to the Ogallala Formation in eastern New Mexico and northwestern Texas. implying similar tectonic, geographic and climatic reasons tor both accumulations. Non-migrant cyclicity it volcanic eruptions may be similar to basaltic fields to the south and cast but is in contrast to the Sail Francisco volcanic field to the west.
- Love, David W., 1989, Bidahochi Formation: An interpretative summary, in: Southeastern Colorado Plateau, Anderson, Orin J.; Lucas, Spencer G.; Love, David W.; Cather, Steven M., New Mexico Geological Society, Guidebook, 40th Field Conference, pp. 273-280.