Hydrogeology of the Cenozoic igneous rocks, Navajo and Hopi Indian Reservations, Arizona, New Mexico, and Utah

Citations Over Time

Abstract

The igneous rocks exposed in widely separated areas in the Navajo and Hopi Indian Reservations are mainly of volcanic origin.Porphyritic rocks of laccolithic origin, however, are exposed in several places in the Carrizo Mountains and in a small outcrop on Navajo Mountain.The volcanic rocks occur as flows, dikes, necks, cinder cones, and bedded tuff in fillings of diatremes and beneath some lava flows in volcanic fields that are grouped, according to composition, into three provinces-the monchiquite province centered in the Hopi Buttes area, the minette province in the northeastern part of the reservations, and the basalt province in the southwestern part of the reservations.Stratigraphic and faunal evidence and potassium-argon age determinations indicate that the igneous rocks of the monchiquite province are of probable Pliocene age; those of the minette province have not been dated precisely but are believed to be older than those of the monchiquite province; and those of the basalt province are late Pliocene to late Holocene in age.The volcanic rocks yield water to wells and springs.Most wells obtain water from the tuffaceous material that fills the diatremes, and most springs discharge from the bedded tuff beneath the lava flows.The diatremes are unique traps for the accumulation of ground water.The funnel-shaped structures have large recharge areas on the surface, which aid in the centripetal movement of water into the permeable materials that fill the orifices.Of the 14 test wells drilled into diatremes in the Hopi Buttes area, eight produced a sufficient quantity of potable water for domestic or stock use, three produced water of insufficient quantity or quality, and three were dry.The concentrations of dissolved solids in water from wells drilled in the diatremes range from 262 to 8,140 parts per million; water from the springs has concentrations ranging from 246 to 1,450 parts per million.Additional development of water from the volcanic rocks is limited mainly to the diatremes that have not been explored in the Hopi Buttes.The amount and quality of water that may be obtained from a given diatreme, however, cannot be predicted.

Related Papers

• → West of the Thirties: Discoveries Among The Navajo And Hopi(1995)15 cited
• → The Hopi-Navajo Colony on the Lower Colorado River: A Problem in Ethnohistorical Interpretation(1963)5 cited
• → Update on Navajo‐Hopi Land Dispute(1986)1 cited
• → 28 preliminary geologic maps covering a part of the Navajo and Hopi Indian Reservations(1954)
• → A Celebration of Being: Photographs of the Hopi and Navajo(1994)