Hydrogeology of the Tapeats Amphitheater and Deer Basin, Grand Canyon, Arizona: a study in karst hydrology.

Abstract

North of the Grand Canyon, water from precipitation infiltrates into the permeable Kaibab Formation which outcrops over the Kaibab and Kanab Plateaus. Water moves vertically downward through a karst drainage network in the Kaibab and Toroweap Formations until it reaches semi-permeable clastic sediments. A portion of the water is perched above these beds and flows toward the west under a gradient imposed on the system by the gentle westward regional dip of the strata. Some of the westward flowing water discharges directly into Tapeats Amphitheater from seeps and small springs but most of it drains into the north-south trending West Kaibab Fault Zone. In the Fault zone, the water encounters large vertical rock permeabilities and readily circulates downward through the otherwise semi-permeable clastic strata to the lower limestone units. At depth, the water is conducted southward to the Grand Canyon in solution tubes which have been dissolved along the fault zone. Within a few miles of the Tapeats Amphitheater, the water is pirated from the Muav Fault of the West Kaibab Fault Zone and moves toward the southwest through solution tubes developed along minor faults in the limestones to discharge points OOO feet below the plateaus in Tapeats Canyon. To the west, a similar but smaller karst system discharges water into Deer Canyon.