Geology of the Sweetwater Drive area and correlation of Santa Cruz Valley gravels

Abstract

The Sweetwater Drive area lies on the eastern dip slope of the Tucson Mountains. The rocks in the region consist mainly of complexly faulted Permian limestone and quartzite, Cretaceous volcanics and sedimentary rocks, and Tertiary volcanics. Erosion has cut through the Tertiary lavas to expose the underlying Cretaceous and older rocks. Numerous small klippen of Permian sedimentary rocks rest on the Cretaceous rocks. Six gravel sections were measured in banks of Quaternary elluvium along a northwest-trending line between the area in the Tucson Mountains and the wells in the Santa Cruz Valley. These gravels consist mostly of felsite, rhyolite, and other volcanics which are correlated with both the bedrocks in the mapped area and well samples from the Santa Cruz Valle7 Quaternary alluvium. Samples were collected from seven wells in the Santa Cruz Valley Quaternary alluvium, along a northwest-trending line paralleling the east side of the Tucson Mountains. These samples consist mostly of felsites and dark volcanics. Correlations are made between: (1) the strata of the various wells, (2) the aquifers among the wells, and (3) the rocks in the well samples and those in the gravel outcrops.