Page 1 The Tale Mining History |
Page 2 Geology of the Area Prospecting Potential |
Page 3 Topographic Maps and Other Imagery |
Page 4 |
Four "pulses" of post-Paleozoic volcanism are recognized in the Basin and Range Province of southern Arizona. The earliest occurred during early-Cretaceous times and produced vast amounts of andesite flows, tuffs, and agglomerates. The second pulse occurred during Laramide times and produced abundant silicic to intermediate flows, dikes, and plugs. Most of the mineralization in southern Arizona is associated with this Laramide igneous activity. The third pulse occurred during mid-Tertiary times and produced vast amounts of rhyolite, basalt, and andesite. The final pulse occurred during Quaternary times and produced widespread basalt flows.
The Little Horn Mountains are a highly weathered block of volcanic rock consisting of Cretaceous-age andesites and rhyolites and much younger Quaternary-age basalts. The Cretaceous andesites and rhyolites are known as the Kofa volcanics - these rocks comprise much of the Kofa Mountains, Tank Mountains, and Castle Dome Mountains. As it turns out, the Little Horn Mountains are mostly overlain by Quaternary basalts (which are generally barren of mineralization). Large exposures of Kofa volcanics occur along the western flank of the Little Horns and along the northern and southeastern slopes of the range. Any mineralization in the Little Horn Mountains would probably be associated with the Kofa volcanics, rather than the basalts.