Volcanic sequence in the Marysvale region in southwest‐central Utah

Abstract

As a consequence of the detailed investigation of the alunite and other mineral deposits of the Marysvale Region in southwest‐central Utah, opportunity was afforded to map and study the succession of volcanic rocks that underlie most of this area. The Marysvale Region is part of a large area of volcanic rocks, which occupies much of the High Plateaus of Utah (Fig. 1). It is believed that the Marysvale Region covers sufficient area to furnish an adequate sample of this volcanic area, and, though horizontal variations are known to occur, the study may serve as a guide as to what may be expected in other parts of the area. The chemical analyses are the most completely representative of any ever taken in this part of Utah, and they furnish a basis of comparison within the High Plateaus and with other areas in Utah.

Field guide to geologic excursions in southwestern Utah and adjacent areas of Arizona and Nevada

“…The basalts have K -Ar dates of about 450,000 years (Fleck and others, 1975). Northeast of Paragonah, the 20-Ma Iron Peak laccolith marks the northeast end of the Iron Axis, and like many of these laccoliths, it breached the surface and erupted volcanic rocks Fleck and others, 1975;Rowley and others, 1994 (Callaghan, 1939;Cunningham and Steven, 1979a;Cunningham and others, 1983). The area west of this exit was mapped by Anderson (1965), some of which was published in Anderson and others (1990b).…”

“…The largest volume of bimodal rocks in the Marysvale field formed the rhyolite of the Mount Belknap Vocanics (Callaghan, 1939;Cunningham and Steven, 1979a), which was erupted between 22 and 14 million years ago from two concurrently active eruptive centers, one in the central Tushar Mountains and the other in the Sevier River valley. Thus these rhyolite eruptive centers generally coincided with areas where the older intrusive and volcanic rocks of the calcalkaline episode were deposited.…”

“…The most voluminous tuffs were derived from the northern half of the volcanic field, some as members of the Bullion Canyon Volcanics (Callaghan, 1939;Steven and others, 1979). Possibly the largest tuff in the field is the Three Creeks Tuff Member, derived from the Three Creeks caldera in the southern Pavant Range (Steven, 1981) about 27 million years ago.…”

“…The second most voluminous rock unit in the Marysvale field is the Bullion Canyon Volcanics (Callaghan, 1939;Steven and others, 1979). This unit consists largely of stratovolcano deposits mapped in the heart and northern half of the Marysvale volcanic field.…”

“…The 24-million-year old Delano Peak Tuff Member of the Bullion Canyon Volcanics (Callaghan, 1939;Steven and others, 1979) is a well welded dacitic ash-flow tuff that had an initial volume of at least 100 km 3 . Its source is the Big John caldera in the central Tushar Mountains (Steven and others, 1984b), but it is not widely exposed outside that mountain range.…”