C. Koeberl et al., A petrographical and geochemical study of quartzose nodules, country rocks, and dike rocks from the Upheaval Dome structure, Utah, METEORIT PL, 34(6), 1999, pp. 861-868
Upheaval Dome, in Canyonlands National Park, Utah, USA, is a unique structu
re on the Colorado Plateau. It has earlier been interpreted as an impact st
ructure or as a pinched-off salt diapir. Some subrounded quartzose fragment
s were found in a ring depression near the eastern margin of the structure
and, based on vesicularity and apparent flow structure, the fragments were
interpreted by early researchers as "impactites." Our petrographic studies
show no indication of a high-temperature history and are in agreement with
a slow, low-temperature formation of the quartz nodules. Compositionally, t
he lag deposit samples are almost pure SiO2. They show no chemical similari
ty to any of the possible target rocks (e.g., Navajo Sandstone), from which
they should have formed by melting if they were impactites. Instead, the s
amples have relatively high contents of elements that indicate fluid intera
ction (e.g., hydrothermal growth), such as As, Sb, Ba, and U, and show posi
tive Ce anomalies. Thus, we interpret the "lag deposit samples" as normal l
ow-temperature (hydrothermally-grown?) quartz that show no indication of be
ing impact-derived. In addition, a petrographic and geochemical analysis of
a series of dike samples yielded no evidence for shock metamorphism or a m
eteoritic component.