Isotopic Analysis- Rock At Valles Caldera - Sulphur Springs Geothermal Area (Phillips, 2004)
Exploration Activity: Isotopic Analysis- Rock At Valles Caldera - Sulphur Springs Geothermal Area (Phillips, 2004)
|Exploration Activity Details|
|Location||Valles Caldera - Sulphur Springs Geothermal Area|
|Exploration Technique||Isotopic Analysis- Rock|
|Activity Date||- 2004|
|Usefulness||useful regional reconnaissance|
The study was undertaken to refine understanding of the post-collapse history of the Valles caldera. The study utilized 40Ar/39Ar age dating to investigate the maximum time window of resurgence and rate of uplift of Redondo Peak; the timing of eruption of the Deer Canyon and Redondo Creek ryholites, and how these eruption ages relate to changes in the magma chamber prior to and during resurgence; and the ages of several megabreccia blocks within the Valles caldera.
Samples were screened based on petrographic relations between different mineral phases, electron microprobe backscattered electron (BSE) imaging, and their major and trace element geochemistry in order to identify ideal phenocryst for 40Ar/39Ar age dating. Representative samples were selected from pre- and post-resurgence volcanic units to refine the age of eruption of the Valles caldera and to better understand the timing of post-eruption volcanism. Megabreccia blocks were also sampled to better constrain the age of deformation within the caldera.