Pyroclastic rocks associated with the Taylor Creek Rhyolite, Scales Canyon
Philip R. Kyle, Ted L. Eggleston, William C. McIntosh, Nelia Dunbar, Charles M. Hammond, W. David Johnson, Michael Knoper, and Judith Moore
Pyroclastic deposits formed during the emplacement of the 28.6 my old Taylor Creek Rhyolite are exposed in a 2 km long section in Scales Canyon. As much as 50 m of pyroclastic fall, surge, and flow deposits as well as eolian sandstone have been recognized in five measured sections. Three eruptive sequences are proposed: I — a lower, predominantly pyroclastic flow and surge sequence; II — a middle pyroclastic fall sequence; and III — an upper sequence of two coarse pyroclastic breccias. Paleomagnetic measurements on clasts from the two units within sequence III indicate the lower unit was emplaced as a hot (>500°C) pyroclastic flow, whereas the upper unit was emplaced as a mixture of hot (>500°C) and cold (<300°C) clasts. Both units apparently represent dome-collapse breccias. The lower unit contains only hot material from the interior of the dome, whereas the upper unit also contains a component of the cooler dome carapace.
The Scales Canyon pyroclastic deposits were apparently erupted over a short span of time from two or more nearby dome-related vents. Individual vents cannot be identified because the deposits are mineralogically similar.
- Kyle, Philip R.; Eggleston, Ted L.; McIntosh, William C.; Dunbar, Nelia; Hammond, Charles M.; Johnson, W. David; Knoper, Michael; Moore, Judith, 1986, Pyroclastic rocks associated with the Taylor Creek Rhyolite, Scales Canyon, in: Truth or Consequences region, Clemons, R. E.; King, W. E.; Mack, G. H., New Mexico Geological Society, Guidebook, 37th Field Conference, pp. 197-201.