BH250-218

BH250-218

Rhyolite (Lava Creek A)

Major Minerals: vitric glass, pumice, and crystals of quartz, sanidine, plagioclase, biotite, and accessory minerals like zircon, apatite, and Fe-Ti oxides.

The Lava Creek Tuff is geologically significant volcanic deposit that marks the most recent supereruption of the Yellowstone volcanic system. It is a rhyolitic ash-flow tuff produced during the Yellowstone Caldera-forming eruption that occurred about 631,000 years ago.

BH250-218 (Lava Creek A) is one of two ash flow tuff units, Lava Creek A and Lava Creek B, that collectively make up the Lava Creek Tuff, a widespread pyroclastic deposit associated with the Yellowstone Caldera-forming eruption about 631,000 years ago. Lava Creek A is Ash-flow tuff (ignimbrite and it is the earlier of the two subunits; it is typically thinner and less voluminous than Lava Creek B and is interpreted as early phase of the main eruption.

It is Silicic composition with SiO2 = 77.04 Wt. %, and is classfied as high-silica rhyolite. It has Similar bulk chemistry to Lava Creek B (SiO2 = 70.69 Wt. %) but can be distinguished based on subtle geochemical differences in glass shards.

Location: Virginia Cascade Dr, Yellowstone, Wyoming, USA
Nearby Geographic Feature: Yellowstone
GPS Coordinates: 44°42'54.18"N, 110°39'15.61"W

Bereket Haileab

From the rock collection of Bereket Haileab. Sample 218. Housed at Carleton College in Minnesota.

Thin section and hand sample

View on ArcGIS Online here