Rhyolite Caldera

An Interactive Poster

V1-09f

Spheroidal rhyolite

Commonly a flow to ash tuff: spheroids formed after the the flow, unit could be almost anywhere in the system (Ootsa Lake)

V1-04f

Flow banded rhyolite

Rhyolite lavas commonly have a distinctive laminated colour banding that represents flow differentiation, may not be compositionally different; folds and contortions are due to turbulent flow, are not due to regional folding. (Ootsa)

V4-13

Air fall lithic crystal vitric (ash) tuff

possibly the most common of all pyroclastic rocks (central BC) : common air distance (km+) from source and may cover many km2

V2-16a

Air fall breccia tuff

“general rule”– the larger the fragments the closer you are to the source, (Clisbako)

V2-08a

Air fall lapilli tuff/breccia

Image Created by Iconasys Shutter Stream

Air fall lapilli tuff/breccia

chaotic mix of large to small volcanic fragments in a fine grained matrix (ash) is generally close to source, in the kilometer= scale. (Ootsa)

(lapilli --- +\- thumb-sized fragments in tuffs)

V2-01a

Rhyolite breccia

V2-01a

Rhyolite breccia

Angular clasts, strongly bleached. This is a good guide-rock for inferring within or proximal to a hydrothermal system, perhaps an interesting system. (Ootsa)

V1-13f

Quartz-eye porphyry

V1-13f

Quartz-eye porphyry

V1-13f

Quartz-eye porphyry

Rounded clear phenocrysts of quartz in a white, fine grained matrix.

A particularly important rock as quartz eye porphyries of many differing types are spatially and temporally tied to many differing mineral deposits. (Nechako)

V2-18a

Volcanic sandstone

Quartz-eye clasts

V2-13a

Tuffaceous lake sediment

fossil wood impressions; explosive volcanic eruptions deposit abundant loose, unconsolidated material that is susceptible to immediate erosion, transportation downslope into rivers, lakes and basins

V1-01f

Obsidian

common in young volcanic flows; obsidian is volcanic glass rich in silica; will recrystallize over a few million years to opaque dense rhyolite or felsite; alters readily in presence of hot water as in hydrothermal system; concoidal, glass-like break is typical. (Mt. Edziza)

V1-02f

Perlite

Hydrated volcanic glass (obsidian):
An interesting rocks, distal from any hydrothermal activity.(Clisbako)

V2-02A

Rhyolite breccia

There are many breccias. The presence of highly angular fragments of large range of sizes (in particular the small shards) suggests a hydrothermal event of local nature as all the clasts are similar rhyolite. A rock worth noting on a map. (Ootsa)

V2-15a

Air fall ash tuff

Fine white matrix of ash turbulently mixed with fine angular fragments, large fragments quartz eyes—(if hardened is a quartz eye porphyry). (Ootsa)

Air fall ash tuff

Fine white matrix of ash turbulently mixed with fine angular fragments, large fragments quartz eyes—(if hardened is a quartz eye porphyry). (Ootsa)

Finely laminated siliceous sinter

Thin lamellae represent hot spring deposition of silica within a lacustrine basin. Presence of fossil plants and fish fragments confirm a sinter origin

Sinter

Finely laminated siliceous sinter

Sinter

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