ash-flow tuff

ash-flow tuff

[′ash‚flō ‚təf]
(petrology)
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The Shin Pond volcanic rocks extend into the adjacent Island Falls quadrangle where they are as much as 300 m thick and consist of slaty felsite, coarse-grained calcareous tuffaceous sandstone and ash-flow tuff (Ekren and Frischknecht 1967).
The aerial extent and continuity of highly-anomalous metal values from the Archibarcacat prospect is suggestive of a more extensive mineralized system at depth covered by a single ash-flow tuff.
A Strathcona Minerals 43- 101 report (July 2003) states that " A serpentinized ultramafic sill or flow in the ash-flow tuff traces a fold structure which is cut by a shear zone (Northwest Arm Shear Zone) under the Northwest Arm".
This stratigraphy includes carbonate rocks interbedded with volcanic ash-fall and ash-flow tuffs of the bimodal basalt-rhyolite assemblage that occupies this area of Nevada.
1970, Ash-flow tuffs of Precambrian age in Southeast Missouri, Missouri Division of Geology and Land Survey Report of Investigations 46.
1984, Chemical signatures of hydrothermally altered Precambrian ash-flow tuffs, St.
The area's geology is fairly typical of the northern Sierra Madre Occidental with structurally disrupted andesite volcanics of the Lower Volcanic Complex (LVC) exposed in the more deeply eroded parts of the district and gently tilted tuffaceous rhyolite ash-flow tuffs of the Upper Volcanic Supergroup (UVS) occupying the higher areas.
Gold and silver mineralization is hosted by Tertiary rhyolitic volcanoclastics, welded ash-flow tuffs and lavas associated with the Jarbidge volcanic center.
The mineralized system consists of one major and several minor northwesterly striking, steeply dipping, sulphide-rich silver-lead-zinc-antimony-gold veins that are hosted in dacitic ash-flow tuffs, agglomerates, and lava flows.