Ignimbrite


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ignimbrite

[′ig·nəm‚brīt]
(petrology)
A rock deposit (welded or not) resulting from one or more ground-hugging flows of hot volcanic fragments and particles commonly produced during explosive eruptions (pyroclastic flows and tephra fall). Most ignimbrites have a sheet-like shape, cover many thousands of square kilometers, and have chemical compositions that span the range commonly exhibited by igneous rocks (basaltic to rhyolitic). Also known as ash-flow tuff; pyroclastic-flow deposit; welded tuff.

Ignimbrite

 

(or welded tuff), fragmental volcanic rocks with a tuff body consisting of lava and ash, with comparatively large inclusions of dark glass embedded in the body. In the marginal zones the glass and tuff usually merge so that the rocks appear to be welded. Against the gray background of the rock the glass inclusions appear either as irregular flakes and sparks or as lenses arranged in a subparallel manner which by their shape resemble tongues of flame. For this reason they are frequently called fiamme from the Italian word for flame. The formation of ignim-brite is explained by deposition from glowing ash clouds that occur during Katmai-type eruptions. Ignimbrite is most often found among persilicic volcanic rocks (rhyolites, trachytes, da-cites, and more rarely andesites) and occurs in the form of horizontal beds in volcanogenic masses. Ignimbrites are characteristic for many of the world’s volcanic regions.

References in periodicals archive ?
Ignimbrites of the Sierra Madre Occidental and their Relation to the Tectonic Evolution of Western Mexico.
Map also shows Ignimbrite distribution and tephra isopachs for a M = 8.
Both anomalies are beneath ignimbrite rocks which blanket this area and mask any geochemical signature at surface.
So to ignimbrite, a word of apparently Latin origin that means "fiery rock dust cloud.
Both factors shape the landscape into two main morphological units: high relief zone with steep slopes (made up of trachy-rhyolitic suite) and the ignimbrite escarpment forming the shelf zone.
Researchers studied the remnants of ash from the Campanian Ignimbrite eruption about 40 000 years ago in sites in Greece, the Aegean Sea, Libya, and four central European caves.
The stone dolls in this area are a natural phenomenon created through centuries of erosion of volcanic rocks of different erodibility: ignimbrite, andesite and tuffs.
Consider the little-known Campanian Ignimbrite eruption, which devastated southern Italy some 39,000 years ago just as Europeans were developing stone tools.
Cappadocia region is largely underlain by sedimentary rocks formed in lakes and streams, and ignimbrite deposits erupted from ancient volcanoes approximately 9 to 3 million years ago, during the late Miocene to Pliocene epochs.
in the second, mixt-over-ground stage, the ignimbrite flows, pyroclastic flows and fallout tuffs emerge, covering the entire massif;
Topics include a new geological map of Stromboli volcano in Italy's Tyrrhenian Sea based on application of a lithostratigraphic and unconformity-bounded stratigraphic (UBS) units, a revised volcanostratigraphy of the Upper Miocene to Lower Pliocene Urgup formation in the central Anatolian volcanic province of Turkey, ignimbrite stratigraphy and chronology on Tercerira Island in the Azores, geologic mapping of Mexico's Colima volcanic complex and implications for hazard assessment, and probabilistic digital hazard maps for avalanches and massive pyroclastic flow using TITAN2D computational model.