Pyroclastic Rocks

Pyroclastic Rocks

 

clastic rocks formed by the accumulation of clastic material (volcanic breccias, tuffs) expelled during volcanic eruptions. Pyroclastic rocks also include deposits formed when mudflows accompanying volcanic eruptions harden. After deposition, pyroclastic rocks either sinter, as is the case with ignimbrite, or undergo diagenesis.

References in periodicals archive ?
The outcomes of the SVM method show that prospective target areas for IOCG deposits are defined mainly by vicinity to NE-SW trending faults and pyroclastic rocks (mainly tuff) and Au-Cu geochemical anomalies.
This area mainly consists of Eocene basaltic-andesite to andesitic volcanic rocks with tuff and other pyroclastic rocks with minor intercalated sedimentary lenses such as shale, gypsiferous marl, and shallow depth limestone (Aftabi and Atapour, 2000).
The main constituent rocks are holocrystalline aegirine phonolite, so-called tinguaite, nepheline syenite, and vent-filling intrusive pyroclastic rocks. The summit level map of 2 km of grid interval shows that its morphologic features are unlikely for a volcanic caldera.
In addition, it is found that extrusive rocks (e.g., basalt and dacite) have much higher [kappa] compared to plutonic rocks; hypabyssal and pyroclastic rocks have relatively lower [kappa] (Table 2).
Gold mineralization within the Courageous Lake deposit is hosted in the upper part of an assemblage of Archeanage felsic pyroclastic rocks just below a transition zone to sedimentary rocks.
The Palomo mine area is composed entirely of volcanic rocks: andesitic lavas, pyroclastic rocks, tuffs and breccias.
12 Pb-Zn deposits (New Brunswick), the presence of peperites in association with pyroclastic rocks and tufflavas indicates the in situ emplacement of pyroclastic rocks (cf., Downey, 2005).
Apart from magmatic rocks, the Lower Silesian basaltoid formation includes as well pyroclastic rocks, such as: volcanic breccias, tuffs, and tuffites.
The Beulah Camp Formation comprises reddish-maroon, coarse- to fine-grained felsic and minor mafic pyroclastic rocks, chiefly felsic lithic-crystal tuff.
The fragmented magma gives rise to pyroclastic rocks, not lava flows.