pyroclastic rock

(redirected from Volcaniclastic)

pyroclastic rock

[¦pī·rə¦klas·tik ′räk]
(petrology)
A rock that is composed of fragmented volcanic products ejected from volcanoes in explosive events.
References in periodicals archive ?
In the section on Porten Road, it is defined as the base of a bed of medium grey, volcaniclastic sandstone containing clasts of plagioclase, about 1 mm in length, and angular fragments of porphyritic rhyolite from I to 10 cm in size; a few clasts of flow-banded rhyolite are also present.
The Thakadu and Makala deposits are sediment-hosted stratabound disseminated sulphide zones in a metamorphosed sedimentary sequence with minor volcanic and volcaniclastic units.
All four drill holes passed through a sequence of volcaniclastic rocks, which host the porphyritic intrusions, and through a shallowly-dipping fault at depth into a sequence of calcareous sediments.
At the district scale the ore is restricted to the Lower-Cretaceous, shallow-marine Lo Prado Formation, composed of bimodal felsic and mafic flow lavas, dykes, and volcaniclastic sedimentary rocks.
Both holes cored interbedded mafic volcaniclastic fragmentals and mudstones occurring above a thick package of sericite-altered rhyolite flows and black matrix breccia.
The seven zoned pegmatite dykes intrude Proterozoic Amisk Group volcanic and volcaniclastic rocks in a 1.
1993) consists of volcanic flows, hyaloclastite and volcaniclastic sandstone and siltstone.
The Boyongan deposit is buried beneath 50-300 metres of volcaniclastic rocks and contains a zone of oxidation extending to an unusual depth of approximately 500 metres.
The stockwork zone consists of centimetre-scale epithermal quartz-chalcedony veins and veinlets hosted in felsic volcanic and volcaniclastic rocks.
The new channel samples from the Escandalosa Zone are from oxidized volcaniclastic rocks exposed on ridges above outcrops of silica-pyrite alteration in the valleys.
Synvolcanic gold-base metal deposits: the widespread base metal prospects and geochemical signatures indicate the potential for these types of deposits, and the style of mineralization at Akasaba is consistent with such an interpretation, including its polymetallic characteristics (Au-Cu-Zn-Ag), the high concentration of sulfides (up to 30%), the stratiform nature of the mineralized zones, multiple stratigraphic targets, and proximity to felsic flows and volcaniclastic layers.