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see conglomerateconglomerate,
in geology, sedimentary rock composed largely of pebbles or other rounded particles whose diameter is larger than 2 mm (.08 in.). Essentially a cemented gravel, conglomerates are formed along beaches, as glacial drift, and in river deposits.
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cemented rock composed of angular fragments (sized 1 cm or more). Breccias may be composed of fragments from one rock (monomictic breccia) or several different rocks (polymictic breccia).

Breccias are volcanic (volcanogenic), sedimentary, or tectonic in origin. Volcanogenic breccias originate when the more liquid lava cements together the lava fragments which have formed during the crushing and breakdown of flowing viscous lava (lava breccia), during the agglomeration of tuff and other volcanogenic elastic materials (tuff breccia), and during the diagenesis of mud flow deposits in volcanic regions (lahars). Sedimentary breccias are formed in continental conditions during the cementation of talus deposits and mud-flow deposits from lahars, and during the collapse of the roofs of karstic cavities (karst breccia). A specific type of breccia is bone breccia, which originates in places where the mass destruction and burial of vertebrates has occurred. In maritime areas breccia originates as a result of the destruction of littoral rocks or reefs. Tectonic breccias (friction breccia) are formed in a rock stratum during tectonic movements when rock is crushed along the fractures. Large fragments in this case are usually buried in a finely granulated mass.



A rock made up of very angular coarse fragments; may be sedimentary or may be formed by grinding or crushing along faults.


Any stone composed of angular fragments embedded and consolidated in a finer ground. Numerous marbles owe their distinctive appearance to brecciation.
References in periodicals archive ?
Freud's brecciation metaphor is examined in studies that have looked at how the material evidence of the past features in the planning of the city.
And yet, the great brecciation that sent this energetic superhot plasma outward to form our universe would most likely have been zipping along at the velocity of light.
Gold at the Santa Rosa mine occurs in the Chimu Formation, both within a steeply dipping zone of shearing and hydrothermal brecciation and as mantos localized by favorable stratigraphic horizons.
Anomalous gold, silver, and arsenic values appear to be associated with areas of more intense multiple-stage silicification and brecciation.
Drill hole RH-01 was located on the eastern anomaly and intersected extremely altered metasediments down to 284 metres, with quartz brecciation at the bottom of the hole.
The available evidence suggests the possibility of karst dissolution, collapse and brecciation, followed by lithification.
Locally, massive sulphides have undergone a strong brecciation accompanied by intense replacement by ribbon-like crystals of pyrite.
Deepening of the open pit mines has revealed the presence of small intrusive bodies of pegmatitic carbonatite, closely associated areas of silicocarbonatite rocks, and local areas of brecciation of the main fine-grained sodic fenites that are cemented by pegmatitic carbonatite.
However, in our field and petrographic observations we round no evidence of brecciation along this boundary or any other evidence of faulting (Fig.