Editing Breccia (section)

===Igneous ===
Igneous clastic rocks can be divided into two classes:

# Broken, fragmental rocks associated with volcanic eruptions, both of the [[lava]] and [[Pyroclastic rock|pyroclastic]] type;<ref name="fisher-schmincke-1984-89-92">{{cite book |last1=Fisher |first1=Richard V. |last2=Schmincke |first2=H.-U. |title=Pyroclastic rocks |date=1984 |publisher=Springer-Verlag |location=Berlin |isbn=3540127569 |pages=89–92}}</ref>
# Broken, fragmental rocks produced by [[intrusion|intrusive]] processes, usually associated with [[Intrusion|plutons]] or [[porphyry (geology)|porphyry]] stocks.<ref>{{cite journal |last1=Wright |first1=A. E. |last2=Bowes |first2=D. R. |title=Classification of Volcanic Breccias: A Discussion |journal=Geological Society of America Bulletin |date=1963 |volume=74 |issue=1 |pages=79 |doi=10.1130/0016-7606(1963)74[79:COVBAD]2.0.CO;2}}</ref><ref>{{cite journal |last1=Olianti |first1=Camille A.E. |last2=Harris |first2=Chris |title=A low-δ18O intrusive breccia from Koegel Fontein, South Africa: Remobilisation of basement that was hydrothermally altered during global glaciation? |journal=Lithos |date=February 2018 |volume=300-301 |pages=33–50 |doi=10.1016/j.lithos.2017.12.006|bibcode=2018Litho.300...33O }}</ref>

====Volcanic====
Volcanic pyroclastic rocks are formed by explosive eruption of lava and any rocks which are entrained within the eruptive column. This may include rocks plucked off the wall of the [[magma]] conduit, or physically picked up by the ensuing [[pyroclastic surge]].<ref name="fisher-schmincke-1984-89-92"/> Lavas, especially [[rhyolite]] and [[dacite]] flows, tend to form clastic volcanic rocks by a process known as ''autobrecciation''. This occurs when the thick, nearly solid lava breaks up into blocks and these blocks are then reincorporated into the lava flow again and mixed in with the remaining liquid magma. The resulting breccia is uniform in rock type and chemical composition.{{sfn|Allaby|2013|loc="Autobrecciated lava"}}

[[Caldera]] collapse leads to the formation of megabreccias, which are sometimes mistaken for outcrops of the caldera floor.{{sfn|Jackson|1997|loc="megabreccia"}} These are instead blocks of precaldera rock, often coming from the unstable oversteepened rim of the caldera.<ref name="goff-etal-2011"/> They are distinguished from ''mesobreccias'' whose clasts are less than a meter in size and which form layers in the caldera floor.{{sfn|Jackson|1997|loc="mesobreccia"}} Some clasts of caldera megabreccias can be over a kilometer in length.<ref name="goff-etal-2011"/>

Within the volcanic conduits of explosive volcanoes the volcanic breccia environment merges into the intrusive breccia environment. There the upwelling lava tends to solidify during quiescent intervals only to be shattered by ensuing eruptions. This produces an ''alloclastic'' volcanic breccia.{{sfn|Fisher|Schmincke|1984|p=89}}{{sfn|Allaby|2013|loc="Alloclast"}}

====Intrusive====
[[Clastic rocks]] are also commonly found in shallow [[subvolcanic rock|subvolcanic]] [[intrusion]]s such as porphyry stocks, [[granite]]s and [[kimberlite]] pipes, where they are transitional with volcanic breccias.<ref>{{cite journal|doi=10.2113/gsecongeo.69.3.412 |title=Origin of breccia pipes |journal=American Journal of Science |volume = 69 | pages = 412–413 |year=1974|last1=Mitcham|first1=T. W.|issue=3|bibcode=1974EcGeo..69..412M }}</ref> Intrusive rocks can become brecciated in appearance by multiple stages of intrusion, especially if fresh magma is intruded into partly consolidated or solidified magma. This may be seen in many granite intrusions where later [[aplite]] [[Vein (geology)|veins]] form a late-stage [[stockwork]] through earlier phases of the granite mass.<ref>{{cite journal |last1=Nurmi |first1=P.A. |last2=Haapala |first2=I. |year=1986 |title=The Proterozoic granitoids of Finland: granite types, metallogeny and relation to crustal evolution |journal=Bulletin of the Geological Society of Finland |volume=58 |number=1 |pages=203–233|doi=10.17741/bgsf/58.1.014 }}</ref><ref>{{cite journal |last1=Vry |first1=V. H. |last2=Wilkinson |first2=J. J. |last3=Seguel |first3=J. |last4=Millan |first4=J. |title=Multistage Intrusion, Brecciation, and Veining at El Teniente, Chile: Evolution of a Nested Porphyry System |journal=Economic Geology |date=1 January 2010 |volume=105 |issue=1 |pages=119–153 |doi=10.2113/gsecongeo.105.1.119|bibcode=2010EcGeo.105..119V |url=https://figshare.com/articles/journal_contribution/22880465 }}</ref> When particularly intense, the rock may appear as a chaotic breccia.<ref>{{cite journal |last1=Ansdell |first1=K. |last2=Normore |first2=N. |title=Constraints on the origin of intrusion breccias: Observations from the Paleoproterozoic Boundary Intrusions in the Flin Flon area |journal=GeoConvention |year=2020 |url=https://geoconvention.com/wp-content/uploads/abstracts/2020/57815-constraints-on-the-origin-of-intrusion-breccias_-o.pdf |access-date=2 April 2022}}</ref>

Clastic rocks in [[mafic]] and [[ultramafic rock|ultramafic]] intrusions have been found and form via several processes:
* consumption and melt-mingling with wall rocks, where the wall rocks are softened and gradually invaded by the hotter ultramafic intrusion (producing ''taxitic texture'');<ref name="BarnesEtal2016">{{cite journal |last1=Barnes |first1=Stephen J. |last2=Cruden |first2=Alexander R. |last3=Arndt |first3=Nicholas |last4=Saumur |first4=Benoit M. |title=The mineral system approach applied to magmatic Ni–Cu–PGE sulphide deposits |journal=Ore Geology Reviews |date=July 2016 |volume=76 |pages=296–316 |doi=10.1016/j.oregeorev.2015.06.012|doi-access=free |bibcode=2016OGRv...76..296B }}</ref>
* accumulation of rocks which fall through the magma chamber from the roof, forming chaotic remnants;<ref>{{cite book |last1=Philpotts |first1=Anthony R. |last2=Ague |first2=Jay J. |title=Principles of igneous and metamorphic petrology |date=2009 |publisher=Cambridge University Press |location=Cambridge, UK |isbn=9780521880060 |edition=2nd |page=80}}</ref>
* autobrecciation of partly consolidated [[cumulate rocks|cumulate]] by fresh magma injections;<ref name="Robins1998">{{cite journal |last1=Robins |first1=Brian |title=The mode of emplacement of the Honningsvåg Intrusive Suite, Magerøya, northern Norway |journal=Geological Magazine |date=March 1998 |volume=135 |issue=2 |pages=231–244 |doi=10.1017/S0016756898008395|bibcode=1998GeoM..135..231R |s2cid=129955208 }}</ref>
* accumulation of [[xenolith]]s within a feeder conduit or vent conduit, forming a [[diatreme]] breccia pipe.{{sfn|Philpotts|Ague|2009|pp=89-93}}