types of breccias

2. Content
Sr. No. Topic
1 Introduction
2 Types of breccia
2 2.1 Sedimentary breccia
2 2.2 Igneous breccia ● Volcanic
● Intrusive
2 2.3 Hydrothermal breccia
2 2.4 Tectonic breccia
2 2.5 Impact breccia
3 Composition of breccia
4 Uses of breccia
5 Summary
6 References

3. Breccia exposed in the walls of mosaic
canyon, Death valley, California, (U.S.A.)

4. Breccia
Breccia is a rock composed of broken fragments of minerals or rock
cemented together by a fine-grained matrix that can be similar to or different
from the composition of the fragments.
Breccia
SEDIMENTARY
IGNEOUS
HYDROTHERMAL
TECTONIC
IMPACT

5. • Sedimentary breccia is a type of clastic sedimentary rock which is made of angular to subangular,
randomly oriented clasts of other sedimentary rocks.
• Sedimentary breccias comprise more than 30% gravel-size (>2mm) angular clasts produced by
mechanical weathering or brittle deformation of nearby rocks.
• Their angular shape implies minimal transport.
Breccia vs conglomerates
Fig. 1. Chert Breccia: The angular clasts in this breccia
are chert fragments. The matrix is an iron-stained mix
of clay through sand-size particles. The specimen is
about two inches (five centimeters) across.
Fig. 2. Chert conglomerate: The
rounded clast in this conglomerate
are chert fragments.
Breccia
SEDIMENTARY BRECCIA
IGNEOUS HYDROTHERMAL TECTONIC IMPACT

6. • Igneous breccias can form during the emplacement of igneous bodies by explosive exsolution of
volatile phases and/or explosive interaction of magma with groundwater .
• Intrusive breccias (such as associated with kimberlite pipes) often contain fragments of both intrusive
and host rocks.
• Igneous breccia dykes may contain a wide range of rock fragments sampled during magma ascent and
thus, provide information about the composition of rocks at deeper levels.
Fig. 3. Basalt breccia; green
groundmass is composed of
epidote
Fig. 5. Black dibase or diorite
brecciated and surrounded by
younger, intrusive white granetic
material. Specimen from the
Hermitage Peninsula, southern
Newfoundland
Breccia
SEDIMENTARY
IGNEOUS BRECCIA
HYDROTHERMAL TECTONIC IMPACT
Fig. 4 . Igneous breccia

7. • Hydrothermal breccias are usually formed by hydrofracturing of rocks by highly pressured hydrothermal
fluids. Hydrothermal breccias usually form at shallow crustal levels (<1 km) between 150 to 350 °C,
• when seismic or volcanic activity causes a void to open along a fault deep underground. The void draws
in hot water , and as pressure in the cavity drops, the water violently boils . In addition, the sudden
opening of a cavity causes rock at the sides of the fault to destabilise and implode inwards, and the
broken rock gets caught up in a churning mixture of rock, steam and boiling water.
• Volatile gases are lost to the steam phase as boiling continues, in particular carbon dioxide . As a result,
the chemistry of the fluids changes and ore minerals rapidly precipitate. Breccia- hosted ore deposits are
quite common.
Fig. 6. Hydrothermal breccia in the
Cloghleagh Iron Mine, near Blessington
in Ireland, composed mainly of quartz
and manganese oxides , the result of
seismic activity about 12 Ma ago
Fig. 7. Silicified and mineralized breccia. Light
gray is mostly dolomite with a little
translucent quartz. Dark gray is jasperoid and
ore minerals. Veinlet along lower edge of
specimen contains sphalerite in carbonates.
Pend Oreille mine, Pend Oreille County,
Washington
Breccia
SEDIMENTARY IGNEOUS
HYDROTHERMAL BRECCIA
TECTONIC IMPACT

8. • In fault zones, where rocks or even continents slide past each other, breccia
zones can be created that can vary from inches across to tens of meters
across.
• Fault breccia results from the grinding action of two fault blocks as they slide
past each other. Subsequent cementation of these broken fragments may
occur by means of the introduction of mineral matter in groundwater
Fig. 9. Boulder of a tectonic
breccia in the Sous River
valley near Alouz,
Morocco,derived from Haut
Atlas.
Fig. 8. Schematic cross section across fault
zones, A shallow fault zone with fault
breccia, After Mason (1978).
Breccia
SEDIMENTARY IGNEOUS HYDROTHERMAL
TECTONIC BRECCIA
IMPACT

10. • Impact melt-breccias form by the fracturing and fusion of rocks under extreme pressures and
temperatures rapidly induced during meteorite impacts.
• Breccia of this type may be present on or beneath the floor of the crater, in the rim, or in the
ejecta expelled beyond the crater.
• Impact breccia may be identified by its occurrence in or around a known impact crater, and/or an
association with other products of impact cratering such as shatter cones, impact glass, shocked
minerals, and chemical and isotopic evidence of contamination with extraterrestrial material (e.g.
iridium and osmium anomalies).
• Impact-melt breccias containing clastic debris and glass fragments produced by meteorite
bombardment have been collected from the surface of the Moon during Apollo missions.
Fig. 11. Alamo bolide impact breccia
(Late Devonian , Frasnian) near Hancock
Summit, Pahranagat Range, Nevada
Fig. 10. Impact crater
Breccia
SEDIMENTARY IGNEOUS HYDROTHERMAL TECTONIC
IMPACT BRECCIA
Apollo 11 breccia

11. Breccias & Metamorphic clastic rocks
• Clastic metamorphic rocks include breccias
formed in faults, Metamorphic rocks can be
brecciated via hydrothermal fluids forming a
hydrofracture breccia
Fig. 12. Breccia structure in agmatite.
• Agmatite shows breccia like
structure

12. Class - breccia can be divided into two broad classes:
• Clast supported - where the clasts touch each other and the matrix fills the voids;
• Matrix supported - where the clasts are not in contact and the matrix surrounds each clast;
• Sorting - a breccia comprising a mixture of clast sizes is poorly sorted, while one comprising
mostly clasts of the same size is well sorted;
Fig. 13. Spectrum of grain frameworks of aggregation fragmentites (A-breccias), resulting
from deposition and diagenesis (including a post-lithification pressure solution).

13. What is Composition of Breccia?
• Breccia has many compositions. Its composition is mainly determined by the rock and mineral
material that the angular fragments were produced from.
• The climate of the source area can also influence composition. Most breccias are a mix of rock
fragments and mineral grains.
• The type of rock that the fragments were produced from is often used as an adjective when
referring to the rock. Some examples: sandstone breccia, limestone breccia, granite breccia, chert
breccia, basalt breccia and others.
• A breccia where the clasts represent more than one rock type is termed polymictic (or
petromictic), while one where the clasts are of a single rock type are monomictic (or oligomictic).
Fig. 14. Polymictic Limestone Breccia:
A breccia that contains clasts of
multiple types of limestone. Specimen
is about four inches (ten centimeters)
across.
Fig. 15. Unusual breccia
cemented by azurite and
malachite , Morenci Mine ,
Arizona
Fig. 16. Tertiary breccia at
Resting Springs Pass,
Mojave Desert, California
Fig. 17. Highland
breccia, Apollo 16
Plagioclase (white)
Impact melt? (black)

14. Uses of Breccia
• Breccias have very unique angular textures and
are prized as ornamental rocks for buildings,
monuments, grave stones, tiles and many
other ornamental uses.
• They have been used by people for centuries
for many ornamental uses and some breccias
are even considered to be semi-precious and
have found uses in jewelry.
• Breccia was used on a limited scale by the
ancient Egyptians ; one of the best- known
examples is the statue of the goddess Tawaret
in the British Museum.
• It was regarded by the Romans as an especially
precious stone and was often used in high-
profile public buildings.
Fig. 18. Breccia statue
of the Ancient
Egyptian goddess
Tawaret

15. SUMMARY
• Breccia is a rock formed from angular gravel and boulder-sized clasts
cemented together in a matrix.
• Sedimentary breccia: Sedimentary breccia is a type of clastic sedimentary
rock which is made of angular to subangular, randomly oriented clasts of
other sedimentary rocks.
• Igneous Breccia: A term used for a rock composed angular fragments of
igneous rocks. "Flow breccia" and "pyroclastic breccia" could be called
"igneous breccia".
• Hydrothermal Breccia: The interaction of hydrothermal fluids with
tectonically brecciated rock produces hydrothermal breccias
• Fault Breccia: Broken rock found in the contact area between two fault
blocks and produced by movement of the fault.
• Impact Breccia: A deposit of angular rock debris produced by the impact
of an asteroid or other cosmic body.
• Composition of breccias : Its composition is mainly determined by the
rock and mineral material that the angular fragments were produced
from. The climate of the source area can also influence composition.
• Uses of breccia: Building material, decorative stones, tiles, tombstones,
monuments, jewelry, aquifers, natural gas and petroleum reservoirs

16. References
• Buckland, A.J., (1819). Breccia in Staffordshire. Trans. Geol. Soc., 1st Ser., vol. 5 (2), pp.
507.
• Geikie, A., (1902). The geology of eastern Fife. Mere. Geol. Surv. Scotland, Nos. 40a, 41,
48a, 49a, 520 pp.
• Laznicka, P., (1989). Breccias and ores. Part 1: History, organization and petrography of
breccias. Ore Geol. Rev., vol. 4, pp. 315-344.
• Ramsay, A.C., (1855). On the occurrence of angular, subangular, polished and striated
boulders in the Permian Breccia of Shropshire, Worcestershire etc. and on the probable
existence of glaciers and icebergs in the Permian Epoch. Q. J. Geol. Soc. London, vol. 11,
pp. 185-205.
• Sedgwick, A., (1835). On the geological relations and internal structure of the
Magnesian Limestone, and the lower portions of the New Red Sandstone series in their
range through Nottinghamshire, Derbyshire, Yorkshire and Durham, to the southern
extremity of Northumberland. Trans. Geol. Soc. London, vol. 3, pp. 37-124.
• Web Links:
• http://en.m.wikipedia.org/wiki/Breccia
• http://www.galleries.com/rocks/breccia.htm
• http://www.encyclopedia.com/topic/Breccia.aspx
• http://geology.com/rocks/breccia.shtml
• https://flexiblelearning.auckland.ac.nz/rocks_minerals/rocks/breccia.html
• http://www.impact-structures.com/impact-rocks-impactites/the-impact-breccia-page/

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