Breccia from basalt fragments cemented by epidote
Breccia ( Italian: breccia - breaking) [1] - a rock composed of angular debris (larger than 1 cm) and cemented. In breccia, unlike conglomerate , there are almost no rounded fragments.
Content
Classification
By composition, breccias are divided into:
- Monomict breccia - composed of fragments of one breed.
- Polymict breccia - consists of several different breeds.
According to the methods of occurrence, breccias are divided into three groups:
1. Volcanogenic breccia
- when cementing with more liquid lava of lava debris
- during crushing of viscous lava flows during their flow ( lava breccia )
- with the accumulation of tuffs and other volcanic debris ( tuff breccia )
- with the diagenesis of sediment of mud flows of volcanic regions ( lahars ).
2. Sedimentary breccia
- in continental conditions arise during cementation of slope deluvium, sediments of mudflows or during the destruction of the roof of karst voids ( karst breccia ).
- Separately, bone breccia is isolated, which is formed in places of mass death and burial of vertebrates .
- in marine conditions, breccias occur due to the destruction of coastal cliffs or reefs.
3. Tectonic breccia
- friction breccias - occur in the thickness of rocks during tectonic movements, during crushing of rocks along faults. Large fragments in such breccias are usually immersed in a finely divided mass. It can be difficult to distinguish between tectonic and sedimentary breccias.
See also
- Conglomerate (breed)
- Nodules
Notes
- ↑ Geological Dictionary, 1978 , Breccia.
Literature
- Levinson-Lessing F. Yu. Brekchiya // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
- Breccia // Geological Dictionary: [in 2 vols.] / Otv. ed. K.N. Paffengoltz . - 2nd ed., Rev. - M .: Nedra , 1978. - T. 1. A - M. - S. 86.
Clastic rocks
| Breed group | Debris size | Uncemented | Cemented | ||
|---|---|---|---|---|---|
| Rounded | Neokatannye | Rounded | Neokatannye | ||
| Coarse rocks ( psephitis ) | 10 - 1 m | Block boulders | Blocks | - | - |
| 1 m - 10 cm | Boulders | Breaks (blocks) | Boulder conglomerate | Breaking (block) breccia | |
| 10 - 1 cm | Pebbles | Crushed stone | Pebble conglomerates | Crushed Breccias | |
| 1 cm - 2 mm | Gravel | Dresva | Gravelites | Gingerbread man | |
| Sand rocks ( psammits ) | 2 - 0.05 mm | Sands | Sandstones | ||
| Dusty rocks (silt) | 0.05 - 0.005 mm | Siltstone | Siltstone | ||
| Clay rocks ( pelite ) | <0.005 mm | Silt , clay | Clays , mudstones | ||