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Metaconglomerate is a rock type which originated from
Metaconglomerate is a rock type which originated from conglomerate
Conglomerate or conglomeration may refer to:
* Conglomerate (company)
* Conglomerate (geology)
* Conglomerate (mathematics)
In popular culture:
* The Conglomerate (American group), a production crew and musical group founded by Busta Rhymes
** ...
after undergoing metamorphism
Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of ch ...
. Conglomerate is easily identifiable by the pebbles or larger clasts in a matrix
Matrix most commonly refers to:
* ''The Matrix'' (franchise), an American media franchise
** '' The Matrix'', a 1999 science-fiction action film
** "The Matrix", a fictional setting, a virtual reality environment, within ''The Matrix'' (franchi ...
of sand
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class ...
, silt
Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel ...
, or clay
Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4).
Clays develop plasticity when wet, due to a molecular film of water surrounding the clay pa ...
. Metaconglomerate looks similar to conglomerate, although sometimes the clasts are deformed. The cement
A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel (aggregate) together. Cement mixe ...
matrix of conglomerate is not as durable as the grains, and hence when broken, conglomerate breaks around the grains. Metaconglomerate, however, breaks through the grains, as the cement has recrystallized and may be as durable as the clasts.
Foliated metaconglomerate is created under the same metamorphic conditions that produce slate
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. It is the finest grained foliated metamorphic rock. ...
or phyllite
Phyllite ( ) is a type of foliated metamorphic rock created from slate that is further metamorphosed so that very fine grained white mica achieves a preferred orientation.Stephen Marshak ''Essentials of Geology'', 3rd ed. It is primarily compo ...
, but with the parent rock (protolith
A protolith () is the original, unmetamorphosed rock from which a given metamorphic rock is formed.
For example, the protolith of a slate is a shale or mudstone. Metamorphic rocks can be derived from any other kind of non-metamorphic rock an ...
) being conglomerate, rather than clay.Essentials of Geology, 3rd Ed, Stephen Marshak
The metaconglomerates of the Jack Hills
The Jack Hills are a range of hills in Mid West Western Australia. They are best known as the source of the oldest material of terrestrial origin found to date: Hadean zircons that formed around 4.39 billion years ago. These zircons have enable ...
of Western Australia
Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to t ...
are the source rocks for much of the detrital zircon
Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of t ...
s that have been dated
Date or dates may refer to:
* Date (fruit), the fruit of the date palm (''Phoenix dactylifera'')
Social activity
* Dating, a form of courtship involving social activity, with the aim of assessing a potential partner
**Group dating
*Play date, ...
to be as old as 4.4 billion years.ftp://rock.geosociety.org/pub/reposit/2002/2002034.pdf from: Peck, W.H., Valley, J.W., Wilde, S.A., and Graham, C.M., 2001, ''Oxygen isotope ratios and rare earth elements in 3.3 to 4.4 ga zircons: Ion microprobe evidence for high δ18O continental crust in the early Archean'': Geochimica et Cosmochimica Acta, v. 65, p. 4215-4229.
References