Citizendia
Your Ad Here

This article is about the geologial usage, for other uses see: Melange (disambiguation).
Melange from Narooma, Australia
Melange from Narooma, Australia

In geologic context, mélange is a large scale breccia formed in the accretionary wedge above a subduction zone. The Narooma Accretionary Complex or Narooma Terrane is a geological structural region on the South coast of New South Wales, Australia that is For a topic outline on this subject see List of basic Australia topics. Geology (from Greek γη gê, "earth" and λόγος Logos, "speech" lit In Geology, a subduction zone is an area on Earth where two tectonic plates meet and move towards one another with one sliding underneath the other The mélange typically consists of a jumble of large blocks of varied lithologies of altered oceanic crustal material and blocks of continental slope sediments in a sheared mudstone matrix. Oceanic crust is the part of Earth's Lithosphere that surfaces in the Ocean basins The continental shelf is the extended perimeter of each Continent and associated Coastal plain, which is covered during interglacial periods such Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of Mudstone (also called mudrock) is a fine grained Sedimentary rock whose original constituents were Clays or Muds Grain size is up The matrix or groundmass of rock is the fine-grained mass of material in which larger grains or Crystals are embedded

Mélange occurrences are associated with thrust faulted terranes in orogenic belts. A thrust fault is a type of fault, or break in the Earth's crust with resulting movement of each side against the other in which a lower stratigraphic position is pushed up Orogeny (Greek for "mountain generating" is the process of natural Mountain building and may be studied as a tectonic structural event as a geographical event and The ultramafic ophiolite sequences which have been obducted onto continental crust are typically underlain by a mélange. Ultramafic (also referred to as ultrabasic) rocks are igneous and meta -igneous rocks with very low Silica content (less than 45% generally An Ophiolite is a section of the Earth's Oceanic crust and the underlying upper mantle that has been uplifted or emplaced to be exposed within Continental Obduction is the overthrusting of Continental crust by Oceanic crust or mantle rocks at a Destructive plate boundary. The continental crust is the layer of granitic, Sedimentary, and Metamorphic rocks which form the Continents and the areas of shallow seabed Examples include the Franciscan Formation along the Coast Ranges of central and northern California and the Bay of Islands ophiolite complex in Newfoundland. The Franciscan Assemblage is a geological term for an accreted Terrane of heterogeneous rocks found on and near the San Francisco Peninsula. California ( is a US state on the West Coast of the United States, along the Pacific Ocean. The Bay of Islands is an area in the Northland region of the North Island of New Zealand. Newfoundland and Labrador (ˈnuːfɨn(dlənd ən(d ˈlæbrəˌdɔr (Terre-Neuve-et-Labrador is a province of Canada, the tenth and latest to join the Confederation Before the advent of plate tectonics in the early 1970s, melanges were quite perplexing to geologists in California (circa 1920 to 1970). A particularly troubling paradox was the occurrence of blueschist blocks (=low temperature and high pressure metamorphic rocks) in direct contact with graywacke (a coarse sandstone with lithic fragments) that was deposited in a sedimentary environment. Incompatible rocks occur together in melanges, thanks to insightsfrom plate tectonics and subduction zones. So the paradox of depositional environment was finally explained in light of plate tectonics. In geology sedimentary depositional environment describes the combination of physical chemical and biological processes associated with the deposition of a particular type of sediment Geologists sometimes think of melanges as analogous to garbage dumps: a lot of strange things can occur together.

An example in the United Kingdom is the Gwna Melange; extending through Anglesey, the Llyn Peninsula and the Island of Bardsey in North Wales. It consists of a jumble of various rock types contained in a matrix of grey-green slaty mudstone and siltstone.

A mélange is a mapable body of rock characterized by a lack of continuous bedding and the inclusion of fragments of rock of all sizes, contained in a fine-grained deformed matrix. Some larger blocks of rock may be as much as 1 km across! Both tectonic and sedimentary processes can form mélange. Olistostromes are mélanges formed by gravitational sliding under water and accumulation of flow as a semi fluid body with no bedding. An olistostrome is a Sedimentary deposit composed of a chaotic mass of Heterogeneous material such as blocks and mud that accumulates as a semifluid body by

Etymology

The term mélange in English language is a loan word from French, used to mean mixture of disparate components (what would be referred to in the sciences as a heterogeneous mixture). English is a West Germanic language originating in England and is the First language for most people in the United Kingdom, the United States A loanword (or loan word) is a word directly taken into one Language from another with little or no translation French ( français,) is a Romance language spoken around the world by 118 million people as a native language and by about 180 to 260 million people Science (from the Latin scientia, meaning " Knowledge " or "knowing" is the effort to discover, and increase human understanding In Chemistry, a mixture is a substance made by combining two or more different materials without a chemical reaction occurring (the objects do not bond together Its derivation, and therefore to some extent its connotation, is similar to Mêlée [1][2]. Melee (from the French mêlée meˈleː generally refers to disorganized Close combat involving a group of fighters Mélange is the modern form of the Old French noun meslance, which comes from the infinitive mêler, meaning "to mix". Old French was the Romance Dialect continuum spoken in territories which span roughly the northern half of modern France and parts of modern Belgium In Grammar, infinitive is the name for certain verb forms that exist in many languages

References

External links

Dictionary

mélange

-noun

  1. Alternative form of melange.
© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
 Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic