- Manto ore deposits
Manto orebodies are stratabound irregular to rod shaped
oreoccurrences usually horizontal or near horizontal in attitude.
Manto deposits are an important source of
copper, forming one of the world major copper resources in Chileand southern North America.
The term "manto" is from the Spanish word for "blanket" although the geologic "manto" is more like a "blanket roll" than a sheetlike structure.
Manto ore deposits are defined by a strict stratigraphic control on their distribution, generally within a porous formation within a structural trap site. They are distinct from other copper ore bodies in that they are not associated with
shear zones, and an intrusive link to manto deposit formation is not conclusively proven.
The genetic model of manto formation is debated, but consists of the following broad principles;
* The "source" of ore within manto deposits is considered to be interformational, from a sedimentary source within an adjacent sedimentary basin, or from ore fluids driven off from a granite intrusive
* The "transport" of copper into the manto deposit position was likely hydrothermal, either a metamorphic solution or copper-bearing hydrothermal solutions generated by intrusive granites
* The "trap" where the ore materials concentrated is typically a coarse-grained member of a formation, and the manto is usually sited in a stratigraphic or structural pinch-out of this formation although it is now thought that
hydrocarbons may have assisted in the migration of metals into favorable trap sites
Manto deposits were first described in great detail in Chile, where they sit within sedimentary strata overlying large granitic intrusions, in regions adjacent to
In Chile, the arid climate and deep regolith development, tended to favor preservation of
chalcocite- malachite- azuriteassemblages in the manto deposits, leading workers to believe that they were weathered equivalents of primary chalcopyritedeposits of porphyry-copper derivation.
However, some recent work (Wilson & Zentilli, 2006) shows that there may be primary
chalcociteand borniteformed within degraded petroleum within trap sites, with copper precipitating from solution by reduction in contact with the reduced carbon. Thus, manto deposits need not be the weathered equivalents of primary chalcopyrite.
Manto deposits may be formed in proximity to intrusives, for instance in the La Providencia mine,
Mexico, a porphyry stock is the feeder for some twenty mantos as the pipe intersects favorable layers in the sedimentary sequence. However, these manto deposits are analogous to skarndeposits, and in some cases terminology may be misused.
Examples of manto orebodies include: Magma Mine, Superior, Arizona; Tintic and Park City, Utah; Leadville and Gilman, Colorado and Pioche, Nevada in the United States.
* Wilson N.S.F., & Zentilli M., 2006. Association of pyrobitumen with copper mineralization from the Uchumi and Talcuna districts, Chile. "Journal of Coal Geology", 65, pp 158-165.
* Evans, Anthony, (1992) "Ore Geology and Industrial Minerals: An Introduction", Blackwell Science; 3rd edition ISBN 0-632-02953-6
*Guilbert, John M. and Charles F. Park, Jr (1986) "The Geology of Ore Deposits", W. H. Freeman ISBN 0-7167-1456-6
Wikimedia Foundation. 2010.
Look at other dictionaries:
Manto ore deposit — For other uses, see Manto (disambiguation). Manto orebodies are stratabound irregular to rod shaped ore occurrences usually horizontal or near horizontal in attitude. Manto deposits are an important source of copper, forming one of the world… … Wikipedia
Manto — may refer to: People Mando (singer), also called Manto Manto Mavrogenous, Greek national heroine Saadat Hasan Manto, writer known by his pen name Manto Manto Tshabalala Msimang (1940 2009), South African politician Other Manto (mythology) Manto… … Wikipedia
Ore genesis — The various theories of ore genesis explain how the various types of mineral deposits form within the Earth s crust. Ore genesis theories are very dependent on the mineral or commodity. Ore genesis theories generally involve three components:… … Wikipedia
Metasomatism — is the chemical alteration of a rock by hydrothermal and other fluids. Metasomatism can occur via the action of hydrothermal fluids from an igneous or metamorphic source. Metasomatic albite + hornblende + tourmaline alteration of metamorphosed… … Wikipedia
Topic outline of mining — For a more comprehensive list, see the List of mining topics. Mining is the extraction of valuable minerals or other geological materials from the earth, usually (but not always) from an ore body, vein or (coal) seam. Materials recovered by… … Wikipedia
Outline of mining — The following outline is provided as an overview of and topical guide to mining: Mining – extraction of valuable minerals or other geological materials from the earth, usually (but not always) from an ore body, vein or (coal) seam. Any material… … Wikipedia
Anticline — In structural geology, an anticline is a fold that is convex up and has its oldest beds at its core. The term is not to be confused with antiform , which is a purely descriptive term for any fold that is convex up. Therefore if age relationships… … Wikipedia
Silver mining in the United States — began on a major scale with the discovery of the Comstock Lode in Nevada in 1858. The industry suffered greatly from the demonetization of silver in 1873 by the Crime of 73, but silver mining continues today.The United States produced 1,200… … Wikipedia
Roca ultrabásica — Saltar a navegación, búsqueda Las rocas ultrabásicas (también referida como ultramáficas) son rocas ígneas y meta ígneas con muy bajo sílice (menos de 45%), generalmente >18% MgO, alto FeO, bajo potasio, y se compone de usualmente más de 90%… … Wikipedia Español
Silver mining in Nevada — Silver mining in Nevada, a state of the United States, began in 1858 with the discovery of the Comstock Lode, the first major silver mining district in the United States. Nevada calls itself The silver state . In 2006, Nevada was the nation s… … Wikipedia