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Автор(ы):Murray W.Hitzman
Издание:PGS Publishing, Linden Park, 2002 г., 17 стр.
Язык(и)Английский
Iron oxide-Cu-Au deposits: what, where, when and why

Abstract - The magnetite-apatite deposits ("Kiruna-type") and the iron oxide-Cu-Au deposits form end members of a continuum. In general the magnetite-apatite deposits form prior to the copper-bearing deposits in a particular district. While the magnetite-apatite deposits display remarkably similar styles of alteration and mineralization from district to district and throughout geologic time, the iron oxide-Cu-Au deposits are much more diverse. Deposits of this family are found in post-Archean rocks from the Early Proterozoic to the Pliocene. There appear to be three "end member" tectonic environments that account for the vast majority of these deposits: (A) intra-continental orogenic collapse; (B) intra-continental anorogenic magmatism; and (C) extension along a subduction-related continental margin. All of these environments have significant igneous activity probably related to mantle underplating, high heat flow, and source rocks (subaerial basalts, sediments, and/or magmas) that are relatively oxidized; many districts contain(ed) evaporites. While some of the magnetite-apatite deposits appear to be directly related to specific intrusions, iron oxide-Cu-Au deposits do not appear to have a direct spatial association with specific intrusions. Iron oxide-Cu-Au deposits are localized along high- to low-angle faults which are generally splays off major, crustal-scale faults. Iron oxide-Cu-Au deposits appear to have formed by: 1) significant cooling of a fluid similar to that responsible for precipitation of magnetite-apatite; 2) interaction of a fluid similar to that causing precipitation of magnetite-apatite with a cooler, copper-, gold-, and relatively sulfate-rich fluid of meteoric or "basinal" derivation; or 3) a fluid unrelated to that responsible for the magnetite-apatite systems but which is also oxidized and saline, though probably cooler and sulfate-bearing. The variability of potential ore fluids, together with the diverse rock types in which these deposits are located, results in the wide variety of deposit styles and mineralogies.

ТематикаПолезные ископаемые
МеткиApatite, Copper, Gold, iron oxide-Cu-Au, Iron-oxide, Kiruna-type, Magnetit
Ленты новостей
2023.3