AUTHORS: Steve Ludington, Robert A. Ayuso, Jane M. Hammarstrom, Michael L. Zientek, Ruizhao Qiu
ABSTRACT : Most porphyry copper deposits worldwide are the products of arc magmatism related to subduction of oceanic lithosphere, but many deposits not directly related to subduction are now recognized in eastern Tethys (China, Vietnam, Iran, Pakistan), in the southwest Pacific (Papua New Guinea, Fiji), and in the North American Pacific margin (United States). These deposits are associated with magmas that have similar compositions to those in oceanic and continental arcs, but formed by the partial melting of metasomatized lower crustal rocks in response to a variety of post-subduction processes. In western China and northern Vietnam, three belts of deposits are known (Yulong, Ailoshan-Red River, Gangdese); all are spatially distributed in distinct linear or curvilinear patterns related to extensional or transcurrent structures. In the western United States, deposits are more widely distributed and structural control is not prominent. Analysis of the distinct distribution patterns in western China may lead to recognition of new exploration models for porphyry copper in the western United States.
KEYWORDS: Porphyry copper, Tethys, North America, subduction, extension
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