Alaskan-type complexes and their associations with economic mineral deposits

Research output: Chapter in Book/Report/Conference proceedingChapter

6 Scopus citations

Abstract

Alaskan-type complexes are commonly known for their lithological zoning of mafic to ultramafic rock units. These complexes are relatively small, typically alkaline in composition and occur in linear zones along convergent tectonic zones. Multiple intrusions of ultramafic magma from the mantle wedge in a subduction zone, and diapiric updoming of crystal mushes, are acceptable mechanisms for the origin of these complexes. Associated PGE mineralization is found mostly in placers near the intrusions. Since Alaskan-type complexes are mostly crystallization products of hydrous magmas in subduction-zone environments, the crystallization is modeled to have taken place at high fO2 conditions, in which sulfide phases are unstable. However, sulfide mineral horizons, enriched in Cu-Ni-PGE, are found in some Alaskan-type complexes and reflect assimilation of graphite-rich sedimentary rocks which lowered the fO2 levels.

Original languageEnglish (US)
Title of host publicationProcesses and Ore Deposits of Ultramafic-Mafic Magmas through Space and Time
PublisherElsevier
Pages269-302
Number of pages34
ISBN (Electronic)9780128111598
ISBN (Print)9780128111604
DOIs
StatePublished - Jan 1 2017
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2018 Elsevier Inc. All rights reserved.

Keywords

  • Alaskan-type complexes
  • Lithological zoning
  • Pge placers
  • Subduction-zone magmatism
  • Sulfide horizons

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