Evidence for modern-style subduction to 3.1 Ga

A plateau-adakite-gold (diamond) association

D. A. Wyman, C. O'Neill, J. A. Ayer

    Research output: Contribution to journalArticle

    29 Citations (Scopus)

    Abstract

    The distribution of lamprophyre-hosted Neoarchean diamond deposits in the southern Superior Province, Canada, corresponds to that of coeval giant (>100 t Au) examples of "orogenic" gold deposits, which are typically associated with quartz-carbonate vein-ing. This common association in the southern Superior Province, and at Yellowknife in the Slave craton, suggests that the occurrence of both diamonds and gold was promoted by the same geodynamic factors. A previously proposed subduction diamond model invokes flat subduction of buoyant oceanic plateau crust as the only means of entraining diamonds in shoshonitic lamprophyres, which are generally derived from relatively shallow mantle depths. Computer modeling of the thermal evolution and dehydration processes associated with this tectonic scenario clarifies observations made in present-day flat subduction settings and suggests many factors that should enhance the hydro-thermal mineralization systems responsible for Archean and post-Archean orogenic gold deposits. The case for links among mantle plume-derived oceanic plateaus, crustal growth, and anomalously large gold deposits is strengthened by the newly recognized association of oxidized granites, lamprophyres, and diamonds at 3.1 Ga in the Kaapvaal craton and by evidence for similar recurring gold-diamond ± lamprophyre associations throughout the geologic record, including the Mother Lode deposits of California.

    Original languageEnglish
    Pages (from-to)129-148
    Number of pages20
    JournalSpecial Paper of the Geological Society of America
    Volume440
    DOIs
    Publication statusPublished - 2008

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