Platinum-group elements in mafic and ultramafic rocks in Alaska

Conference · Thu Apr 01 04:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5290043

Foley, J Y ^[1]

---

1. Bureau of Mines, Anchorage, AK (United States). Alaska Field Operations Center

Anomalous concentrations of platinum-group elements (PGE) have been geochemically detected or PGE minerals have been identified at over 100 sites in Alaska. These sites include both placer and lode occurrences; most are in areas that are underlain by or are derived from mafic and ultramafic rocks. PGE-bearing mafic-ultramafic rocks in Alaska comprise Ural-Alaskan, ophiolitic, layered, sill-form, composite, and miscellaneous other types of igneous complexes. Production of PGE minerals in Alaska has predominantly been from placers and lobes associated with Ural-Alaskan type complexes (Goodnews Bay and Salt Chuck complexes). Minor productions of PGE minerals from placer gold concentrates is reported at more numerous sites where alluvium has eroded from more varied mafic-ultramafic provenances. PGE occur in several tectonic settings in Alaska. Among the identified lode occurrences, outstanding examples exist in supra-subduction settings of the western Brooks Range and Border Ranges ophiolite complexes. In active continental margin accretionary complexes of the eastern and central Alaska Range, composite plutons and a belt of highly differentiated, mostly sill-form intrusions host PGE occurrences of varied chemical, mineralogic, and petrologic character. Ural-Alaskan type complexes tend to occur in volcanic arc settings. Lacking in Alaska are Archean layered mafic complexes; Tertiary analogues in southeastern Alaska locally contain PGE associated with iron-copper-nickel sulfide minerals.

• OSTI ID: 5290043
• Report Number(s): CONF-9305259--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:5
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ALASKA
CHEMICAL COMPOSITION
CHEMISTRY
DEVELOPED COUNTRIES
ELEMENTS
GEOCHEMISTRY
GEOLOGIC DEPOSITS
GEOLOGY
IGNEOUS ROCKS
METALS
MINERAL RESOURCES
NORTH AMERICA
ORES
PLACERS
PLATINUM METALS
PLUTONIC ROCKS
RESOURCES
ROCKS
TRANSITION ELEMENTS
USA