PGE mineralization of dunite-wehrlite massifs at the Gutara-Uda interfluve, Eastern Sayan

PGE mineralization of dunite-wehrlite massifs at the Gutara-Uda interfluve, Eastern Sayan

The Pt-Pd and Au-Ag mineralization hosted in both wehrlite without visible links to sulfide mineralization (dispersed assemblage of the Tartai massif) and disseminated Cu-Ni sulfide ore (ore assemblage of the Ognit massif) was found in dunite-wehrlite massifs localized in the fold framework of the S...

Full description

Saved in:
Bibliographic Details
Published in:Geology of ore deposits Vol. 55; no. 3; pp. 162 - 175
Main Authors: Mekhonoshin, A. S., Tolstykh, N. D., Podlipsky, M. Yu, Kolotilina, T. B., Vishnevsky, A. V., Benedyuk, Yu. P.
Format: Journal Article
Language:English
Published: Boston Springer US 01-05-2013
Subjects:
Earth and Environmental Science
Earth Sciences
Mineral Resources
Native Copper
Ultramafic Massif
Platinum Group Mineral
Main Sulfide Zone
Platinum Group Element
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The Pt-Pd and Au-Ag mineralization hosted in both wehrlite without visible links to sulfide mineralization (dispersed assemblage of the Tartai massif) and disseminated Cu-Ni sulfide ore (ore assemblage of the Ognit massif) was found in dunite-wehrlite massifs localized in the fold framework of the Siberian Craton. The Pt minerals in both assemblages comprise sperrylite (PtAs 2 ) and secondary Pt-Fe-Ni alloys in the Ognit massif and Pt-Fe-Cu and Pt-Cu alloys in the Tartai massif. The Pd minerals are widespread in the ore assemblages as compounds with Te, Sb, and Bi, whereas in the dispersed assemblage Pd is concentrated primarily in Pd-Cu-Sb compounds. Both assemblages are characterized by similar substitution of sperrylite with orcelite (Ni 5 − x As 2 ) and then with secondary Pt-Fe-Ni or Pt-Fe-Cu and Pt-Cu alloys; the occurrence of Au-Ag alloys with prevalence of Ag over Au; and replacement of them with auricupride (Cu 3 Au) at the late stage. Sperrylite in both assemblages contains Ir impurities, while the Pd minerals contain Cu and Ni admixtures, which are typical of mineral assemblages related to the ultramafic intrusions with nickel specialization. PGM were formed under a low sulfur fugacity and high As, Bi, and Sb activities. The postmagmatic fluids affected the primary mineral assemblages under reductive conditions, and this effect resulted in replacement of sperrylite with Ni arsenide (orcelite) and Pt-Fe-Ni and Pt-Fe-Cu alloys; Ni and Cu sulfides were replaced with awaruite and native copper.
ISSN:1075-7015
1555-6476
DOI:10.1134/S1075701513030021