Formation of giant high-grade hypogene porphyry copper deposits during phyllic to advanced argillic alteration: textural evidence from automated SEM mapping at the resolution and Hugo Dummett North deposits
File(s)
Accepted version
Author(s)
Yang, Chao
Wilkinson, Jamie J
Type
Journal Article
Abstract
Detailed core logging, combined with TESCAN TIMA mineral quantification at two globally significant, high-grade porphyry deposits – Resolution, USA, and Hugo Dummett North, Mongolia – indicate that most chalcopyrite ± bornite-pyrite is intergrown with muscovite that overprints earlier potassic alteration assemblages containing biotite and/or K-feldspar. Copper grades increase with the intensity of muscovite overprint on primary potassic assemblages supporting a link between high-grade Cu mineralization and phyllic alteration. Another zone of high-grade Cu mineralization occurs in the upper parts of the phyllic alteration zone and/or within later advanced argillic alteration, associated with high-sulfidation bornite ± digenite ± covellite ± chalcocite-pyrite assemblages, that partly replace earlier chalcopyrite. These two high grade domains have comparable features in many other significant high-grade Cu porphyry deposits (Chuquicamata, Rosario, MMH, Onto, Butte) – all strongly telescoped systems that host significant amounts of high-grade Cu mineralization in phyllic and/or advanced argillic alteration that overprint potassic alteration. We suggest there are at least three reasons for the development of high-grade hypogene ore in telescoped porphyry systems: (1) rapid unroofing and exhumation can generate steep thermal gradients, promoting a rapid decrease in Cu solubility and efficient precipitation of sulfides; (2) rapid, syn-mineralization exhumation and magma doming when the rock mass behaves in an increasingly brittle fashion, create significant permeability in late stages of porphyry systems; (3) telescoping during syn-mineralization exhumation leads to overprinting of early sulfide assemblages by late-stage acidic and oxidized hydrothermal fluids that remobilize and concentrate early Cu, leading to the precipitation of sulfides with high Cu/S ratios. We conclude that the coincidence of rapid exhumation and long-lived hydrothermal activity exerts a first order control on the formation of high-grade hypogene porphyry Cu mineralization.
Date Issued
2026-03-01
Date Acceptance
2025-09-08
Citation
Mineralium Deposita, 2026, 61 (3), pp.621-644
ISSN
0026-4598
Publisher
Springer
Start Page
621
End Page
644
Journal / Book Title
Mineralium Deposita
Volume
61
Issue
3
Copyright Statement
Copyright © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025. This is the author’s accepted manuscript made available under a CC-BY licence in accordance with Imperial’s Research Publications Open Access policy (www.imperial.ac.uk/oa-policy)
License URL
Subjects
Advanced argillic alteration; superimposition
CENTRAL CHILE
COLLAHUASI DISTRICT
CU-AU DEPOSIT
EL-TENIENTE
Geochemistry & Geophysics
High-grade hypogene porphyry copper
HYDROTHERMAL SYSTEM
Mineralogy
MOLYBDENUM DEPOSIT
OYU TOLGOI
Phyllic alteration
Physical Sciences
Science & Technology
STABLE-ISOTOPE
U-PB
VEIN FORMATION
Publication Status
Published
Date Publish Online
2025-11-04