Recognizing Propylitic Alteration Associated with Porphyry Cu-Mo Deposits in Lower Greenschist Facies Metamorphic Terrain of the Collahuasi District, Northern Chile--Implications of Petrographic and Carbon Isotope Relationships

2012 ◽  
Vol 107 (7) ◽  
pp. 1457-1478 ◽  
Author(s):  
M. L. Djouka-Fonkwe ◽  
K. Kyser ◽  
A. H. Clark ◽  
E. Urqueta ◽  
C. J. Oates ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Greenschist Facies ◽  
Northern Chile ◽  
Porphyry Cu ◽  
Metamorphic Terrain ◽  
Propylitic Alteration

Element transport and enrichment during propylitic alteration in Paleozoic porphyry Cu mineralization systems: Insights from chlorite chemistry

2018 ◽  
Vol 102 ◽  
pp. 437-448 ◽  
Author(s):  
Bing Xiao ◽  
Huayong Chen ◽  
Pete Hollings ◽  
Yunfeng Wang ◽  
Juntao Yang ◽  
...  
Keyword(s):  
Porphyry Cu ◽  
Element Transport ◽  
Propylitic Alteration

Timing and formation of porphyry Cu–Mo mineralization in the Chuquicamata district, northern Chile: new constraints from the Toki cluster

2013 ◽  
Vol 48 (5) ◽  
pp. 629-651 ◽  
Author(s):  
Fernando Barra ◽  
Hugo Alcota ◽  
Sergio Rivera ◽  
Victor Valencia ◽  
Francisco Munizaga ◽  
...  
Keyword(s):  
Northern Chile ◽  
Porphyry Cu

Overheated, Cu-bearing magmas in the Zaldı́var porphyry-Cu deposit, Northern Chile. Geodynamic consequences

2002 ◽  
Vol 345 (1-4) ◽  
pp. 229-251 ◽  
Author(s):  
E Campos ◽  
J.L.R Touret ◽  
I Nikogosian ◽  
J Delgado
Keyword(s):  
Northern Chile ◽  
Porphyry Cu ◽  
Porphyry Cu Deposit

scholarly journals Linking Mineralogy to Lithogeochemistry in the Highland Valley Copper District: Implications for Porphyry Copper Footprints

2020 ◽  
Vol 115 (4) ◽  
pp. 871-901 ◽  
Author(s):  
Kevin Byrne ◽  
Guillaume Lesage ◽  
Sarah A. Gleeson ◽  
Stephen J. Piercey ◽  
Philip Lypaczewski ◽  
...  
Keyword(s):  
Infrared Imaging ◽  
White Mica ◽  
Coarse Grained ◽  
Late Triassic ◽  
Material Transfer ◽  
Rock Composition ◽  
Porphyry Cu ◽  
Propylitic Alteration ◽  
Shortwave Infrared ◽  
Pathfinder Elements

Abstract The Highland Valley Copper porphyry deposits, hosted in the Late Triassic Guichon Creek batholith in the Canadian Cordillera, are unusual in that some of them formed at depths of at least 4 to 5 km in cogenetic host rocks. Enrichments in ore and pathfinder elements are generally limited to a few hundred meters beyond the pit areas, and the peripheral alteration is restricted to narrow (1–3 cm) halos around a low density of prehnite and/or epidote veinlets. It is, therefore, challenging to recognize the alteration footprint peripheral to the porphyry Cu systems. Here, we document a workflow to maximize the use of lithogeochemical data in measuring changes in mineralogy and material transfer related to porphyry formation by linking whole-rock analyses to observed alteration mineralogy at the hand specimen and deposit scale. Alteration facies and domains were determined from mapping, feldspar staining, and shortwave infrared imaging and include (1) K-feldspar halos (potassic alteration), (2) epidote veins with K-feldspar–destructive albite halos (sodic-calcic alteration), (3) quartz and coarse-grained muscovite veins and halos and fine-grained white-mica–chlorite veins and halos (white-mica–chlorite alteration), and two subfacies of propylitic alteration comprising (4) prehnite veinlets with white-mica–chlorite-prehnite halos, and (5) veins of epidote ± prehnite with halos of chlorite and patchy K-feldspar. Well-developed, feldspar-destructive, white-mica alteration is indicated by (2[Ca-C] + N + K)/Al values <0.85, depletion in CaO and Na2O, enrichment in K2O, and localized SiO2 addition and is spatially limited to within ~200 m of porphyry Cu mineralization. Localized K2O, Fe2O3, and depletion in Cu, and some enrichment in Na2O and CaO, occurs in sodic-calcic domains that form a large (~34 km2) nonconcentric footprint outboard of well-mineralized and proximal zones enriched in K. Water and magmatic CO2-rich propylitic and sodic-calcic–altered rocks form the largest lithogeochemical footprint to the mineralization in the Highland Valley Copper district (~60 km2). Calcite in the footprint is interpreted to have formed via phase separation of CO2 from a late-stage magmatic volatile phase. Several observations from this study are transferable to other porphyry systems and have implications for porphyry Cu exploration. Feldspar staining and shortwave infrared imaging highlight weak and cryptic alteration that did not cause sufficient material transfer to be confidently distinguished from protolith lithogeochemical compositions. Prehnite can be a key mineral phase in propylitic alteration related to porphyry genesis, and its presence can be predicted based on host-rock composition. Sodic-calcic alteration depletes the protolith in Fe (and magnetite) and, therefore, will impact petrophysical and geophysical characteristics of the system. Whole-rock loss on ignition and C and S analyses can be used to map enrichment in water and CO2 in altered rocks, and together these form a large porphyry footprint that extends beyond domains of enrichment in ore and pathfinder elements and of pronounced alkali metasomatism.

A revised late Eocene age for porphyry Cu magmatism in the Escondida area, northern Chile

1999 ◽  
Vol 94 (8) ◽  
pp. 1231-1247 ◽  
Author(s):  
Jeremy P. Richards ◽  
Stephen R. Noble ◽  
Malcolm S. Pringle
Keyword(s):  
Late Eocene ◽  
Northern Chile ◽  
Porphyry Cu

scholarly journals The Geology, Geochemistry, and Origin of the Porphyry Cu-Au-(Mo) System at Vathi, Serbo-Macedonian Massif, Greece

2021 ◽  
Vol 11 (2) ◽  
pp. 479
Author(s):  
Christos L. Stergiou ◽  
Vasilios Melfos ◽  
Panagiotis Voudouris ◽  
Paul G. Spry ◽  
Lambrini Papadopoulou ◽  
...  
Keyword(s):  
Native Gold ◽  
Metallogenic Province ◽  
Potassic Alteration ◽  
Fluid Inclusion Data ◽  
Porphyry Cu ◽  
Basement Rocks ◽  
Metallogenic Belt ◽  
Quartz Monzonite ◽  
Propylitic Alteration ◽  
Stage 1

The Vathi porphyry Cu-Au ± Mo mineralization is located in the Serbo-Macedonian metallogenic province of the Western Tethyan Metallogenic Belt. It is mainly hosted by a latite and is genetically associated with a quartz monzonite intrusion, which intruded the basement rocks of the Vertiskos Unit and the latite, 18 to 17 Ma ago. A phreatic breccia crosscuts the latite. The quartz monzonite was affected by potassic alteration, whereas the latite was subjected to local propylitic alteration. Both styles of alteration were subsequently overprinted by intense sericitic alteration. M-type and A-type veins are spatially associated with potassic alteration, whereas D-type veins are related to the sericitic alteration. Three ore assemblages are associated with the porphyry stage: (1) pyrite + chalcopyrite + bornite + molybdenite + magnetite associated with potassic alteration; (2) pyrite + chalcopyrite related to propylitic alteration; and (3) pyrite + chalcopyrite + native gold ± tetradymite associated with sericitic alteration. A fourth assemblage consisting of sphalerite + galena + arsenopyrite + pyrrhotite + pyrite ± stibnite ± tennantite is related to an epithermal overprint. Fluid inclusion data indicate that the A-type veins and related porphyry-style mineralization formed at 390–540 °C and pressures of up to 646 bars (<2.6 km depth) from boiling hydrothermal fluids. A later condensation of vapor-rich inclusions resulted in a moderately saline fluid (8.4–11.2 wt % NaCl equiv) at temperatures between 311 and 392 °C, which were related to sericitic alteration, D-type veins, and associated metallic mineralization. Subsequent dilution of the moderately saline fluid at lower temperatures (205–259 °C) produced a less saline (1.4–2.9 wt % NaCl equiv.) fluid, which is likely associated with the late epithermal overprint.

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