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Fluids and ore forming processes in the continental crust (cont)

English title Fluids and ore forming processes in the continental crust (cont)
Applicant Fontboté Lluis
Number 146353
Funding scheme Project funding (Div. I-III)
Research institution Département des sciences de la Terre Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Geochemistry
Start/End 01.04.2013 - 31.03.2015
Approved amount 418'100.00
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Keywords (4)

geochemistry; deposits; Ore; metallogeny

Lay Summary (French)

Lead
Fluides et processus formateurs de formateurs de gisements métallifères dans la croûte continentaleLes ressources minérales sont essentielles pour la société. La compréhension des mécanismes de formation des gisements métallifères est indispensable pour l’exploration minérale. Cette étude doit apporter des réponses à plusieurs questions fondamentales concernant l'origine de deux types de gisements de plomb-zinc: les gisements de type Cordilleran et les gisements de type Laisvall.
Lay summary

A) Les gisements de type "Cordilleran", dont les éléments économiques sont le cuivre, le zinc, le plomb, l’argent et traces  d'autres métaux, sont liés à la migration de fluides aqueux riches en métaux dans la croute continentale. Ils sont formés à <3 km de profondeur et à des températures inférieures à 350°C. Ils sont spatialement associés à des intrusions magmatiques similaires à celles qui forment les gisements de type porphyre (principale ressource de cuivre). De précédentes recherches montrent une similitude entre les fluides à l’origine des porphyres cuprifères et ceux qui forment ces gisements polymétalliques. Le fluide minéralisateur provient d’un processus d’exsolution de fluides aqueux pendant la cristallisation de magmas générés à l'aplomb de zones de subduction. En utilisant plusieurs méthodes géochimiques, nous souhaitons étudier l’évolution de ces fluides hydrothermaux dans le temps et dans l’espace depuis les fluides les plus chauds (>300°C) qui précipitent principalement des minéraux du cuivre (malgré leur teneur importante en autres métaux) jusqu’aux fluides de température moindre (<300 °C) à l’origine des gisements polymétalliques de type Cordilleran. Pour cette étude, deux gisements polymétalliques de type Cordilleran particulièrement bien étudiés, situés dans les Andes Péruviennes, Cerro de Pasco et Colquijirca, ont été choisis.

B) Gisements de plomb et zinc dans de roches sédimentaires formés par des fluides aqueux de basse température d'origine non-magmatique. Les exemples choisis, qui incluent le gisement de Laisvall, se trouvent dans la chaine Calédonienne en Suède. Une approche innovante utilisant géophysique aérienne, cartographie structurale et modélisation des gisements connus en 3D cherche à comprendre les contrôles structuraux de ces gisements. L'âge de la minéralisation et les mécanismes de précipitation des sulfures de plomb et de zinc (y compris le rôle joué par le soufre réduit par des hydrocarbures) sont  des questions fondamentales qui sont étudiées via diverses techniques.

Direct link to Lay Summary Last update: 15.05.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Reported supergene sphalerite rims at the Chuquicamata porphyry deposit (northern Chile) revisited: Evidence for a hypogene origin
Pinget M.C., Dold B.S., Zentilli M., Fontboté L. (2015), Reported supergene sphalerite rims at the Chuquicamata porphyry deposit (northern Chile) revisited: Evidence for a hypogene origin, in Economic Geology, 110, 253-262.
Control of reactivated basement structures on sandstone–hosted Pb–Zn deposits along the Caledonian Front, Sweden: Evidence from airborne magnetic field data, structural analysis and ore grade modeling
Saintilan N.J., Stephens M.B., Lundstam E., Fontboté L. (2015), Control of reactivated basement structures on sandstone–hosted Pb–Zn deposits along the Caledonian Front, Sweden: Evidence from airborne magnetic field data, structural analysis and ore grade modeling, in Economic Geology, 110, 91-117.
Timing of porphyry (Cu-Mo) and base metal (Zn-Pb-Ag-Cu) mineralisation in a magmatic-hydrothermal system—Morococha district, Peru
Catchpole Honza, Catchpole Honza, Kouzmanov Kalin, Bendezú Aldo, Ovtcharova Maria, Spikings Richard, Stein Holly, Stein Holly, Fontboté Lluís (2015), Timing of porphyry (Cu-Mo) and base metal (Zn-Pb-Ag-Cu) mineralisation in a magmatic-hydrothermal system—Morococha district, Peru, in Mineralium Deposita, online.
Zoned Base Metal Mineralization in a Porphyry System: Origin and Evolution of Mineralizing Fluids in the Morococha District, Peru
Catchpole Honza, Kouzmanov Kalin, Putlitz Benita, Seo Jung Hun, Fontbote Lluis (2015), Zoned Base Metal Mineralization in a Porphyry System: Origin and Evolution of Mineralizing Fluids in the Morococha District, Peru, in ECONOMIC GEOLOGY, 110(1), 39-71.

Collaboration

Group / person Country
Types of collaboration
Prof. Urs Schaltegger, Dr. Massimo Chiaradia, Dr. Richard Spikings/UNIGE Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Dr. Michael Stephens/Geological Survey Sweden Sweden (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Prof. Torsten Venemann/UNIL Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Associated projects

Number Title Start Funding scheme
160071 Fluids and ore forming processes in the continental crust (cont) 01.04.2015 Project funding (Div. I-III)
158097 In situ stable and radiogenic isotope composition of orogenic gold veins, Val-d'Or (Canada) 01.01.2015 International short research visits
134872 Fluids and ore forming processes in the continental crust (cont) 01.04.2011 Project funding (Div. I-III)

Abstract

Sub-project A (Continuation of two Ph.D. theses, supervision Prof. L. Fontboté and Dr. K. Kouzmanov) focuses on the evolution of ore-related fluids forming Cordilleran polymetallic mineralization in the shallow epithermal environment of magmatic-hydrothermal systems. The deposits of Colquijirca and Cerro de Pasco in central Peru are revisited. Based on existing detailed descriptions of their geology, alteration and mineralization zoning, and precise geochronology of different magmatic and hydrothermal events from our group, the aim of the present project is to characterize the PTVX properties and metal and sulfur content, as well as stable and radiogenic isotope signatures of fluid inclusions synchronous to the economic mineralization, using a combination of analytical techniques: visible and near-IR light microthermometry, Raman spectroscopy, LA-ICP-MS, O and H isotope determination, noble gas determination, Sr, Pb, Cl and potentially Cu isotopes, and cation and anion analyses by chromatography. The main goal is to trace the fluid evolution in this type of epithermal to sub-epithermal polymetallic deposits and compare it with fluid processes in the deep porphyry senso strictu part of magmatic-hydrothermal systems in order to constrain intensive parameters of and processes leading to ore-formation (e.g, cooling, wall-rock reaction, fluid mixing) in the shallow epithermal environment.The work has been structured in the following way:A1) Ph.D. student Vincent Casanova (Ph.D. thesis started on 1 April 2012) will focus on the fluid evolution in the Colquijirca deposit and will perform Sr, Pb, and possibly Cu-isotope analyses. He will also perform the cation and anion chromatography analyses on 40 samples from both, Colquijirca and Cerro de Pasco deposits.A2) Ph.D. student Bertrand Rottier (Ph.D. thesis starts on 1 October 2012) will focus on the fluid evolution in the Cerro de Pasco deposit. In addition he will perform O, H, and Cl-isotope analyses, as well as noble gas determinations on the same set of samples (40 in total) from the two deposits.Sub-project B (Ph.D. thesis of Nicolas Saintilan (start May 2011) on stratabound sandstone-hosted deposits in the Swedish Caledonides, supervision Prof. L. Fontboté and Dr. Michael Stephens, Geological Survey of Sweden at Uppsala). Non-stratiform yet stratabound, sandstone-hosted Pb-Zn deposits and minor occurrences are known along the front of the Scandinavian Caledonides over a distance of more than 1000 km and include the Laisvall and Vassbo deposits. Mineralisation is emplaced in the Ediacaran-Cambrian autochthonous sedimentary rocks beneath the Caledonian thrust nappes resting unconformably on top of Precambrian crystalline basement, as well as in the lowermost allochthonous units within these nappes. Sub-project B tackles the spatial controls, age and origin of this belt of sandstone-hosted Pb-Zn deposits. In addition of using a large palette of geological, geophysical, mineralogical and geochemical methods, the rationale behind this sub-project is to a large extent to scientifically exploit the wealth of new field and drilling data gathered in the last years by the mining Company New Boliden. These data are being mainly used to construct 3D representations of selected deposits to give insight into the paleo-hydrology during mineralization and so constrain the different models. The hypothesis that economic ore precipitated in places where reduced sulfur was trapped together with hydrocarbons will be examined together with the other proposed models. The project is carried out in collaboration with the Mining Company New Boliden, and the Ph. D. student had worked for this Company on the exploration so that he had a solid knowledge of the Pb-Zn deposits in the Swedish Caledonides before starting the project.
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