Tectonic and climatic controls on porphyry copper enrichment in the Central Andes

Lead Research Organisation: University of Bristol
Department Name: Earth Sciences


Porphyry copper deposits (PCDs) are the world's principal commercial source of copper. Formed from metal-bearing hydrothermal fluids associated with granitic batholiths, they are typically found in convergent plate margin settings, such as northern Chile in the Central Andes. Although these systems begin their life a few kilometres deep in the crust, erosion and tectonic activity exhume them to the surface, where they interact with oxygenated groundwater. Chemical reactions between sulphide minerals and this oxygenated water create acid that leaches the copper and reprecipitates it in an enriched "supergene blanket" of ore. This process can more than double the copper content of a deposit, making supergene zones a primary target for mineral exploration. Northern Chile hosts some of the largest and richest supergene blankets in the world (notably the huge Chuquicamata and Escondida deposits) and yet the area lies in the Atacama Desert, one of the driest places on Earth. The onset of this dry climate is thought to relate to uplift of the Andes mountains, which created a rain shadow on their western side. This raises fundamental questions about how and when supergene enrichment occurred, when and why it stopped, and how regional changes in tectonics, climate, sedimentation, and hydrology might have affected mineralisation. Project goals and methods This PhD project will investigate the roles of tectonic uplift, exhumation, and climate on supergene enrichment along the western Andean margin in northern Chile. In this area, extensive deposition of fluvial gravels proximal to major sites of mineralisation offers an opportunity to place spatial and temporal constraints on patterns of exhumation, transportation, and deposition of igneous material related to PCDs. Project goals include: (1) Conduct a detrital provenance study of gravels using U-Pb geochronology and (U-Th)/He thermochronometry. (2) Use numerical modelling to constrain the exhumation history of igneous clasts in the gravels, from emplacement at depth to exhumation and fluvial transportation on the surface. (3) Relate patterns of exhumation and deposition to regional tectonic and climatic constraints. (4) Determine how these patterns may affect the formation and preservation of enriched PCDs.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
NE/W503174/1 31/03/2021 30/03/2022
1941973 Studentship NE/W503174/1 03/09/2017 31/12/2021 Joseph Shaw
Description Society of Economic Geologists Student Research Grant (McKinstry Fund)
Amount $4,300 (USD)
Funding ID SRG18 - 104 
Organisation Society of Economic Geologists (SEG) 
Sector Charity/Non Profit
Country United States
Start 04/2018 
Description BHP CASE support for PhD 
Organisation BHP Billiton
Country Australia 
Sector Private 
PI Contribution BHP are the industry (CASE) partner to my NERC studentship. I have visited BHP mine sites twice during my studies, to collect samples and meet with mine geologists working on active projects. During each visit to South America, I have visited BHP's head office in Santiago, Chile, to present an update of my work.
Collaborator Contribution Allowing access to mine sites, allowing the collection of rock samples, assisting with shipping rock samples from Chile to UK, providing constructive advice and discussion of PhD project during mine visits.
Impact Ongoing PhD.
Start Year 2017
Description Caltech Noble Gas Laboratory (Prof Ken Farley) 
Organisation California Institute of Technology
Country United States 
Sector Academic/University 
PI Contribution Funds awarded by the SEG (Hugh McKinstry Student Research Grant) used to fund (U-Th)/He dating of hematite samples by Prof Ken Farley and his team at Caltech. I supplied samples and context (e.g. sample locations and depth) and conducted the preparatory lab work in Bristol prior to sending the samples for dating.
Collaborator Contribution (U-Th)/He analysis of hematite using the single aliquot method developed by Prof Ken Farley and colleagues.
Impact (U-Th)/He geochronology data for use in my PhD thesis and as part of a publication currently being drafted, with Prof Ken Farley and others from the Caltech Noble Gas Laboratory included as co-authors.
Start Year 2018
Description University of Wisconsin-Madison WiscAr Geochronology Laboratory (Prof Brad Singer) 
Organisation University of Wisconsin-Madison
Country United States 
Sector Academic/University 
PI Contribution Cooperative development of an in situ Ar/Ar method for dating alunite. I prepared samples and provided context (e.g. sample location and depth), prior to analysis.
Collaborator Contribution Prof Brad Singer and team at WiscAr developed the in situ Ultra Violet Laser Ablation MicroProbe (UVLAMP) for use on alunite, firstly on a subset of samples which yielded positive results, followed by analysis of a larger sample set.
Impact Anticipated technical paper on the applicability of novel in situ dating methods to alunite.
Start Year 2019
Description BHP Porphyry Copper Deposit Research Group annual workshop 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Annual workshop of Vice President of BHP Copper and colleagues with researchers from the University of Bristol. Two days of talks and discussion, presented a 20 minute research update.
Year(s) Of Engagement Activity 2018,2019,2020