Controls on enrichment of REE at the Serra Verde deposit, Brasil
A collaborative PhD research project between Imperial College London, The Natural History Museum (via the LODE
research group) and Serra Verde Mining LLC, funded by Serra Verde Mining LLC.
KEY AIMS

The aim of the project is to develop a model for the introduction, enrichment and mineralogical residence of
REE at the Serra Verde deposit, Goiás Province, central Brasil
OBJECTIVES




To establish the links between multiple magmatic events and the introduction of REE
To determine and quantify the processes leading to REE enrichment
To assess the effect of tropical weathering on REE grades and distribution
To identify the residence of the REE within primary, secondary and supergene minerals
BACKGROUND
The Serra Verde REE deposit is associated with a Proterozoic alkali granite within the Goiás province of Brasil. Three
main stages in the geological evolution of the area have been identified as potentially important for the introduction
and enrichment of the REE: (1) Emplacement of the Pela Ema tin granites (~1.8 Ga); (2) Intrusion of an evolved alkaline
(carbonatite?) complex at depth (~540 Ma); (3) Miocene (?) lateritization. Stage 1 resulted in the formation of typical
tin-bearing greisen veins hosting monazite and xenotime. Stage 2 resulted in potassium metasomatism (K-feldsparbiotite) with additional introduction (or recrystallization) of monazite, xenotime and magnetite. The development of a
30-35 m thick lateritic weathering profile resulted in breakdown of feldspars to clay and dissolution of REE-bearing
minerals with reprecipitation in the saprolite ore zone. Colluvial accumulations of rare earth minerals are also present.
APPROACH
The research will involve the following tasks:
1.
2.
3.
4.
5.
6.
7.
Comprehensive literature review. Review of REE-enriched alkaline igneous provinces and clay-associated
REE deposits as well as the geology of the Serra Verde district.
Fieldwork at Serra Verde. Mapping of the geology and lateritic weathering zones; sampling of primary
igneous rocks and the lateritic weathering profile.
Conventional whole rock chemical analyses. These will be carried out to determine the petrogenetic
evolution of the igneous rock suites, and identification of processes leading to REE enrichment. Protolith
compositions will be used as a basis for chemical mass transfer analysis to quantify enrichment-depletion
patterns in the weathering profile.
Petrography of samples. Sample preparation (polished thin sections / resin mounts) and petrographic study
using a range of techniques (transmitted and reflected light microscopy, cathodoluminescence, SEM) to
determine mineralogy and mineral associations in situ, in particular the paragenesis of the REE minerals.
Mineral identification and chemistry. XRD methods will be used to identify unusual silicates and clay
minerals. Microprobe and laser ablation ICP-MS analysis will be used to determine the REE content of various
phases to constrain the main residence and thus the controls on the distribution of REE.
Isotope studies. Where appropriate, stable and radiogenic isotope studies may be required (including agedating).
Development of REE distribution model. Building a detailed model for the development of the enriched
profile combining field observations, petrography and geochemistry.
DELIVERABLES




Archived sample suite
Sample database with analytical methods used, sample descriptions, representative macroscopic and
microscopic digital images and associated geochemical datafile list
Maps, sections and 3D representations of geology and REE distribution, illustrating controlling
lithologies/structures
Mineralogy and classification of rock types and alteration facies



Geochemical database: whole rock analyses (fresh, altered and weathered rocks), mineral chemistry
Five six-monthly reports
Hard copy and digital copy of PhD thesis
KNOWLEDGE TRANSFER
Knowledge transfer to the project partner will occur by: (i) progress meetings/reports; (ii) presentations on site.
Knowledge transfer to scientists and wider industry will be achieved by: (i) presentations at international/national
conferences; (ii) publishing papers in leading journals, e.g. Geology, Chemical Geology, Economic Geology.
SUPERVISION DETAILS
Dr Jamie Wilkinson, has a permanent appointment as Reader in Geochemistry at Imperial College London (ICL). The
project will be co-supervised by Professor Richard Herrington at the Natural History Museum (NHM), London. Training
in the field skills necessary for the project will be delivered on site by the supervisors and company geologists, plus
appropriate short courses (if available). Laboratory studies will be carried out at ICL and in the Imaging and Analysis
Centre (IAC) and LODE laboratory at the Natural History Museum. The work will be carried out within the LODE
research group which is a collaboration between the Department of Earth Science and Engineering (ESE) at ICL and the
NHM. All postgraduates in the Department of Earth Science and Engineering have access to workshops organised by
the Graduate School of Engineering and Physical Science which include: personal organisation and effectiveness;
thesis writing and completing the PhD; technical writing; teamwork; professional issues in science; research ethics;
and presentation skills. There are also optional courses in career planning, IT skills, media and entrepreneurship.
Attendance at regular seminars on ore geology, geochemistry and the wider Earth Sciences is compulsory.
PROJECT MANAGEMENT
The student will be subject to standard PhD management and reporting procedures as operated in the Department of
Earth Science and Engineering at Imperial College London, plus the additional 6-monthly reporting requirement of
Serra Verde Mining LLC. 3 months: Project outline and initial plan of study prepared in consultation with supervisors. 6
months: Progress review with supervisors. 9 months: first year report of ~30 pages should demonstrate an
understanding of the research programme and include a work plan for the remainder of the project. The report is read
by an independent examiner and the student is examined orally. Passing this stage is a pre-requisite to continuation
on the PhD programme. 21 months: Mid-term review, seminar presentation to research group and submission of
thesis outline. 24-30 months: writing-up commences and a PhD exam entry form is submitted. 36 months: submission
of thesis.
The PhD student would meet formally once a fortnight with the main and/or secondary supervisor to discuss research
progress and forward planning. Fortnightly email updates will be provided by the PhD student to Serra Verde Mining.
TIME PLAN The anticipated schedule of work will be agreed prior to project start-up, anticipated to be November
2013.
STUDENT PROFILE We are looking for a well-qualified and highly motivated Earth Sciences/Geology graduate who
wishes to carry out a cutting edge PhD in economic geology/geochemistry and gain experience working with a junior
mineral exploration company. Excellence in geochemistry and mineralogy are essential; experience of microanalytical
techniques and statistical data evaluation are desirable. Involvement with the Imperial Student Chapter of the Society
of Economic Geologists and outreach activities will be encouraged.
FURTHER INFORMATION If you are interested in the project and would like to have further details please contact
Jamie Wilkinson at j.wilkinson@imperial.ac.uk or Richard Herrington at r.herrington@nhm.ac.uk.
http://www3.imperial.ac.uk/people/j.wilkinson
http://www3.imperial.ac.uk/earthscienceandengineering/research/lode