Highlights:
·
Design and undertake new experimental procedures to
generate synthetic gold veins in the first systematic study of its kind
Produce some seminal work on understanding the process of
gold precipitation and its relationship to gold compositional variations
Produce the first crystallographic-compositional
characterization of gold from different deposit styles and use experimentation
and modelling to investigate post- depositional changes
·
Synthesize new data from all experimental avenues to develop
a novel and holistic approach to gold particle characterization
Apply new understanding to refine methodologies for
exploration geology leading to close contact with industry
Natural
gold, precipitated from hydrothermal systems exhibits a wide range of
mineralogical features. The degree of heterogeneity within gold particles has only
recently been recognised and comprises zones or tracks of alloy exhibiting
elevated concentrations of other metals such as Ag, Cu, Hg or Pd. New analyses of
polished gold sections by ToF-LA-ICP-MS show that trace element distribution is
highly heterogeneous because of inclusions of other minerals (typically 1-20µm)
and as a consequence of localised micron scale concentrations (‘clusters’) of
elements in the Au-Ag alloy. The initial compositional features may be modified
by grain boundary migration, either in late stages of mineralization or
subsequent residence in the hypogene setting.
At present we have little
understanding of the controls of initial compositional heterogeneity or
subsequent modification. You will address these questions through compositional
and crystallographic characterization of gold precipitated in a synthetic
hydrothermal system, and the relation of outcomes to observations of natural
gold from different ore deposit styles.
Project elements
i. Gold synthesis will focus on simulating hydrothermal systems typical of orogenic and
porphyry- epithermal systems. The high temperature (>200ºC) fluids contain
low Cl and low CO2 and transport gold as a bisulphide complex, and silver
as a chloride complex. Gold precipitation results from changes in P
and T associated with fracturing or through change in chemical parameters such
as pH or fS2 associated with fluid-rock
interaction. Synthetic gold will be
characterized according to composition, microtextures and crystallography.
ii. Generation of the first data base to characterize gold from different deposit styles
according to trace element chemistry (ToF-LA-ICP-MS and atom probe tomography)
and crystallography (EBSD).
iii. Definition of parameters which control crystallographic modification of pre - existing
gold through design of experiments to observe changes in real time using optical
and SEM techniques. Correlation of experimental data with Elle simulation
models to generate a predictive tool.
iv. Synthesis of all project results to interpret characteristics of natural gold in terms of
processes of formation.
v. Application of project outcomes to refine existing approaches to the use of detrital gold as an indicator mineral during
exploration.
Expertise gained and opportunities flowing from the project
You will gain experience of laboratory based research through design of new
experimental approaches, and application of various high- end analytical tools.
Geological expertise in ore deposits will be greatly enhanced through study of
gold from a range of deposit styles. Depending on project direction a field
component could be included involving learning traditional prospecting
techniques to collect further gold samples. Finally the research has a
practical application in mineral exploration facilitating dialogue with
industry professional. The project provides an excellent foundation for further
academic or applied ore deposit studies.
Research environment and support
You will join a vibrant community of researchers active in a wide range of
geoscience disciplines within both the Institute of Applied Geosciences and the
Institute of Geophysics and Tectonics. The program of external speakers and
internal seminars is well established and postgraduate students are fully
involved. Your academic home will be the Ores and
Mineralisation Group, (OMG: @OMG Leeds, https://www.facebook.com/OMGLeeds)
which currently supports six post-graduate students. OMG students benefit from
the networking opportunities provided through membership of the Leeds Chapter
of the Society for Economic Geology, (e.g.
Leeds staff and students attend the Vancouver Exploration Roundup), and
the extensive contacts of the supervisory panel. As NERC DTP student, you also have access to a
wide range of training opportunities.
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