What role do mafic magmas play in metal transport from mantle to crust?

A geochemical project investigating the copper content of magmas and their importance to economic geology.

Mafic Magmas

This photo shows fine-grained mafic enclaves within intrusive granitoids in the Sierra Nevada batholith of California. The mafic intrusion has clearly broken up and dispersed throughout the cooling magma. What elements do these enclaves bring into the system from below? Could these transport metals and volatiles to hydrothermal and epithermal deposits at the surface?

Economic deposits of minerals such as Cu, Mo or gold require sources of metals and fluids and a method of transporting these to the surface where they become enriched in profitable concentrations. But how much of these materials are sourced from the shallow environment and how much from the mantle?

Mafic enclaves within more felsic lavas or intrusions may provide the answer to this question. Recent work in the Gawler Craton and active volcanoes has revealed Cu isotope signatures that may point to the enclaves being a carrier of Cu towards the surface.

In this project, the student will visit the Murray lands and South East regions in outcrop and drill core records where abundant mafic enclaves within felsic igneous rocks can be examined.

The investigation of the relationship between the mafic enclaves and their hosts will involve:

  1. petrographic analysis
  2. whole rock chemical analysis
  3. MELTs modelling to look at the link between the two end members in terms of their crystallisation
  4. Cu isotopes to look at the potential for volatile transport of Cu from enclave to host

Lucy McGee

Supervisors

Dr Lucy McGee, Dr Juraj Farkas

Research area: Mineral and energy systems, Tectonics and solid earth processes

Recommended honours enrolment: Honours in Geology

Tagged in Honours projects - Geology, Honours Projects - Lucy McGee, Honours Projects - Juraj Farkas