School of Earth Sciences

Regional Metamorphic Evolution of Archean rocks

from part of SW Greenland

Supervisor: Dr. John C. Schumacher

This project is part of multidisciplinary study sponsored by GEUS (Geological Survey of Denmark & Greenland) involving, geochemists, structural geologists, petrologists and economic/exploration geologists. The objective is a better understanding of the regional geology and geologic evolution, as well as, to evaluate the potential for economic resources in the classic Archean terrain south of Nuuk extending from about 61.5°N - 64°N.

The last regional study of the area dates from early 1960’s, and we will be attempting to collect modern sets of data of various kinds for the terrain. The duration of the project will be 4 years (2011-2014). Samples have been collected during fieldwork from 2007-2010. However, the candidate may be able to do fieldwork in Greenland that is planned for 2012 or 2013. If fieldwork is possible, we anticipate that all travel logistics relating to the fieldwork in this period will be covered. There may also be an opportunity to liaise with True North Gems, who are doing exploration for rubies in these metamorphic rocks.

The aim of this research is to characterise the formation, the mineralogy and evolution of metamorphic rocks from the exposed Archean area south of Nuuk to the area around Fiskenaesset with the goals of (1) assessing the regional distribution mineral assemblages, (2) making quantitative peak P-T estimates and inferences of P-T path and (3) understanding the timing of peak and retrograde metamorphic stadia (to be done in cooperation with the geochronology team). This characterisation and analysis will include:

1. Detailed petrographic and mineral analyses of samples to characterise both major and minor mineral contents and compositions.
2. Thermodynamic modelling to understand reaction sequences and compositional zoning.

The main desired outcomes will be a characterisation of the regional metamorphism and metamorphic gradients in an exceptionally well exposed Archaean and integrating the regional metamorphic evolution with the tectonic and magmatic activity in this region.

A few references and other information:

• Peck, WH, and Valley, JW, 1996, The Fiskenaesset anorthosite complex: Stable isotope evidence for shallow emplacement into Archean ocean crust: Geology, v.24, p. 523-526.
• Myers, J. S., 1985, Stratigraphy and structure of the Fiskenaesset Complex, southern West Greenland: Grønlands Geologiske Undersøgelse Bulletin 150, 72p.
• Weaver, B. L., Tarney, J., Windley, B. F., and Leake, B. E., 1982, Geochemistry and petrogenesis of Archean metavolcanic amphibolites from Fiskenaesset, S.W. Greenland: Geochimica et Cosmochimica Acta, v. 46, p. 2203–2215.

See the link to the Geological Map of Greenland. The study area lies within Area 7 of the map.