APPLIED MINERALOGY
Linking the Faroese area and Greenland: An innovative, integrated provenance study

Thomas Rasmussen, Dirk Frei and Christian Knudsen, in collaboration with Michael Larsen (Department of Stratigraphy) and Andy Whitham and Andy Morton (CASP, UK).

The aim of the study is to develop a thorough understanding of the sedimentary link between the Faroese area and Greenland. Our approach is a modern, multianalysis provenance study. In the course of the study, new techniques of general interest to hydrocarbon exploration are being further developed, tested and refined. The results of the study will clarify the source, nature and potential of reservoir rocks in the Faroese area and help to construct a stratigraphy of the pre-basaltic rocks.
The work is financed by the SINDRI group in the Faroes, and the project is co-ordinated with two other SINDRI projects dealing with the regional geology and evolution of the Faroese area.

To be able to construct a reliable stratigraphy and to develop a thorough understanding of the basin development in this part of the North Atlantic, sites and times of sedimentation must be identified. The methods used in this study are four well known methods in endogene geology, which we have adapted to sedimentary geology.
The four methods are:
1. Whole-rock geochemistry including major and trace elements analysis.
2. CC-SEM analysis of mineral compositions in heavy-mineral and raw samples.
3. LA-ICPMS analysis of isotopes and trace elements in single grains.
4. Heavy mineral paragenesis analysis.

Together, these four methods provide a very strong tool for provenance studies.

(Link to Dirk-instrument page)
1. The whole rock geochemistry provides us with geochemical signatures of the sediments. These signatures make it possible to compare two or more samples from different localities, and their geochemical composition will indicate their provenance. The geochemical compositions can also be used to link two ore more separate sediments over long lateral distances.

(Link to Dirk-instrument page)
The CC-SEM (Computer Controlled Scanning Electron Microscope) analysis is a unique automatized method that provides data on the chemical variations in all the heavy minerals and all the minerals in the raw sample. The advantages of the CC-SEM method is the automatized and highly efficient processing of the data by software specifically developed for this purpose. The CC-SEM analysis also provides useful information about grain sizes and shapes.

(Link to Dirk-instrument page)
The LA-ICPMS (Laser-excited Inductively Coupled Plasma Mass Spectrometry) analysis is used to 'fingerprint' a sample by 207Pb/206Pb age dating of the populations of zircons in the given sample. The 207Pb/206Pb ages from the zircons are plotted in histograms, and the different peaks of the age destribution reflect the provenance of the sediment.

The heavy mineral paragenesis analysis is a method based on the ratios of heavy minerals in the sediments. It is a well-known and accepted method to identify sandstone lithologies, and in this study the method is used to document the reliability of the new techniques.

(Figure with the northsea area.)

Figure of histogram

CC-SEM picture