This activity will focus on preparing a digital dyke compilation layer (linked with related sills, volcanics and layered intrusions) in a GIS compatible format. Additional geochemical, geochronologic and paleomagnetic analyses of archival material will be undertaken to fill knowledge gaps that arise during the compilation exercise.

Illustrated below are dyke swarms and related units from the Slave Province and vicinity. The information was extracted from Buchan, K.L. and Ernst, R.E. (2004). The first map below depicts the Mackenzie dyke swarm. The second map below corresponds to inset A and displays the remaining dykes after the Mackenzie dykes have been removed. This information has been upgraded by Buchan and ernst (Feb. 2005).

References:

Buchan, K.L. and Ernst, R.E. 2004, Diabase dyke swarms and related units in Canada and adjacent regions: Geological Survey of Canada Map 2022A; Scale: 1: 5,000,000.

Fingerprinting Large Igneous Provinces (LIPs)

The Slave craton contains the exposed plumbing system (mainly dykes) for many Large Igneous Provinces (LIPs). These LIPs are important for understanding the mantle plume and breakup history of this old cratonic fragment. Paleomagnetism and geochronology are proven tools for distinguishing LIPs (Buchan and Ernst, 2004; Ernst and Buchan 2004). In this study we explore the use of geochemistry (especially incompatible trace elements) to 'fingerprint' LIPs. We utilize a subset of the database obtained during the Targeted Geoscience Initiative project #010004 (2001-2003) (Ernst and Hulbert 2003). This database contains nearly 1000 analyses from about 60 mafic magmatic events in Canada. A preliminary analysis (see diagrams below) indicates that 'fingerprinting' is possible at least in some cases. For example, the Lac de Gras and perhaps the Dogrib dykes are disctinctive. On the other hand, the similar-aged Mackenzie and '305' dykes have overlapping compositions.

Dyke swarms of the southern Slave Province (extracted from Buchan & Ernst 2004) (1.27 Ga Mackenzie dykes omitted for clarity; only labeled swarms are discussed)

Acknowledgments: Some of the samples analyzed were provided by A.N. LeCheminant, B. Kjarsgaard, and from the archives of W. Fahrig.

References:

Buchan, K.L. & Ernst, R.E. 2004. Diabase Dyke Swarms and Related Units in Canada and Adjacent Regions. Geological Survey of Canada, 1:5,000,000 scale Map #2022A.

Ernst, R.E., & Buchan, K.L. 2004. Igneous Rock Assocations in Canada 3: Large Igneous Provinces (LIPs) in Canada and adjacent regions, 3 Ga to Present. Geoscience Canada, v. 31, pp. 103-126.

Ernst, R.E., & Hulbert, L.J. 2003. Background Pt-Pd levels in mafic Large Igneous Provinces (LIPs) in Canada. GSC Open File 4472. (poster).