Geochemical Quantification of the Clastic Component of Labrador Lake Sediments, and Applications to Exploration

S. Amor

St. John’s, Newfoundland, June, 2014

Abstract

An association consisting primarily of the following elements: Al, Ba, Hf, K, Li, Mg, Na, Nb, Rb, Sc, Sr, and Ti is universal in the analyses of lake sediments from Labrador. It appears to be related to the amount of inorganic clastic material in the sediment, and is often more than sufficient to mask any responses of these elements (some of which are of potential economic significance) to local geology. It is not, however, directly complementary to the amount of organic material in the sediment, as represented by loss-on-ignition (LOI).

Modelling the clastic component numerically by regression analysis identifies departures from the model, in the form of regression residuals. The effectiveness of this method of removing the clastic contribution from the lake sediments’ composition, thereby highlighting local areas of enrichment and depletion, is demonstrated by the emergence of a number of features whose geological significance is indisputable. Furthermore, the method has drawn attention to certain well-defined features whose source is unknown, but which may have economic significance: specifically, the Colville River and Bondurant Lake Ba anomalies, and the Thompson Lake / Michikamats Li anomaly.

This study shows that regression analysis offers a readily implementable method of isolating and compensating the effects of the clastic contribution to lake sediments in Labrador, with potential application in the analysis of lake-sediment geochemical data elsewhere in Canada.

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