Indicator minerals of the Meliadine orogenic gold deposits, Nunavut (Canada), and application to till surveys

Abstract

The Meliadine Gold District is located about 25 km north of Rankin Inlet, Nunavut (Canada), in the Archean Rankin Inlet greenstone belt. The bedrock is composed of greenschist facies metamorphic rocks. The composition of tourmaline and scheelite is investigated by electron probe micro-analyser (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS). The chemical composition of these indicator minerals from the Meliadine deposits is compared with the composition of grains extracted from till samples along a 2 km transect parallel to the direction of ice flow at the Mustang showing. Tourmaline from the deposit is characterized by a flat rare earth element (REE) pattern having a positive europium anomaly also found in tourmaline grains in till samples down-ice of the Mustang showing. Scheelite from the Mustang showing shows a bell-shaped REE pattern with a negative europium anomaly, which is also found in scheelite from down-ice till samples. Scheelite and tourmaline recovered from till down-ice from the Mustang showing have a composition diagnostic of the gold mineralization. Determining the composition of tourmaline and scheelite in unconsolidated sediments can serve to identify gold mineralization and has the potential to be applied in mineral exploration in the Meliadine Gold District and elsewhere.