Till geochemical signatures associated with the Sisson W-Mo deposit, New Brunswick, Canada

Abstract

A till composition study was carried out around the Sisson W-Mo deposit, New Brunswick, Canada, one of the largest W deposits in the world, to test modern analytical methods for W in till and document glacial dispersal from a significant W source. The <0.063 mm fraction of till defines glacial dispersal down ice of the deposit and use of this fraction is recommended for W-Mo exploration in the region. Metal-rich till overlying the deposit contains up to 816 ppm W and 63 ppm Mo. One km down ice, till contains 75 ppm W and 8 ppm Mo, and till in background areas contains a maximum of 7 ppm W, and 2 ppm Mo. Indicator elements for the deposit include W and Mo, and pathfinder elements include Ag, As, Bi, Cd, Cu, In, Pb, Te, and Zn. This list of elements is more extensive than previously identified for the Sisson deposit or identified in other published till geochemical studies because of the polymetallic nature of the Sisson deposit and the broad suite of elements that can now be determined using modern analytical techniques. Lithium meta/tetraborate fusion inductively coupled plasma-mass spectrometry was used to determine the total concentration of W in till and is a fast and cost effective method as compared to those reported in the older literature. Glacial dispersal of W and Mo from the Sisson deposit is detectable at a regional scale at least 14 km down ice (southeast) using surface till sampling. A 2 km till sample spacing should be sufficient to detect glacial dispersal from a W-Mo deposit of this size.

Keywords:

• till geochemistry,
• glacial dispersal train,
• tungsten,
• Sisson deposit