A statistical technique for determining the source area of glacially transported granite erratics in the Queen Elizabeth Islands, Nunavut

Abstract

This paper develops a technique that utilizes spatial and compositional trends in granite erratics distributed across the eastern and northwestern Queen Elizabeth Islands to discriminate between glacial dispersal trains originating from the Precambrian Shield of Ellesmere Island and the Canadian mainland. The distribution of glacially transported granite erratics in the eastern and northwestern Queen Elizabeth Islands defines a coherent pattern of regional dispersal from the Precambrian Shield of eastern Ellesmere Island. Principal components and cluster analyses demonstrate that most erratics within this dispersal train cluster within the same compositional group. Other members of this group represent outcrops on eastern Ellesmere Island, which define the locations of possible source areas. However, other compositional groups, which are unique to outcrops on the mainland, are absent from this dispersal train. Collectively, these spatial and compositional trends suggest that granite erratics on southwest Ellesmere, Amund Ringnes, and Meighen islands occur within a single dispersal train that resulted from the westward expansion of the Innuitian Ice Sheet from the Precambrian Shield of eastern Ellesmere Island. This technique may determine what differences, if any, exist among the composition of granite erratics deposited by the westward expansion of the Innuitian Ice Sheet across the Queen Elizabeth Islands and those deposited by the northward expansion of the Laurentide Ice Sheet. Any such differences may be useful in determining whether granite erratics of presently unknown provenance elsewhere in the Queen Elizabeth Islands are of Laurentide or Innuitian origin.