The chemistry and tectonic setting of Ordovician volcanic rocks in northern Maine and their relationship to contemporary volcanic rocks in northern New Brunswick

Abstract

A geochemical study of Ordovician volcanic rocks in northern Maine shows that the mafic rocks can be divided geographically into three groups dominated by tholeiite. Two of these groups (Stacyville-Lobster Mountain group and Munsungun-Winterville group) are chemically similar but geographically separated and were erupted in a within-plate setting. A third, dissimilar volcanic group (Pinkham Road group), intervening between the other two, is characterized by rifted island-arc magmatism. The within-plate basalt groups are thought to be related to each other and to correlate with coeval basalts in the Tetagouche Group of northern New Brunswick. By contrast the rifted island-arc basalts closely resemble some basalt suites from the Fournier Group in New Brunswick. -from Authors