In the early 1990s, Labbé (1994) began mapping the vast Amos-Landrienne area, updating the previous work of Weber and Latulippe (1964) and Imreh (1984). He informally created the Dalquier group with the aim of characterizing lithological units previously associated with the Amos Group (Imreh, 1984; Otis and Béland, 1986), but with geochemical characteristics different from basalts of this group.

The Dalquier Group consisted at that time of two distinct stratigraphic units: the Jonpol rhyolite and the Lac Arthur formation.

In the continuation of his 1994 work, Labbé (1995) redefined the Dalquier Group into two informal formations with distinct geochemical affinities: 1) the La Morandière formation, the basal unit outcropping mainly in the half-centre of sheet 32C12 and consisting mainly of tholeiitic basalt, and 2) the larger Lac Arthur formation (Labbé, 1994), consisting mainly of calc-alkaline andesite. The Jonpol rhyolite is then incorporated into the Lac Arthur formation.

In a synthesis of his work, Labbé (1999) proposed new formal stratigraphic divisions, now including the Lac Arthur and La Morandière groups, which were previously informal formations within the Dalquier group (Labbé, 1995). The name “Dalquier group” was then abandoned.

References