western quebec and southern ontario - Department of Geology

Metasedimentary Belt boundary tectonic zone (CMBbtz) in the southeast to the GrenvilleFront tectonic zone (GFtz) in the northwest (Figure 2.2). This margin containsPaleoproterozoic and Mesoproterozoic rocks (1800-1350 Ma), which were formed byAndean-style arcs (Carr et al., 2000). The pre-Grenvillian Laurentian margin has a longtectonic history including ca. 1700 and 1450 Ma deformation, magmatism andmetamorphism, and was progressively reworked during the ca. 1120-980 Ma Grenvilleorogen (Rivers 1997). The main tectonic elements of the Grenville province (theGrenville Front tectonic zone, CMBbtz, and the Elzevir Frontenac boundary zone (EFbz)are divided by major shear zones several kilometres wide (Easton, 1992). These zones arecharacterized by deformed rocks with northeast striking, shallow southwest-dippingtectonic fabric, and southeast-plunging mineral lineation (Carr et al., 2000).The Composite Arc Belt (1300-1250 Ma) is predominantly composed ofMesoproterozoic volcanic arcs and sedimentary rocks from various arcs and marginalbasins (Carr et al., 2000). This belt extends from the Central Metasedimentary Beltboundary thrust zone (CMBbtz) in the northwest to the Elzevir Frontenac boundary zone(EFbz) in the southeast (Easton, 1992; Carr et al., 2000) (Figure 2.2). Carr et al. (2000)interpreted this belt as a series of island arcs that were accreted and thrust onto Laurentia.The arcs are also interpreted to have formed an offshore oceanic crust and were probablyamalgamated by ca. 1240 Ma (White et al. 2000).The Frontenac–Adirondack Belt southeast of the EFbz is characterized bysupracrustal marbles, granitic rocks, and quartzo-feldspathic gneisses. These rocksformed within continental crust or arc segments of uncertain age and were deformed by8