FORMATION AND EVOLUTION OF THE AILLIK DOMAIN, MAKKOVIK PROVINCE: A PALEOPROTEROZOIC ACCRETIONARY OROGEN PRESERVED IN LABRADOR, CANADA
Deformation in the Aillik Group is predominantly characterized by regional-scale, open to isoclinal, moderately plunging, upright to overturned folds (F1 in the Aillik domain) that were subsequently refolded (F2). Folding and the development of regional-scale shear zones was contemporaneous with the formation of an axial-planar fabric in the Aillik Group and regional amphibolite-facies metamorphism, all of which are attributed to compressional tectonic regimes associated with the Makkovikian orogeny. With the exception of the porphyritic, syn-volcanic granites, all of the plutonic rocks appear to postdate regional-scale folding in the area. Although some of the ca. 1800 Ma plutons have acquired the regional penetrative fabric, indicating that they intruded synchronous to deformation, they do not appear to be folded.
Lithological characteristics of the Aillik Group support formation in a transitional environment, from a shallow marine to a marginal marine or subaqueous environment. Although depositional basement has not been identified, it cannot be coincident with present-day basement, as folding and shearing during Makkovikian orogenesis transported these Aillik Group rocks northwestward.