Abstract The Superior province, a major Archean craton of the Canadian Shield, was formed during middle and late Archean tectono-magmatic events from rocks of mantle or recycled juvenile crustal origin assembled by accretionary mechanisms in convergent tectonic settings. The Superior province consists of northern and southern high-grade gneiss terranes and a broad central region of alternating lower grade greenstone- and metasediment-rich subprovinces, all intruded by voluminous granitoid plutons. Subprovince boundaries are complex zones of facies, metamorphic, and structural transition, commonly telescoped by crustal-scale faults. Volcanism, plutonism, and sedimentation occurred at ca 3.1 to 2.8 Ga, notably in the north, and again at ca 2.75 to 2.7 Ga throughout the Superior province, in settings analogous to modern oceanic island arc-interarc basin-accretionary wedge systems. Polyphase deformation, metamorphism, and plutonism at ca 2.7 Ga, all products of subduction-driven accretion, resulted in ductile deformation and granulite facies metamorphism at deep crustal levels represented by the high-grade gneiss terranes and in ductile to brittle deformation and lower grade metamorphism at high crustal levels represented by the greenstone-granite subprovinces. Lode gold deposits formed during late ductile-brittle stages of deformation are related to major fault systems and to zones of rock alteration within greenstone-granite subprovinces. Granulite metamorphism at depth, involving dehydration and formation of HO 2 − and CO 2 -rich fluids, was synchronous with brittle deformation, rock alteration, and formation of lode gold deposits at high crustal levels. Although granulitization models probably best account for most genetic aspects of the Superior province lode gold deposits except their confinement to greenstone-granite terranes, degree of greenstone belt preservation is an important factor in their present distribution.

Abstract Phanerozoic tectonics have not affected the basic integrity of the North American continent. From time to time, sialic crustal elements have been rifted off, accreted onto, and slipped along the continent’s margins, but the vast continental interior has remained intact. Furthermore, the dimensions of the continent are little different now than they were in early Paleozoic time. No such assertions can be made for the Precambrian of North America. The structure of the shield (Fig. 1) and buried basement of the interior platform (Fig. 2) is part of a continent-wide “tectonic collage” (Helwig, 1974) consisting of (1) five or more old cratonic elements having crystalline basement rocks of Archean age (3.8 to 2.5 b.y.) and remnants of Early Proterozoic (2.5 to 1.6 b.y.) cratonic cover: (2) anastomosing Early Proterozoic orogenic belts, mostly culminating between 1.9 and 1.8 b.y., that enclose and marginally affect the Archean cratons; (3) intracratonic igneous and sedimentary rocks, mairtly of Middle Proterozoic age (1.6 to 0.9 b.y.), that document consolidation of the various Archean cratons and Early Proterozoic orogens to form a vast composite craton here called “Proto-Laurentia;” and (4) the Grenville Orogen, culminating at about 1.1 b.y., which developed along the presumed southeast margin of Proto-Laurentia and may contain elements exotic to it. In addition, the bounding Phanerozoic orogens contain Middle and Upper Proterozoic rocks deposited marginal to Proto-Laurentia, as well as Precambrian rocks outboard of Phanerozoic sutures that may not belong to Precambrian North America at all.