The Lithoprobe Abitibi-Grenville transect: two billion years of crust formation and recycling in the Precambrian Shield of Canada

High-pressure granulites in the Grenvillian Grand Lake thrust system, Labrador: Pressure-temperature conditions and tectonic evolution

“…They comprise the high-pressure (HP) belt, which is in turn overlain by a low-pressure (LP) belt that lacks evidence for Grenvillian high-pressure metamorphism ( Fig. 1; Ludden and Hynes, 2000;Rivers et al 2002). Thus, it is possible that the high-pressure granulites in the Grand Lake thrust system and the base of the Cape Caribou River allochthon form the northeasterly continuation of the HP belt into the eastern Grenville Province, a proposition we now evaluate.…”

“…The orogen has been subdivided into a series of (semi-) continuous subparallel stacked belts known as the Parautochthonous Belt and the overlying Allochthonous Belt (Rivers et al, 1989(Rivers et al, , 2002. The recently recognized high-pressure (HP) belt (Ludden and Hynes, 2000;Rivers et al, 2002), comprising the structurally lowest of the allochthonous belts, is characterized by relict highpressure (eclogite-facies and HP granulite-facies) assemblages. It is tectonically overlain by a low-pressure (LP) belt in which high-pressure assemblages are lacking.…”

“…1005 Ma (Krogh, 1994). Lithoprobe crustal-scale seismic sections in the western and central Grenville Province (Ludden and Hynes, 2000) show that the Grenville Front is the lowest thrust in the Grenville orogen, and so it is inferred to underlie the Grand Lake thrust system at depth (Fig. 10, E).…”

Forty years of TTG research

“…However it must be noted that the only requirement to form these rocks is the burial and dehydration of surface rocks under a mantle wedge, irrespective of the actual size and geometry of the buried portions of rock. Additional evidence includes the map pattern of many Archaean provinces (Czarnota et al, 2010;Percival et al, 2002;Poujol et al, 2003), reminiscent of lateral accretion of stitched terranes (Coney et al, 1980), as well as the existence of flat seismic reflectors, possibly representing fossil subduction planes (de Wit and Tinker, 2004;Goleby et al, 2004;Ludden and Hynes, 2000). Finally, the existence of Archaean highpressure and medium to low temperature metamorphism (Block et al, 2012;Saha et al, 2010Saha et al, , 2011Volodichev et al, 2004), sometimes associated with "hotter" metamorphic rocks in Archaean analogues of paired metamorphic belts (Banno and Nakajima, 1992;Brown, 2002;Patrick and Day, 1995), suggests the existence of some form of subduction process in the Archaean.…”

Crustal development at the pre-Grenvillian Laurentian margin: a record from contrasting geochemistry of mafic and ultramafic orthogneisses in the Chochocouane River area, Quebec

“…It marks the junction between the well-documented Grenville terranes in Ontario and western Quebec and a largely uncharted gneissose domain of the central Grenville Province (see Fig. 2 in Ludden and Hynes 2000). In western Quebec and Ontario, the Archean Abitibi and Pontiac subprovinces of the Superior Province, the Paleoproterozoic Huronian Supergroup, and the 1.7 Ga Killarney magmatic belt extend southeastward, beyond the Grenville Front, in the Grenville Province (Davidson and van Breemen 1994;Davidson 1998aDavidson , 1998bLudden and Hynes 2000).…”