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Modern Accretionary Processes The Geological Society, London, Special Publications The Palaeoproterozoic Trans-Hudson Orogen: a prototype of modern accretionary processes D. Corrigan, S. Pehrsson, N. Wodicka and E. de Kemp Geological Society, London, Special Publications 2009; v. 327; p. 457-479 doi:10.1144/SP327.19 Email alerting click here to receive free email alerts when new articles cite this service article Permission click here to seek permission to re-use all or part of this article request Subscribe click here to subscribe to Geological Society, London, Special Publications or the Lyell Collection Notes Downloaded by University of Massachusetts on 25 March 2010 © 2009 Geological Society of London The Palaeoproterozoic Trans-Hudson Orogen: a prototype of modern accretionary processes D. CORRIGAN*, S. PEHRSSON, N. WODICKA & E. DE KEMP Geological Survey of Canada, 615 Booth Street, Ottawa, Ontario, Canada, K1A 0E8 *Corresponding author (e-mail: [email protected]) Abstract: The Trans-Hudson Orogen (THO) of North America is one of the earliest orogens in Earth’s history that evolved through a complete Wilson Cycle. It represents c. 150 Ma of opening of the Manikewan Ocean, from c. 2.07–1.92 Ga, followed by its demise in the interval 1.92–1.80 Ga, during the final phase of growth of the Supercontinent Columbia (Nuna). It is characterized by three lithotectonic divisions: (i) Churchill margin (or peri-Churchill); (ii) Reindeer Zone; and (iii) Superior margin (or peri-Superior). The peri-Churchill realm records progressive outward continental growth by accretion of Archaean to Palaeoproterozoic micro-con- tinents (Hearne, Meta Incognita/Core Zone, Sugluk) and eventually arc terranes (La Ronge–Lynn Lake) to the Slave-Rae nuclei, with attendant development of orogenies and basin inversions related to the specific accretion events (1.92–1.89 Ga Snowbird; 1.88–1.865 Ga Foxe; 1.87–1.865 Ga Reindeer orogenies). The Reindeer Zone is characterized by primitive to evolved oceanic arcs, back-arc basins, oceanic crust and ocean plateaus that formed during closure of the Manikewan Ocean, and accretion of a micro-continent (Sask Craton) and smaller Archaean crustal fragments. The terminal phase of the Trans–Hudson orogeny represents collision between the Superior craton, the Reindeer Zone and the composite western Churchill Province during the interval 1.83–1.80 Ga. Introduction of South Dakota and perhaps even further to the Grand Canyon area (Bickford & Hill 2007), over a The Palaeoproterozoic Era (2.5–1.6 Ga) forms a distance of c. 3000 km across the Canadian Prairies, unique period of Earth’s evolution, highlighted by Hudson Bay, Baffin Island, Greenland and Scandi- profound changes in continental plate configuration navia (Hoffman 1988). It may originally have and tectonic processes (e.g. Griffin et al. 2008; Hou been even more extensive, as both ends are now et al. 2008), ocean and atmospheric compositions truncated by younger orogenic belts. In Canada, (e.g. Anbar & Knoll 2002) and the biosphere (e.g. the THO is generally well exposed and remained Konhauser et al. 2002). By 2.5 Ga, Archaean relatively intact after its formation, providing the cratons had grown by tectonic and magmatic accre- opportunity to study its evolution both parallel to tion into large, stable continental masses buoyed by and across orogenic strike. thick, depleted lithospheric roots that could accom- The THO is the site of closure of the Manikewan modate the deposition of laterally extensive passive Ocean (Stauffer 1984), the oceanic plate that once margin sequences (e.g. Artemieva & Mooney 2001; existed between the Superior Craton and the Rae Be´dard 2006; Percival 2007; Francis 2003). Wilson- Craton (Fig. 2a), stretching from South Dakota to Cycle tectonics also appeared in the Palaeoprotero- the Ungava Peninsula in northern Que´bec (present- zoic, resulting in the oldest documented obducted day geometry). It is likely that this ocean once contin- ophiolites and development of tectonostratigraphic ued eastwards past the Ungava Peninsula, but its sequences akin to those observed in the Phanerozoic extent from there is unclear. Closure of the Manike- (e.g. Hoffman 1988). Within the Canadian Shield, wan Ocean was traditionally associated with for- the Trans-Hudson Orogen (THO, Fig. 1; Hoffman mation of juvenile crust and its eventual accretion 1988; Lewry & Collerson 1990) represents the to the Superior craton and composite western largest and most completely preserved segment Churchill Province (Gibb & Walcott 1971; Gibb amongst a number of Palaeoproterozoic collisional 1975). Recent studies have highlighted that it also belts that formed during the amalgamation of super- involved accretion of a number of smaller interven- continent Nuna (also known as Columbia) during ing Archaean to earliest-Palaeoproterozoic conti- the interval 2.0–1.8 Ga (Rogers & Santosh 2002; nental fragments, including the Sask Craton (Lewry Pesonen et al. 2003; Hou et al. 2008). Before the et al. 1994; Hajnal et al. 1996). From a tectonostrati- opening of the North Atlantic Ocean, the THO graphic perspective, the THO preserves a relatively formed part of a nearly continuous orogenic complete Wilson-Cycle, from early c. 2.45– system that extended from the present-day location 1.92 Ga rift to drift sedimentary assemblages From:MURPHY, J. B., KEPPIE,J.D.&HYNES, A. J. (eds) Ancient Orogens and Modern Analogues. Geological Society, London, Special Publications, 327, 457–479. DOI: 10.1144/SP327.19 0305-8719/09/$15.00 # The Geological Society of London 2009. 458 D. CORRIGAN ET AL. Fig. 1. Simplified geological map of the Canadian Shield and west Greenland, with extension of western Precambrian terranes shown beneath Phanerozoic cover (pale colours SW of thick hashed line). The area affected by Trans–Hudson age tectonothermal reactivation (1.83–1.80 Ga) is delimited by the thick red hashed line. Limit of the Reindeer Zone is shown (thick stippled blue line). Minimum limit of Trans-Hudson age tectonothermal overprint (thick hashed red line). Terrane names and major faults: BH, Buffalo Head terrane; BK, Black Hills; C, Chinchaga belt; CZ, Core Zone; FS, Fort Simpson terrane; FFB, Foxe Fold Belt; GB, Great Bear; GSL, Great Slave Lake shear zone; H, Hottah terrane; KS, Ksituan belt; L, Lacombe belt; N, Nahanni belt; NO, New Que´bec; NV, Nova terrane; RB, Rimbey Belt; STZ, Snowbird Tectonic Zone; T, Thorsby basin; TA, Tasiuyak domain; W, Wabamun belt. deposited along Archaean craton margins, to for- Hoffman (1981) to identify the Palaeoproterozoic mation of c. 2.00–1.88 Ga oceanic and pericratonic collision zone that formed between the Superior arcs and back-arc basins, as well as younger (1.88– Province and the Archaean domains of the western 1.83 Ga) continental arcs, foredeep and collisional Churchill Province (Green et al. 1985). This usage basins, and eventual terminal collision (Ansdell differs from the one proposed by Lewry et al. 2005). This paper provides a synopsis of the accre- (1985) and Lewry & Collerson (1990), who prefer- tionary and collisional evolution of the THO in ably based their definition on timing and contiguous Canada. The objective is to provide the reader with extent of peak ‘Hudsonian-age’ tectonothermal an appreciation of the complexity of this composite overprint, defined at c. 1.83–1.80 Ga. Within that orogenic system, the scale and age of colliding framework, the latter authors refer to Hoffman’s crustal fragments, and the type of geodynamic pro- THO as the Reindeer Zone, an area represented by cesses that were in place during the Palaeoprotero- the Palaeoproterozoic juvenile internides (Fig. 1). zoic. This paper considers the whole of the They include within the definition of the THO a Canadian THO, in comparison to Ansdell (2005), vast region represented by reactivated Archaean Corrigan et al. (2007) and St-Onge et al. (2006) rocks of the western Churchill Province encompass- that provide overviews of selected parts of the ing nearly all of the Hearne Craton, as well as a large orogen. The evolution of the eastern Churchill Pro- portion of the Rae Craton (Fig. 1). vince is not discussed in detail in this paper, but uti- The THO as defined by Lewry & Collerson (1990) lizes the overview published by Wardle et al. (2002). ismoreinclusiveandhelpsunderstandtheorogeninits entirety in terms of ocean closure, terrane accretion, Tectonic context continental margin reactivation and syn- to post- orogenic tectonothermal overprint. The THO is Historically, the usage of the term ‘Trans-Hudson herein more broadly defined as an area of contiguous Orogen’ has varied widely. It was introduced by or nearly-contiguous structural and metamorphic THE PALAEOPROTEROZOIC TRANS-HUDSON OROGEN: A PROTOTYPE OF MODERN 459 overprint caused by c. 1.83–1.80 Ga collision The Sugluk block [introduced by Hoffman between the Superior Craton, the Reindeer Zone, (1985) as ‘Sugluk Terrane’] contains crystalline and a previously amalgamated continental collage basement rocks that fall in a narrow Mesoarchaean north of the Manikewan Ocean consisting of the age range of c. 2.8–3.2 Ga (whole rock Rb–Sr Slave, Rae and Hearne cratons, with the latter two col- on sedimentary rocks, Doig 1987; whole rock lectively referred to as the ‘western Churchill Sm–Nd, Dunphy & Ludden 1998; U–Pb on Province’ (Fig. 1). This zone of tectonometamorphic zircon, Wodicka & Scott 1997; Rayner et al. overprint reaches a maximum width of c. 1800 km 2008) and in contrast to the Meta Incognita micro- across strike of the orogen, from the reactivated edge continent, has no known 2.4–2.5 Ga magmatism. of the Superior Craton to the northwestern limit of Its main exposure lies in the northwestern edge of the orogenic front in the western Churchill Province Ungava Peninsula where it has been variably (Lewry & Collerson 1990; Corrigan 2002; Pehrsson named ‘Sugluk Terrane’ (Hoffman 1985, 1990), et al. 2004). The southeastern Churchill Province, ‘Narsajuaq Terrane’ (St-Onge & Lucas 1990) and which separates the Superior Craton from the North ‘Narsajuaq arc’ (St-Onge et al.
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