Tectonic evolution of the western Superior Province from NATMAP and Lithoprobe studies

Abstract

Five discrete accretionary events assembled fragments of continental and oceanic crust into a coherent Superior craton by 2.60 Ga. They exhibit similar sequences of events at ~10 million year intervals: cessation of arc magmatism, early deformation, synorogenic sedimentation, sanukitoid magmatism, bulk shortening, regional metamorphism, late transpression, orogenic gold localization, emplacement of crust-derived granites, and postorogenic cooling. The Northern Superior superterrane recorded 3.7–2.75 Ga events prior to 2.72 Ga collision with the 3.0 Ga North Caribou superterrane. Following 2.98 Ga rifting, the Uchi margin of the North Caribou superterrane evolved in an upper plate setting before 2.72–2.70 Ga collision of the <3.4 Ga Winnipeg River terrane, which trapped synorogenic English River turbidites in the collision zone. The Winnipeg River terrane was reworked in 2.75–2.68 Ga magmatic and tectonic events, including the central Superior orogeny (2.71–2.70 Ga) that marks accretion of the juvenile western Wabigoon terrane. In the south, the Wawa–Abitibi terrane evolved in a mainly oceanic setting until Shebandowanian collision with the composite Superior superterrane at 2.695 Ga. Synorogenic Quetico turbidites were trapped in the collision zone. The final accretionary event involved addition of the Minnesota River Valley terrane (MRVT) from the south, and deposition and metamorphism of synorogenic turbidites of the Pontiac terrane during the ~2.68 Ga Minnesotan orogeny. Seismic reflection and refraction images indicate north-dipping structures, interpreted as a stack of discrete 10–15 km thick terranes. A slab of high-velocity material, possibly representing subcreted oceanic lithosphere, as well as Moho offsets, support a model of progressive accretion through plate-tectonic-like processes.

Palaeoproterozoic supercontinents and global evolution: correlations from core to atmosphere

“…Of these, a Siberia -northern Laurentia connection, if not directly adjacent then slightly separated, is allowed by numerous independent palaeomagnetic comparisons from 1.5 to 1.0 Ga (Pisarevsky & Natapov 2003;Pisarevsky et al 2008;Wingate et al 2009), and lack of tectonic activity after 1860 Ma in southern Siberia would suggest that this position had been established by that time (Poller et al 2005;Pisarevsky et al 2008). A long-lived Atlantica continent is difficult to test palaeomagnetically, due to a dearth of reliable results from its constituent cratons (Meert 2002;Pesonen et al 2003). Minor transcurrent motions between West Africa and Amazon, sometime between original craton assembly at 2.1 Ga (Ledru et al 1994) and their Gondwanan amalgamation in the Cambrian (e.g.…”

“…These models lack robust palaeomagnetic constraints, and the reconstructions are commonly distorted by unscaled cut-outs from a Mercator projection of Pangaea. When palaeomagnetic data are incorporated into geometrically accurate reconstructions, the sparsity of reliable results has led authors to conflicting conclusions of either non-existence of a 1.8 Ga supercontinent altogether (Meert 2002), or one that accommodated substantial internal shears (Laurentia -Baltica motions illustrated in Pesonen et al 2003), or the consideration of at most a few fragments with applicable data from discrete time intervals (Li 2000;Salminen & Pesonen 2007;Bispo-Santos et al 2008).…”

“…The younger two of these entities are most commonly given alternative names Rodinia (for recent reviews, see Evans 2009), and Nuna or Columbia (Hoffman 1997;Rogers & Santosh 2002); 'Grenvilleland' has been forgotten, and 'Hudsonland' almost so (cf. Pesonen et al 2003). Here we favour 'Nuna' for the supercontinent that assembled at 1.9-1.8 Ga (see Zhao et al 2002 for a global review) because it represents a preferred renaming of 'Hudsonland' by one of the co-authors of the original study (Hoffman 1997) and has priority over 'Columbia' (Rogers & Santosh 2002), the latter of which was also defined by a specified palaeogeography that has been modified in subsequent references (e.g.…”

“…Its etymology derives from the Kenoran orogeny (Stockwell 1982) that represents cratonization of the Superior craton at about 2.72 -2.68 Ga (Card & Poulsen 1998;Percival et al 2006) and of that age or younger in the Neoarchaean on other cratons (Bleeker 2003). Breakup of Kenorland would be represented by numerous large igneous provinces starting with a global pulse at 2.45 Ga (Heaman 1997).…”

Logan Medallist 2. Geophysics and Geology: An Essential Combination Illustrated by LITHOPROBE Interpretations–Part 1, Lithospheric Examples

“…The observed geologic relationships between and within these subprovinces are most often explained in terms of a modern tectonic model of terrane accretion (e.g. Hoffman 1989;Percival et al 2006). Alternative scenarios are also proposed, although they typically refer to a different region of the Superior Province (e.g.…”