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’Taters versus Sliders: Evidence for a Long-

Lived History of Strike-Slip Displacement

along the Canadian Arctic Transform

System (CATS)

William C. McClelland, Dept. of Earth & Environmental Sciences, University of Iowa, Iowa City, Iowa 52242, USA; Justin V. Strauss,
Dept. of Earth Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA; Maurice Colpron, Yukon Geological Survey,
Whitehorse, Yukon Y1A 2C6, Canada; Jane A. Gilotti, Dept. of Earth & Environmental Sciences, University of Iowa, Iowa City, Iowa
52242, USA; Karol Faehnrich, Dept. of Earth Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA; Shawn J. Malone,
Dept. of Geoscience, University of Wisconsin, Green Bay, Wisconsin 54311, USA; George E. Gehrels, Dept. of Geosciences, University of
Arizona, Tucson, Arizona 85721, USA; Francis A. Macdonald, Earth Science Dept., University of California, Santa Barbara, California
93106, USA; John S. Oldow, Borealis, 200 E. Troxell Road, Oak Harbor, Washington 98277, USA, and Dept. of Geology, Western
Washington University, Bellingham, Washington 98225, USA

ABSTRACT the northwestern Alaskan and Canadian followed mafic magmatism associated with
Recent field-based studies indicate that the Arctic margins provide the clearest rationale the Franklin Large Igneous Province at 720
northern margin of North America is best for the rotation model (Embry, 1990), which Ma (Macdonald et al., 2010; Cox et al.,
interpreted as a tectonic boundary that experi- is by far the most commonly expressed 2015). The basin is flanked to the north by
enced a long, complex history of strike-slip mechanism (e.g., Hutchinson et al., 2017; Ordovician to Silurian clastic and subduction-
displacement. Structures juxtaposing the Miller et al., 2018). In contrast, we explore related mafic and ultramafic rocks and alloch-
Pearya and Arctic Alaska terranes with North the implications of a growing set of onshore thonous units of the Pearya terrane (Fig. 1;
America are linked and define the Canadian observations that indicate that the northern Trettin, 1998). The Pearya terrane is domi-
Arctic transform system (CATS) that accom- Laurentian margin has experienced a pro- nated by two assemblages juxtaposed in
modated Paleozoic terrane translation, trun- tracted history of translation. This view is the Ordovician: a displaced peri-Laurentian
cation of the Caledonian orogen, and shorten- bolstered by a variety of data that support crustal fragment that records early Neo-
ing within the transpressional Ellesmerian models of Paleozoic large-magnitude terrane proterozoic (Tonian) and Ordovician conver-
orogen. The structure was reactivated during translation through the Arctic region (Colpron gent margin magmatism (Malone et al., 2017,
Mesozoic translational opening of the Canada and Nelson, 2009). Despite early calls for 2019) and a latest Neoproterozoic (Ediacaran)
Basin. Land-based evidence supporting trans- large-magnitude sinistral offsets (e.g., Boreal to Ordovician mafic arc complex built on
lation along the Canadian Arctic margin is fault of Bally in Kerr et al., 1982; Canadian Tonian basement (Majka et al., 2021). Steeply
consistent with transform structures defined transcurrent fault of Hubbard et al., 1987; dipping faults juxtaposed Pearya with the
by marine geophysical data, thereby provid- Porcupine fault of Oldow et al., 1989), the Laurentian passive margin by the Devonian
ing a robust alternative to the current consen- Canadian Arctic margin generally has not (Trettin, 1998; Malone et al., 2019). Sub-
sus model for rotational opening of the been viewed as a viable candidate for trans- sequently, units of both the Pearya terrane
Canada Basin. form boundaries to accommodate evolution and Franklinian basin were deformed within
of the Arctic region (e.g., Doré et al., 2016). the Devonian–Carboniferous Ellesmerian
INTRODUCTION Results of our recent field studies on the fold belt and overlain by Carboniferous and
Recent ocean- and land-based studies of northern margin of Laurentia challenge this younger deposits of the Sverdrup basin.
the circum-Arctic region bring significant conclusion and support translation. Structures of the Ellesmerian fold belt extend
advances in high-quality data to formulate westward to Prince Patrick Island where they,
new models for the tectonic evolution of the CURRENT SETTING and Carboniferous to Mesozoic structures of
Arctic margin (e.g., Pease and Coakley, 2018; The Canadian Arctic Islands expose a the Sverdrup basin, are truncated at a high
Piskarev et al., 2019; Piepjohn et al., 2019). south to north transition from shallow marine angle by the present-day Arctic margin (Fig.
Nevertheless, evolution of the Canada Basin deposits of the Paleozoic Arctic platform into 1; Harrison and Brent, 2005).
remains one of the most enigmatic and con- deep-water rocks of the late Proterozoic to Autochthonous strata of the Laurentian
tentious topics of the Arctic. Two end-mem- early Paleozoic Franklinian basin that were margin in northern Yukon are juxtaposed
ber models for the Mesozoic opening of the deformed in the Devonian and overlain by late with peri-Laurentian platform and basinal
Canada Basin invoke Arctic Alaska (1) rift- Paleozoic and early Mesozoic rocks of the strata of the North Slope subterrane of Arctic
ing and rotating (’taters) from or (2) translat- Sverdrup basin. Rocks of the Franklinian Alaska (Macdonald et al., 2009; Strauss et al.,
ing (sliders) along the Canadian Arctic basin were deposited after the Neoproterozoic 2019a, 2019b; Colpron et al., 2019) on a near-
margin (Fig. 1 inset). Late Paleozoic and breakup of Rodinia and rifting along the vertical fault zone broadly referred to as the
Mesozoic stratigraphic correlations between northern Laurentian margin, which closely Porcupine shear zone (Fig. 1; von Gosen et al.,

GSA Today, v. 31, https://doi.org/10.1130/GSATG500A.1. CC-BY-NC.

4 GSA Today | July 2021