Deformable plate tectonic models of the southern North Atlantic
Introduction
The opening of the modern North Atlantic Ocean represents the final dispersal and end of the Laurasia continental amalgamation that formed the northern portion of the Pangaea supercontinent (Gaina et al., 2009; Hansen et al., 2009; Frizon De Lamotte et al., 2015; Peace et al., 2019) (Fig. 1). The ocean is divided into two main spreading branches; the Northeast Atlantic between Greenland and Europe, and the Labrador Sea – Baffin Bay system between Greenland and North America (Srivastava, 1978; Beniest et al., 2017), that form a complex junction with the northeast Atlantic to the north of the Charlie-Gibbs Fracture Zone (CGFZ) (Gaina et al., 2009).
In addition to the primary breakup axes, complex styles of deformation occurred on the continental margins, including the preservation of relatively undeformed continental fragments (Peron-Pinvidic and Manatschal, 2010; Peron-Pinvidic et al., 2012a, 2012b; Nirrengarten et al., 2018; Schiffer et al., 2018), continental transform systems (e.g., the Davis Strait; Suckro et al., 2013; Peace et al., 2018b), and multiple failed rift axes (e.g., the North Sea; Rattey and Hayward, 1993). Despite the significant role that such deformation had upon the geological evolution of the continental margins, including the prospective petroliferous basins, plate tectonic reconstructions often struggle to account for much of this deformation prior to breakup (Ady and Whittaker, 2018). For this reason, it is the deformation in these continental rifted margins and basins, including the driving mechanisms, that form the focus of this study.
Here, we primarily use published constraints (e.g., Müller et al., 2016; Matthews et al., 2016; Nirrengarten et al., 2018; Welford et al., 2018) to construct deformable plate tectonic models for the southern North Atlantic using the open source GPlates environment (Williams et al., 2012a; Gurnis et al., 2018; Müller et al., 2018). We then compare the results obtained from the deformable models with both geological and geophysical observations including: crustal structure derived through gravity inversion (Welford et al., 2012; Roberts et al., 2018), regional seismic reflection lines (e.g., Tucholke et al., 2007; Tucholke and Sibuet, 2007), the age of syn-rift strata in passive margin rift basins (e.g., Gouiza et al., 2016), documented inversion (e.g., Yang, 2012), and occurrences of rift-related magmatism (e.g., Keen et al., 2014). The aim of this analysis was to investigate: 1) the reliability of published constraints as model components; 2) the reliability and applicability of the current generation of GPlates deformable models to reproduce realistic passive margin deformation, and 3) the implications for the spatio-temporal evolution of the region, including the consequences for magmatism, conjugate margin, and connected basin studies.
Section snippets
Geological setting: The southern North Atlantic
In this study, the southern North Atlantic (Fig. 1) includes the conjugate Newfoundland-Iberia margins to the south and extends as far north as the southern Labrador Sea, southeast Greenland and the conjugate northwest European margin south of Iceland, approximately the same study area as that of Nirrengarten et al. (2018). This study area was chosen as the large-scale post-breakup plate movements are well constrained from studies of the oceanic crust (e.g., Barnett-Moore et al., 2018) and
Reconstructions of the southern North Atlantic: the need for deformable plate tectonic models
Many plate tectonic models and reconstructions have been produced for the Mesozoic-Cenozoic rifting and breakup of the North Atlantic region (Bullard et al., 1965; Rowley and Lottes, 1988; Dunbar and Sawyer, 1989; Hosseinpour et al., 2013; Barnett-Moore et al., 2018; Nirrengarten et al., 2018). Each of these models inherently comes with its own assumptions, simplifications and omissions, depending on the scientific question being evaluated. Many, but not all (e.g., Whittaker and Ady, 2011; Ady
Crustal thickness, evolution, and beta factors
The evolution of crustal thickness through time in all models shows general similarities as the large-scale movement of the major plates (i.e. North America, Greenland, Iberia and Eurasia) are ultimately driven by similar poles of rotation (e.g., Barnett-Moore et al., 2018). However, the small (basin) scale manifestations of deformation are highly variable. Implications for this deformation form the focus of this study and are more susceptible to minor variations in model inputs such as
Comparison between deformable model results and regional observations
In this section, the results of the GPlates deformable models (Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11, Fig. 12, Fig. 13, Fig. 14) are compared to geological and geophysical observations from across the modelled region, principally the gravity inversion results from Welford et al. (2012) (Fig. 15), but also other observations such as the interpretation of seismic reflection data (e.g., Yang, 2012; Keen et al., 2014; Gouiza et al., 2016). This was undertaken to test whether the various
Conclusions
A suite of deformable plate tectonic models based on published constraints for the southern North Atlantic has been created in GPlates. The purpose was to test the viability of the GPlates deformable modelling approach, the published model inputs, and the influence of various pre-rift configurations. The conclusions of this study are as follows:
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The GPlates deformable modelling tool has proven to be an effective means of testing different scenarios for the tectonic development of the southern
Acknowledgements
Alexander L. Peace’s postdoctoral fellowship at Memorial University of Newfoundland was funded by the Hibernia Project Geophysics Support Fund and Innovate NL. We would like to thank the GPlates development and maintenance team and the members of the MAGRiT group at Memorial University of Newfoundland for valuable scientific discussions. We would also like to acknowledge TGS for the generous provision of the seismic reflection data from the Orphan Basin. To prevent visual distortion of the
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