Revised plate motions relative to the hotspots from combined Atlantic and Indian Ocean hotspot tracks

Role of subaerial volcanic rocks and mantle plumes in creation of South Atlantic margins: implications for salt tectonics and source rocks

“…These were ®rst recognized on the continental margins of the Norwegian Sea (Hinz & Weber, 1976;Mutter, Talwani & Sto a, 1982;Roberts, Backman, Morton, Murray & Keene, 1984a;Roberts & Schnitker, 1984b) and are now known to be widespread. Most drilling refraction surveys on SDRs have been done in the North Atlantic.…”

“…North of the Walvis Ridge and Rio Grande Rise (the trails of the Tristan and Gough hot spots), early ocean opening apparently coincided with the long, normally magnetized period of the Cretaceous Quiet Zone (119±85 Ma) (MuÈ ller, Royer & Lawver, 1993) so is poorly constrained by magnetic reversals. Estimates for the end of rifting and the onset of sea-¯oor spreading have the following ranges in African basins, listed from south to north: Cape± Orange±LuÈ deritz, 137 Ma (Austin & Uchupi, 1982;Gladczenko, Hinz, Eldholm, Meyer, Neben & Skogseid, 1997;Peate, 1997) (Brice et al, 1982) to 117 Ma (Teisserenc & Villemin, 1989;Guiraud & Maurin, 1992;Karner & Driscoll, 1998 These ages provide crude but useful benchmarks to calibrate the tectonic setting of extension, magmatism, stratigraphy and salt tectonics.…”

“…Seaward-retreating magmatic vents lie downdip of the SDRs. The convex-upward curvature and seaward dip of the lavas probably result from di erential subsidence caused by loading by younger¯ows farther seaward (Pa lmason, 1980;Hinz, 1981;Mutter et al, 1982). (SDR divergence appears too extreme to be accounted for by di erential cooling over such a brief time.…”

Geology, Mantle Tomography, and Inclination Corrected Paleogeographic Trajectories Support Westward Subduction During Cretaceous Orogenesis in the North American Cordillera

“…With improvements in computing power and high-resolution seismic arrays, such as USArray (Williams et al 2010), these advances have now reached a level where they can be integrated with geological models based on surface geology (Sigloch 2011;Sigloch and Mihalynuk 2013). Moreover, the seismic tomography can be used in consort with recently developed kinematic models for plate motions in deep-mantle reference frames based on seafloor-spreading history, hotspot migration, paleomagnetism, and moving continents (Müller et al 1993;O'Neill et al 2005;Torsvik et al 2008a, b;Doubrovine et al 2012;Shephard et al 2012;Seton et al 2012) to constrain the tectonic development of orogenic belts. My goal here is to provide a brief, but modern treatment of the geology, then to show how existing plate trajectories -once modified to account for compaction errors -fit remarkably well with the geology, both spatially and temporally.…”

“…One can use Gplates (Boyden et al 2011;Gurnis et al 2012;Williams et al 2012) as did Sigloch and Mihalynuk (2013) to compare the location of the eastern vertical slab with the predicted paleogeographic trajectories for North America from 140 Ma to present as deduced from the five separate models of Shephard et al (2012): (1) a hybrid hotspot model, which uses moving hotspots in both the Atlantic and Indian oceans from 100 Ma to the present (O'Neill et al 2005), and fixed hotspots for older ages (Müller et al 1993); (2) a fixed hotspot reference frame model (Müller et al 1993); (3) framework that also assumes no longitudinal motion of Africa (Steinberger and Torsvik 2008;Seton et al 2012); and (5) an entirely different type of model that matches subducted slabs with subduction zones (van der Meer et al 2010). Uncertainty pervades nearly every aspect of the reconstructions, including possible errors in properly locating and dating hotspots, the shape of the North American margin, error envelopes in paleomagnetic pole locations and ages, errors in assigning movement to hotspots, and in the case of the subduction model, mistakes in matching mantle anomalies with subduction zones once the subducting slab has broken.…”