Global plate motion frames: Toward a unified model

Abstract

[1] Plate tectonics constitutes our primary framework for understanding how the Earth works over geological timescales. High-resolution mapping of relative plate motions based on marine geophysical data has followed the discovery of geomagnetic reversals, mid-ocean ridges, transform faults, and seafloor spreading, cementing the plate tectonic paradigm. However, so-called ''absolute plate motions,'' describing how the fragments of the outer shell of the Earth have moved relative to a reference system such as the Earth's mantle, are still poorly understood. Accurate absolute plate motion models are essential surface boundary conditions for mantle convection models as well as for understanding past ocean circulation and climate as continent-ocean distributions change with time. A fundamental problem with deciphering absolute plate motions is that the Earth's rotation axis and the averaged magnetic dipole axis are not necessarily fixed to the mantle reference system. Absolute plate motion models based on volcanic hot spot tracks are largely confined to the last 130 Ma and ideally would require knowledge about the motions within the convecting mantle. In contrast, models based on paleomagnetic data reflect plate motion relative to the magnetic dipole axis for most of Earth's history but cannot provide paleolongitudes because of the axial symmetry of the Earth's magnetic dipole field. We analyze four different reference frames (paleomagnetic, African fixed hot spot, African moving hot spot, and global moving hot spot), discuss their uncertainties, and develop a unifying approach for connecting a hot spot track system and a paleomagnetic absolute plate reference system into a ''hybrid'' model for the time period from the assembly of Pangea ($320 Ma) to the present. For the last 100 Ma we use a moving hot spot reference frame that takes mantle convection into account, and we connect this to a pre -100 Ma global paleomagnetic frame adjusted 5°in longitude to smooth the reference frame transition. Using plate driving force arguments and the mapping of reconstructed large igneous provinces to core-mantle boundary topography, we argue that continental paleolongitudes can be constrained with reasonable confidence.

Keuper magnetostratigraphy in the southern Mesozoic margin of the Holy Cross Mts. (southeastern edge of the German Basin)

“…These val ues cor re spond well to the Late Tri as sic (Norian) seg ment of the ref er ence Phanerozoic Ap par ent Po lar Wan der Path for Baltica/Eu rope (Torsvik et al, 2012). Sim i lar val ues of ~305-311° dec li na tion and ~-50° have been obtained from the 215-226 Ma Eu ro pean Up per Tri as sic (Walderhaug, 1993;Torsvik et al, 2008). In 33 sam ples (28% of the to tal sam ples; Figs.…”

Earth evolution and dynamics—a tribute to Kevin Burke

“…This is known as the global hybrid frame (Torsvik et al 2008a). TPW is the rotation of the crust and mantle relative to the spin axis.…”

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

“…The non-TPW-corrected paleomagnetic model (#3) is probably the best fit but the paleolatitudes are too far south for a good fit with the known geology. However, as pointed out by Kent and Irving (2010) the majority of the paleolatitudes from North America and other continents used by Torsvik et al (2008a) were determined from sedimentary rocks and thus subject to inclination errors that yielded paleolatitudes that were too low. By using the paleomagnetic determinations from igneous rocks and inclination-corrected poles from sedimentary rocks of Kent and Irving (2010) to correct the non- Sigloch and Mihalynuk 2013), illustrating the approximate relative positions of North America at different times using the five paleogeographical models discussed in the text relative to the tomographically imaged slabs beneath North America.…”

“…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.…”

“…During the opening of the Atlantic Ocean, at least during the JurassicEarly Cretaceous periods, North America was moving westward from a more or less fixed Africa (Coney 1971;Torsvik et al 2008a;Steinberger and Torsvik 2008;Seton et al 2012). This implies that the slab wall formed during westward-dipping subduction because if the slab was easterly dipping beneath western North America -as generally assumed by most workers to have been the case since at least the Triassic -the trench would have migrated westward and, as long as the slab sank vertically, left an inclined slab at depth which dips toward older trench positions.…”