Apparent polar wander paths for the major continents (200 Ma to the present day): a palaeomagnetic reference frame for global plate tectonic reconstructions

Abstract

and Antarctica for the last 200 Myr are proposed. Computation of these APW paths is based upon the latest version (4.5a) of the Global Paleomagnetic Database (GPMDB), a revised global plate tectonic model since the Early Jurassic, and a new technique for generating smoothed APW paths. The smoothing technique includes the following steps: (1) pre-selection of palaeopoles, including pre-filtering parameters (number of sites, number of samples per site, 95 per cent confidence circle about mean direction, cleaning procedure, and time uncertainty); (2) generation of palaeolatitude and declination plots for a reference site on each continent that combines palaeopoles via a global plate tectonic circuit; (3) independent spline regression analyses of the palaeolatitude and declination plots; (4) removal of palaeolatitude or declination data that deviate by more than 10 • from the regression curves (post-filtering process); (5) generation of synthetic APW paths from the resulting palaeolatitude and declination plots. These synthetic APW paths are then rotated into African coordinates to determine the best-fit APW path and a global palaeomagnetic reference frame. Four representative plate tectonic reconstructions and global plate velocity fields are presented for the three time intervals that correspond to globally synchronous changes in plate motion.Plate tectonic reconstructions are based upon hierarchical data structures that describe the relative positions between pairs of plates. Each position of a plate A in the geological past is specified through the Euler pole and angle of a finite rotation that carries this plate from the present position to the position assumed at time t relative to a plate B, which is considered at rest with respect to the present geographical frame of reference. Hence, all the rotation poles included in a plate tectonic model are expressed through standard geographical coordinates. However, in these tree-like structures a reference continent occupies the topmost node. The motion of this reference plate must be first determined with respect to an external reference frame. Then, a transformation must be found that translates coordinates relative to the external frame into standard geographical coordinates. The identification of a physically meaningful external reference frame is one of the most interesting fields of research in plate tectonics. In this paper we use palaeomagnetic data to determine the orientation of the root continent with respect to a palaeomagnetic frame of reference.This determination, as well as the translation of the palaeomagnetic coordinates into the corresponding geographical coordinates, requires two basic assumptions.A first assumption is that the Earth's time-averaged palaeomagnetic field can be modelled through a spherical harmonic expansion having tesseral and sectoral coefficients equal to zero. This geocentric axial hypothesis is justified by the observation that the field is calculated by averaging the data over intervals of time that are supposed to be sufficien...

Guadalupe pluton–Mariposa Formation age relationships in the southern Sierran Foothills: Onset of Mesozoic subduction in northern California?

“…The intrusion of $170 Ma granitoid bodies in the westernmost Klamaths and restricted occurrences of younger plutons to progressively more easterly belts [Hacker et al, 1995;Irwin and Wooden, 1999;Irwin, 2003] suggest that the left-lateral offset of the Klamath salient took place over the interval $150-140 Ma as the crustal assembly of oceanic terranes and superjacent strata gradually migrated westward off the subducting plate's deep-seated magmagenic zone. This seaward transport of the Klamath Province apparently occurred during a relatively brief period characterized by sinistral slip along the western margin of the continent [Saleeby, 1992;Saleeby et al, 1992], and terminated at the time of development of the KimmeridgianTithonian cusp in the North and South American apparent polar wander paths [May and Butler, 1986;Schettino and Scotese, 2005]. The Guadalupe Igneous Complex itself exhibits the effects of sinistral shear.…”

“…Mid-Cretaceous and later head-on convergence involved at least a modest component of Late Cretaceous dextral transpression [Engebretson et al, 1984;Nadin and Saleeby, 2008], followed by Neogene overriding Ma and intra-arc spreading of the medial Klamath terrane assembly, with oceanic crust produced and/or tectonically inserted outboard (Rattlesnake Creek terrane and Jura-Triassic arc belt) and inboard (North Fork terrane), followed by onset of an important component of transpressive underflow, generating a Middle Jurassic calcalkaline belt with orange trend line of volcanic-plutonic arc from compilation by Irwin [2003] and outboard Red Ant blueschists. (c) Transpressive convergence resulting in hot hanging wall generation of high-grade amphibolites, blueschists, and eclogites at $170-150 Ma, landward arc formation, and deposition of the Galice-Mariposa sequence, followed by westward step out of the transpressive plate junction, with sinistral migration of the Klamath salient relative to the alongstrike Sierran arc attending the 150-140 Ma development of cusps in the North and South American apparent polar wander tracks [May and Butler, 1986;Schettino and Scotese, 2005]; continuing transpression created a modestly active volcanic-plutonic arc, fore-arc section, and trench deposits, giving way at $125 -120 Ma [Sager, 2007] to mid and Late Cretaceous nearly orthogonal subduction and production of the massive Sierra Nevada batholith, involving minor dextral transpression. The red dashed line is the trend of the mid Cretaceous batholith, after the compilation by Irwin [2003].…”

Absolute plate motions since 130 Ma constrained by subduction zone kinematics

“…We test the van der Meer et al (2010; herein denoted V2010) reference frame as well as 185 two purely paleomagnetic reference frames: those of Schettino and Scotese (2005;186 herein denoted S2005), and the 'Running Mean' reference frame of 187 herein denoted T2012). We also consider a 'no--net rotation' APM model derived for the 188 last 130 Ma by removing the net rotation stage pole at 1 Myr intervals, and determining 189 the APM path for Africa that minimizes NLR (see also .…”

Plate subrotations

“…[64] Considering results obtained in other data sets, such as paleomagnetic data [Schettino and Scotese, 2005], we find that rotation of North America can be compared in different reference frames. In fact, in their recent paper, Schettino and Scotese [2005] present rotations for North America relative to North Africa, in order of 20°during the Cenozoic (Dt = 67.7 Ma), whereas using the two-rotation model, and inverting data of [Gordon and Jurdy, 1986] relative to the hot spots, we obtain rotations of 7.2°during a time interval Dt = 43 Ma, with small subrotation adjustments in order of 1.4°during the same time interval.…”