Figure 1. Cartoon illustrating principal features of mesoplate-lithoplate hypothesis, modified after Pilger (2004). Two mesoplates, four large lithoplates, one microlithoplate, and one hotspot (with trace) are shown. Bullseye symbol implies relative fixity of the indicated mesoplate and microlithoplate; that is, other objects are moving relative to them. Note divergence of Mesoplate B relative to A in the vicinity of the subduction zone bounding Lithoplates 2 and 3, with low-angle subducting Lithoplate 3 filling the gap between the mesoplates. Note convergence of Mesoplates A and B in the vicinity of the Lithoplate 4 subduction zone beneath the microlithoplate and Lithoplate 1, forming a “double” subduction zone. Spreading center between Lithoplates 3 and 4 occurs entirely above Mesoplate B; isostatic rise of asthenosphere results in partial melting of Mesoplate B beneath ridge, progressively converting mesoplate to asthenosphere. Hotspot a is moving relative to Mesoplate A, while Lithoplate 3 is moving relative to both Mesoplates B (with embedded hotspot) and A.
Figure 2. Inferred boundaries of the three principal mesoplates (modified after Pilger, 2004). Dotted curves are boundaries taking into account satellite gravity field (Lui et al., 2003). Dash-dot curves are boundaries initially inferred by Pilger (2003a).
Figure 3a. Pacific Ocean hotspot trace dates and loci: Sample location (crosses), with age (Ma) (compilation of Pilger, 2003). Reconstructed data points (solid circles) and calculated loci (+/- 5 m.y.) according to parameters of Harada and Hamano (2000), interpolated by method of Pilger (2003a). Magnetic isochrons and boundaries from Müller et al. (1997).
Figure 3b. As Figure 3a, with parameters of Norton (2000).
Figure 3c. As Figure 3a, with parameters of Raymond et al. (2000).
Figure 4a. Hawaiian-Emperor trace dates: Sample location (crosses), with age (Ma) (compilation of Pilger, 2003a). Reconstructed data points (solid circles) and calculated loci (+/- 5 m.y.) according to parameters of Harada and Hamano (2000), interpolated by method of Pilger (2003a). Magnetic isochrons and plate boundaries from Müller et al. (1997). Seamounts (open diamonds) from Wessel (2004).
Figure 4b. As Figure 4a, with parameters of Norton (2000).
Figure 4c. As Figure 4a, with parameters of Raymond et al. (2000).
Figure 5a. Louisville trace dates: Sample location (crosses), with age (Ma) (compilation of Pilger, 2003). Reconstructed data points (solid circles) and calculated loci (+/- 5 m.y.) according to parameters of Harada and Hamano (2000), interpolated by method of Pilger (2003a). Magnetic isochrons and boundaries from plate Müller et al. (1997). Seamounts on Pacific plate (open diamonds) from Wessel (2004).
Figure 5b. As Figure 5a, with parameters of Norton (2000).
Figure 5c. As Figure 5a, with parameters of Raymond et al. (2000).
Figure 6a. Easter (north cluster) and Foundation (south cluster) trace dates: Sample location (crosses), with age (Ma) (compilation of Pilger, 2003). Reconstructed data points (solid circles) and calculated loci (+/- 5 m.y.) according to parameters of Harada and Hamano (2000), interpolated by method of Pilger (2003a). Magnetic isochrons and plate boundaries from Müller et al. (1997). Seamounts on Pacific plate (open diamonds) from Wessel (2004).
Figure 6b. As Figure 6a, with parameters of Norton (2000).
Figure 6c. As Figure 6a, with parameters of Raymond et al. (2000).
Figure 7a. Austral-Cook trace(s) dates: Sample location (crosses), with age (Ma) (compilation of Pilger, 2003a, supplemented by Koppers and Staudigel, 2005). Reconstructed data points (solid circles) and calculated loci (+/- 5 m.y.) according to parameters of Harada and Hamano (2000), interpolated by method of Pilger (2003a). Magnetic isochrons and plate boundaries from Müller et al. (1997). Seamounts on Pacific plate (open diamonds) from Wessel (2004). Note intersections of pre-Bend and post bend loci, forming two clusters. (Cluster in center-north is Societies Islands
Figure 7b. As Figure 7a, with parameters of Norton (2000).
Figure 7c. As Figure 7a, with parameters of Raymond et al. (2000).
Figure 8. Reunion (north cluster) and Kergulen (south cluster) trace dates, Indian Ocean : Sample location (crosses), with age (Ma) (compilation of Pilger, 2003a). Reconstructed original data points (solid squares), filtered and recalculated data points (open squares; Baksi, 1999) and calculated loci (+/- 5 m.y.) according to parameters of Müller et al. (1993), interpolated by method of Pilger (2003a). Magnetic isochrons and plate boundaries from Müller et al. (1997).
Figure 9. Tristan trace dates, South Atlantic Ocean : Sample location (crosses), with age (Ma) (compilation of Pilger, 2003a). Reconstructed original data points (solid squares) and calculated loci (+/- 5 m.y.) according to parameters of Müller et al. (1993), interpolated by method of Pilger (2003a). Magnetic isochrons and plate boundaries from Müller et al. (1997).
Figure 10. Trinidade trace dates, South Atlantic Ocean : Sample location (crosses), with age (Ma) (compilation of Pilger, 2003a). Reconstructed original data points (solid squares) and calculated loci (+/- 5 m.y.) according to parameters of Müller et al. (1993), interpolated by method of Pilger (2003a). Magnetic isochrons and plate boundaries from Müller et al. (1997).
Figure 11a. Central North Atlantic Ocean trace dates: Sample location (crosses), with age (Ma) (compilation of Pilger, 2003a). Reconstructed original data points (solid squares) and calculated loci (+/- 5 m.y.) according to parameters of Müller et al. (1993), interpolated by method of Pilger (2003a). Magnetic isochrons and plate boundaries from Müller et al. (1997).
Figure 11b. Central North Atlantic Ocean trace dates (close-up): Sample location (crosses), with age (Ma) (compilation of Pilger, 2003a). Reconstructed original data points (solid squares) and calculated loci (+/- 5 m.y.) according to parameters of Müller et al. (1993), interpolated by method of Pilger (2003a). Magnetic isochrons and plate boundaries from Müller et al. (1997).
Figure 12. East Australia trace dates (close-up): Sample location (crosses), with age (Ma) (compilation of Pilger, 2003a). Reconstructed original data points (solid squares) and calculated loci (+/- 5 m.y.) according to parameters of Müller et al. (1993), interpolated by method of Pilger (2003a). Magnetic isochrons and plate boundaries from Müller et al. (1997).
Figure 13. K/Ar ages from East Africa . Sample locations (crosses, compilation of Pilger, 2003), reconstructed data points (solid circles) and calculated loci (+/- 5 m.y.) according to parameters of M2000, interpolated by method of Pilger (2003a).
Figure 14a. K/Ar ages of basalts (<40 Ma) from western North America. Larger and lighter circles are younger; compilation of USGS: Zartman et al., 1995), Loci of North America in Tristan (closed circles) and Hawaiian (open diamonds) reference frames, anchored near inferred Yellowstone and Raton hotspots (5 m.y. intervals) are also shown.
Figure 14b. Reconstructed data points as in Fig. 13a, from North America to Tristan reference frame according to parameters of M2000 interpolated by method of Pilger (2003a). Larger and lighter circles are younger.
Figure 14c. Reconstructed data points as in Fig. 13a, in North America to Hawaiian reference frame according to parameters of Raymond et al. (2000) interpolated by method of Pilger (2003a). Larger and lighter circles are younger.
Figure 15. Locations of Antilles volcanic arcs reconstructed relative to North American plate (gray symbols) according to Pindell and Kennan (2001; 2002). Black symbols are equivalent arcs reconstructed to Tristan reference frame according to the parameters of M2000, interpolated by method of Pilger (2003a). Squares: present; circles: 9.5 Ma; diamonds: 19 Ma; north-triangles: 33Ma; south-triangles: 46 Ma; west-triangles: 56 Ma; pluses: 72 Ma; X’s: 84 Ma; north-semicircles: 100 Ma.
Figure 16. Map of present stress measurements and flow-lines. Bars: Maximum principal horizontal compressive stress measurements (s1). Flow-lines (small circles): Instantaneous direction of motion of North American (to the southwest) relative to the global instantaneous hotspot reference frame of Gripp and Gordon (1990). Data from World Stress Map Project, 2003.
Figure 17a.
Figure 17b.
Figure 17c.
Figure 17. Maps of paleostress measurements and flow-lines 0 to 90 Ma in 10 m.y. intervals, Western United States. Bars: Maximum principal horizontal compressive paleostress measurements (s1; compiled by Pilger, 2003a). Flow-lines (small circles): Instantaneous direction of motion of North American (to the west) relative to the global hotspot reference frame of Müller et al. (1993), calculated using method of Pilger (2003a). Solid curves: 0, 20, 40, 60, and 80 Ma; dashed curves: 5, 15, 25 … Ma; dotted curves: 10, 30, 50, 70, 90 Ma. Contemporary stress measurements are not included in 0 to 10 Ma map.
Figure 18. Maps of paleostress measurements and flowlines 90 to 130 Ma in 10 m.y. intervals, United States and Canada
Figure 19. Data points from Hawaiian-Emperor island-seamount chain with loci of calculated motion of Pacific plate relative to Pacific (Hawaiian; PCFC-HAWA) hotspot reference frame, according to Raymond et al. (2000) reconstruction model, interpolated using methods of Pilger (2003a). Also shown are loci of Pacific plate relative to Atlantic-Indian Ocean
Figure 20. Map of reconstructed West Antarctica relative to present-day Antarctica coast, using parameters of Müller et al. (1993) and Raymond et al. (2000) interpolated using method of Pilger (2003a); darker outlines are younger. Adjacent seafloor with magnetic isochrons and plate boundaries from Müller et al. (1997) and reconstructions at 10 m.y. increments from 0 to 80 Ma based on Müller et al. (1993) and Raymond et al. (2000), interpolated using method of Pilger (2003a). Note increasing overlap of reconstructed West Antarctica for earlier reconstructions.
Figure 21. Schematic evolution of the Nazca Ridge (N.R.) and Tuamotu Ridge (T.R.) from the Easter hotspot (after Pilger and Handschumacher, 1981). Reconstructions for indicated magnetic isochrons with ages (Ma) in parentheses. From prior to isochron 13 (perhaps as early as isochron 22) until isochron 11, the Easter hotspot was overlain by the Pacific-Farallon ridge, with “mirror-image” Tuamotu and Nazca Ridges resulting. By isochron 9 a transform fault moved over the hotspot and subsequently, up to the present, the Farallon/Nazca plate has overlain the hotspot.
Figure 22. Reconstructed magnetic isochrons (Müller et al., 1997) and hotspot loci relative to Easter hotspot according to Raymond et al. (2000) model, interpolated using method of Pilger (2003a). Note convergence of isochrons between 21 and 5 near the inferred hotspot. Locus on west is relative to Pacific plate; locus on left is relative to Nazca/Farallon plate.
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