Fig. 1. Pacific apparent polar wander path. (Top) mid- to Late Cretaceous poles. Filled circles represent poles calculated from magnetic lineation skewness (Acton and Gordon, 1991, Vasas et al., 1994 and Petronotis and Gordon, 1999). Stars are poles determined from seamount paleomagnetic studies (Sager and Pringle, 1988 and Sager and Koppers, 2000). Filled squares are composite poles from skewness, seamount, and core data (Petronotis et al., 1992 and Sager, 2003). Open star shows pole from Chatham Island, near New Zealand (Grindley et al., 1977). (Bottom) Early Cretaceous to Jurassic poles, calculated from magnetic lineation skewness (Larson and Sager, 1992). Two different pole paths result from solutions computed with (left; filled diamonds) and without (right, open squares) anomalous skewness factor. A 125 Ma combined pole shown for reference. (Inset) Polar wander path of Cox and Gordon (1984). Gray area shows inferred pole path. Pole K is from DSDP basalt cores; pole S from seamount anomaly inversions; KT, from latest Cretaceous cores, M and 307 at either end of the pole path are colatitude arcs from cores from DSDP Site 307 and Midway Atoll. In all plots, thin ellipses and circles show 95% confidence regions.

Fig. 2. Site locations of basalt core and seamount data analyzed in this study. Different core symbols denote age. “X” symbols show locations of seamounts used for declination data. Gray lines show representative magnetic lineations (labeled by anomaly number and age). Gray area shows Ontong Java Plateau.

Fig. 3. Colatitude arcs determined from Pacific plate basalt cores. Each arc is a segment of the small circle upon which a paleocolatitude constrains the paleomagnetic pole to lie. Heavier lines show data from N ≥ 5 independent units. Solid arcs show data from seamounts; dashed arcs, from crustal basalt; and long-dash arcs from intrusives.

Fig. 4. Histogram of paleomagnetic data vs. age, in 5 Myr bins. Black bars show the number of site colatitudes, whereas gray bars show the estimated number of independent magnetic units. Three gray bars are truncated and numbers atop these bars give the number of independent units. Small open circles show seamount declination data.

Fig. 5. Mean paleomagnetic pole for 80 Ma (age range 75–82). Solid and dashed arcs show paleocolatitudes from basalt core data. Solid lines represent paleocolatitudes from seamounts; short dashed lines denote ocean crust; and long dashed line show intrusives. Gray, dash–dot lines show loci of the paleomagnetic pole constrained by seamount declination data. Numeric identifiers correspond to DSDP and ODP site numbers (see Table 1). Letter identifiers abbreviate a seamount name (Table 2). Ellipse shows 95% confidence region for mean pole, whoses location is shown by the open circle. Filled circle symbol shows the location of the pole determined without using seamount declination data.

Fig. 6. Mean paleomagnetic pole for 92 Ma (age range 90–94 Ma). Conventions as in Fig. 5. Filled square shows pole determined from oriented sediment cores recovered from ODP Site 869 (Sager et al., 1995).

Fig. 7. Mean paleomagnetic pole for 112 Ma (data range 110–115 Ma). Conventions as in Fig. 5. Filled square is 125 Ma pole of Petronotis et al. (1992), which is based mainly on the skewness of anomaly M0, augmented with seamount magnetic anomaly inversion poles and core paleocolatitudes. Heavier lines show paleocolatitudes determined from N ≥ 5 independent units.

Fig. 8. Mean paleomagnetic poles for 123 Ma (left; age range 118–130 Ma) and 121 Ma (right; age range 118–122 Ma) from cores recovered from Ontong Java Plateau. Conventions as in Fig. 5 and Fig. 6.

Fig. 9. Apparent polar wander path summary. Published paleomagnetic poles shown as in Fig. 1 (filled circles, stars, and squares) with the addition of poles from this study (open circles). Ellipses show 95% confidence regions. Heavy gray arrows represent polar wander. Dashed Jurassic section shows probable southward polar motion, which is poorly defined by existing data. Solid arrow from 123 to 92 Ma shows slow Early to mid-Cretaceous motion. Dashed line between 92 and 81 Ma poles shows section of possible rapid motion. Arrow at northern end of polar path shows northward drift in Late Cretaceous and afterwards.

Fig. 10. Plot showing areas with anomalous paleomagnetic data in the south Pacific. Filled circles show sites with data used to determine the Pacific APWP. Note that no data are available from south of the equator, except for OJP and Chatham Island. Open stars show sites with anomalous paleolatitudes on OJP. Light gray areas show magnetic lineations that give anomalous effective inclinations from skewness studies (Larson and Sager, 1992 and Petronotis and Gordon, 1999). Box shows location of anomalous Jurassic ocean crust on island of Malaita (Ishikawa et al., 2005). Star shows Chatham Island, a site that gives a paleomagnetic pole that is apparently concordant with north Pacific plate. KQZ and JQZ stand for Cretaceous Quiet Zone and Jurassic Quiet Zone, respectively. Straight lines show magnetic lineations and fracture zones. Heavy isochrons are from Müller et al. (1997) and thin lines are M-anomalies from Nakanishi et al. (1992).

Paleomagnetic colatitude data

Table heads: Flows (n) = number of lava flows or igneous units; Units (N) = number of independent magnetic units; Colat = mean, corrected colatitude; Std. Err. = standard error of colatitude; Pol. = polarity (N = normal, R = reversed, M = mixed); Age type = method of determining age (Ar = ⁴⁰Ar–³⁹Ar radiometric; Os = osmium–rhenium isochron; L = from magnetic lineation; P = from position and polarity; B = from biostratigraphy); Poles = used for calculation of pole of noted age; OJP = Ontong Java pole.

References: (1) Kono (1980); (2) Cox and Gordon (1984); (3) Nakanishi and Gee (1995); (4) Tarduno et al. (2003); (5) Tarduno and Cottrell (1997); (6) Sager (2005); (7) Cockerham and Hall (1976); (8) Helsley (1993); (9) Steiner (1981); (10) Wallick and Steiner (1992a); (11) Hammond et al. (1975); (12) Mayer and Tarduno (1993); (13) Riisager et al. (2003); (14) Tarduno and Sager (1995); (15) Tominaga et al. (2005); (16) Wallick and Steiner (1992b); (17) Doubrovine and Tarduno (2004); (18) Marshall (1978); (19) Cockerham (1979); (20) Larson and Lowrie (1975); (21) Sager and Horner-Johnson (2005); (22) Sharp and Clague (2002); (23) Koppers (1998); (24) Duncan and Keller (2004); (25) Keller et al. (1995); (26) Pringle and Duncan (1995); (27) Schlanger et al. (1984); (28) Ozima et al. (1983); (29) Mahoney et al. (1993); (30) Waggoner (1993); (31) Ozima et al. (1981); (32) Pringle (1992); (33) Parkinson et al. (2003); (34) Mahoney et al. (2005); (35) Koppers et al. (2003a); (36) Eittreim et al. (1992); (37) Sager (2003); (38) Nakanishi et al. (1999); (39) Nakanishi et al. (1992).

Declination and age data

Table headings: Dec. = declination; Age type = method of determining age (P = inferred from polarity (Chron 33r); Ar = ⁴⁰Ar–³⁹Ar radiometric); Pmag, Age ref. = paleomagnetic and age references; Poles = used for calculation of pole of noted age; OJP = Ontong Java pole.

References: (1) Sager (1992); (2) Francheteau et al. (1970); (3) Sager and Pringle (1987); (4) Cottrell and Tarduno (2003); (5) Sager et al. (1993); (6) Hildebrand and Parker (1987); (7) Sager (1983); (8) Bryan et al. (1993); (9) Ueda (1985); (10) Sager and Pringle (1988); (11) Gordon (1983); (12) Pringle (1993); (13) Keller et al. (1995); (14) Koppers et al. (2003b); (15) Takigami et al. (1989).

Mean paleomagnetic poles

Table headings: Pole type: A = including seamount declinations; B = excluding seamount declinations; C = basalt, seamount declination, and sediment data. Maj., Min., Azim. = major semi-axis, minor semi-axis, and azimuth of major semi-axis of 95% confidence ellipse; N = number of independent magnetic units, with seamount declinations having a value of one.