We present a synthesis of 0–5 Ma paleomagnetic directional data collected from 17 different locations under the collaborative Time Averaged geomagnetic Field Initiative (TAFI). When combined with regional compilations from the northwest United States, the southwest United States, Japan, New Zealand, Hawaii, Mexico, South Pacific, and the Indian Ocean, a data set of over 2000 sites with high quality, stable polarity, and declination and inclination measurements is obtained. This is a more than sevenfold increase over similar quality data in the existing Paleosecular Variation of Recent Lavas (PSVRL) data set, and has greatly improved spatial sampling. The new data set spans 78°S to 53°N, and has sufficient temporal and spatial sampling to allow characterization of latitudinal variations in the time‐averaged field (TAF) and paleosecular variation (PSV) for the Brunhes and Matuyama chrons, and for the 0–5 Ma interval combined. The Brunhes and Matuyama chrons exhibit different TAF geometries, notably smaller departures from a geocentric axial dipole field during the Brunhes, consistent with higher dipole strength observed from paleointensity data. Geographical variations in PSV are also different for the Brunhes and Matuyama. Given the high quality of our data set, polarity asymmetries in PSV and the TAF cannot be attributed to viscous overprints, but suggest different underlying field behavior, perhaps related to the influence of long‐lived core‐mantle boundary conditions on core flow. PSV, as measured by dispersion of virtual geomagnetic poles, shows less latitudinal variation than predicted by current statistical PSV models, or by previous data sets. In particular, the Brunhes data reported here are compatible with a wide range of models, from those that predict constant dispersion as a function of latitude to those that predict an increase in dispersion with latitude. Discriminating among such models could be helped by increased numbers of low‐latitude data and new high northern latitude sites. Tests with other data sets, and with simulations, indicate that some of the latitudinal signature previously observed in VGP dispersion can be attributed to the inclusion of low‐quality, insufficiently cleaned data with too few samples per site. Our Matuyama data show a stronger dependence of dispersion on latitude than the Brunhes data. The TAF is examined using the variation of inclination anomaly with latitude. Best fit two‐parameter models have axial quadrupole contributions of 2–4% of the axial dipole term, and axial octupole contributions of 1–5%. Approximately 2% of the octupole signature is likely the result of bias incurred by averaging unit vectors.

The Phanerozoic tectonic evolution of the Circum-North Pacific is recorded mainly in the erogenic collages of the Circum-North Pacific mountain belts that separate the North Pacific from the eastern North Asian and western North American Cratons. The collages consist of tectonostratigraphic terranes, composed of fragments of igneous arcs, accretionary-wedge and subduction-zone complexes, passive continental margins, and cratons, that are overlapped by continental margin arc and sedimentary basin assemblages. The geologic history of terranes and overlap assemblages is highly complicated because of post-accretion dismemberment and translation during strike-slip faulting that occurred subparallel to continental margins. The complex tectonics of this region is analyzed by the following steps. (1) Tectonic environments for the erogenic collage are assigned from regional compilation and synthesis of stratigraphic and faunal data. The tectonic environments include cratonal, passive continental margin, metamorphosed continental margin, continental-margin arc, island arc; oceanic crust, seamount, and ophiolite, accretionary wedge and subduction zone, turbidite basin, and metamorphic. (2) Correlations are made between terranes. (3) Coeval terranes are grouped into a single tectonic origin, i.e., a single island arc or subduction zone. (4) Igneous arc and subduction zone terranes, that are interpreted as being tectonically linked, are grouped into coeval, curvilinear arc-subduction zone complexes. (5) By use of geologic, faunal, and paleomagnetic data, the original positions of terranes are interpreted. And (6) the paths of tectonic migration are constructed. Six processes overlapping in time were responsible for most of the complexities of the collage of terranes and overlap assemblages around the Circum-North Pacific. First, in the Late Proterozoic, and the Late Devonian and Early Carboniferous, major periods of rifting occurred along the margins of Northeast Asia and northwestern part of the North American Cordillera. The rifting resulted in fragmentation and formation of cratonal and passive continental margin terranes from each continent that eventually migrated and accreted to other sites along the evolving margins of the original or adjacent continents. Second, from about the Late Triassic through the mid-Cretaceous, a succession of island arcs and tectonically paired subduction zones formed near continental margins. Third, from about mainly the mid-Cretaceous through the Present, a succession of igneous arcs and tectonically paired subduction zones formed along the continental margins. Fourth, from about the Jurassic to the Present, oblique convergence and rotations caused orogen-parallel sinistral and then dextral displacements within the upper plate margins of Northeast Asia and the North American Cordillera. The oblique convergences and rotations resulted in the fragmentation, displacement, and duplication of formerly more-continuous arcs, subduction zones, and passive continental margins. These fragments were su...

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