S U M M A R YA paleomagnetic and rock magnetic study of the Carboniferous Deer Lake Group red beds of Newfoundland was performed to detect and correct for inclination shallowing. Results indicate a primary remanence carried by magnetite, with a mean direction of D = 179.7 • , I = 33.7 • , α 95 = 7.2 • which corresponds to a paleopole position of 22.2 • N, 122.3 • E, A 95 = 7.6 • . Correcting the inclination using anisotropy of anhysteretic remanence and the measured individual particle anisotropy gives a corrected direction of D = 178.8 • , I = 50.9 • , α 95 = 6.3 • corresponding to a paleopole position at 8.4 • N, 122.7 • E, A 95 = 7.2 • . This correction is larger than that of other red beds from the Maritime Provinces of Canada, but is consistent with paleoenvironmental reconstructions, placing North America in a more arid climate zone. Our inclination-corrected results have important implications for this portion of North America's apparent polar wander path and suggest a correction is needed for other red bed-derived APWPs. We have determined the range of flattening factors f , defined as the proportionality constant between the tangents of the measured (I m ) and field (I o ) inclinations, tan(I m ) = f tan(I 0 ), from this study and previous inclination correction studies to estimate inclination corrections. Using the range of haematite f factors observed in this study to correct the Neogene red bed inclinations from the Vallès-Penedès Basin (NE Spain) yields inclinations consistent with the known geomagnetic field inclination in the Neogene, thus indicating that the range of f factors reported here may be used to estimate the magnitude of inclination shallowing in red beds.

Tectonic processes, fl exure due to crustal loading, and dynamic mantle fl ow each impart a unique imprint on topography and geomorphic responses over time scales of 10 4 to 10 6 yr. This paper explores the mobility of regional drainage divides as a key geomorphic metric that can distinguish between the various processes driving crustal deformation in the greater Yellowstone region of the northwestern United States. We propose a new analysis that quantifi es the differences between the location of the presentday drainage divide from divides synthetically generated from fi ltered topography to determine the relative impact of tectonic and dynamic mantle infl uences on landscape development. The greater Yellowstone region is an opportune location for this investigation because contrasting models have been proposed to explain the parabolic shape of elevated topography and active seismicity that outline the imprint of hypothesized hotspot activity. Drainage divides synthesized from topography fi ltered at 50, 100, and 150 km wavelengths within the greater Yellowstone region show that the locations of the actual and synthetic Snake River drainage divides are controlled by both dynamic and fl exural mechanisms in the eastern greater Yellowstone region, but by fl exural mechanisms only in the western greater Yellowstone region. The location of the actual divide deviates from its predicted position in the fi ltered topography where tectonic controls, such as active faults (e.g., Centennial and Teton faults), have uplifted large footwall blocks. Our results are consistent with the notion of a northeastward-propagating greater Yellow stone region topographic and seismic parabola, and suggest that Basin and Range extension follows from, rather than precedes, greater Yellowstone region dynamic topography. Furthermore, our analysis suggests that eastward migration of the Snake River drainage divide lags behind the continued northeastward propagation of high-standing topography associated with the Yellowstone geophysical anomaly by 1-2 m.y.

Magnetic fields in the early solar system may have driven the inward accretion of the protoplanetary disk (PPD) and generated instabilities that led to the formation of planets and ring and gap structures. The Allende carbonaceous chondrite meteorite records a strong early solar system magnetic field that has been interpreted to have a PPD, dynamo, or impact‐generated origin. Using high‐resolution magnetic field imaging to isolate the magnetization of individual grain assemblages, we find that only Fe‐sulfides carry a coherent magnetization. Combined with rock magnetic analyses, we conclude that Allende carries a magnetization acquired during parent body chemical alteration at ~3.0–4.2 My after calcium aluminum‐rich inclusions in an >40 µT magnetic field. This early age strongly favors a magnetic field of nebular origin instead of dynamo or solar wind alternatives. When compared to other paleomagnetic data from meteorites, this strong intensity supports a central role for magnetic instabilities in disk accretion and the presence of temporal variations or spatial heterogeneities in the disk, such as ring and gap structures.

S U M M A R YThe potential of using high-field anisotropy of isothermal remanence magnetization (hf-AIR) measurements for determining the origin of natural remanent magnetization in red beds and for identifying and correcting possible red-bed inclination shallowing was investigated for specimens of the Carboniferous Shepody Formation of New Brunswick and Nova Scotia, Canada. The technique makes it possible for a typical paleomagnetic laboratory to measure the remanence anisotropy of high-coercivity hematite.High-field (hf) AIR was used in conjunction with 100 mT alternating field (af) and 120 • C thermal demagnetization to separate the contribution of hematite to the remanence anisotropy from that of magnetite/maghemite and goethite, respectively. A 5-T impulse DC magnetic field was used for the hf-AIR to reset the magnetic moment of high-coercivity hematite so that demagnetization between AIR orientations was not necessary. The ability of a 5-T field to reset the magnetization was tested by generating an isothermal remanent magnetization acquisition curve for hematite by using impulse DC magnetic fields up to 5 T in one orientation and followed by applying a field in the opposite direction at each step. Each field application was treated by 120 • C heating and 100 mT af demagnetization before measurement. At 5T, the difference between the magnetizations applied in opposite directions disappeared indicating that no magnetic memory persisted at this field strength. We performed a validity and reproducibility test of our hf-AIR measurement technique by measuring three specimens multiple times along two orthogonal coordinate systems. The method yielded highly reproducible results and, on rotating the specimen's coordinates, the fabric rotated by 90 • as expected, showing that it is not an artifact of the technique. We also measured hf-AIR on samples that had previously been chemically demagnetized in 3N HCl to remove the secondary, chemically grown pigmentary hematite. The hf-AIR fabric of leached samples is similar to that of untreated samples, but shows a better-defined magnetic lineation and imbrication. We interpret the fabric observed for the Shepody Formation to be a compactional fabric that has been reoriented by strain during folding following a flexural-slip model.

S U M M A R YA palaeomagnetic and magnetic anisotropy study was conducted on the lower-middle Carboniferous Maringouin and Shepody red bed formations of the Maritime Provinces of Canada to detect and correct inclination shallowing. Because of the shallow inclinations commonly observed in red beds and the strong dependence of North America's Palaeo-Mesozoic apparent polar wander (APW) on red beds, inclination shallowing may substantially affect large portions of North America's APW path.Hematite is the primary magnetic mineral carrier in these red beds, accompanied by secondary magnetite, maghemite, goethite and pigmentary hematite.Thermal and chemical demagnetization of the Shepody Fm. successfully isolated characteristic remanence directions of D = 177 • , I = 20.4 • , α 95 = 6.5 • , N = 19 and D = 177.8 • I = 17.7 • , α 95 = 6.9 • , N = 16, respectively. Thermal demagnetization of the Maringouin Fm. isolated a characteristic remanence direction of D = 178.7 • , I = 24.9 • , α 95 = 14.5 • , N = 9.High field anisotropy of isothermal remanence followed by alternating field and thermal cleaning on leached samples was used to isolate the fabric of hematite. Individual particle anisotropy was measured directly from magnetic separates using a new technique. Hematite's magnetic fabric and particle anisotropy were used to apply an inclination correction.Our inclination corrections indicate up to 10 • of inclination shallowing, corresponding to corrected palaeopole positions of 27.2 • N, 118.3 • E, A 95 = 6.2 • and 27.4 • N, 117.2 • E, A 95 = 13.1 • for the Shepody and Maringouin formations, respectively. This correction corresponds to a ∼ 6 • increase in colatitude for Carboniferous North America, which translates into approximately a 650 km change in North America's palaeogeographic position. The proposed position of North America supports a Pangea B-type reconstruction.