U.S. Geological Survey Professional Paper Volume 1626

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1902 Excerpt: ...northern-accretion interpretation, and the moderately abundant paleomagnetic data that support the southern-accretion interpretation. Accepting the northernaccretion interpretation requires radical reinterpretation of the paleomagnetic studies. Accepting the southern-accretion interpretation require (1) radical reinterpretation of the geologic data supporting the northern-accretion interpretation (Monger and others, 1996); (2) construction of a southerly route of tectonic migration starting in the Late Triassic, when the Wrangellia superterrane is interpreted to have formed at about 10 paleolatitude (as discussed by lrving and others, 1996, and Cowan and others, 1997); (3) accretion of the Wrangellia (lnsular) superterrane and, possibly, the western part of the 1ntermontane superterrane at the latitude of present-day Baja California at about 90 to 95 Ma (1rving and others, 1996; Cowan and others, 1997); and (4) a complex tectonic and rapid migration of the Wrangellia (lnsular) superterrane and the western part of the 1ntermontane superterrane along the western part of the North American cratonal margin for a distance of about 3,000 km from about 83 to 34 Ma (Cowan and others. 1997) along a series of faults (such as the Fraser Figure 5.--Paleolatitude versus time for terranes and overlap assemblages in the Russian Far East, Alaska, and the Canadian Cordillera. A, Kolyma-Omolon superterrane. B, Outboard terranes in the Russian Northeast. C, lnterior and Arctic Alaska. D, South-central Alaska. E, Southeastern Alaska and the Canadian Cordillera. Time scale from Palmer (1983). Plots are derived from table 3 and cited references; vertical bars represent range of paleolatitude in samples. See subsection of text entitled Paleomagnetic-Variation Diagrams...