Early Permian location of western North American terranes based on brachiopod, fusulinid, and coral biogeography

Brachiopod, rugose coral, and fusulinid faunas present in Early Permian rocks along northern and western margins of North America, in both cratonal localities and accreted terranes, have been compared statistically, allowing refinement in placement of these terranes relative to the North American continental margin at that time. Statistical tests, including conventional and probabilistic indices of similarity, as well as multivariate analysis, show that the faunas of Wrangellia-Alexander are most similar to those of Stikinia and Quesnellia, and to the Yukon-Canadian Rocky Mountains part of the continental margin. They also show that faunas of the Eastern Klamath terrane are most similar to those of Stikinia, Quesnellia, and the central cordilleran part of the continental margin. These results suggest that during the Early Permian Wrangellia-Alexander was the northernmost of these terranes, lying west of the Yukon-Canadian Rocky Mountains region, and the Eastern Klamath terrane was the southernmost, lying west of the central Cordillera. Stikinia and Quesnellia were in intermediate positions. These relative latitudes are compatible with latitudinal determinations based on paleomagnetic data. Faunal diversity in the Eastern Klamath and Stikine terranes is similar to that at similar latitudes on the craton, whereas diversity in the Wrangellia-Alexander terrane is considerably lower than that of the latitudinally similar Yukon-Canadian Rocky Mountains area. As diversity is, in part, a function of temperature, this may suggest water around the Wrangellia-Alexander terrane was cooler than that along the continental margin. Therefore, we suggest that warm-water currents bathed the southern terranes and the southern and central parts of coastal North America, whereas cool-water currents influenced the northernmost terrane (Wrangellia-Alexander). Revised Otsuka similarity coefficients for corals show higher similarities between western North American terranes and the western continental margin than previously published, but they still are relatively low. This and the overall patterns of similarity and limits on distribution of Tethyan corals and fusulinids in the eastern Panthalassa suggest that Wrangellia-Alexander, Stikinia, and the Eastern Klamath terranes were at approximately the same distance (estimated at 2000-3000 km) from their latitudinally equivalent segments of the North American craton. (C) 2002 Elsevier Science B.V. All rights reserved.