Tracking the Late Jurassic apparent (or true) polar shift in U-Pb-dated kimberlites from cratonic North America (Superior Province of Canada)
Articolo
Data di Pubblicazione:
2015
Citazione:
Tracking the Late Jurassic apparent (or true) polar shift in U-Pb-dated kimberlites from cratonic North America (Superior Province of Canada) / D.V. Kent, B.A. Kjarsgaard, J.S. Gee, G. Muttoni, L.M. Heaman. - In: GEOCHEMISTRY, GEOPHYSICS, GEOSYSTEMS. - ISSN 1525-2027. - 16:4(2015), pp. 983-994. [10.1002/2015GC005734]
Abstract:
Different versions of a composite apparent polar wander (APW) path of variably selected global poles assembled and averaged in North American coordinates using plate reconstructions show either a smooth progression or a large (∼30°) gap in mean paleopoles in the Late Jurassic, between about 160 and 145 Ma. In an effort to further examine this issue, we sampled accessible outcrops/subcrops of kimberlites associated with high-precision U-Pb perovskite ages in the Timiskaming area of Ontario, Canada. The 154.9±1.1 Ma Peddie kimberlite yields a stable normal polarity magnetization that is coaxial within less than 5° of the reverse polarity magnetization of the 157.5±1.2 Ma Triple B kimberlite. The combined ∼156 Ma Triple B and Peddie pole (75.5°N, 189.5°E, A95=2.8°) lies about midway between igneous poles from North America nearest in age (169 Ma Moat volcanics and the 146 Ma Ithaca kimberlites), showing that the polar motion was at a relatively steady yet rapid (∼1.5°/Myr) pace. A similar large rapid polar swing has been recognized in the Middle to Late Jurassic APW path for Adria-Africa and Iran-Eurasia, suggesting a major mass redistribution. One possibility is that slab breakoff and subduction reversal along the western margin of the Americas triggered an episode of true polar wander.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
APW; Jurassic; Kimberlites; TPW; U-Pb perovskite; Geochemistry and Petrology; Geophysics
Elenco autori:
D.V. Kent, B.A. Kjarsgaard, J.S. Gee, G. Muttoni, L.M. Heaman
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