Wrangellia flood basalts in Alaska: A record of plume-lithosphere interaction in a Late Triassic accreted oceanic plateau. ...

• Main Authors: Greene, Andrew R., Scoates, James, Weis, Dominique
• Format: Text
• Language: English
• Published: American Geophysical Union 2016
• Subjects: alaska range; Alaska; Ocean Island
• Online Access: https://dx.doi.org/10.14288/1.0075971; https://doi.library.ubc.ca/10.14288/1.0075971

The Wrangellia flood basalts are part of one of the best exposed accreted oceanic plateaus on Earth. They provide important constraints on the construction of these vast submarine edifices and the source and temporal evolution of magmas for a plume head impinging beneath oceanic lithosphere. Wrangellia flood basalts (∼231–225 Ma) extend ∼450 km across southern Alaska (Wrangell Mountains and Alaska Range) where ∼3.5 km of mostly subaerial flows are bounded by late Paleozoic arc volcanics and Late Triassic limestone. The vast majority of the flood basalts are light rare earth element (LREE) -enriched high-Ti basalt (1.6–2.4 wt % TiO2) with uniform ocean island basalt (OIB) -type Pacific mantle isotopic compositions (ɛ Hf(t) = +9.7 to +10.7; ɛ Nd(t) = +6.0 to +8.1; t = 230 Ma). However, the lowest ∼400 m of stratigraphy in the Alaska Range is LREE-depleted low-Ti basalt (0.4–1.2 wt % TiO2) with pronounced negative high field strength element (HFSE) anomalies and Hf isotopic compositions (ɛ Hf(t) = +13.7 to ...