Geochronology of the Wrangell Arc: Spatial-temporal evolution of slab-edge magmatism along a flat-slab, subduction-transform transition, Alaska-Yukon
نویسندگان
چکیده
Abstract The Wrangell Arc in Alaska (USA) and adjacent volcanic fields the Yukon provide a long-term record of interrelations between flat-slab subduction Yakutat microplate, strike-slip translation along Denali–Totschunda–Duke River fault system, magmatism focused within proximal to Cretaceous suture zone. Detrital zircon (DZ) U-Pb (n = 2640) lithic (DARL) 40Ar/39Ar dates 2771) from 30 modern river sediment samples document spatial-temporal evolution magmatism, which includes construction some largest Quaternary volcanoes on Earth. Mismatches DZ DARL date distributions highlight impact variables such as mineral fertility downstream mixing/dilution resulting provenance signatures. Geochronologic data initiation at ca. 30–17 Ma both sides Totschunda north flank Wrangell–St. Elias Mountains Alaska, followed by southeastward progression 17–10 Duke Yukon. This is attributable dextral intra-arc, faults change geometry subducting slab (slab curling/steepening). Magmatism then progressed generally westward outboard 13–6 southern northwestward 6 present western Mountains. 13 consistent with previously documented changes plate boundary conditions, include an increase convergence rate angle Ma. Voluminous attributed shallow subduction-related flux melting edge that driven asthenospheric upwelling lateral flat slab. was persistently or remnant zone, indicates upper crustal heterogeneities influenced arc magmatism. Rivers sampled also yield subordinate Paleozoic–Mesozoic age populations reflect earlier episodes underlying accreted terranes match magmatic flare-ups Cordilleran margin.
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ژورنال
عنوان ژورنال: Geosphere
سال: 2021
ISSN: ['1553-040X']
DOI: https://doi.org/10.1130/ges02417.1