Publication Date:
2019
Description:
〈span〉〈div〉Abstract〈/div〉Recent studies have debated the timing and spatial configuration of a possible intersection between the Pacific-Izanagi spreading ridge and the northeast Asian continental margin during Cretaceous or early Cenozoic times. Here we examine a newly compiled magmatic catalog of ∼900 published Cretaceous to Miocene igneous rock radioisotopic values and ages from the northeast Asian margin for ridge subduction evidence. Our synthesis reveals that a near-synchronous 56–46 Ma magmatic gap occurred across ∼1500 km of the Eurasian continental margin between Japan and Sikhote-Alin, Russian Far East. The magmatic gap separated two distinct phases of igneous activity: (1) an older, Cretaceous to Paleocene pre–56 Ma episode that had relatively lower ε〈sub〉Nd(t)〈/sub〉 (−15 to + 2), elevated (〈sup〉87〈/sup〉Sr/〈sup〉86〈/sup〉Sr)〈sub〉0〈/sub〉 (initial ratio, 0.704–0.714), and relatively higher magmatic fluxes (∼1090 km〈sup〉2〈/sup〉/m.y.); and (2) a younger, late Eocene to Miocene post–46 Ma phase that had relatively elevated ε〈sub〉Nd(t)〈/sub〉 (−2 to + 10), lower (〈sup〉87〈/sup〉Sr/〈sup〉86〈/sup〉Sr)〈sub〉0〈/sub〉 (0.702–0.707), and a lower 390 km〈sup〉2〈/sup〉/m.y. magmatic flux. The 56–46 Ma magmatic gap links other geological evidence across northeast Asia to constrain an early Cenozoic, low-angle ridge-trench intersection that had profound consequences for the Eurasian continental margin, and possibly led to the ca. 53–47 Ma Pacific plate reorganization.〈/span〉
Print ISSN:
0091-7613
Electronic ISSN:
1943-2682
Topics:
Geosciences
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