Age of Oceanic Basalts of Bol'shoi Lyakhov Island (New Siberian Islands): Implication for the Western Boundary of the South Anyui Ocean in the Jurassic

摘要

Serpentinites and pillow basalts exposed in the southeastern part of Bol'shoi Lyakhov Island are considered the northwestern continuation of the South Anyui suture of Chukotka [1, 2]. However, some researchers doubt that these rocks represent the lithos-phere of the Mesozoic South Anyui oceanic basin. According to the rotation hypothesis of the opening of the Amerasian basin, it should be confined to Chukotka structures and not extend to the west [3]. Previous data on the inferred Paleozoic age of the oceanic pillow basalts exposed on the island [4] suggest that the northwestern continuation of the suture is the Paleozoic col-lisional zone, which lacks a direct relation to the Mesozoic tectonic events in the East Arctic. We present new data on the Middle-Late Jurassic age of the oceanic basalts of Bol'shoi Lyakhov Island. Consequently, they formed precisely in the South Anyui oceanic basin. These data are of great importance for reconstructing the Mesozoic tectonic evolution of the East Arctic region and for discrediting the validity of the popular rotation hypothesis of the opening of the Amerasian oceanic basin.