The Ushky anomaly (Figure A89) is located below northeast Asia in the upper mantle and uppermost part of the lower mantle. It is E-W trending and at ~920 km depth it connects to the N-S trending Sakhalin slab in the west, and the NE-SW trending Kamchatka-Kuriles slab in the east. The anomaly’s location is consistent with the inferred paleo-position of the continental margin Okhotsk-Chukotka arc. According to Nokleberg et al. (2000), the arc started activity in the Cenomanian-Santonian and ended in the Miocene. In recent model of Shephard et al. (2013), the arc was presumed to be active in the middle-Late Cretaceous (108–67.1 Ma). This was based on the study of Stone et al. (2009), giving a 90-67.1 Ma age range, and Akinin and Miller (2011) who gave a 107-77 Ma age range. This was followed by the accretion of the Okhotsk block to Siberia, followed by an eastward jump of subduction to the Kamchatka-Kuriles trench. We adopt the age range given by Shephard et al. (2013) to reflect the subduction period of the anomaly that we interpret as the Ushky slab.
Ushky — No Comments
HTML tags allowed in your comment: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>