Geodynamics of the formation of the Paleogenic island arc of the Bauers submarine ridge (Bering Sea)

The large marginal seas in the northwest of the Pacific Ocean are characterized by a complex tectonic structure with a combination of abyssal basins and uplifts of various geodynamic nature and various ages, whose formation marks the long term history of the active margin development. Reconstruction of the tectonic nature of the uplifts within the deepwater basins is an important contribution to the study of the geodynamics of the formation of such structures, and the Bering Sea is a typical representative of marginal seas. It is separated from the Pacific Ocean by the Aleutian island arc and consists of three oceanic basins: the Aleutian, the Commander, and the Bauers, the dividing Shirshov and Bauers aseismic submarine ridges, and the big Bering continental shelf that joins the Asian and North American continents. According to the seismic data of the current structure, the Bering Sea with the Aleutian island arc, southwestern Alaska, the coastal zone of the Koryak Upland, and Chukotka are a part of the Beringiya small lithospheric plate. The Bauers submarine ridge par tially bounds the biggest Aleutian oceanic basin from the south, which is usually considered as a Cretaceous part of the oceanic plate bounded by the island arc [2]. The geodynamic nature and age of formation of the Bauers ridge have been long discussed, since there were no data on the character of its basement rocks and their age. The structural features of the ridge, such as an arc shaped profile and a deep downwarp along the arching side, were the most appropriate for the interpretation of the Bauers Ridge as a passive island arc structure. However, it remained unclear, whether or not this structure was formed in situ or if it were an exotic terrain related to a trapped fragment of the Pacific.