The Geodynamic Evolution of Intraoceanic Island-Arc Systems: Expansive (Izu-Bonin-Mariana), Accretionary (Nemur-Olutor) and Stationary (Aleutian) Types

The authors propose a typification of intraoceanic island-arc systems according to the geodynamics of their development in the oceanic space. The currently existing and reconstructed (represented by terranes at the margins of the continents) Late Mesozoic-Cenozoic intraoceanic island-arc systems are subdivided into the expansive, accretionary, and stationary types. The expansive-type systems (Izu-Bonin-Mariana and Lesser Antilles) are advanced both towards the subducting oceanic plate and towards the free oceanic space. Their geodynamics is determined by processes in the oceanic plates. The mantle currents under the overhanging lithospheric plate are directed towards the subducting plate. Accretionary systems such as the Olyutor-East Kamchatka, Nemuro-Lesser Kuril, and Talkeetna systems completed their development as part of active continental margins. The paleotectonic reconstruction of such systems shows that they were reduced in the course of their development to relict terranes, tectonically aligned with continental margins. The geodynamics of intra-ocean systems of the accretion type also depends on processes in oceanic plates. However, this leads to the opposite result compared to expansive systems. This is due to the direction of mantle flows under the overhanging plate, which is opposite to the expansion type, i.e., coinciding in direction with the mantle flow under the absorbed plate. The stationary Aleutian island-arc system is intercontinental and its development in space and the formation of internal structures (the Paleogene island arc of the Bowers Ridge) are depended on the difference in the relative movement of the Eurasian and North American lithospheric plates. The most specific feature of this system is the absence of signs of back-arc basin opening, which is invariably characterizes expansive and accretionary island-arc systems. It is assumed that this specific feature of the system may be related to the mantle flow under the overhanging slab, which has a transverse direction with respect to the direction of the subducting plate. From the time of its formation the Aleutian system had remained autochthonous in relation to the North American and Eurasian continents.