A review of the western part of the Altaids: A key to understanding the architecture of accretionary orogens

Abstract The Altaids is one of the largest accretionary collages in the world, and the tectonic styles of the accretionary processes have been interpreted in several ways, including as an amalgamation of multiple terranes, as a result of oroclinal bending of a long, single arc, or as a Caledonian continental collision. Based on recent tectonostratigraphic analyses together with paleomagnetic data, the tectonic styles of the Neoproterozoic to Paleozoic accretionary processes of the Altaids are discussed. The Western Altaids is the main focus of the study, which was mainly composed of several independent linear components such as arcs and microcontinents with Proterozoic basement and cover rocks. Various kinds of arcs existed in the Paleo-Asian Ocean, including a complicated type of arc (Alaskan-type), which is a combination of the Japan- and Mariana-type intra-oceanic arcs and the Cordillera-type continental arcs. These linear components rotated and collided with each other with multiple subduction polarities, which could have been an important result of multiple linear element amalgamation, and which has contributed greatly to the architecture of the Eurasian continent. The basic tectonic styles of the Altaids can be summarized as arc–arc collision, oroclinal bending and large-scale rotation, and multiple subductions with a complicated archipelago paleogeography. These basic features of accretionary orogens in general can be attributed to the amalgamation of complicated multiple linear elements. Some Mesozoic to Cenozoic accretionary orogens in the world are also characterized by processes of multiple linear element amalgamation. More attention should be paid to the multiple linear element amalgamation of ancient accretionary orogens, which will shed light on lateral and vertical continental growth.