Types of Quaternary Crustal Movements in the Circum-Pacific Zone

Abstract

Various types of crustal movements are distributed in the mobile belts of the Circum-Pacific zone, which occur mostly along the subduction plate boundaries (cf. Table 1), and partly along the collision, transform fault, and divergent plate boundaries. Types of Quaternary crustal movements are fairly well recognized through tectonic landforms ; hence, types of tectonic landforms are treated as visible figures of crustal movements.Large scale tectonic features are classified by the concept of plate tectonics as shown in Fig. 1, and types of them are designated by abbreviations in the same figure. Compressional and extensional stress regimes are important criteria of the classification, therefore, features of Uyeda's two end members (two typical types) of subduction are compared in Fig. 2, and the Jarrard's seven strain classes in the upper plate of subduction boundary, which are cited in Table 1, are shown in Table 2. Neutral stress regime of subduction (Sn, strain class 4 in Table 2) should be added in Fig. 1, but the judgement of “neutral” is not easy task in practice. Oblique subduction and oblique transform fault are common as seen in the plate boundaries of Fig. 4 ; two contrasting tectonic features seen in forearc and back-arc under oblique subduction are shown in Fig. 3.Quaternary crustal movements around the Pacific Ocean and Philippine Sea are reviewed briefly, and their types of movements are given by the abbreviations in Fig. 4.