BASIN EVOLUTION IN THE ARC ARC IZU COLLISION ZONE, MIO-PLIOCENE MIURA GROUP, CENTRAL JAPAN

A comparative study of the present collision zone between the Izu-Bonin Ridge (island are) with mainland Japan (Honshu Are), and the Mio-Pliocene of onshore SE Japan, suggests that are-are collision processes and the resulting stratigraphic successions may be repetitious and predictable. Are-are collision has led to the incremental accretion of segments of delaminated Izu-Bonin Are crust onto the Honshu Are, associated with the sequential southward migration in jumps of the plate boundary and trench, Prior to accretion of a segment of Izu-Bonin Are crust, the leading edge underwent uplift to generate an approximately trench-parallel topographic high, the Zenisu Ridge being the present example with the Hayama-Mineoka uplift zone as a Mio-Pliocene example. The ridge separated a northern trench or trough from a southern intra-oceanic are basin. During collision-accretion, the trench received both Honshu Are-derived, terrigenous, and Izu-Bonin Are-derived volcaniclastic, sediments, whereas the are basin tended to receive only are deposits. During the final stages of accretion, the are basin began to receive ever-increasing volumes of terrigenous, Honshu Are-derived, detritus fed through basement-controlled canyons. The accretionary process was accompanied by intense deformation and the residual deep-marine basin was then infilled above an angular unconformity.