Abstract

A comparative study of the present collision zone between the Izu–Bonin Ridge (island arc) with mainland Japan (Honshu Arc), and the Mio-Pliocene of onshore SE Japan, suggests that arc—arc collision processes and the resulting stratigraphic successions may be repetitious and predictable. Arc—arc collision has led to the incremental accretion of segments of delaminated Izu—Bonin Arc crust onto the Honshu Arc, associated with the sequential southward migration in jumps of the plate boundary and trench. Prior to accretion of a segment of Izu-Bonin Arc 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 arc basin. During collision-accretion, the trench received both Honshu Arc-derived, terrigenous, and Izu-Bonin Arc-derived volcaniclastic, sediments, whereas the arc basin tended to receive only arc deposits. During the final stages of accretion, the arc basin began to receive ever-increasing volumes of terrigenous, Honshu Arc-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.

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