Extremely rapid up-and-down motions of island arc crust during arc-continent collision

Abstract Mountain building and the rock cycle often involve large vertical crustal motions, but their rates timescales in unmetamorphosed rocks remain poorly understood. We utilize high-resolution magneto-biostratigraphy backstripping analysis of marine deposits an active arc-continent suture zone eastern Taiwan to document short cycles oscillations. A basal unconformity formed on Miocene volcanic arc crust uplifting forebulge starting ~6 Ma, followed by rapid foredeep subsidence at 2.3–3.2 mm yr −1 (~3.4–0.5 Ma) response oceanward-migrating flexural wave. Since ~0.8–0.5 has undergone extremely (~9.0–14.4 ) uplift form modern Coastal Range during transpressional strain. The northern sector may have recently entered another phase related a subduction polarity reversal. These transient motions are under-detected thermochronologic methods, likely characteristic continental growth accretion over geologic timescales.