Variable rates of Late Quaternary surface uplift along the Banda Arc-Australian plate collision zone, eastern Indonesia

Abstract

Abstract Radiometrically dated emergent coral terraces from southeastern Indonesia provide estimates of differential vertical strain in the Banda Arc-continent collision complex. At Semau island, two samples from the lowest emergent reef (5–7 m) yield 230 Th dates that correspond to the 5a ( c. 83 ka) sea-level highstand and a low surface uplift rate of 0.2–0.3 m per 1000 years. At Rote island, samples from the lowest emergent reef ( c. 1–2 m) on both north and south sides of the island yield late Holocene ages and an average short-term uplift rate of c. 1–1.5 m per 1000 years. Similarity of ages from different samples on the north coast of Rote suggests possible coseismic emergence. Survey data from nine emergent reefs and marine notches up to 170 m in altitude on the south side of Rote indicate that uplift rates may have been c. 1–1.5 m per 1000 years for c. 120 000–130 000 years. Combined with previous studies, these results indicate that late Quaternary surface uplift rates vary an order of magnitude along the strike of the Banda orogen. Vertical displacement rates are greatest in young parts of the orogen where the shelf-slope break recently has been underthrust beneath the orogenic wedge, as at Rote, and in older parts of the orogen where retroarc thrust faulting occurs, as at Alor island.