Sequences of coral reef terraces from Butonand Tukang Besi archipelagos, SoutheastSulawesi, Indonesia: the most comprehensiverecord of Plio-Quaternary highstands ?
Résumé
The Indonesian archipelago displays spectacular Late Cenozoicsequences of marine and coral reef terraces, in particular onthe Tukang Besi and Buton archipelagos (SE Sulawesi). In thisarea, the late Cenozoic uplift of submarine banks and other topographichighs led to major geographic changes: reef platformsand/or table reefs arose over topographic highs, then sequencesof coral reef terraces emerged and covered the rising slopes of theislands. Remote sensing imagery associated to preliminary fieldmapping and U/Th dating of these sequences of terraces enabledthe identification of at least 23 islands covered with fossil reefs.In SE Buton, a sequence includes more than 40 successive terracesand reaches a maximum elevation of 650 +/-10 m. On theSampolawa peninsula, a sequence includes some 20 strandlinesand culminates at 430 +/- 10 m. U/Th dating of four of its lowstandingterraces suggest that they have formed during the lastfour interglacial periods (MIS 5e, 7, 9 and 11), yielding an averagemean uplift rates of 0.12+/-0.04 mm/yr. By extrapolationof these uplift rate, the sequences of SE Buton could potentiallyprovide a record of sea level highstands for the last ~3.5 Ma, consequentlymaking these sequences the most comprehensive knownrecord of Plio-Quaternary sea level stands worldwide.