Tectonic history of Sumba Island, Indonesia, since the Late Cretaceous and its rapid escape into the forearc in the Miocene
2001; Elsevier BV; Volume: 19; Issue: 4 Linguagem: Inglês
10.1016/s1367-9120(00)00032-8
ISSN1878-5786
AutoresEverett Rutherford, Kevin Burke, Jennifer Lytwyn,
Tópico(s)Geological and Geochemical Analysis
ResumoThe island of Sumba lies within the Sunda-Banda forearc and contains volcanic, plutonic and volcaniclastic rocks that record a history of arc volcanism extending from Late Cretaceous (∼80 Ma or earlier) to Oligocene (∼31 Ma) time. During the Late Cretaceous, Sumba formed part of a Great Indonesian Volcanic Arc system near southeastern Eurasia. Between Late Cretaceous and Early Miocene time, Sumba remained part of that arc system, which ceased to be volcanically active by ∼31 Ma. During the Late Miocene (∼18 Ma), Sumba, as part of the relict arc system, was situated near the present site of Alor and Wetar. At ∼16 Ma, Sumba was torn from the relict arc and began to move at a velocity of ∼50 mm/yr in a west-south-westerly direction. Volcanism along the modern Banda Arc soon followed. By ∼7 Ma, Sumba finally came to rest, after having moved ∼450 km into the forearc. We interpret the rapid motion of Sumba into the forearc as a discrete block to have been a response to the collision between Australia and Indonesia in the area of Timor. The Savu Basin possibly originated as an arc-crestal rift which then opened behind Sumba as the latter moved westward. Over the past 16 My, more than 3 km of sediment have been deposited in the Savu Basin by erosion from the surrounding islands. Sumba stopped moving to the west-south-west at ∼7 Ma after reaching approximately its present location. Since then, the island has ceased to be a discrete tectonic fragment and has behaved as an integral part of the forearc. During the past ∼7 My, compressional tectonics within the forearc has led to elevation of the rocks exposed on Sumba by as much as 4 km.
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