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| Titel |
Th-230 Dates of MIS 5e Coral Terraces in Kisar Island, Eastern Indonesia |
| VerfasserIn |
H. W. Chiang, R. A. Harris, C. Prasetyadi, C. C. Shen, T. C. Chiu, N. L. Cox, Y. G. Chen |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250043569
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| Zusammenfassung |
| 2004 Sumatra earthquakes caused a devastating tsunami and cost the lives of nearly 260,000
people in the South Asian region. These earthquakes and associated tsunami are sourced from
convergence of the Indo-Australian and Asian Plates. In the eastern part of this plate
boundary the Australian continent is colliding with Asia. The first turbiditic sand in Timor
island was around 5 Ma and the collision propagated to the southwestern until ~2 Ma. But
the activities of the neighborhood of the Timor island in the Quaternary or the Holocene is
unknown. This study provides the new 230Th dates from the raised coral terraces at Kisar
Island, eastern Indonesia. Eight fossil corals were measured by MC-ICP-MS at
the National Taiwan University with permil-level precision. Two out of the eight
samples having ~1.5 % calcite and acceptable δ234Uinitial showed robust ages
of 123-121 ka. Another three open-system model ages were from 125-119 ka by
Thompson et al.’s method (2003). These different elevated fossil corals with ages of
125-119 ka favored the two-peak sea-level curve in MIS 5e explained by Chappell
and Veeh (1978). New age results relocated the second peak should be about three
thousand years earlier than their proposed 119 ka. A minimum uplift rate of 0.1 m/kyrs
is derived from the highest-position fossil corals. The 230Th-dated fossils in the
north coast of Timor-Leste suggest the MIS 5e terraces could reach 55 m high,
hence a referable uplift rate of ~0.4 m/kyrs could be a maximum estimate. The
uplift rate of 0.1-0.4 m/ka since late Pleistocene is well consistent with published
values from Atauro Island and Timor-Leste in eastern Indonesia. Based on the uplift
rate, the terraces in eastern Kisar, with elevation lower than 100 m, expectedly
located at MIS 7, 9, or 11; while the higher western terraces ranged from MIS 9-15.
Besides, no remanet of Holocene fringe reefs around Kisar Island also suggests a
relatively low activity of tectonics, in agreement with the modern GPS observation. |
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