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| Titel |
Can cosmogenic nuclides (36Cl) unravel the timing of dislocation of tsunami blocks on Bonaire (Leeward Antilles)? |
| VerfasserIn |
Max Engel, Gilles Rixhon, Helmut Brückner, S. Matthias May, Steve Binnie, Tibor J. Dunai |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250072366
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| Zusammenfassung |
| On Bonaire (Leeward Antilles) and rocky coasts worldwide, high-energy wave events
(tsunamis, storms) dislocate coarse-clast deposits (Engel and May, 2012). Using these
onshore blocks and boulders to derive ages for the most powerful events on millennial scales
is still a major challenge. We apply terrestrial cosmogenic nuclides (TCN), in particular 36Cl,
in case of the largest blocks in order to directly date the transport event(s), i.e. the inferred
tsunami(s). This dating method has hitherto been disregarded in the coastal environment,
particularly in the context of block transport. The following characteristics of the blocks
are fundamental for the success of the presented dating approach: (1) due to the
lithology (aragonite, calcite), concentration measurements of 36Cl are performed;
(2) only large and thick boulders and blocks (>50 t, >2 m thickness) for which
tsunami transport was inferred (Engel and May, 2012) were sampled; (3) since the
boulders stem from the edge of the coral reef platform, they had been exposed to
cosmic radiation prior to the transport event(s) and had already accumulated a certain
amount of TCN. To avoid this problem of inheritance, we only sampled the thickest
clasts, and those having experienced a 180Ë overturn during transport; thus, having
exposed a “blank” side to cosmic rays only since the event. The complete overturn is
attested by the presence of inactive rock pools in upside-down position and bioerosive
notches.
Engel, M., and May, S. M.: Bonaire’s boulder fields revisited: Evidence for
Holocene tsunami impact on the Leeward Antilles, Quat. Sci. Rev., 54, 126–141, 2012. |
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