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| Titel |
Reconstructing Mid- to Late Holocene sea-level change from coral microatolls, French Polynesia |
| VerfasserIn |
Nadine Hallmann, Gilbert Camoin, Anton Eisenhauer, Alberic Botella, Glenn Milne, Claude Vella, Elias Samankassou, Virginie Pothin, Philippe Dussouillez, Jules Fleury, Jan Fietzke |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250145881
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| Publikation (Nr.) |
 EGU/EGU2017-9858.pdf |
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| Zusammenfassung |
| Coral microatolls are sensitive low-tide recorders, as their vertical accretion is limited by the
mean low water springs level, and can be considered therefore as high-precision recorders of
sea-level change. They are of pivotal importance to resolving the rates and amplitudes of
millennial-to-century scale changes during periods of relative climate stability such as the
Mid- to Late Holocene, which serves as an important baseline of natural variability prior
to the industrial revolution. It provides therefore a unique opportunity to study
coastal response to sea-level rise, even if the rates of sea-level rise during the Mid- to
Late Holocene were lower than the current rates and those expected in the near
future.
Mid- to Late Holocene relative sea-level change in French Polynesia was reconstructed
based on the coupling between absolute U/Th dating of in situ coral microatolls and their
precise positioning via GPS RTK (Real Time Kinematic) measurements. The twelve studied
islands represent ideal settings for accurate sea-level studies because: 1) they can be
regarded as tectonically stable during the relevant period (slow subsidence), 2) they
are located far from former ice sheets (far-field), 3) they are characterized by a
low tidal amplitude, and 4) they cover a wide range of latitudes which produces
significantly improved constraints on GIA (Glacial Isostatic Adjustment) model
parameters.
A step-like sea-level rise is evidenced between 6 and 3.9 ka leading to a short sea-level
highstand of about a meter in amplitude between 3.9 and 3.6 ka. A sea-level fall, at an
average rate of 0.3 mm.yr-1, is recorded between 3.6 and 1.2 ka when sea level approached its
present position. In addition, growth pattern analysis of coral microatolls allows the
reconstruction of low-amplitude, high-frequency sea-level change on centennial to
sub-decadal time scales. The reconstructed sea-level curve extends the Tahiti last deglacial
sea-level curve [Deschamps et al., 2012, Nature, 483, 559-564], and is in good agreement
with a geophysical model tuned to fit far-field deglacial records [Bassett et al., 2005, Science,
309, 925-928]. |
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