Multiple dating approach (14C, 230Th/U and 36Cl) of tsunami-transported reef-top boulders on Bonaire (Leeward Antilles) – Current achievements and challenges

peer reviewed ; Dating the transport/deposition time of supratidal coarse-clast deposits is difficult, limiting their value for inferring frequency-magnitude patterns of high-energy wave events. On Bonaire (Leeward Antilles, Caribbean), these deposits form prominent landforms, and transport by one or several Holocene tsunamis is assumed at least for the largest clasts. Although a large dataset of 14C and electron spin resonance (ESR) ages is available for major coral rubble ridges and ramparts, it is still debated whether these data reflect the timing of major events, and how these datasets ar... Mehr ...

Verfasser: RIXHON, G.
MAY, S.M.
ENGEL, M.
MECHERNICH, S.
SCHROEDER-RITZRAU, A.
FRANK, N.
FOHLMEISTER, J.
Boulvain, Frédéric
DUNAI, T.
BRÜCKNER, H.
Dokumenttyp: journal article
Erscheinungsdatum: 2018
Verlag/Hrsg.: Elsevier Science
Schlagwörter: reef top boulders / tsunami transport / 14C dating / Th/U dating / 36 Cl exposure dating / Bonaire / Physical / chemical / mathematical & earth Sciences / Earth sciences & physical geography / Physique / chimie / mathématiques & sciences de la terre / Sciences de la terre & géographie physique
Sprache: Englisch
Permalink: https://search.fid-benelux.de/Record/base-28973290
Datenquelle: BASE; Originalkatalog
Powered By: BASE
Link(s) : https://orbi.uliege.be/handle/2268/216436

peer reviewed ; Dating the transport/deposition time of supratidal coarse-clast deposits is difficult, limiting their value for inferring frequency-magnitude patterns of high-energy wave events. On Bonaire (Leeward Antilles, Caribbean), these deposits form prominent landforms, and transport by one or several Holocene tsunamis is assumed at least for the largest clasts. Although a large dataset of 14C and electron spin resonance (ESR) ages is available for major coral rubble ridges and ramparts, it is still debated whether these data reflect the timing of major events, and how these datasets are biased by the reworking of coral fragments. As an attempt to overcome the current challenges for dating the dislocation of singular boulders, three distinct dating methods are implemented and compared: (i) 14C dating of boring bivalves attached to the boulders; (ii) 230Th/U dating of post-depositional, secondary calcite flowstone and subaerial microbialites at the underside of the boulders; and (iii) surface exposure dating of overturned boulders via 36Cl concentration measurements in corals. Approaches (ii) and (iii) have never been applied to coastal boulder deposits so far. The three 14C age estimates are older than 40 ka, i.e. most probably beyond the applicability of the method, which is attributed to post-depositional diagenetic processes, shedding doubt on the usefulness of this method in the local context. The remarkably convergent 230Th/U ages, all pointing to the Late Holocene period (1.0–1.6 ka), are minimum ages for the transport event(s). The microbialite sample yields an age of 1.23 ± 0.23 ka and both flowstone samples are in stratigraphic order: the older (onset of carbonate precipitation) and younger flowstone layers yield ages of 1.59 ± 0.03 and 1.23 ± 0.03 ka, respectively. Four coral samples collected from the topside of overturned boulders yielded similar 36Cl concentration measurements. However, the computed ages are affected by large uncertainties, mostly due to the high natural chlorine ...