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Luminescence dating of cyclone-induced washover fans at Point Lefroy (NW Australia)


Brill, Dominik ; May, Simon Matthias ; Shah-Hosseini, Majid ; Rufer, Daniel ; Schmidt, Christoph ; Engel, Max:
Luminescence dating of cyclone-induced washover fans at Point Lefroy (NW Australia).
In: Quaternary Geochronology. Bd. 41 (August 2017) . - S. 134-150.
ISSN 1871-1014
DOI: https://doi.org/10.1016/j.quageo.2017.03.004


Reliable age dating of coastal sedimentary landforms is crucial for inferring storm frequencies and magnitudes from geological archives. However, in highly energetic coastal settings, radiocarbon dating is often biased by reworking and/or poorly constrained marine reservoir effects. Due to this, most cyclonedriven sediment archives from the semiarid coast of NW Australia e a region frequently affected by tropical cyclones but with a historical record limited to ~150 a, and therefore strongly in need of longterm data inferred from geological evidence e are affected by chronological inaccuracies. Optically stimulated luminescence dating (OSL) may overcome these shortcomings by dating the transport of sediment directly. In turn it may be related to other challenges when applied to cyclone deposits from semiarid environments. The cyclone-induced washover fans at Point Lefroy, NWAustralia, are composed of a heterogeneous mixture of coral fragments, shell hash and siliciclastic sand. This makes them particularly prone to high dose scatter resulting from a combination of partial bleaching, sediment mixing and dose-rate heterogeneity. The washover fans are further characterised by a discontinuous nature of cyclone deposition, as indicated by erosional features and macroscopic brunification horizons. By using a combination of quartz single grain dating, autoradiography, alpha counting and gamma spectrometry, sediment mixing and dose rate heterogeneity are identified as the main sources of dose scatter. The resulting chronology allows us to discriminate at least four well constrained phases of washover fan activity at ~180, ~360, ~870, and ~1300 a ago. Older but less well constrained activity phases occurred ~1950, ~2300, and ~2830 a ago. While these phases of increased cyclone activity correlate with depositional units separated by potential palaeosols, OSL ages, quasi-continuous portable OSL reader measurements and gamma spectrometry measured with increased sampling resolution point to deposition of distinct washover units within a very short period of time. However, unambiguous discrimination between deposition of individual units by single events and deposition by several cyclones within periods of only a few decades is currently not possible.

Weitere Angaben

Publikationsform: Artikel in einer Zeitschrift
Begutachteter Beitrag: Ja
Keywords: OSL; Cyclone deposit; Washover fan; Equivalent dose scatter; Beta-dose heterogeneity; Single grain dating; Australia
Institutionen der Universität: Fakultäten
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften > Lehrstuhl Geomorphologie
Profilfelder > Advanced Fields > Ökologie und Umweltwissenschaften
Profilfelder > Advanced Fields > Nichtlineare Dynamik
Forschungseinrichtungen > Forschungszentren > Bayreuther Zentrum für Ökologie und Umweltforschung - BayCEER
Profilfelder > Advanced Fields
Forschungseinrichtungen > Forschungszentren
Titel an der UBT entstanden: Nein
Themengebiete aus DDC: 500 Naturwissenschaften und Mathematik > 550 Geowissenschaften, Geologie
Eingestellt am: 01 Aug 2017 07:02
Letzte Änderung: 01 Aug 2017 07:02
URI: https://eref.uni-bayreuth.de/id/eprint/39026