Identifying a reliable target fraction for radiocarbon dating sedimentary records from lakes

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dc.contributor.authorHowarth, JDen_AU
dc.contributor.authorFitzsimons, SJen_AU
dc.contributor.authorJacobsen, GEen_AU
dc.contributor.authorVandergoes, MJen_AU
dc.contributor.authorNorris, RJen_AU
dc.date.accessioned2014-01-23T01:15:46Zen_AU
dc.date.available2014-01-23T01:15:46Zen_AU
dc.date.issued2013-06-01en_AU
dc.date.statistics2014-01-23en_AU
dc.description.abstractLake basins that experience rapid rates of deposition act as high-resolution environmental archives because they produce sedimentary records that have centennial or even decadal resolution. However, identifying target fractions for radiocarbon dating of lake sediments remains problematic because reworked organic material from fluvial catchments can produce anomalously old radiocarbon ages. This study determines the extent to which reworked material from catchment soils impacts radiocarbon dates on pollen and other organic concentrates by comparing radiocarbon dates produced by these techniques against a chronostratigraphic marker in cores from Lake Mapourika, New Zealand. Pollen preferentially preserved and reworked from catchment soils was identified using soil palynology. A technique was then developed to remove reworked pollen types from pollen concentrates extracted from lake sediment. Identification and removal of reworked pollen from pollen concentrates produced ages that were consistently closer to the age of the chronostratigraphic horizon than other organic concentrates. However, these dates were still between 736 and 366 calendar years older than expected. The only organic fractions that reliably reproduced the age of the chronostratigraphic horizon were terrestrial leaf macrofossils, although terrestrial leaf macrofossils isolated from megaturbidite deposits, which are formed by high-energy depositional events, also provided anomalously old ages. The results indicate that leaf material extracted from hemipelagite, which accumulates gradually, is likely to be the only organic fraction to produce reliable chronology in lakes where a component of sedimentation is driven by the fluvial system. The results also demonstrate the importance of conducting a detailed investigation of physical sedimentology before selecting material for radiocarbon dating lake sediments. Crown Copyright © 2013, Elsevier Ltd.en_AU
dc.identifier.citationHowarth, J.D., Fitzsimons, S.J., Jacobsen, G.E., Vandergoes, M.J., & Norris, R.J. (2013). Identifying a reliable target fraction for radiocarbon dating sedimentary records from lakes. Quaternary Geochronology, 17, 68-80. doi:10.1016/j.quageo.2013.02.001en_AU
dc.identifier.govdoc5333en_AU
dc.identifier.issn1871-1014en_AU
dc.identifier.journaltitleQuaternary Geochronologyen_AU
dc.identifier.pagination68-80en_AU
dc.identifier.urihttp://dx.doi.org/10.1016/j.quageo.2013.02.001en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/5179en_AU
dc.identifier.volume17en_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.subjectEarthquakesen_AU
dc.subjectSedimentationen_AU
dc.subjectPollenen_AU
dc.subjectDepositionen_AU
dc.subjectSoilsen_AU
dc.subjectFossilsen_AU
dc.titleIdentifying a reliable target fraction for radiocarbon dating sedimentary records from lakesen_AU
dc.typeJournal Articleen_AU
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