Estimated chronology in a continuous lake sediment sequence from Kai Iwi Lake, New Zealand using MIS boundaries as age markers

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dc.contributor.authorEvans, Gen_AU
dc.contributor.authorAugustinus, PCen_AU
dc.contributor.authorGadd, PSen_AU
dc.contributor.authorZawadzki, Aen_AU
dc.contributor.authorDitchfield, Aen_AU
dc.date.accessioned2023-06-14T01:28:24Zen_AU
dc.date.available2023-06-14T01:28:24Zen_AU
dc.date.issued2019-07-30en_AU
dc.date.statistics2024-03-24en_AU
dc.description.abstractIt is a common problem in paleoclimate research to have long sediment sequences that are difficult to date due to the ~50 ka age limitation of 14C dating. A possible solution where other laboratory methods are not available is to approximate the chronology using Marine Isotope Stages (MIS) as age markers via robust interpretation of environmental proxy data. A 9.3 m lake sediment core obtained from dune impounded Kai Iwi Lake in Northland, New Zealand provides a nearly continuous record of environmental changes in multi-proxy and µ-XRF data estimated to MIS 5d. Chronology for the upper 3 m of the core is well established until ca. 45 ka via 210Pb, 14C and tephrochronology. To identify patterns in the µ-XRF proxy data associated with environmental change, principal component analysis (PCA) and cluster analysis were performed on a data set including nine common elements in lake sediments (P, S, Fe, Ti, K, Ca, Si, Al, and Zr) and six element ratios (Sr/Ca, Br/Cl, Mn/Fe, (Fe+Ti)/K, Ti/K, and Inc/coh). PCA indicates that Component 1 represents the detrital fraction, and Component 2 is associated with nutrient influx and biological productivity. The elements and ratios in the Component 2 µ-XRF variables also indicate a wind component to the data as P, Mn/Fe, Fe, Ca and S are also indicators of anoxic/oxic conditions as a result of wind driven mixing in the water column. The cool periods of MIS 2 and 4 are well-defined in the µ-XRF data as having increased detrital influx (Ti, K, Si, Al), less thermal stratification in the water column (P), and more sea spray (Br/Cl, S). Warm periods are identified by high P variability, less detrital influx and increased organic productivity (Inc/coh). MIS 5b is estimated from similar changes in the data as MIS 2 and 4, however the difference between MIS 5c and 5d is not as evident and so the alignment of the cluster analysis of the µ-XRF proxy data was used as the definition of this boundary. These environmental interpretations define a framework of age markers from the MIS boundary ages and allow an age/depth profile estimated from a sediment accumulation rate to be calculated in addition to the age profile established via 210Pb, 14C and tephrochronology. Since MIS 2 has a slower accumulation rate in the Kai Iwi Lake chronology and the proxy data profile for MIS 2 is similar to MIS 4, it may also be possible to further refine the estimated chronology for MIS 4 by adjusting the accumulation rate for that section of the core.en_AU
dc.identifier.citationEvans, G., Augustinus, P., Gadd, P., Zawadzki, A., Ditchfield, A. (2019). Estimated chronology in a continuous lake sediment sequence from Kai Iwi Lake, New Zealand using MIS boundaries as age markers. Poster presented to the 20th INQUA Congress 25th - 31st July 2019, Dublin, Ireland. Retrieved from: https://virtual.oxfordabstracts.com/#/event/public/574/submission/832en_AU
dc.identifier.conferenceenddate31 July 2019en_AU
dc.identifier.conferencename20th INQUA Congressen_AU
dc.identifier.conferenceplaceDublin, Irelanden_AU
dc.identifier.conferencestartdate25 July 2019en_AU
dc.identifier.urihttps://virtual.oxfordabstracts.com/#/event/public/574/submission/832en_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15053en_AU
dc.language.isoenen_AU
dc.publisherInternational Union for Quaternary Research (INQUA)en_AU
dc.subjectLakesen_AU
dc.subjectSedimentsen_AU
dc.subjectNew Zealanden_AU
dc.subjectCarbon 14en_AU
dc.subjectIsotopesen_AU
dc.subjectEnvironmenten_AU
dc.subjectClimatic changeen_AU
dc.subjectDataen_AU
dc.titleEstimated chronology in a continuous lake sediment sequence from Kai Iwi Lake, New Zealand using MIS boundaries as age markersen_AU
dc.typeConference Posteren_AU
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