Verification of wavelet analysis interpretation of µ-XRF paleoclimate data from lake sediments using PCA, cluster analysis and empirical climate data

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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.accessioned2023-06-14T01:19:10Zen_AU
dc.date.available2023-06-14T01:19:10Zen_AU
dc.date.issued2019-07-30en_AU
dc.date.statistics2023-03-24en_AU
dc.description.abstractReliable interpretation of annual resolution climate proxies for wind, precipitation, and detrital influx are a necessity for understanding the onset and periodicities of climatic events. In particular, verification of individual climate proxies in a µ-XRF time series data set is essential for the evaluation of inter-annual, decadal, and centennial periodicities driven by shifting positions of the South Westerly Winds (SWW) and subsequent storm belts associated with the Southern Annular Mode (SAM) and El Niño Southern Oscillation (ENSO) using wavelet analysis. Chronology for the Late Holocene section of lake sediment cores from Lake Kanono, Northland, New Zealand indicate an annual to sub-annual accumulation rate at a 500 µm Itrax µ-XRF scanning resolution. This fast accumulation rate provides the opportunity to produce quasi-annual µ-XRF time series data. Here we present twelve ca. 2200 year long elemental and element ratio µ-XRF time series including P, S, Ti, Ca, K, Si, Fe, Mn/Fe, (Fe+Ti)/K, Sr/Ca, Br/Cl, and Inc/coh. These twelve variables were interpreted as environmental proxies using a combination of principal component analysis (PCA) and cluster analysis, then verified with comparison to regionally averaged empirical rainfall and wind climate station data from Northland. Our results show that the wavelet patterns align with the PCA results allowing the µ-XRF time series to be classified into: Group I (detrital) and Group II (biological productivity and normalized climate proxies). The normalized Group II µ-XRF time series wavelet analyses displayed periodicities in the 2-16 year frequency, likely associated with ENSO, from ca. 237 BCE – 1330 CE. The data shows clear evidence of from both Polynesian and European settlement phases in this part of northern New Zealand as increased detrital influx. There is indication that Polynesian settlement impact was coeval with changes in ENSO intensity and a phase shift in SAM ca. 1350 CE, however European settlement is less associated with climatic shift. The Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA) appear in the µ-XRF time series data as separate clusters. This data shows that the MCA is associated with windy/dry conditions with intermittent storms. During the LIA, the 2-16 year periodicity associated with ENSO decreased and centennial length periodicities increase, which may be an indication of an underlying SAM signal within the data. The combination of the methods of PCA, cluster analysis, and wavelet analysis indicates that sediment loading after ca. 1330 CE may be accentuating the climate signal in the Group I (detrital) proxies, and so interpretations after this time must be made with caution.en_AU
dc.identifier.citationEvans, G. Augustinus, P., Gadd, P., Zawadzki, A., & Ditchfield, A. (2019). Verification of wavelet analysis interpretation of µ-XRF paleoclimate data from lake sediments using PCA, cluster analysis and empirical climate data. Poster presented to the 20th INQUA Congress 25th - 31st July 2019, Dublin, Ireland. Retrieved from: https://virtual.oxfordabstracts.com/#/event/public/574/submission/827en_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/827en_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15052en_AU
dc.language.isoenen_AU
dc.publisherInternational Union for Quaternary Research (INQUA)en_AU
dc.subjectVerfificationen_AU
dc.subjectLakesen_AU
dc.subjectSedimenten_AU
dc.subjectX-ray fluorescence anaylsisen_AU
dc.subjectPolar-cap absorptionen_AU
dc.subjectDataen_AU
dc.subjectClimatesen_AU
dc.subjectQuaternary perioden_AU
dc.subjectWindsen_AU
dc.subjectNew Zealanden_AU
dc.subjectRainen_AU
dc.titleVerification of wavelet analysis interpretation of µ-XRF paleoclimate data from lake sediments using PCA, cluster analysis and empirical climate dataen_AU
dc.typeConference Posteren_AU
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