Late holocene record of environmental changes, cyclones and tsunamis in a coastal lake, Mangaia, Cook Islands

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dc.contributor.authorChagué-Goff, Cen_AU
dc.contributor.authorHang Chan, JCen_AU
dc.contributor.authorGoff, JRen_AU
dc.contributor.authorGadd, PSen_AU
dc.date.accessioned2019-11-12T02:06:51Zen_AU
dc.date.available2019-11-12T02:06:51Zen_AU
dc.date.issued2016-09-04en_AU
dc.date.statistics2019-11-12en_AU
dc.description.abstractA 4.3 m-long peat sequence from the shore of Lake Tiriara, Mangaia, Cook Islands, was analyzed using an ITRAX core scanner equipped with a magnetic susceptibility meter. Variations in the elemental profiles, providing insights into long- and short-term environmental changes over the last 3500 years, are supported by grain size data and diatom assemblages. The scattering ratio (Mo Inc/Mo Coh) was evaluated and found to represent a good proxy for organic matter in peat. X-Ray Fluorescence (XRF) data were processed by principal component analysis that confirmed the distinction of biogenic and detrital phases, organic matter and elements of marine origin. The record preserved in the peat sequence includes a peatland infilling stage followed by alternating drier and wetter periods. A notable steady increase in clay associated with high counts of detrital elements from 2000–1700 cal yr BP is attributed to increased erosion, which is most probably linked with human colonization and/or more intense chemical weathering linked with a wetter climate. Freshwater gastropods (Melanoides sp.), which were possibly introduced by humans, or are native, occupied the wetland during a period of lower water level about 1000–1100 cal yr BP. Short-term changes in the elemental profiles are often linked with slight coarsening of the inorganic fraction that is, however, only revealed after grain size analysis. Peaks in marine indicators (Br, Cl, S, and/or Ca) associated with marine-dominated diatom assemblages most probably represent marine incursions through the underground tunnel in the makatea, a fossilized, uplifted coral limestone rim. While none of the marine event units present characteristics typical of cyclone or tsunami deposits, the concurrent or absent peak of detrital elements (Fe, Si, Rb, Ti, K) attributed to increased erosion of the volcanic cone associated with a cyclone is used to distinguish both types of events, as also suggested by principal component analysis. © 2016 John Wiley & Sons Australia, Ltden_AU
dc.identifier.citationChagué‐Goff, C., Chan, J. C. H., Goff, J., & Gadd, P. (2016). Late holocene record of environmental changes, cyclones and tsunamis in a coastal lake, Mangaia, Cook Islands. Island Arc, 25(5), 333-349. doi:10.1111/iar.12153en_AU
dc.identifier.govdoc8921en_AU
dc.identifier.issn1038-4871en_AU
dc.identifier.issn1440-1738en_AU
dc.identifier.issue5en_AU
dc.identifier.journaltitleIsland Arcen_AU
dc.identifier.pagination333-349en_AU
dc.identifier.urihttp://dx.doi.org/10.1111/iar.12153en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/9083en_AU
dc.identifier.volume25en_AU
dc.language.isoenen_AU
dc.publisherWiley Online Libraryen_AU
dc.subjectCyclonesen_AU
dc.subjectTsunamisen_AU
dc.subjectEnvironmental impactsen_AU
dc.subjectGeochemistryen_AU
dc.subjectVolcanic regionsen_AU
dc.subjectAquatic ecosystemsen_AU
dc.subjectPeaten_AU
dc.subjectDiatomsen_AU
dc.subjectX-ray fluorescence analysisen_AU
dc.titleLate holocene record of environmental changes, cyclones and tsunamis in a coastal lake, Mangaia, Cook Islandsen_AU
dc.typeJournal Articleen_AU
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