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dc.contributor.authorBadesab, Firoz
dc.contributor.authorvon Dobeneck, Tilo
dc.contributor.authorBryan, Karin R.
dc.contributor.authorMüller, Hendrik
dc.contributor.authorBriggs, Roger M.
dc.contributor.authorFrederichs, Thomas
dc.contributor.authorKwoll, Eva
dc.identifier.citationBadesab, F., von Dobeneck, T., Bryan, K.R., Müller, H., Briggs, R.M., ..., Kwoll, E. (2012). Formation of magnetite-enriched zones in and offshore of a mesotidal estuarine lagoon: An environmental magnetic study of Tauranga Harbour and Bay of Plenty, New Zealand. Geochemistry Geophysics Geosystems, 13(6), Q06012.en_NZ
dc.description.abstractMagnetic iron minerals are widespread and indicative sediment constituents in estuarine, coastal and shelf systems. We combine environmental magnetic, sedimentological and numerical methods to identify magnetite-enriched placer-like zones in a complex coastal system and delineate their formation mechanisms. Magnetic susceptibility and remanence measurements on 245 surficial sediment samples collected in and around Tauranga Harbour, the largest barrier-enclosed tidal estuary of New Zealand, reveal several discrete enrichment zones controlled by local hydrodynamic conditions. Active magnetite enrichment takes place in tidal channels, which feed into two coast-parallel nearshore magnetite-enriched belts centered at water depths of 6–10 m and 10–20 m. A close correlation between magnetite content and magnetic grain size was found, where higher susceptibility values are associated within coarser magnetic crystal sizes. Two key mechanisms for magnetite enrichment are identified. First, tide-induced residual currents primarily enable magnetite enrichment within the estuarine channel network. A coast-parallel, fine sand magnetite enrichment belt in water depths of less than 10 m along the barrier island has a strong decrease in magnetite content away from the southern tidal inlet and is apparently related to active coast-parallel transport combined with mobilizing surf zone processes. A second, less pronounced, but more uniform magnetite enrichment belt at 10–20 m water depth is composed of non-mobile, medium-coarse-grained relict sands, which have been reworked during post-glacial sea level transgression. We demonstrate the potential of magnetic methods to reveal and differentiate coastal magnetite enrichment patterns and investigate their formative mechanisms.en_NZ
dc.publisherAGU and the Geochemical Societyen_NZ
dc.relation.ispartofGeochemistry Geophysics Geosystems
dc.subjectenvironmental magnetismen_NZ
dc.subjectmagnetite enrichmenten_NZ
dc.subjectplacer depositen_NZ
dc.subjectresidual currentsen_NZ
dc.titleFormation of magnetite-enriched zones in and offshore of a mesotidal estuarine lagoon: An environmental magnetic study of Tauranga Harbour and Bay of Plenty, New Zealanden_NZ
dc.typeJournal Articleen_NZ
dc.relation.isPartOfGeochemistry Geophysics Geosystemsen_NZ
uow.identifier.article-noARTN Q06012en_NZ

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