Paper No. 112-21
Presentation Time: 8:00 AM-5:30 PM
PREPARATION OF MARINE SURFACE SEDIMENTS AROUND TE PATAKA O RAKAIHAUTU (BANKS PENINSULA) FOR PROVENANCE ANALYSIS USING PXRF
BENGSTON, Emily1, JENSEN, Claire2, NOLON, Ian3, RANDALL, Luke4, GRAVLEY, Darren5 and HAMPTON, Samuel J.5, (1)Department of Geosciences, Oberlin College, Oberlin College, 52 W. Lorain St, Oberlin, OH 44074; School of Earth and Environment, University of Canterbury, Christchurch, Canterbury 8140, New Zealand; Frontiers Abroad Aotearoa, Christchurch, 8041, New Zealand, (2)Department of Geology, Amherst College, Amherst, MA 01002; School of Earth and Environment, University of Canterbury, Christchurch, Canterbury 8140, New Zealand; Frontiers Abroad Aotearoa, Christchurch, 8041, New Zealand, (3)Department of Earth and Climate Sciences, Middlebury College, Middlebury, VT 05753; School of Earth and Environment, University of Canterbury, Christchurch, Canterbury 8140, New Zealand; Frontiers Abroad Aotearoa, Christchurch, 8041, New Zealand, (4)Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI 02912; School of Earth and Environment, University of Canterbury, Christchurch, Canterbury 8140, New Zealand; Frontiers Abroad Aotearoa, Christchurch, 8041, New Zealand, (5)School of Earth and Environment, University of Canterbury, Christchurch, Canterbury 8140, New Zealand; Frontiers Abroad Aotearoa, Christchurch, 8041, New Zealand
In modern sedimentary environments such as the marine areas around Te Pataka o Rakaihautu (Banks Peninsula), New Zealand, provenance research can clarify sediment dynamics. Understanding the sediment transport dynamics of this location is of particular importance because of the impact of sedimentation on the ecology and the cultural significance of local marine biota. Potential sources of sediment include local basaltic volcanic deposits and loess deposits. The northern Waimakariri River and southern Rakaia River may also supply sediment that is deposited around the peninsula via longshore transport.
The aim of this research is to develop a methodology for treating marine surface sediments for provenance analysis using pXRF. Currently, there is no standardised procedure for removing carbonates and organic materials from marine surface sediments prior to pXRF analysis. Here we show that common treatments (HCl, H2O2, and Loss on Ignition) affect unintended elements, thus biassing the results. We found that drying the sample in a 60 ℃ oven for ~12 hours and then handpicking carbonates >2 mm in size produced the most stable results. Following this procedure, we prepared a preliminary set of marine surface sediment samples, on which we performed pXRF analysis. Our preliminary results show that some samples have geochemical signatures that overlap with the geochemical signature of Lyttelton Loess, while few samples overlap the geochemical signature of local volcanic deposits. Additionally, most samples overlap with the geochemical signature of southern beaches and the Rakaia River sources, and fewer samples reflect the geochemical signature of northern sources and the Waimakariri River. This is consistent with existing research which suggests a strong overall northward current. Our findings demonstrate the potential for provenance studies to address the issue of sedimentation around Te Pataka o Rakaihautu and also provide a methodology for future pXRF analysis of samples.
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