Abstract
The use of XRF measurements of Si and Ti to estimate biogenic silica contents of lake sediment is evaluated by comparison of datasets from Lake Malawi sediment cores spanning 25 kyr of deposition under a range of environmental conditions. This approach is particularly attractive as it offers a several hundred-fold reduction in labor required for these analyses. Silicon can be present in both clastic and biogenic phases, and these phases dilute one another, so a simple relationship to calibrate XRF results to estimate percent biogenic silica was developed. This requires selection of an appropriate element (or elements) to use as a proxy for clastic sedimentary phases. Paired %BSi and XRF Si and Ti data from a short core (~ 35 cm) were used to develop a calibration scale. This calibration was applied to a 25,000-year record to estimate %BSi from XRF results. Comparison of this calculated BSi record with measured %BSi indicates that calibration parameters can vary with depth in sediment due to changes in chemical and physical characteristics. XRF scanning counting times for Si are evaluated; typically these should be set to allow > 500 counts.
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Brown, E. (2015). Estimation of Biogenic Silica Concentrations Using Scanning XRF: Insights from Studies of Lake Malawi Sediments. In: Croudace, I., Rothwell, R. (eds) Micro-XRF Studies of Sediment Cores. Developments in Paleoenvironmental Research, vol 17. Springer, Dordrecht. https://doi.org/10.1007/978-94-017-9849-5_9
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DOI: https://doi.org/10.1007/978-94-017-9849-5_9
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