- Chapter contents
- Abstract
- Introduction
- Methods
- Results
- Acknowledgments
- References
-
Figures - PDF file
doi:10.2204/iodp.proc.341.203.2017
Methods
Scanning XRF data were collected at the XRF core facility located at the International Ocean Discovery Program Gulf Coast Repository (GCR) at Texas A&M University, using a third-generation Avaatech XRF core scanner. The core scanner is able to measure the surface of half-round core sections for elements between Mg and U on the periodic table (http://www.avaatech.com). Only core sections located on the continuous Site U1419 splice were analyzed (see Table T10 in the “Site U1419” chapter [Jaeger et al., 2014b]), rather than every core section collected at the site. However, some off-splice sections located near questionable splice tie points (see Figs. F16B and F17B in the “Site U1419” chapter [Jaeger et al., 2014b]) were also analyzed in order to help refine the Site U1419 splice.
Prior to scanning, each core section was warmed up to room temperature, scraped to clean the core surface, and covered with 4 µm thick Ultralene plastic film to prevent contamination of the measuring prism. Cores were warmed up before covering with the film to prevent condensation underneath the plastic, which can affect X-ray attenuation (Tjallingii et al., 2007).
XRF data were collected every 2 cm, with sample locations occasionally being shifted to avoid protruding clasts, cracks, and depressions along the core surface. Two scans were completed for each core section at different voltages: 10 and 30 kV. The 10 kV scan was for the elements Al, Si, P, Cl, Ar, K, Ca, Ti, Cr, Mn, Fe, Rh, and Ba and the 30 kV scan was for Fe, Ni, Cu, Zn, Ga, Ge, As, Br, Rb, Sr, Y, Zr, Nb, Mo, Pb, and Bi. Settings used for the 10 kV scan were a tube current of 0.5 mA and detection time of 20 s. For the 30 kV scan a tube current of 1 mA and a detection time of 30 s were used. The sample irradiation area was 10 mm in the downcore direction and 15 mm in the crosscore direction. All XRF data are presented as counts per second in XRF in “Supplementary material.”