Portable X-ray fluorescence identification of the Cretaceous–Paleogene boundary: Application to the Agost and Caravaca sections, SE Spain

Abstract

We show that portable x-ray fluorescence (pXRF) is a powerful tool for the unambiguous identification and geochemical characterization of prospective Cretaceous-Paleogene (K-Pg) boundary sites. We have performed in-situ analyses in two well-known K-Pg boundary sequences, located at Agost and Caravaca, SE Spain. A sizable enrichment around the K-Pg horizon of several elements such as K, Ti, Fe, Ni, Cr, Cu, Zn, As or Pb, together with a strong reduction in the Ca content, is found with the pXRF instrument. These observations represent a primary geochemical signature of the K-Pg boundary in distal marine sections such as those of Agost and Caravaca. We show that the intensities of the XRF peaks correlate well with elemental composition data obtained by inductively coupled plasma-mass spectrometry (ICP-MS) on collected samples. Hence, the pXRF field measurements are shown to provide fast and useful quantitative information about K-Pg boundary sequences.

Portable X‐Ray Fluorescence Spectroscopy as a Tool for Cyclostratigraphy

“…X‐ray fluorescence spectroscopy (XRF) of sedimentary rocks, particularly using core scanners, has long been used as a chemostratigraphic and palaeoenvironmental tool (e.g., Algeo & Maynard, ; Kujau et al, ; Kylander et al, , ; Naeher et al, ; Weltje & Tjallingii, ; Wilhelms‐Dick et al, ). Recent studies have commented on the use of portable XRF (pXRF) in sedimentary rock analyses, particularly for linking elemental changes to stratigraphic and paleoclimatic observations, and the calibration of pXRF instruments to other elemental analyzers (Dahl et al, ; de Winter et al, ; Ibañez‐Insa et al, ; Kessler & Nagarajan, ; Lenniger et al, ; Mejia‐Pina et al, ; Quye‐Sawyer et al, ; Rowe et al, ; Thibault et al, ). The ability to measure elemental concentrations, and sensitivity of modern pXRF instruments, provides a clear rationale for employing pXRF analysis for cyclostratigraphy (e.g., Ruhl et al, ; Sinnesael et al, ; Thibault et al, ).…”