A Traditional Approach to Using New Technology: Maximizing the Efficacy of Handheld X-Ray Florescence Data – An Example From the Rietavas Licence of Lithuania

Abstract

Handheld X-ray fluorescence (HHXRF) instruments are increasingly used to acquire elemental data in unconventional plays. Because the instruments provide a means to quickly acquire inorganic geochemical data by direct, high resolution, non-destructive analysis of cores, they are powerful tools in helping to understand unconventional resource plays. However, with the proliferation of HHXRF data acquisition, the basic concepts of geologically understanding elemental data have become somewhat forgotten; the need to understand the controls on elemental changes and combine elemental data with other datasets are often omitted from HHXRF studies, which greatly diminishes the usefulness of the datasets. A 14 well chemostratigraphic correlation of Ordovician and Silurian sediments from the Rietavas Licence of Lithuania constructed from data acquired by HHXRF and handheld magnetic susceptibility (HHMS) instruments will be presented. The correlation incorporates over 1000 HHXRF and HHMS determinations made by direct measurement of conventional cores at storage facilities in Lithuania and the UK. Although the correlation defined is chemostratigraphically robust, its geological significance would have remained enigmatic if the additional data outlined below had not been acquired. A lack of understanding of the controls on elemental and magnetic susceptibility data in any study, unconventional or conventional, greatly diminishes the amount information that can be gleaned from the data and can render chemostratigraphic correlations meaningless. Here, X-ray diffraction, petrographic, and TOC data were acquired from a subset of core samples and sedimentological logs were compiled for select cores. By integrating these traditional data with the hand held datasets, it is shown that key variables used to define the chemostratigraphic correlation are responding to paleosol development (Fe₂O₃, MS, MgO), marine productivity (P₂O₅), provenance (Zr, TiO₂), paleoredox (U, Mo, V) and facies (Al₂O₃, SiO₂, CaO, MgO). Not only does this provide context to the chemostratigraphic correlation, it adds to understanding the depositional evolution of study intervals. This “return-to-basics” approach to using HHXRF data provides a clear demonstration that when carefully interpreted, elemental data acquired by direct analysis of core, using handheld instruments, is able to provide enhanced stratigraphic and geological understanding in subsurface studies.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015