Large‐scale geochemical survey by pXRF spectrometry of archaeological settlements and features: new perspectives on the method

Over the past several decades the geochemical study of archaeological sediments has experienced an increase in interest from archaeologists in search of new methods to investigate spatial organization and space function. Used with other proxies like geophysics, archaeobotany and micromorphology, geochemistry provides a new insight into microscopic pollution generated by past human activities, and thus can explain or confirm the function of features and spaces. Portable X‐ray fluorescence (pXRF) spectrometry offers new perspectives to the archaeological community to test, develop and integrate geochemical surveys in the daily routine of fieldwork, especially in the developer‐funded archaeology sector. We have undertaken over 20 geochemical surveys using pXRF spectrometry, both in the field and on bulk samples, and from a wide variety of sites, sedimentological, and chronological contexts. Working exclusively on developer‐funded projects, we present a series of results detailing a range of chemical element associations, including details on how the data is organized spatially and how these data may be interpreted. For some associations, such as that between phosphorus, calcium and strontium, our work confirms and builds on existing studies. For other elements such as zirconium, or the association between potassium, chromium and vanadium, our work presents new data patterns as well as a series of new hypothesis; the interpretation of these patterns remains at an early stage and we hope that further work will be done to test and detail the origins of these chemical associations and enrichments, with the goal of confirming the human activities and/or natural processes from which they originated. The rapidity and cost‐efficiency of pXRF, especially when used in situ in the field, makes it the ideal method for documenting the geochemical characteristics of landscapes; the approach we have developed means that geochemical survey can become a regular part of archaeological practice.