Marta Sánchez de la Torre

The geochemical characterization of two long distance chert tracers by ED-XRF and LA-ICP-MS. Implications for Magdalenian human mobility in the Pyrenees (SW Europe)

ABSTRACT We geochemically characterize two chert formations outcropping in the Pyrenees and presenting similar characteristics at the visual and microscopic scale: The Montgaillard flysch cherts and the Montsaunès cherts. Cherts presenting identical textural and micropalaeontological features as both types have been found in several Magdalenian Pyrenean sites. We are face to a long distance chert type whose geochemical characterization is essential for knowing where the tracer comes from. Analyses have been done using Energy-dispersive X-ray fluorescence (ED-XRF) and laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS). Results show that despite obtaining similar data concerning major and minor elements, differences have been observed regarding trace elements. The establishment of differences between both formations at the geochemical level has allowed specifying the origin of this chert type recovered at the Magdalenian levels of Parco Cave (Alòs de Balaguer, Spain). Results demonstrate long lithic raw material circulation and thus, human mobility in the Pyrenees during the Upper Palaeolithic.

Reconsidering prehistoric chert catchment sources: new data from the Central Pyrenees (Western Europe)

In the framework of a postdoctoral project to geochemically characterise Pyrenean cherts, a new marine chert outcrop in the Central Pyrenees has been defined. This new discovery, called the Buala outcrop, and its flysch chert type, provide new information about marine chert sources in the Pyrenean chain, leading us to reconsider prehistoric chert procurement in this area. Until now, two geological formations from the Central Pyrenees were considered as potential sources for a type of marine chert usually appearing in the Magdalenian record of several Pyrenean sites: Montgaillard flysch cherts and Montsaunès cherts. With both formations presenting similar characteristics, it was only through the use of geochemical methods that differences were recently established as reported by Sánchez de la Torre et al. (STAR 3:15–37, 2017b). This paper presents the new marine flysch chert outcrop of Buala. The visual, micropalaeontological and geochemical characterisation of this chert has permitted the definition of a new potential source for this marine chert type, which is common in several Palaeolithic sites in the Pyrenees, as Cova del Parco (Alòs de Balaguer, Spain), Forcas I Shelter (Graus, Spain), Montlleó open-air-site (Prats i Sansor, Spain), or Caune de Belvis (Belvis, France) (Sánchez de la Torre 2015). Geochemical characterisation of the three potential sources was carried out using energy-dispersive X-ray fluorescence (ED-XRF) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Results show that Buala flysch cherts are clearly different from the previously known chert types in terms of major, minor, and trace elements.