Geochemistry and petrology of striped chert as a provenance tool for artefacts from the KRZEMIONKI NEOLITHIC mining area (Poland)

Abstract

A prehistoric flint mine in Krzemionki with a neighboring area covers at least 2,300-year history of striped chert extraction and dressing, spanning the age bracket of 3900 through 1600 B.C. The striped cherts occur in the form of concretions (nodules) varying from centimeters to at least 2 m across. This paper presents updated results of petrological and geochemical study of these siliceous rocks using optical and scanning electron microscopy, electron microprobe analysis (major/trace elements), and laser ablation-inductively coupled plasma-quadrupole mass spectrometry (rare earth elements). Striped chert concretions show strong light REENASC enrichments in relation to heavy REENASC; distinctly positive Eu, Pr, Tb, Ho, and Tm anomalies (≥1.2); as well as predominantly low (<0.6) Al2O3/Al2O3 + Fe2O3 + Mn2O3 ratios. These features discriminate these siliceous rocks from most chert occurrences in Europe. Microanalysis of individual concretions has confirmed multiphase provenance of striped chert concretions as evidenced by variations in concentrations of REE and other minor and trace elements. These characteristic markers may be used as geochemical proxies for studying the chert geologic/geographic origin and for sourcing of chert artefacts.