The Hallstatt D1-D2 Armorican-type socketed axes hoard of Trelly (Manche, France): Interpretations from elementary chemical analysis

摘要

Discovered in 1998, the Trelly hoard (Manche, France) was discovered through electromagnetic surveys. A quick emergency dig revealed the presence of many artefacts, most of which had been displaced by recent ploughing. The main interest of this small hoard, consisting of about thirty copper-based artefacts, resides in an association of Armorican-type socketed axes with bracelets typical of the Hallstatt D1-D2 period. While this hoard was well-known due to the presentation of several artefacts at the exhibition "Nos ancêtres les Gaulois" held at Nantes in 1999, no analyses had been carried out and the artefacts remained unexploited. In the framework of a new research programme concerning prehistoric copper artefacts and their elementary composition, most of the artefacts from this hoard were the subject of chemical analyses. Many large hoards discovered in Brittany, Normandy and the Channel Islands contained only Armorican-type socketed axes. These deposits were said to belong to the final stage of the Bronze Age (Briard, 1965; Rivallain, 1971). New archaeological excavations in Brittany and in Normandy, such as Kergariou, Quimper, Finistère (Menez et al., 2005; Menez and Gomez de Soto, 2006; Gomez de Soto et al., 2009) confirm that this original phenomenon dates from the second period of the First Iron Age. The Trelly hoard also belongs to this period, because of the synchronism of Armorican-type socketed axes and bracelets dated from the middle/late Hallstatt period. This hoard is composed of socketed axes (one of the Tréhou type, one Plurien and eighteen of the Couville type, and two fragments of large axes), five bracelets and fragments of bracelets (one open bracelet decorated with transverse incisions, one open massive bracelet with a sub-rectangular section resembling a gear-wheel, a fragment of an open and massive boss bracelet with a plano-convex section, a fragment of a massive bracelet with a plano-convex section decorated with four transverse incisions, a closed and massive bracelet with a circular section), a fragment of a shank with a rectangular section, a fragment of an artefact made of grey metal composed of a shank with a sub-rectangular section ending in a conic boss, a circular ring with a 'bezel' composed of two plates with joined central cupulae. The main artefacts of the Trelly hoard have been analysed to check their homogeneity. Similarly, the homogeneity of the artefacts' composition was controlled by performing duplicate analyses whenever possible. Each sample consisted of 40 mg of metal. The samples were dissolved in 20 ml of 2/5 aqua regia in order to analyse them by inductively coupled plasma atomic emission spectrometry (Jobin-Yvon 138 Ultrace ICP-AES). The concentration of the metallic solution was 2 g.L'1. In order to determine the concentration of each metal studied by ICP-AES, a calibration range was defined between 0 and 2 g.L'1. Standards of the main elements (Cu, Pb, Sn) were prepared twice in order to have a calibration range close to the concentration of these elements in the samples (table 2).