Constraining a bioavailable strontium isotope baseline for the Lake Garda region, Northern Italy: A multi-proxy approach. (February 2022)

• Record Type: Journal Article
• Authors: Ladegaard-Pedersen, Pernille; Frei, Robert; Frank, Anja B.; Saracino, Massimo; Zorzin, Roberto; Martinelli, Nicoletta; Kaul, Flemming; Kristiansen, Kristian; Frei, Karin M.
• Is Part Of: Journal of archaeological science. Volume 41(2022)
• Publication Date: 2022-02
• Subjects: Strontium isotopes -- Northern Italy -- Bioavailable 87Sr/86Sr baseline -- Environmental multi-proxy approach -- Mobility and provenance studies -- Archaelogy -- Lake Garda; Archaeology -- Periodicals; Archaeology -- Research -- Periodicals; 930.1
• DOI: 10.1016/j.jasrep.2022.103339
• Languages: English
• ISSNs: 2352-409X

Abstract

Graphical abstract: Highlights: We present multi-proxy Sr isotope baselines for the Lake Garda region (Italy) Two baselines (Po plain north of River Po and Fersina Valley) are discriminated. Baselines are suitable for provenance and mobility studies of Bronze Age humans. Strong agreement in 87 Sr/ 86 Sr signatures of proxies in carbonate-dominated areas. High variability of strontium isotope signatures in Alpine terranes. Abstract: The evidence of prehistoric long-distance exchange networks in northern Italy is overwhelming, attested by several finds of non-local raw materials in Bronze Age pile-dwelling settlements of Lake Garda and eastern Po plain, like amber beads and bronze artefacts. Metals are dispersed throughout Bronze Age Europe from mining communities within the Alpine regions, and possibly local artefacts, like the Peschiera-type daggers, are known from archaeological records throughout Europe. This positions the region as part of organized networks of trade and communication connecting prehistoric Europe from north to south. This, however, does not in itself indicate a similar long-distance mobility of prehistoric individuals. To investigate individual, human provenance and mobility, the strontium (Sr) isotope methodology compares strontium isotope analysis of human remains to bioavailable strontium isotope baselines characterizing the regions of interest. We present here environmentally based, multi-proxy (water, soil leachates and plants) Sr baselines from the Lake Garda region. Our results show two separate baselines, roughly corresponding to the geographical distribution of rock types and erosional products thereof. One baseline is valid for the Lake Garda region, where Mesozoic carbonates are a dominant surface-near strontium source, and for the central Po plain north of River Po. We constrain this to 87 Sr/ 86 Sr = 0.7088 ± 0.0014 (2σ; n = 44) when including 9 compatible samples reported previously. The second Sr-baseline is valid for Alpine areas dominated by magmatic (basalts excluded) and metamorphic bedrock around the Fersina valley. We constrain this to 87 Sr/ 86 Sr = 0.7146 ± 0.0058 (2σ; n = 22) when including 11 compatible samples reported in previous studies. The baselines are compatible with previously reported results of other Sr proxies such as snails, archaeological fauna, and agricultural soils and products from the region.