Trace-elemental and multi-isotopic (Sr-Nd-Pb) discrimination of jade in the circum-Caribbean: Implications for pre-colonial inter-island exchange networks

Dense and strong, hydrothermal-metasomatic jadeitite and jadeite-omphacite rocks were used as tools and adornments throughout the wider Caribbean since initial inhabitation. Regionally, rich sources of jadeitite and jadeite-omphacite jade are known only in Guatemala (north and south of the Motagua Fault Zone), eastern Cuba and the northern Dominican Republic, establishing that humans transported jadeitic material over vast distances. This study validates that geochemical fingerprinting is a viable provenance method for Caribbean pre-colonial jadeitic lithologies. An assemblage of 101 source rocks has been characterised for trace element and combined Sr-Nd-Pb isotope compositions. Four statistical approaches (Principal Component Analysis, t-Distributed Stochastic Neighbour Embedding, Decision Tree, and Multiclass Regression) were assessed, employing source-distinct trace element ratios. A multiclass regression technique based on trace element ratios of immobile high field strength, light to medium rare earth and fluid-mobile, large-ion-lithophile elements is shown to be most effective in discriminating the four source regions. Ninety-one % of the Guatemalan samples can be discriminated from the Dominican and Cuban sources using La/Th, Zr/Hf and Y/Th ratios. Jadeitic rocks cropping out in the Dominican Republic can be distinguished from Cuban jades employing Er/Yb, Nb/Ta and Ba/Rb ratios with 71% certainty. Furthermore, the two Guatemala sources, north and south of the Motagua Fault Zone, can be discriminated by using (among others) Zr/Hf, Ta/Th, La/Sm and Dy/Y ratios with an 89% success rate. This raises the possibility of determining, in detail, former trading and mobility networks between different islands and the Meso- and Central American mainland within the Greater Caribbean. The provenance technique was applied to 19 pre-colonial jade celts excavated from the Late Ceramic Age Playa Grande archaeological site in the northern Dominican Republic. Three artefacts are discriminated as derived from the Guatemalan source, indicating that, despite a source of jade within 25 km, material was traded from Guatemala. The presence of Guatemalan jade in the Playa Grande lithic assemblage provides further evidence of large scale (>3000 km), regional trading and indigenous knowledge transfer networks.This research received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007–2013)/ERC grant agreement No 319209 (ERC-Synergy NEXUS 1492) and the European Union’s Horizon 2020 research and innovation programme under grant agreement No 654208 (Europlanet 2020 RI). We are grateful to the Museo del Hombre Dominicano for providing the Playa Grande samples. Thanks to Richard Smeets, Bas van der Wagt, Kirsten van Zuilen, Bouke Lacet, Eva Kelderman and Quinty Boosten for analytical assistance

Geochemical characterisation of jadeitite in the Greater Caribbean and source discrimination applying multiclass regression analyses: Implications for precolonial inter-islands exchange networks

25th Annual Meeting of the European Association of Archaeologists (EAA), from 4-7 September 2019 in Bern, Switzerlan

“Non-invasive” portable laser ablation sampling of art and archaeological materials with subsequent Sr–Nd isotope analysis by TIMS using 10 13

A new integrated trace element and multi-isotope provenancing methodology is presented that uses a portable “non-invasive” pulsed laser ablation sampling technique. Samples are collected on location onto Teflon filters for return to a clean laboratory for low blank (pg) geochemical procedures. Ablation pits approximately 60 or 120 μm in width and depth remove mg amounts of material. Following dissolution, trace element ratios are determined by inductively coupled plasma mass spectrometry and combined Sr–Nd isotopes by thermal ionization mass spectrometry. Use of 1013 Ω resistors allows precise analysis of subnanogram amounts of Sr-Nd isotopes, which coupled with the trace element data, provides highly effective multi-variant discrimination for material provenance and authenticity verification. Monitoring of blank contributions is required

Resolution of Singularities: an Introduction.

International audienceThe problem of resolution of singularities and its solution in various contexts can be traced back to I. Newton and B. Riemann. This paper is an attempt to give a survey of the subject starting with Newton till the modern times, as well as to discuss some of the main open problems that remain to be solved. The main topics covered are the early days of resolution (fields of characteristic zero and dimension up to three), Zariski's approach via valuations, Hironaka's celebrated result in characteristic zero and all dimensions and its subsequent strenthenings and simplifications, existing resutls in positive characteristic (mostly up to dimension three), de Jong's approach via semi-stable reduction, Nash and higher Nash blowing up, as well as reduction of singuarities of vector fields and foliations. In many places, we have tried to summarize the main ideas of proofs of various results without getting too much into technical details