First 40Ar/39Ar analyses of Australasian tektites in close association with bifacially worked artifacts at Nalai site in Bose Basin, South China: The question of the early Chinese Acheulean.

The recently discovered Nalai site is one of the Bose Basin localities, which is key to studying the earliest bifaces in China. The Nalai site has yielded an abundance of lithic artifacts, including bifaces and tektites in close association. The total fusion 40Ar/39Ar method was applied to four tektites discovered beside and contemporaneous with bifaces in the red laterite sediments of the upper levels of the T4 terrace (layers 4 and 5). Our 40Ar/39Ar data with a weighted mean age of 809 ± 12 ka provide for the first time unequivocal dates for bifacial production at Bose, broadly consistent with the precise Australasian tektite age of 788.1 ± 2.8 ka, recently published by other investigators. The relatively important errors reported here suggest sample contamination by clasts or bubbles for the oldest aliquots and alteration for the younger ones. The lithic assemblage from layers 4 and 5 of the Nalai site is quite similar to that found at other sites in the Bose Basin. The assemblages are dominated by choppers, but bifaces, picks, and unifaces give a Mode 2 and Acheulean-type character to the series. The high frequency of the round tongue-shaped tip, a low elongation index, and a wide and thick base characterize the Large Cutting Tools. These results contribute to resolving ongoing debates on the timing and origin of bifaces and the Acheulean in China.

Multi-Technique Characterization of 3.45 Ga Microfossils on Earth: A Key Approach to Detect Possible Traces of Life in Returned Samples from Mars.

The NASA Mars 2020 Perseverance rover is actively exploring Jezero crater to conduct analyses on igneous and sedimentary rock targets from outcrops located on the crater floor (Máaz and Séítah formations) and from the delta deposits, respectively. The rock samples collected during this mission will be recovered during the Mars Sample Return mission, which plans to bring samples back to Earth in the 2030s to conduct in-depth studies using sophisticated laboratory instrumentation. Some of these samples may contain traces of ancient martian life that may be particularly difficult to detect and characterize because of their morphological simplicity and subtle biogeochemical expressions. Using the volcanic sediments of the 3.45 Ga Kitty's Gap Chert (Pilbara, Australia), containing putative early life forms (chemolithotrophs) and considered as astrobiological analogues for potential early Mars organisms, we document the steps required to demonstrate the syngenicity and biogenicity of such biosignatures using multiple complementary analytical techniques to provide information at different scales of observation. These include sedimentological, petrological, mineralogical, and geochemical analyses to demonstrate macro- to microscale habitability. New approaches, some unavailable at the time of the original description of these features, are used to verify the syngenicity and biogenicity of the purported fossil chemolithotrophs. The combination of elemental (proton-induced X-ray emission spectrometry) and molecular (deep-ultraviolet and Fourier transform infrared) analyses of rock slabs, thin sections, and focused ion beam sections reveals that the carbonaceous matter present in the samples is enriched in trace metals (e.g., V, Cr, Fe, Co) and is associated with aromatic and aliphatic molecules, which strongly support its biological origin. Transmission electron microscopy observations of the carbonaceous matter documented an amorphous nanostructure interpreted to correspond to the degraded remains of microorganisms and their by-products (extracellular polymeric substances, filaments…). Nevertheless, a small fraction of carbonaceous particles has signatures that are more metamorphosed. They probably represent either reworked detrital biological or abiotic fragments of mantle origin. This study serves as an example of the analytical protocol that would be needed to optimize the detection of fossil traces of life in martian rocks.

Compositional and provenance study of glass beads from archaeological sites in Mali and Senegal at the time of the first Sahelian states.

The presence of glass beads in West African archaeological sites provides important evidence of long-distance trade between this part of the continent and the rest of the world. Until recently, most of these items came from historical Sub-Saharan urban centers, well known for their role in the medieval trans-Saharan trade. We present here the chemical analysis by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) of 16 glass beads found in three rural sites excavated during the past decade: the funerary site of Dourou-Boro and settlement sites of Sadia, in central Mali, as well as the settlement site of Djoutoubaya, in eastern Senegal, in contexts dated between the 7th-9th and the 11th-13th centuries CE. Results show that the raw materials used to manufacture the majority of the glass most probably originated in Egypt, the Levantine coast and the Middle East. One bead is of uncertain provenance and shows similarities with glass found in the Iberian Peninsula and in South Africa. One bead fragment found inside a tomb is a modern production, probably linked to recent plundering. All of these ancient beads were exchanged along the trans-Saharan trade routes active during the rise of the first Sahelian states, such as the Ghana and the Gao kingdoms, and show strong similarities with the other West African bead assemblages that have been analysed. Despite the remoteness of their location in the Dogon Country and in the Falémé River valley, the beads studied were therefore included in the long-distance trade network, via contacts with the urban commercial centers located at the edge of the Sahara along the Niger River and in current southern Mauretania. These results bring a new light on the relationships between international and regional trade in Africa and highlight the complementarity between centres of political and economic power and their peripheries, important because of resources like gold for eastern Senegal.

The trade of glass beads in early medieval Illyricum: towards an Islamic monopoly.

The trade of glass beads has long been assumed to have been under Islamic dominance during the early centuries following the Arab conquest of the Middle East, judged by the prevalence of Islamic beads in the archaeological contexts from Viking Scandinavia to medieval Morocco. This paper explores the impact of the Byzantine-Slavic transition on the use and by extension trade of glass beads in the Balkans from the seventh to the ninth century CE. A series of 48 glass beads and 4 vessel fragments from two excavated sites in modern day Albania have been analysed morphologically, technologically and chemically by LA-ICP-MS. The seventh-century beads from Lezha have typological parallels among central European assemblages and are made from recycled natron-type glass. The presence of a high lead-iron-natron variant is of particular interest as it potentially reflects a regional production. The ninth-century beads from Komani are made from soda-rich plant ash glass from the eastern Mediterranean and Mesopotamia and correspond to an Islamic typology. The chronological and geographical differences are reflected in the distinctive cobalt sources used for the two groups. While the beads from Lezha are coloured with a cobalt not correlated with any particular element, the cobalt source of the Komani samples is associated with zinc, typical of Islamic glass making. It thus appears that the supply of beads during the seventh century when the Balkans were under Slavic occupation relied on regional production and recycled material, and that a long-distance trade with the eastern Mediterranean was revived following the Byzantine re-conquest of the south-eastern Adriatic in the ninth century. Intriguingly, the Albanian finds confirm the Islamic control of the production and trade of glass beads during this period and highlight the mediatory role of the Byzantine Empire.

Comprehensive Chemical Characterisation of Byzantine Glass Weights.

The understanding of the glass trade in the first millennium CE relies on the characterisation of well-dated compositional groups and the identification of their primary production sites. 275 Byzantine glass weights from the British Museum and the Bibliothèque nationale de France dating to the sixth and seventh century were analysed by LA-ICP-MS. Multivariate statistical and graphical data analysis discriminated between six main primary glass types. Primary glass sources were differentiated based on multi-dimensional comparison of silica-derived elements (MgO, Al2O3, CaO, TiO2, Fe2O3, ZrO2) and components associated with the alkali source (Li2O, B2O3). Along with Egyptian and Levantine origins of the glassmaking sands, variations in the natron source possibly point to the exploitation of two different natron deposits. Differences in strontium to calcium ratios revealed variations in the carbonate fractions in the sand. At least two cobalt sources were employed as colouring agents, one of which shows strong correlations with nickel, indicating a specific post-Roman cobalt source. Typological evidence identified chronological developments in the use of the different glass groups. Throughout the sixth century, Byzantine glass weights were predominately produced from two glasses that are probably of an Egyptian origin (Foy-2 and Foy-2 high Fe). Towards the second half of the sixth century a new but related plant-ash glass type emerged (Magby). Levantine I was likewise found among the late sixth- to early seventh-century samples. The use of different dies for the same batch testifies to large-scale, centralised production of the weights, while the same die used for different primary production groups demonstrates the co-existence of alternative sources of supply. Given the comprehensive design of our study, these results can be extrapolated to the wider early Byzantine glass industry and its changes at large.

Middle palaeolithic and neolithic occupations around Mundafan Palaeolake, Saudi Arabia: implications for climate change and human dispersals.

The Arabian Peninsula is a key region for understanding climate change and human occupation history in a marginal environment. The Mundafan palaeolake is situated in southern Saudi Arabia, in the Rub' al-Khali (the 'Empty Quarter'), the world's largest sand desert. Here we report the first discoveries of Middle Palaeolithic and Neolithic archaeological sites in association with the palaeolake. We associate the human occupations with new geochronological data, and suggest the archaeological sites date to the wet periods of Marine Isotope Stage 5 and the Early Holocene. The archaeological sites indicate that humans repeatedly penetrated the ameliorated environments of the Rub' al-Khali. The sites probably represent short-term occupations, with the Neolithic sites focused on hunting, as indicated by points and weaponry. Middle Palaeolithic assemblages at Mundafan support a lacustrine adaptive focus in Arabia. Provenancing of obsidian artifacts indicates that Neolithic groups at Mundafan had a wide wandering range, with transport of artifacts from distant sources.