Using cryptotephra to link Neanderthal and AMH Middle Paleolithic sites in NW Italy

Description

Establishing robust and reliable chronologies at archaeological sites is essential for understanding the sequence and timing of past events. At Middle and Upper Paleolithic sites like Arma Veirana and Riparo Bombrini, robust chronologies are especially important for answering questions regarding the Middle-to-Upper Paleolithic transition in Europe. Arma Veirana is located in the Ligurian pre-Alps of northwest Italy and Riparo Bombrini is located along the Mediterranean coast, about 80 km away. Both sites have deposits that overlap in age and contain cultural industries attributed to Neanderthals and anatomically modern humans (AMH). Stratigraphic evidence suggests that Neanderthals may have been present at Arma Veirana while AMHs were present at Riparo Bombrini, making it an ideal area to understand the interactions and dynamics of these two species during a key transitional phase. Cryptotephra, also known as microscopic volcanic ash, were recently identified at Arma Veirana in a stratigraphic unit known as the Black Mousterian (BM). AMS radiocarbon dates of charcoal samples collected in the BM, range from 43,781 to 43,121 (68.2%) cal. Yr. BP. Because these dates are close to the measurement limit of radiocarbon, the presence of cryptotephra provides a way to test these existing dates as well as establish a precise isochron to correlate with other sites. Major element chemistry obtained by electron microprobe indicate that the shards found in the BM layers are high silica rhyolite (>75 wt. %) with FeO < 1 wt.%. Trace elements by LA-ICP-MS show depletions in Ba, Sr, and Eu and an enrichment in Th, U and Pb. Both major and trace chemistries show unique geochemical signatures and are rare for volcanoes in the central Mediterranean region. The source volcano is currently unknown; however, this unique chemistry eliminates volcanoes from Iceland, North America, Canaries or Azores, and Aeolian Islands. Potential source volcanoes are located in Turkey (Acigol Dagi Volcano), the Carpathian Mountains (Ciomadul Volcano) and Greece (Nisryos volcano and Santorini Caldera). To test the hypothesis that Neanderthals were displaced from the coast when modern humans arrived in the region, I will take cryptotephra samples at Riparo Bombrini in the summer of 2018 with the goal of directly linking both sites. Identifying the same cryptotephra horizon at Riparo Bombrini will provide an unprecedented temporal correlation between the two sites. This will lead to a better understanding of Neanderthal and AMH interactions during the Middle to Upper Paleolithic transition in Europe.

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