Search

Abstract: Calcareous pericarps of the tribe Lithospermeae (fam. Boraginaceae) are a common component of archaeobotanical macroremain assemblages in the Mediterranean region. In this study, the relationship between oxygen isotopic composition of fruit biogenic carbonate and climatic conditions was examined. δ 18O and δ 13C values of biogenic carbonate were measured in modern Lithospermeae fruits from seven Eurasian sites (Berlin, Kirchentellinsfurt, Göttingen, Athens, Ankara, Tbilisi, and Almaty) and in fossil fruits from three archaeological sites in the eastern Mediterranean (Troy, Kumtepe, and Hirbet ez-Zeraqon). Additionally, three 14C measurements were performed on ancient fruit carbonate from Hirbet ez-Zeraqon. The δ 18O and δ 13C values varied from −9 to 5‰ PDB and between −35 and −7‰ PDB respectively. In modern fruits, δ 18O of biogenic carbonate was correlated to local summer precipitation amounts (inversely proportional) and summer air temperatures (proportional). In fossil fruits, the δ 18O values of carbonate from Troy and Kumtepe were significantly lower than that from Hirbet ez-Zeraqon (ca. −5 vs. 2‰ PDB respectively). The vertical distribution of stable isotopic values and 14C dates in cultural layers of Hirbet ez-Zeraqon indicate that fruit biogenic carbonate can persist in sediment without appreciable diagenetic alteration. These findings suggest that biogenic carbonate of Lithospermeae fruits can be useful as a paleoclimate proxy at least in the Mediterranean. [Copyright &y& Elsevier]

Abstract: It has been suggested that pedogenic carbonate coatings on stones in archaeological sites can be used to reconstruct late Quaternary environmental changes in the area of the Fertile Crescent. This research compares a pedogenic carbonate record from southeastern Turkey with three other local or regional sources of palaeoenvironmental information in order to evaluate the correlation of this new proxy with other independent data from the area: (1) ancient plant macroremains from archaeological sites as ecological indicators, (2) stable carbon isotope composition of ancient plant macroremains available in the literature and from our own investigations in six mid-Holocene archaeological sites, and (3) modelled Holocene precipitation and temperature changes in the northern Fertile Crescent. Comparison involved selected palynological and isotopic data from lacustrine sediments as well as speleothem isotopic records in Near Eastern locations available in the literature. Although the data show a certain amount of variation of proxy records on the regional scale, for the northern Fertile Crescent (Upper Mesopotamia) they suggest three pronounced features of the Holocene environmental history: (1) a trend toward warmer temperatures may have affected the area during the early Holocene (between ca. 10,000–6000cal BP), (2) increased moisture availability and relatively high temperatures in the mid-Holocene (ca. between 5000 and 4000cal BP), and (3) a significant decrease in moisture availability around 4000cal BP. Further research is needed to enhance the chronological resolution of both pedogenic carbonate and plant macrofossil records. This study stresses the complexity of the Holocene palaeogeography of the Near East and underlines the need for careful analysis of local sources of palaeonvironmental information in the region. [Copyright &y& Elsevier]

Abstract: The analysis of carbon isotope discrimination (Δ13C) in crop plant remains from seven Bronze Age sites in northern Mesopotamia and the Levant shows clear differences in water availability between the different geographic areas and throughout the different periods (3000–1200 BC). Amongst the different moisture variables modelled precipitation minus evaporation (P-E—using a macrophysical climate model (MCM)) results in very high correlation (0.74) with Δ13C values in barley, supporting the significance of climate parameters (effective moisture) in carbon fixation in this species. The comparison of Δ13C values of different crops in different periods confirms increased aridity during the Middle Bronze Age (2000–1600 BC), compared to the later Early Bronze Age (2700–2000 BC) particularly in the north-eastern Syrian territory with generally lower Δ13C values during the Middle Bronze Age, as has been documented in palaeoclimate proxies, and in agreement with the MCM. Standard deviation in Δ13C values from grains or seeds of one species originating from different samples of an individual site may be understood as variability in moisture conditions during the grain-filling period around the considered location. Large standard deviations occur preferably in sites with low mean annual precipitation (e.g. at Emar) and suggest that in these sites, at least some of the crops were irrigated. [Copyright &y& Elsevier]

Abstract: Lithospermum (Boraginaceae) belongs to a small group of plant taxa that accumulate biogenic carbonate in their fruits. In this genus, carbonate incrustations form in the cells of the epidermis and sclerenchyma of the pericarp. Fossil Lithospermum fruits (nutlets) with well-preserved calcified tissues commonly occur in Quaternary sediments and cultural layers. We tested the suitability of biogenic carbonate of Lithospermum fruits for radiocarbon dating using a total of 15 AMS measurement results from four modern and 11 fossil samples. The 14C data from modern samples suggest that Lithospermum utilises only atmospheric carbon to synthesise calcite in the nutlets. In general, the ages determined through 14C dating of fossil fruitscorresponded well with the absolute-age intervals for archaeological sites over the last 5000 yr. Biogenic carbonate of Lithospermum fruits, like that of Celtis, represents a new source of chronological information for late Quaternary studies. [Copyright &y& Elsevier]