4 research outputs found
Recommended from our members
Mid- to late-Holocene archaeology, environment and climate in the northeast Kurdistan region of Iraq
This work presents new data from phytolith and speleothem analyses that cover the middle to late Holocene from northeastern Iraq in the Kurdistan region. Coupling these data with previous work, we demonstrate how the region’s environment and climate developed during a time when agriculture became not only established but settlements started to transform into larger urban areas. Results demonstrate a wetter phase during the middle Holocene relative to the present period; a highly seasonal climate with one rainy season is also suggested between 8025 ± 38 and 6977 ± 219 BP. Phytoliths not only suggest a relatively wet environment but they also indicate a diversity of plants used for settlement activity. Sedimentary results complement the indication of a relatively wetter middle Holocene. Archaeologically, terraced construction found in Gurga Chiya and the presence of drought tolerant crops suggest adaptation to stronger, seasonal rains and seasonal droughts in the middle Holocene. Sedimentary, phytolith, and speleothem results suggest relatively drier late-Holocene conditions, although the region continued to be conducive for rainfed agriculture
The Origin and MgCl2–NaCl Variations in an Athalassic Sag Pond: Insights from Chemical and Isotopic Data
The examination of past and new chemical–isotopic data (2H/1H–18O/16O,11B/10B and87Sr/86Sr ratios) shows the meteoric origin of the Sawa Lake (Muthanna Governorate, Iraq) and its connection with the local aquifers, which feed the lake via the groundwater emerging from its floor through fault systems. The chemical and isotopic evaporation models are traced by geochemical computer codes by using a different composition of some potential inflows to the lake (e.g., the Euphrates River and Dammam aquifer). The main product of the chemical evaporation models is gypsum, as confirmed by the mineralogical examination of the sediment and the surrounding outcrops. A strong18O–2H enrichment is a consequence of the evaporation effect in arid regions; δ18O–Cl models and δ11B = + 23.4‰ exclude the contribution of any seawater-derived fluids. This latter value along with87Sr/86Sr = 0.707989 suggests a mixed origin from the Eocene–Miocene aquifers. The isotope and chemical evaporation paths from the meteorically recharged sources match the lake composition. However, compositional switches from NaCl toward MgCl2occurred in the last decade and are related to post-drought periods, showing that the interaction of the recharging waters with the local soils (Na–Mg exchange and/or the leaching of the top layer salts) have a role in the chemical composition. This demonstrates that the lake is significantly influenced by climatic variations