Fire activity in North West Africa during the last 30,000 cal years BP inferred from a charcoal record from Lake Ifrah (Middle atlas-Morocco): Climatic implications

摘要

Paleofire activity in North Africa and its connections with past climatic changes still remains poorly documented. A new multiproxy analysis using mineralogy, geochemistry and microcharcoal data from Lake Ifrah (Middle Atlas, Morocco) provides new insights for better understanding paleofire occurrence from the Last Glacial Maximum to the present. The comparison between microcharcoal distribution and lacustrine multiproxy data highlights the variability of paleofire activity that is interpreted in term of long-term climate-driven changes. From 20,000 to 13,000 cal yr BP, the concentration in microcharcol was very low in connection with low fire activity and cold climate. The early to mid-Holocene (between 10,800 and 4,500 cal yr BP) marked a significant increase in microcharcoal abundance which likely testifies to regional emissions from forest fires. Such biomass burning events were associated to prolonged periods of drought, as inferred by synchronous abrupt decreases in surface runoff input records (e.g. organic matter, trace elements and magnetic susceptibility) and increases in carbonate content, calcite and Mg-calcite concentrations.