Holocene climatic and environmental evolution on the southwestern Iberian Peninsula: A high-resolution multi-proxy study from Lake Medina (Cádiz, SW Spain)

The climatic and environmental history of the SW Iberian Peninsula is explored to fill in the gap of continental palaeoclimate data by a high-resolution study of Lake Medina sediments from core Co1313. A multi-proxy approach comprising sedimentary facies analysis, elemental geochemistry, mineralogy, palynology and micropaleontology was employed to reconstruct the complex limnological response to climate change and catchment dynamics since the early Holocene. The further definition of abrupt climate change events was supported by a robust age model and rapid sediment accumulation rate at the study site. Proxies indicate arid and warm climate conditions during the Early Holocene, from around 9.5 to 7.8 cal ka BP, with a desiccation event at 8.8 cal ka BP as well as tentative evidence for the regional expression of a cold and abrupt arid climate event centering on ca. 8.2 cal ka BP. The Holocene Climate Optimum, from around 7.8 to 5.5 cal ka BP, is characterized by a humid climate and maximum lake level. Anoxic bottom water conditions are indicated by the preservation of sediment laminae and the occurrences of Sulfur mottles, which were observed for the first time within Holocene sediments of saline lakes. Mid-to Late Holocene times are governed by the 4.2 cal ka BP dry event as well as progressive aridification accompanied by the development of typical Mediterranean low-land vegetation. During recent times, further progressive loss in precipitation as well as fluctuating but overall increasing anthropogenic influence on Lake Medina sediments is observed.