Palaeoenvironmental changes in the Iberian central system during the Late-glacial and Holocene as inferred from geochemical data: A case study of the Navamuño depression in western Spain

This study was funded by the LATESICE-CGL2016-78380-P, FINICES-PID2020-117685 GB-I00 and MED-REFUGIA-RTI2018-101714-BI00 (Plan Nacional I + D + I, Spanish Ministry of Science, Innovation and Universities) projects. This study was also funded by the OROMEDREFUGIA project (P18-RT-4963) from the Andalusian Office of Economy and Knowledge. Luelmo Lautenschlaeger was funded by the Spanish Ministry of Education, Culture, and Sports (FPU16/00676). We sincerely thank Dr. Guy Jalut for the constructive and helpful comments that improved our original draft. We would also like to sincerely thank Professor Eneko Iriarte, University of Burgos, Spain, for his help and advice in interpreting the geochemical records. We also thank the editor and the anonymous reviewers for their helpful comments and constructive suggestions that have significantly improved this manuscript.The Iberian Central System (ICS) is a clue region to reveal Mediterranean/Atlantic inferences over Iberia. We present a multidisciplinary study from western Spain conducted in the Navamuño depression (ND), covering the last 16.8 ka (cal BP). A reconstruction of the palaeotemperature from the resulting geochemical data highlights four cold and dry intervals, namely, the Oldest Dryas, Older Dryas, Intra-Allerød Cold Period (IACP), and the Younger Dryas, along with warmer intervals: the Bølling (14.7–14 ka) and the Allerød (12.9–12.6 ka); however, the Greenland Interstadial GI-1c (13.4–13.1 ka) is barely distinguishable in the ND. Despite the shortage of biomass to sustain fire, the earliest charcoals are from ~14.4–13.8 ka. Evidence of ash/dust events overprinting the geochemical background starts at ~13.8–12.8 ka. Significant fire activity in the Early Holocene at ~11.7–10.6 ka affected the ND, matching the westernmost ICS data. This period includes short oceanic spells inferred from Cl peaks at ~10.9–10.2 ka and three cold intervals at 11.4, 9.3, and 8.2 ka disrupted the progressive temperature increase. The Mid-Holocene showed a continuously increasing trend towards an arid climate, peaking at 4.2 ka under a pervasive dust influx from North Africa, which has prevailed since almost ~7.9 ka. A prominent volcanic event at ~6.8–5.8 ka is in Navamuño and Roñanzas (Asturias, N Spain; Gallego et al., 2013) identified from heavy metal-rich layer, synchronous with the last known eruption of the Calatrava volcanic field (South-Central Spain; Poblete-Piedrabuena et al., 2019). This volcanic eruption could affect many other regions half north of Iberia. The pervasive presence of oceanic aerosols in the last three millennia (2.8 ka ~ ) allowed the formation of a Cl-rich peat layer during the Ibero-Roman humid period ~2.1 ka, before a changing around ~0.4 ka toward colder and drier conditions at the Little Ice Age (LIA) period.Plan Nacional I + D + I, Spanish Ministry of Science, Innovation and Universities LATESICE-CGL2016-78380-P FINICES-PID2020-117685 GB-I00 MED-REFUGIA-RTI2018-101714-BI00Andalusian Office of Economy and Knowledge P18-RT-4963Spanish Ministry of Education, Culture, and Sports FPU16/0067