Abstract
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.
Highlights
The ‘last termination’ refers to the warm period between the last glacial maximum (LGM) and the onset of the Holocene (~11.7 ka cal BP)
The lowest part of the core between ~16.8–15.6 ka cal BP was sacriffied for accelerator mass spectrometry (AMS) dates and geomechanical testing (Turu et al, 2018)
The bulk δ13C values in the analysed samples mainly range from − 25.5 ‰ to − 29.3 ‰ (Table 1), indicating the presence of terrestrial C3-type plants (Deines, 1980); no ageing effect was observed (Turney et al, 2000), and the samples come from different organic sources (Table 1)
Summary
The ‘last termination’ refers to the warm period between the last glacial maximum (LGM) and the onset of the Holocene (~11.7 ka cal BP). Proxy studies reveal multi-phase deglaciation in SW Europe (Allard et al, 2021) and are linked to distant climate teleconnections (Turu, 2018). In contrast to the northern Iberia (Gonzalez-Samperiz et al, 2006; Jalut et al, 2010) in the central Iberian mountains, a limited number of long (>11 ka cal BP) and continuous terrestrial sedimentary records have been described by van der Knaap and van Leeuwen, 1994, 1995, 1997; Connor et al, 2012; Turu et al, 2018; Lopez-Saez et al, 2020). Significant progress in studying glacial phases and peat-based palaeoenvironments has allowed the reconstruction of Holocene vegetation dynamics (MoralesMolino et al, 2013; Lopez-Saez et al 2014, 2020 and references therein). Only a few Iberian continental records have focused on this aspect, and our study aims to fill this gap
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