Western Mediterranean climate and environment since Marine Isotope Stage 3: a 50,000-year record from Lake Banyoles, Spain

We present new stable isotope (δ¹⁸Ocalcite and δ¹³ Ccalcite) and diatom data from a 67-m sediment core (BAN II) from Lake Banyoles, northeastern Spain. We reassessed the chronology of the sequence by correlating stable isotope data with a shorter U-series-dated record from the lake, confirming a sedimentological offset between the two cores and demonstrating that BAN II spans Marine Isotope Stages (MIS) 3–1. Through comparison with previous records, the multi-proxy data are used to improve understanding of palaeolimnological dynamics and, by inference, western Mediterranean climate and environmental change during the past ca. 50,000 years. Three main zones, defined by isotope and diatom data, correspond to the MIS. The basal zone (MIS 3) is characterised by fluctuating δ¹⁸Ocalcite and benthic diatom abundance, indicating a high degree of environmental and climate variability, concomitant with large lake-level changes. During the full glacial (MIS 2), relatively constant δ¹⁸Ocalcite and a poorly preserved planktonic-dominated diatom assemblage suggest stability, and intermittently, unusually high lake level. In MIS 1, δ¹⁸Ocalcite and δ¹³Ccalcite initially transition to lower values, recording a pattern of Late Glacial to Holocene change that is similar to other Mediterranean records. This study suggests that Lake Banyoles responds limnologically to changes in the North Atlantic ocean–atmosphere system and provides an important dataset from the Iberian Peninsula, a region in need of longer-term records that can be used to correlate between marine and terrestrial archives, and between the western and eastern Mediterranean

Western Mediterranean climate and environment since Marine Isotope Stage 3: a 50,000-year record from Lake Banyoles, Spain

We present new stable isotope (δ18Ocalcite and δ13Ccalcite) and diatom data from a 67-m sediment core (BAN II) from Lake Banyoles, northeastern Spain. We reassessed the chronology of the sequence by correlating stable isotope data with a shorter U-series-dated record from the lake, confirming a sedimentological offset between the two cores and demonstrating that BAN II spans Marine Isotope Stages (MIS) 3–1. Through comparison with previous records, the multi-proxy data are used to improve understanding of palaeolimnological dynamics and, by inference, western Mediterranean climate and environmental change during the past ca. 50,000 years. Three main zones, defined by isotope and diatom data, correspond to the MIS. The basal zone (MIS 3) is characterised by fluctuating δ18Ocalcite and benthic diatom abundance, indicating a high degree of environmental and climate variability, concomitant with large lake-level changes. During the full glacial (MIS 2), relatively constant δ18Ocalcite and a poorly preserved planktonic-dominated diatom assemblage suggest stability, and intermittently, unusually high lake level. In MIS 1, δ18Ocalcite and δ13Ccalcite initially transition to lower values, recording a pattern of Late Glacial to Holocene change that is similar to other Mediterranean records. This study suggests that Lake Banyoles responds limnologically to changes in the North Atlantic ocean–atmosphere system and provides an important dataset from the Iberian Peninsula, a region in need of longer-term records that can be used to correlate between marine and terrestrial archives, and between the western and eastern Mediterranean

The Baelo Claudia Tsunami Archive (SW Spain)—Archaeological Deposits of High-Energy Events

Over the past decades, substantial progress has been made in tsunami research. Be that as it may, little is still known about tsunami deposits and their related depositional mechanisms in coastal areas in historical and archaeological contexts. In particular, the Phoenician, Greek and Roman trade and military networks along the Mediterranean and Atlantic coasts, with their cities, harbours and additional facilities, are susceptible to serving as archives for extreme wave events. The ruins of the Roman city of Baelo Claudia, located on the Bay of Bolonia Bay (southern Spain), offer a unique environment for studying historical tsunamis in the Gulf of Cadiz. Baelo Claudia suffered at least two earthquakes in Roman times, namely, in the first and fourth centuries CE. The latter, associated with a tsunami, led to the city’s destruction and subsequent decline. Accordingly, three tsunami deposits in Baelo Claudia, dated to ca. 4000 cal BP (2000 BCE), ca. 400 CE and 1755 CE, the last corresponding to the Lisbon tsunami, are described here. The multi-disciplinary research conducted on the sedimentary, archaeological and palaeontological records has revealed event deposits, together with major landscape changes in the environs of the bay after tsunami landfall. Furthermore, the significant archaeoseismic damage detected in recently excavated buildings has been dated to the end of the fourth-century CE. The results presented here serve to supplement the earthquake and tsunami record of coastal Iberia.The authors are grateful to German Science Foundation (DFG grant, RE 1361/28-1) and the MINECO-FEDER Spanish Research Project CGL2015-67169-P (QTECSPAIN-USAL) for their support.Peer reviewe

Late Quaternary climate variability from western Mediterranean lake archives by multi-proxy data

Climate change is under global debate, due to increasing occurrence of extreme weather events affecting the present-day life. Predicting future climate is challenging, because of the complex interactions in the climate system. Only full understanding of past climate processes and forcing mechanisms allows us to understand and evaluate on-going changes. Some regions are more vulnerable than others. The Western Mediterranean, due to the transitional location between complex atmospheric and marine circulation systems, is highly sensitive to climatic changes. This work is affiliated to a Collaborative Research Centre (CRC 806 “Our Way to Europe”) dealing with history of human mankind and is in particular a contribution to the sub-project investigating the disappearance of Neanderthals in the Iberian Peninsula, which is supposed to be connected to high frequent climate variability. Three different sites, aligned on a SW-NE-axis from Southern Spain to Northern Italy, have been under investigation for Late Quaternary palaeoenvironmental reconstruction. Aiming on terrestrial records, which are scarce for the Western Mediterranean, sediment cores from three lakes revealed palaeoinformation: i) Laguna de Fuente de Piedra (LFP; SW-Spain), ii) Lake Banyoles (NE-Spain), and iii) Lake Como (N-Italy). LFP a shallow endorheic saline lake, whereas Lake Banyoles is a tectono-karstic open fresh-water lake, and Lake Como is a large 450 m-deep, semi-closed lake, all three are obviously of particularly difference in their characteristics. Multi-proxy data acquisition has been carried out and palaeoclimatic records at different temporal resolution with different temporal range have been achieved. Due to the different control mechanisms on sedimentation processes, the selection of climate-sensitive proxies for each site was challenging. For the hydro-sensitive LFP, optical description of sediment cores (max. 14 m long), elemental data (Ti, Ca, S, Sr, ratios, and time series analyses), mineralogical data including crystal habits and stable isotopic signatures of carbonates and gypsum have been acquired. This dataset leads for lithofacies-based palaeohydrological reconstruction. The obtained age control has been achieved by radiocarbon dating. But the low TOC content, bacterial sulfate reduction processes as well as saline groundwater circulation (with long mean residence times) increased the complexity of this site and probably affected datings. The identified lake level changes have been correlated with North Atlantic cold events for the past approximately 28,000 years. The Lake Banyoles sediment core (66 m long) characterization contains optical description, elemental data, and sediment-physical properties, isotopic data, and diatom analyses leading to different lithofacies. Robust age control has been achieved by U/Th dating, which has been re-assessed by stable isotope record correlation for the upper 30,000 years. Radiocarbon ages were used cautiously, due to an approx. 5,000 year reservoir effect. The high content of endogenic carbonates in Banyoles sediments makes this site highly sensitive to terrigenous influx, as observed in elemental data and their ratios, particularly K/Ca ratio. Potassium-rich material has been correlated to North Atlantic cold events (Heinrich Events 1-5), which are supposed to originate in clay minerals transported either fluvial or aeolian to the lake. The impact of North Atlantic circulation has also be proven by stable isotopic signatures, which rather show an Atlantic than Mediterranean signal.From a sedimentary record (65 m long) from Lake Como, different lithofacies have been revealed by optical description, elemental and sediment-physical properties (core logging). The radiocarbon chronology encompasses to upper 32 m and two age-depth models have been discussed for the entire record. Implications for palaeoclimate have been obtained from the younger chronology, assuming ca. 17,000 years at the base. This site also recorded effects from North Atlantic cold events, for the Holocene and have been further discussed for the Deglaciation. Two event layers composed of significantly coarser material are most probable related to climatic forcings as they coincide with warming phases, but seismotectonic triggers cannot be fully excluded.This work narrows the gap in terrestrial long-term records from the Western Mediterranean. It is shown that the sites are affected by North Atlantic Circulation, but all three show certain differences in their response to past North Atlantic Cold Events, which needs further work for detailed causative analyses