The SISAL database: a global resource to document oxygen and carbon isotope records from speleothems

Stable isotope records from speleothems provide information on past climate changes, most particularly information that can be used to reconstruct past changes in precipitation and atmospheric circulation. These records are increasingly being used to provide “out-of-sample” evaluations of isotope-enabled climate models. SISAL (Speleothem Isotope Synthesis and Analysis) is an international working group of the Past Global Changes (PAGES) project. The working group aims to provide a comprehensive compilation of speleothem isotope records for climate reconstruction and model evaluation. The SISAL database contains data for individual speleothems, grouped by cave system. Stable isotopes of oxygen and carbon (δ 18O, δ 13C) measurements are referenced by distance from the top or bottom of the speleothem. Additional tables provide information on dating, including information on the dates used to construct the original age model and sufficient information to assess the quality of each data set and to erect a standardized chronology across different speleothems. The metadata table provides location information, information on the full range of measurements carried out on each speleothem and information on the cave system that is relevant to the interpretation of the records, as well as citations for both publications and archived data. The compiled data are available at https://doi.org/10.17864/1947.147

Evaluating model outputs using integrated global speleothem records of climate change since the last glacial

Although quantitative isotopic data from speleothems has been used to evaluate isotope-enabled model simulations, currently no consensus exists regarding the most appropriate methodology through which to achieve this. A number of modelling groups will be running isotope-enabled palaeoclimate simulations in the framework of the Coupled Model Intercomparison Project Phase 6, so it is timely to evaluate different approaches to use the speleothem data for data-model comparisons. Here, we illustrate this using 456 globally-distributed speleothem δ18O records from an updated version of the Speleothem Isotopes Synthesis and Analysis (SISAL) database and palaeoclimate simulations generated using the ECHAM5-wiso isotope-enabled atmospheric circulation model. We show that the SISAL records reproduce the first-order spatial patterns of isotopic variability in the modern day, strongly supporting the application of this dataset for evaluating model-derived isotope variability into the past. However, the discontinuous nature of many speleothem records complicates procuring large numbers of records if data-model comparisons are made using the traditional approach of comparing anomalies between a control period and a given palaeoclimate experiment. To circumvent this issue, we illustrate techniques through which the absolute isotopic values during any time period could be used for model evaluation. Specifically, we show that speleothem isotope records allow an assessment of a model’s ability to simulate spatial isotopic trends. Our analyses provide a protocol for using speleothem isotopic data for model evaluation, including screening the observations to take into account the impact of speleothem mineralogy on 18O values, the optimum period for the modern observational baseline, and the selection of an appropriate time-window for creating means of the isotope data for palaeo time slices

Palaeoenvironmental and sedimentological formation conditions of North-Aegean beachrocks

This dissertation incorporates the study of the palaeoenvironmental and sedimentological conditions that prevailed in Northern Aegean area, using multi-methodological approach on multiple sedimentary proxies (beachrocks, speleothem, clastic deposits. The reconstruction of the conditions under which the beachrocks of North-Aegean region were formed took place by the application of advanced methods on the carbonate cement, by analysis and comparison of modern unconsolidated beach deposits and the clastic fraction of the respective beachrocks and finally by the high-resolution analysis of MAR_L stalagmite from Thassos island. In this study, 20 beachrock formations from 11 different sites of North Aegean Sea were used. The analysis results of the carbonate precipitates which cemented the coastal sediments and formed the beachrocks indicated three main mechanisms that acted in the coastal micro-environment. The two first are quite similar in that they took place in marine water, either with evaporation and carbonate precipitaion, or with intense evaporation and CO2 degassing. Different precipitation conditions were found in specific sites, where lithification took place due to mixing of marine and meteoric water. Clastic sedimentology offered important information relatively to the depositional processes that prevailed in the coastal zone in comparison to the modern environment. The results indicate two differentiating factors; a) an early immature sedimentological stage of the beaches during the formation of beachrocks in comparison with modern regime and b) impact of the beachrock outcrops in the modern coastal energy regime, which prevents the processing and reworking of the beach deposits from waves. The high-resolution dating of MAR_L stalagmite from Skala Marion cave (Thassos) in combination with the multi-methodological analysis of its carbonate layers led to a detailed reconstruction of the palaeoenvironment in North-Aegean region from 4900 to 1400 yr BP. The combination of all data-proxies made possible to determine a distinct period in Late Holocene (2950-1950 yr BP), which was characterized by prolonged arid conditions in the coastal areas. This phase differed from all other phases in that all parameters analyzed were affected immensely. The combination of all data of this dissertation concluded in the time window that the majority of beachrocks were formed in North Aegean Sea. That was the dry phase of Holocene that was spotted in MAR_L. During this period, the arid environmental conditions favored the evaporation of sea water in coastal sediments and the stabilization of sea level allowed the lithification of the deposits of the immature coasts of North Aegean. The posterior wet period (Roman Warm Period, 1950-1500yr BP in the study area) favored the influx of meteoric waters in the coastal aquifer, resulting in the precipitation of carbonate sediments from the mixing of meteoric and marine waters in the upper level of the beach and the formation of beachrocks.This dissertation incorporates the study of the palaeoenvironmental and sedimentological conditions that prevailed in Northern Aegean area, using multi-methodological approach on multiple sedimentary proxies (beachrocks, speleothem, clastic deposits. The reconstruction of the conditions under which the beachrocks of North-Aegean region were formed took place by the application of advanced methods on the carbonate cement, by analysis and comparison of modern unconsolidated beach deposits and the clastic fraction of the respective beachrocks and finally by the high-resolution analysis of MAR_L stalagmite from Thassos island. In this study, 20 beachrock formations from 11 different sites of North Aegean Sea were used. The analysis results of the carbonate precipitates which cemented the coastal sediments and formed the beachrocks indicated three main mechanisms that acted in the coastal micro-environment. The two first are quite similar in that they took place in marine water, either with evaporation and carbonate precipitaion, or with intense evaporation and CO2 degassing. Different precipitation conditions were found in specific sites, where lithification took place due to mixing of marine and meteoric water. Clastic sedimentology offered important information relatively to the depositional processes that prevailed in the coastal zone in comparison to the modern environment. The results indicate two differentiating factors; a) an early immature sedimentological stage of the beaches during the formation of beachrocks in comparison with modern regime and b) impact of the beachrock outcrops in the modern coastal energy regime, which prevents the processing and reworking of the beach deposits from waves. The high-resolution dating of MAR_L stalagmite from Skala Marion cave (Thassos) in combination with the multi-methodological analysis of its carbonate layers led to a detailed reconstruction of the palaeoenvironment in North-Aegean region from 4900 to 1400 yr BP. The combination of all data-proxies made possible to determine a distinct period in Late Holocene (2950-1950 yr BP), which was characterized by prolonged arid conditions in the coastal areas. This phase differed from all other phases in that all parameters analyzed were affected immensely. The combination of all data of this dissertation concluded in the time window that the majority of beachrocks were formed in North Aegean Sea. That was the dry phase of Holocene that was spotted in MAR_L. During this period, the arid environmental conditions favored the evaporation of sea water in coastal sediments and the stabilization of sea level allowed the lithification of the deposits of the immature coasts of North Aegean. The posterior wet period (Roman Warm Period, 1950-1500yr BP in the study area) favored the influx of meteoric waters in the coastal aquifer, resulting in the precipitation of carbonate sediments from the mixing of meteoric and marine waters in the upper level of the beach and the formation of beachrocks

Holocene palaeogeographical and palaeoenvironmental reconstructions of the Messara alluvial-coastal plain (Southern Crete, Greece): the Phaistos project and the Dikida program, in Abstract Volume , Pisa, 15-17 February 2012, 60

The Yeropotamos alluvial-coastal plain (Southern Crete, Greece) lies on the E-W oriented graben of the Messara, which is mainly constituted by Late Pleistocene and Holocene alluvial, fluvial-marshy, slope and coastal deposits. All the Messara basin is characterized by important seismicity, which caused damages and destructions on several archaeological settlements of Minoan, Hellenistic and Roman age. Within the PHAISTOS project and the DIKIDA program, in order to reconstruct the Holocene paleogeographical and paleoenvironmental evolution, in relation to the settling history of the Messara, new archeo-stratigraphical and geomorphological studies were carried out. The geomorphological approach, based on 1:5.000 and 1:10.000 cartography, photo-aerial remote sensing and field-survey allowed to identify the main landscape units and helped to better understand the ancient and the present-day morphodynamics, mainly induced by climatic changes, tectonic, and man. This approach distinguished the areas under aggradation and erosion processes during the Holocene times, in order to provide useful data about presence/absence of archaeological remains and traces. The archaeo-stratigraphical approach was based on field-survey and new drilled cores, supported by facies analyses and age-constrained by 14C and archeological datings. Preliminary data from the cores drilled in the Grya Saita area, a large fluvial-marshy depression located near the Festos archaeological site, identified the main palaeoenvironmental changes occurred during the Holocene. For the Holocene coastal evolution the available data allow to suppose that the Minoan shoreline was very close to the Festos and Agia Triada settlements, forming a ria into the Yeropotamos alluvial-coastal plain. Then the shoreline rapidly shifted westwards, forming prograding barrier-lagoon systems, that existed until very recent times. The main causes of the shoreline progradation can be related to the decrease of the sea level rise rate together with the increase of the sediment load by the rivers, connected to the more intense land use by Minoans, Greeks and Romans, and to the vertical land movements connected to the seismicity

Geoarchaeological study of Katarraktes cave system (Macedonia, Greece): isotopic evidence for environmental alterations

Archaeological excavations began in 2004 in the Katarraktes cave system, near Sidirokastro, Macedonia, Greece, and brought to the surface a great number of historical and prehistoric findings. Archaeological excavations concentrated on a rockshelter, with findings aged from Early Bronze Age. The main activity of that location seemed to be food preparation and storage. In order to investigate the correlation between human use of the cave and the environmental conditions of the area during those parts of prehistoric and historical time, an isotopic study was conducted dealing with the calcitic and organic deposits of a stalagmite from the cave. The analysis of the δ13C and δ18O isotopes in carbonate sediments provided information about the conditions at the time of precipitation of the carbonate material inside the cave. A succession of drier and wetter phases was highlighted, describing the unstable environment of the cave. A general reconstruction of the period of human occupation in the Katarraktes cave system was established, on the basis of a combination of the archaeological, geomorphological and isotopic data. The speleothem isotopic signatures indicate abrupt changes of the atmospheric conditions inside the cave, which are correlated to reported changes in rainfall during 3500-4500 BP in Mediterranean region.Des fouilles archéologiques ont débutées en 2004 dans la grotte de Katarraktes située à proximité de Sidiokastro en Macédoine (Grèce). Elles ont mis à jour un nombre important de trouvailles datant des périodes préhistorique et historique. Un abri sous roche et de nombreux artefacts datant du début de l’Age du Bronze ont été trouvés. Les principales activités liées à l’occupation du site semblent avoir été la préparation et le stockage de nourriture. Dans le but d’étudier les relations entre l’utilisation de cette grotte et l’évolution des conditions environnementales pendant les périodes préhistorique et historique, une étude isotopique a été menée sur des dépôts calciques et organiques provenant d’une stalagmite trouvée dans la grotte étudiée. L’analyse des rapports isotopiques δ13C et δ18O effectuée à partir des sédiments carbonatés a permis préciser les conditions environnementales qui prévalaient à l’époque de la précipitation des matériaux carbonatés à l’intérieur de la grotte. Une alternance de phases sèches et humides a été mise en évidence. Une reconstitution globale des données environnementales sur la période d’occupation humaine dans les grottes de Katarraktes a été réalisée en exploitant les données archéologiques, géomorphologiques et isotopiques. Les signatures isotopiques du spéléothème indiquent de rapides modifications des conditions atmosphériques et doivent être associés au changement climatique global survenu au cours Subboréal dans la région méditerranéenne entre 3500 et 4500 BP

Chemometric Discrimination of the Geographical Origin of Three Greek Cultivars of Olive Oils by Stable Isotope Ratio Analysis

International audienceΑ stable isotope ratio mass spectrometer was used for stable isotope ratio (i.e., δ13C, δ18O, and δ2H) measurements, achieving geographical discrimination using orthogonal projections to latent structures discriminant analysis. A total of 100 Greek monovarietal olive oil samples from three different olive cultivars (cv. Koroneiki, cv. Lianolia Kerkyras, and cv. Maurolia), derived from Central Greece and Peloponnese, were collected during the 2019–2020 harvest year aiming to investigate the effect of botanical and geographical origin on their discrimination through isotopic data. The selection of these samples was made from traditionally olive-growing areas in which no significant research has been done so far. Samples were discriminated mainly by olive cultivar and, partially, by geographical origin, which is congruent with other authors. Based on this model, correct recognition of 93.75% in the training samples and correct prediction of 100% in the test set were achieved. The overall correct classification of the model was 91%. The predictability based on the externally validated method of discrimination was good (Q2 (cum) = 0.681) and illustrated that δ18O and δ2H were the most important isotope markers for the discrimination of olive oil samples. The authenticity of olive oil based on the examined olive varieties can be determined using this technique

Evolution holocène de l’estuaire de la Maye (secteur de Rue, Picardie, France) et implications pour l’occupation humaine

International audienceCette communication présente une reconstitution de l’évolution holocène de la ligne de rivage de l’estuaire de la Maye (dans le secteur de Rue, au Sud du Marquenterre) ainsi que des informations nouvelles sur la configuration de ses ressources et de ses paysages côtiers depuis le moyen-âge. Les données présentées ont été acquises dans le cadre du programme PaleoportRue, soutenu par le Conseil régional de Picardie entre 2011 et 2014, en adoptant une approche géoarchéologique. Des moyens d’investigation de terrain, associant une étude de géophysique (8 profils de tomographie de résistivité électrique) et 8 carottages (par vibro-percussion) réalisés à l’ouest de Rue, ont été mis en œuvre parallèlement à l’exégèse de sources documentaires manuscrites et imprimées (figurées ou non figurées). De nos jours, la ville de Rue est située à environ 7 km du trait de côte, au cœur de la plaine maritime picarde. Cependant, selon différentes sources historiques, elle était lors de son édification à l’époque gallo-romaine, et jusqu’au moyen-âge, l’un des principaux ports maritimes de la côte picarde. Bâtie sur un îlot de galets d’âge pléistocène (localement appelé « foraine »), à l’embouchure de la Maye, Rue devait bénéficier d’un accès direct à la mer et à la rivière pour la pratique de la pêche et le transport des denrées. L’analyse sédimentologique en laboratoire des carottages (mesures de granulométrie LASER et de perte au feu -réalisées au CEREGE- et 20 datations par le radiocarbone) a permis de distinguer quatre unités sédimentaires principales au-dessus des « cailloutis » pléistocènes : i) des dépôts marins datant de la fin du 3e millénaire av. J.-C., ii) une formation tourbeuse qui s’est développée aux 2e et 3e millénaires av. J.-C., iii) des sédiments littoraux qui se sont déposés jusqu’au XIIIe siècle et iv) des remblais modernes. Le croisement des données sédimentologiques, géophysiques et documentaires amène à proposer une évolution originale de l’estuaire de la Maye au cours des 3 derniers millénaires : vers 1000 av. J.-C., la « foraine » de Rue était bordée de vallons marécageux et tourbeux, puis, durant l’Âge du Fer, l’estran était très probablement proche de la « foraine » de Rue. Enfin, durant le Moyen-Âge classique (XIe-XIIIe siècles), le chenal d’écoulement permettant l’accès maritime au port de Rue devait être réduit dans un estuaire ensablé.L’étude des documents issus d’archive apporte des éléments de discussion, notamment sur les ressources locales et les échanges commerciaux. Elle indique par exemple l’exploitation de salines du XIe siècle au XIIIe siècle, dont la localisation précise reste à établir, sans doute sur l’estran

The impact of rapid early- to mid-Holocene palaeoenvironmental changes on Neolithic settlement at Nea Nikomideia, Thessaloniki Plain, Greece

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Geoarchaeological and Palaeoenvironmental Researches in the Area of Ancient Phaistos (Crete, Greece): Preliminary Results

The need to extend knowledge of the area of Phaistós and its surrounding area through an investigation of its settlement patterns, urban history, and, more in general, its landscape in its diachronic dimension, prompted the Italian Archaeological School in Athens to undertake an Italian-Greek synergasia in the summer of 2007, in close collaboration with the local ephoria. This need led to the idea of drawing up a project based on surface investigations, archive researches and material analyses. This project is presently being coordinated by Maria Bredaki (director of the 23rd Ephoria from 2007 to 2010, and currently director of the Institute of Cretan Studies), Emanuele Greco (director of the Italian Archaeological School in Athens), and Fausto Longo (assistant professor at the University of Salerno). The project places special emphasis on geomorphological and paleoenvironmental investigations begun in 2009, also thanks to a collaboration with IGME, the CNRS of Aix-en-Provence, UMR 7330, and Project DIKIDA. Over the last two years, a geomorphological map was perfected and the geological study furthered. The geomorphological approach, in particular – based on 1:5000 and 1:10,000 maps, aerial photointerpretation, field surveys, and a DEM constructed for the purpose – has allowed the team to highlight certain aspects of the landscape and understand the principal ancient and current morphological dynamics of climatic change and tectonic and human activity. During the 2011 campaign, nine core samples were taken along a 50-meter-long stretch of the riverine-marshy depression of Gria Saita, east of the Phaistós plain. The CEREGE laboratories of Aix-en-Provence are presently conducting sedimentological analyses, analyses of fossiliferous content, studies of ceramic remains, bioindicator analyses, and radiocarbon dating. We intend to present their results at the meeting to shed light on the environmental characteristics of the plain at the foot of the site of Phaistós and the transformation dynamics of the ancient landscape

Mid- to Late Holocene shoreline reconstruction and human occupation in Ancient Eretria (South Central Euboea, Greece)

International audienceFew studies have aimed to reconstruct landscape change in the area of Eretria (South Central Euboea, Greece) during the last 6000 years. The aim of this paper is to partially fill in this gap by examining the interaction between Mid- to Late Holocene shoreline evolution and human occupation, which is documented in the area from the Late Neolithic to the Late Roman period (with discontinuities). Evidence of shoreline displacements is derived from the study of five boreholes (maximum depth of 5.25 m below the surface) drilled in the lowlands of Eretria. Based on sedimentological analyses and micro/macrofaunal identifications, different facies have been identified in the cores and which reveal typical features of deltaic progradation with marine, lagoonal, fluvio-deltaic and fluvial environments. In addition, a chronostratigraphy has been obtained based on 20 AMS 14C radiocarbon dates performed on samples of plant remains and marine/lagoonal shells found in situ. The main sequences of landscape reconstruction in the plain of Eretria can be summarized as follows: a marine environment predominated from ca. 4000 to 3200 cal. BC and a gradual transition to shallow marine conditions is observed ca. 3200-3000 cal. BC due to the general context of deltaic progradation west of the ancient city. Subsequently, from ca. 3000 to 2000 cal. BC, a lagoon occupied the area in the vicinity of the Temple of Apollo and the settlement's development was restricted to several fluvio-deltaic levees, thus severely limiting human activities in the plain. From ca. 2000 to 800 cal. BC, a phase of shallow marine presence prevailed and constrained settlement on higher ground, forcing abandonment of the major part of the plain. Finally, since the eighth century BC, the sea has regressed southward and created the modern landscape