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... However, tectonic instability of the region has continued throughout the Miocene up to the late Quaternary until becoming to the present form (Dermitzakis 1990;Rögl 1999;Meulenkamp & Sissingh 2003;Popov et al. 2004;Harzhauser & Piller 2007). Along with the turbulent tectonic dynamic process, the climate of the area has fluctuated, especially during the Miocene (Fauquetta et al. 2007;Ivanov et al. 2010;Suc et al. 2018), as an important evolutionary driver in the establishment of regional biodiversity. These large/small-scale tectonic/climatic events have resulted in a reticulate biogeography in the East Mediterranean. ...
... Among the majority of these publications, the species level lineages that radiated in the post-Tortonian period were considered, and vicariance was reported as the dominant pattern for radiation since the Tortonian transgression created several islands within the Aegean Sea (Poulakakis et al. 2015). However, again, these studies rarely attributed the divergence events to ecological changes, as the significant climatic fluctuations predated the Tortonian (Suc et al. 2018). Compared to the Aegean area, publications on the lineages distributed in other parts of the East Mediterranean, such as the Black Sea Basin, Caucasus, Zagros, and the Arabian Peninsula, are relatively rare (Wielstra et al. 2010;Ahmadzadeh et al. 2013;Guy-Haim 2018;Stahls et al. 2016;Salvi 2018;Solovyeva et al. 2018). ...
... The geography of the region in the origin time of the Pholidopterini was relatively stable, but fluctuations in the climate were prominent. The Aquitanian climate was reported as dry-cold due to Antarctic "Mi-1 glaciation", but later it reverted to warming reaching to Mid-Miocene Climatic Optimum by the beginning of Langhian (Fauquette et al. 2007;Popescu 2008;Ivanov et al. 2011;Suc et al. 2018). From this combination of the paleo-events, it is more plausible to assume ecological speciation for the splitting of Bolua and Pholidopterini and for the early radiation of the tribe. ...
Article
The present study examines the phylogeography of Pholidopterini (Orthoptera, Tettigoniidae), a lineage distributed in the East Mediterranean and estimated substitution rates for the three mitochondrial and two nuclear gene segments. The last common ancestor of Pholidopterini was dated to 18 myr ago, in Early Miocene. Phylogeography of the lineage was marked with three waves of radiations, first during the Middle Miocene Climatic Optimum, during the Serravallian, and third during at the ending of Messinian. The substitution rate estimations were 0.0187/0.018/0.0141/0.0010207 s/s/myr for COI/ND2/12S-tRNAval-6S/ITS1-5.8S rRNA-ITS2. The following main conclusions were drawn; (i) Radiation of Pholidopterini directed by the climatic shifts, (ii) signs of vicariant speciation were poor, contrary to the active tectonic history, (iii) the ultimate generic ancestors were dated to the Langhian and Serravallian, and (vi) the Tortonian transgression of Mid-Aegean Trench appears to be a reliable geographic calibration point for lineage splitting between Crete and Anatolia.
... The main changes include the rise of mountain ranges (the Himalayas, Carpathians, Alps, Pyrenees, etc.), a new configuration of seaways and ocean circulation system, the appearance of the Sahara Desert, and the establishment of a permanent ice cap in the northern hemisphere (e.g. Ehleringer and Monson, 1993;Haug et al., 2001;Griffin, 2002;Tuenter, 2004;Wang et al., 2006;Potter and Szatmari, 2009;Dowsett et al., 2009;Haywood et al., 2009Haywood et al., , 2016Athanasiou et al., 2015;Jiménez-Moreno et al., 2018). Overlapping the long-term cooling, shorter-scale changes also occurred, whose local effects are less well known, especially in continental areas in which long and well-dated climate records are still lacking (e.g. ...
... The connection between the warmer/drier stages is also in line with climate interpretations for the Teruel Basin and other Iberian records (Daams et al., 1988;van Dam and Weltje, 1999;Hernández Fernández et al., 2007;Domingo et al., 2009Domingo et al., , 2013van Dam and Reichart, 2009;Matson and Fox, 2010;De Miguel et al., 2018). Nevertheless, in Mediterranean coastal zones, a connection between warming and more humid stages has been proposed, as well as a latitudinal temperature and precipitation gradient between northern and southern areas since the Middle Miocene (Suc, 1978;Fauquette et al., 1999;García-Alix et al., 2008;Matson and Fox, 2010;Suc et al., 2018;Jiménez-Moreno et al., 2019). Accordingly, in the Iberian area when the climate was warmer and more humid in the northern Mediterranean, warmer and drier conditions prevailed in the southern Mediterranean. ...
... Increasing temperature and warming conditions for the Late Miocene-Early Pliocene have also been inferred from fauna and vegeta-tion in western European and Mediterranean regions (Fauquette et al., 2007;Hernández Fernández et al., 2007), with severe aridity occurring in many regions Barrón et al., 2010;Pellegrino et al., 2018;Suc et al., 2018;Jiménez-Moreno et al., 2019), followed by a general temperature decrease (Fauquette et al., 2006). Our isotope curve suggests that although aridity intensified during the Messinian, no dramatic climate changes occurred during the Messinian Salinity Crisis (~5.9 to 5.3 Ma), as previously proposed for the Mediterranean coastal zone (Fauquette et al., , 2006Jiménez Moreno et al., 2009;Barrón et al., 2010). ...
Article
Paleoclimate reconstructions are mostly based on continuous oceanic records, but continental records, controlled by global and regional conditions, are paramount in identifying long- and short-term climatic variability between regions and investigating forcing mechanisms. Here we present a high-resolution lacustrine log from a western Mediterranean intramountain basin; it is based on calcite oxygen isotope composition (δ¹⁸Oc) and records detailed paleoclimatic information from the Late Miocene to the Early Pleistocene (9.8–1.8 Ma). Evidence is found for orbital forcing in the regional paleoclimate, with minimum and maximum eccentricity related to drier and wetter conditions respectively. Superimposed onto this variability, the long-term trend reflects the influence of global paleogeographic and climate change. Variations inferred in precipitation-evaporation (P–E) are related to SST in the North Atlantic, which evidences a connection between marine dynamics and continental climate in areas far from the coast in southwestern Europe and a relation between dry periods and high SST inland. It is proposed that the regional climate was impacted by the effect of the closure of the Central Atlantic Seaway and changes in the Atlantic Meridional Overturning Circulation (AMOC). Warmer/drier conditions were related to a more permanent, stable, high-pressure centre over the mid-Atlantic in a situation of strengthened AMOC, which would have blocked westerly winds, increasing aridity in southwestern Europe. The inferred warm/dry connection differs from other western Mediterranean records, supporting previous interpretations of a regional climate gradient in western Europe. As occurs at present, isolation from the influence of the humidity of the Mediterranean Sea during warm periods as a result of' to the local orography could well have been the cause of regional differences.
... The oldest records of dryland soils in Asia are of Late Eocene and Early Oligocene age, associated with the retreat of the Neotethys Ocean, ice-sheet growth in Antarctica and the uplift of the Tibetan Plateau (Li et al., 2018;Renner, 2016;Sun and Windley, 2015). Later on, weakening of the African summer monsoon system due to retrieval of the Tethys Sea during the Tortonian allowed the widespread aridification from adjacent Asia into Northern Africa and the Mediterranean (Zhang et al., 2014;Suc et al., 2018). Around the same time period, aridification of Eastern Africa was probably initiated by tectonic uplift of the East African Rift System that interrupted the zonal circulation and with it associated constant supply of moisture (Sepulchre et al., 2006). ...
... These were caused by the continuous global cooling and the associated glacio-eustatic sea-level drop (Jiménez-Moreno et al., 2012;Zachos et al., 2008). Increased aridity promoted establishment of Mediterranean sclerophyllous flora, Artemisia-Ephedra steppes and even semi-desert elements such as Calligonum, Nitraria, Lygeum and Ziziphus (Suc et al., 2018). A big portion of the contemporary Mediterranean flora has its roots in western Asia (Banasiak et al., 2013;Jabbour and Renner, 2011;Karl and Koch, 2013;Manafzadeh et al., 2013) and Mediterranean Atriplex is no exception. ...
Article
Atriplex is the most species-rich genus of Amaranthaceae and one of the largest C4 clades in eudicots. Distributed predominantly in the arid subtropical and temperate regions worldwide, many Atriplex species dominate the plant communities of harsh and inhospitable inland and coastal habitats. Current threats of aridification and salinisation increase the ecological and economic value of this highly stress tolerant xerophytic genus. We compiled sequence data of approximately 80% (208 spp.) of all currently recognised species and carried out a phylogenetic reconstruction using nuclear-encoded internal and external transcribed spacers. In addition, time divergence estimation analysis and ancestral area reconstruction were carried out to reconstruct the worldwide spread of Atriplex. Our results show that Atriplex originated in continental Asia during the Oligocene and dispersed from there across the world, often via long-distance dispersal from the Aralo-Caspian and the Pontic regions, or the floristic province of Turkestan. The highest alpha diversity was retrieved from arid habitats of Australia and the New World resulting from extensive radiation events of the Late Miocene and Pliocene. Most dispersal events took place into the Mediterranean region. Atriplex invaded most continents several times independently from different regions throughout the continuous cooling trend of the Neogene and the Quaternary. Despite limited resolution power of the used molecular markers, this study allows for a more comprehensive understanding of the evolutionary history of Atriplex and lays the foundation for future evolutionary studies of saltbushes.
... The speciation within the P. major complex appears to have coincided with the glacial and interglacial periods during the early Pleistocene (2.46 to 2.11 mya) (Poulakakis et al. 2015;Suc et al. 2019), and ancestral reconstruction showed that the complex has an Asiatic origin. During these periods, cycles of alternating hot, dry and cold, wet seasons were present in the Aegean area, with glacial periods outlasting the interglacial (Poulakakis et al. 2015). ...
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The genus Phlebotomus (Diptera: Psychodidae: Phlebotominae) comprises a group of small winged insect species of medical importance. To date, ten species of Phlebotomus are known to be present in Greece; yet their evolutionary history is poorly studied due to the lack of comprehensive phylogenetic and phylogeographic studies. Herein, we aim to clarify the phylogenetic relationships amongst the local species collected from 12 Aegean Islands, Cyprus and Turkey; and to identify which of the palaeogeographic events may have influenced their biogeographic history. Our analyses revealed for the first time the presence of P. cf. major and P. sergenti in the Aegean Islands. All studied local species were retrieved as monophyletic and the mtDNA and nDNA phylogenetic trees indicated a plausible mitochondrial introgression between the closely related species of the P. major complex. From a palae-ogeographic viewpoint, the major driving force that shaped the biogeographic history of the studied Phlebotomus species seems to be the dispersal that started in the Oligocene epoch, followed by several speciation events that occurred at the end of Miocene and the Plio-Pleistocene, including multiple dispersal events of Asiatic origin. The Messinian Salinity Crisis, the bimodal Mediter-ranean climate, and the glacial and interglacial periods were identified as key drivers for the diversification of the local species of Phlebotomus.
... Pollen data are shown in synthetic pollen diagrams where the taxa are grouped according to both their present-day ecological significance and to their behaviour during the Cenozoic (Table S2; Suc et al., 2018Suc et al., , 2020. ...
Article
Aim Past pollen records reveal the changes in latitudinal distribution of plants in relation to climate, particularly their expansion in response to global warming. The maximum northward expansion of the mangrove genus Avicennia since the Early Eocene is known, but this information is missing for other mangrove taxa. Here, we evaluate the diversity of past mangroves with respect to latitude during three Cenozoic thermal maxima (PETM: 56 Ma; EECO: 54–49 Ma; MMCO: 17–14 Ma). Location North Atlantic, Mediterranean. Taxa Avicennia, other mangrove taxa (Rhizophoraceae, Nypa, Xylocarpus, Pelliciera, etc.). Method We collected well-dated marine sediments along a Northern Hemisphere latitudinal transect and we analysed their pollen content in order to compare the past distribution of mangrove taxa with the present. The analysis of 89 samples (PETM: 13; EECO: 31; MMCO: 45) was performed and interpreted using a robust botanical background for identification of pollen grains and their representativeness in marine sediments. Results During the Early Eocene, two palaeolatitudinal thresholds at 65–70°N and 35°N, respectively, delimited the Avicennia-only mangrove from a diversified but scrawny mangrove and finally from a diversified and well-developed mangrove. The Avicennia threshold was selective at 40°N during the Mid-Miocene. The Avicennia range limit was up to 10–15° poleward of the limit for other mangrove taxa during the Early Eocene and the Mid-Miocene compared with 9° at present. Main conclusions A buffer zone characterised by a diversified but scrawny mangrove co-occurring with a few megathermal plants occurred in the Early Eocene between 35°N and 65–70°N. This finding questions the relative influence of a more ‘equable’ climate and/or the ability of some taxa to expand towards areas with cooler conditions in the past. Mangrove provincialism, which was established progressively after the Early Eocene, was probably forced by plate tectonics. The taxonomic impoverishment of the Atlantic East Pacific province was probably caused by successive periods of global cooling. These results support the Tethyan origin of the mangroves.
... Pollen data are shown in synthetic pollen diagrams where the taxa are grouped according to both their present-day ecological significance and to their behaviour during the Cenozoic (Table S2; Suc et al., 2018Suc et al., , 2020. ...
Chapter
Humans evolved in the dynamic landscapes of Africa under conditions of pronounced climatic, geological and environmental change during the past 7 million years. This book brings together detailed records of the paleontological and archaeological sites in Africa that provide the basic evidence for understanding the environments in which we evolved. Chapters cover specific sites, with comprehensive accounts of their geology, paleontology, paleobotany, and their ecological significance for our evolution. Other chapters provide important regional syntheses of past ecological conditions. This book is unique in merging a broad geographic scope (all of Africa) and deep time framework (the past 7 million years) in discussing the geological context and paleontological records of our evolution and that of organisms that evolved alongside our ancestors. It will offer important insights to anyone interested in human evolution, including researchers and graduate students in paleontology, archaeology, anthropology and geology.
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The olive tree was an iconic plant for most of the past Mediterranean civilizations, for which it had important economic value. Here we report the earliest use of fruits and wood from olive trees in Africa so far, around 100,000 years ago. These findings suggest the presence of olive trees on the Atlantic coast of Morocco during most of the last glacial period, and the use of olives by the early Homo sapiens for fuel management and most probably for consumption. Across the Mediterranean Basin, two varieties of olive trees (Olea europaea) exist: a wild O. europaea subsp. europaea L. var. sylvestris and a cultivated O. europaea subsp. europaea L. var. europaea. The oldest wild olive findings have been recovered at the Acheulean site Gesher Benot Ya'aqov (Israel), dating back to ~790 thousand years ago (ka) 1. Since then, little archaeological evidence has been retrieved 2-5 : circa 62-55, 49 and 43-41 ka in Greece, Israel and Spain, respectively. From ~30 ka onwards, archaeological occurrences of olive remain rather rare until the Epipalaeolithic 4,6. It is only from the Neolithic onwards that wild olives have been intensively used by Mediterranean human groups, for the direct use of the entire tree (for example, food, fuel, lighting, medicine and cosmetics) and for their conceptualization in mythology and religion 7,8 .
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L’origine des déformations en domaine intraplaque est mal connue et ne s’intègre pas pleinement au sein de la théorie de la tectonique des plaques. Le cas des orogènes en particulier puisque, au-delà de la question de l‘activité sismique, un mécanisme de production de forte topographie est nécessaire. La question même de l’âge de ces orogènes intraplaques est sujette à discussion : ces zones sont-elles actuellement actives ou s’agit-il de reliefs hérités ? Le Massif-Central (France) est un exemple de ce genre d’orogène. L’axe principal de cette thèse consiste en la caractérisation de la dynamique du Massif-Central à travers des approches géomorphologiques et géochronologiques. Une analyse des morphologies régionales fait ressortir la présence d’un signal régional interprétable au-delà des nombreuses variations et spécificités locales. Le centre du massif, entre plateau Ardéchois et massif de la Margeride présente des morphologies héritées, actuellement portée à une altitude supérieure à 1000 m. Cette zone à morphologie héritée est progressivement démantelée à partir des régions périphériques. Cette érosion régressive est à l’origine du creusement des vallées et canyons régionaux. La production de plus d’une centaine de nouvelles mesures de concentrations en isotopes cosmogéniques au sein des sédiments alluviaux actuels, ou anciens et piégés dans l’endokarst, a permis de quantifier les vitesse moyennes d’évolution du paysage. Une vitesse de dénudation régionale de ~ 60 mm/ka sur les derniers ~ 10 à 20 ka est obtenu. La vitesse d’incision long terme, déduite des étagements de sédiments au sein des karsts est estimé à ~ 80 – 100 m/Ma. Cette différence entre les vitesses d’érosion linéaire au niveau du système fluviatile et d’érosion diffusif au niveau des versants permet de déduire une vitesse d’incision relative réelle, donc de création de relief, de l’ordre de 20 à 40 m/Ma. Au niveau de la Faille des Cévennes, les résultats obtenus indiquent un mouvement vertical différentiel sur les derniers ~ 5 Ma avec une surrection du compartiment Nord de la faille de l’ordre de 40 m/Ma. En posant une hypothèse de linéarité dans le temps long (> Ma) des taux d’incision et de dénudation, il est possible de remonter à l’époque d’initiation du creusement et du début de la surrection : ~ 6 Ma. Des compléments sur la vitesse d’incision sur le temps courts (~ 50 ka) mettent en avant une probable cyclicité de ces processus érosifs sur cette gamme de temps. L’intégration de ces nouveaux taux d’érosions dans des modèles numériques permet de tester la réponse de la lithosphère à ce forçage La réaction mécanique de la lithosphère à ce déchargement est associée à une surrection, ce processus est souvent invoqué pour expliquer les mouvements verticaux loin des zones de frontières de plaques. Cette hypothèse est une extrapolation des résultats déduits du rebond glacio-eustatiques observé, par exemple au Canada, en lien avec la disparition des calotte glaciaire il y a ~ 10-15 ka. Dans le cas de la réaction à l’érosion, le formalise de flexure de plaque élastique semble être en limite de validité du fait de la forte non linéarité spatio-temporelle des processus érosifs engendrant des taux de contrainte variables et une réponse rhéologique lithosphérique complexe. Ces questions nécessiterons une intégration plus complète au sein de modèles numériques 3D et permettrons également de préciser le rôle de ces processus dans les dynamiques de failles tel que mis en évidences au niveau du faisceau cévenol, et à terme d’apporter une meilleur estimation de l’aléa sismique.
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The Southern Rifian Corridor was a gateway connecting the Mediterranean Sea to the Atlantic Ocean in the Late Miocene. Its rapid narrowing at the Tortonian - Messinian transition around 7.2 Ma, resulting from very intense tectonic activity, has triggered an ecological crisis well before the deposition of the Messinian Salinity crisis evaporites. The sedimentary successions deposited in the Saïs Basin have recorded different events regarding biostratigraphic, environmental, tectonic, and eustatic that characterized the area during the late Miocene. In order to get information on the marine and continental environment during the Tortonian-Messinian Transition (TMT), a palynological and biostratigraphic study was carried out on two boreholes in the Saïs Basin. The biostratigraphic analyses based on the planktonic foraminifera of the boreholes studied reveals the succession of several biostratigraphic events, allowing us to attribute these sedimentary deposits to the late Tortonian - early Messinian time interval including the recognition of the T/M boundary. The abundance of continental inputs (pollen, spores, BOM, WOM, and COM in the palynofacies) and the low D/S ratio values indicated that the Saïs basin was a neritic epicontinental environment suffering a significant influence of terrigenous inputs. The temperature index shows that the thermal conditions of the surface water were warm. In the late Tortonian, faunal and floristic assemblages indicate an open, relatively deep, outer platform type marine environment with a slight tendency towards an inner platform context. At the Tortonian-Messinian boundary, there is an increase in land inputs and relative reduction in the diversity of both microfauna and microflora. The presence of cold-water taxa probably indicates moderate cooling. In Lower Messinian the marine environment, was external platform with tendencies towards an internal area. The cover is opened and dominated by herbaceous plants that colonize the low altitudes, while trees colonized the middle altitudes. The climate was hot and humid in the mid-altitude and dry in the lowlands.
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An investigation of Nagyipollis pollen from the Lower Eocene to Lower-Middle Miocene of Western Europe makes it possible to distinguish two pollen types attributed to Buxus L., and also, to establish, for the first time, a biochronological sequence with three evolutionary stages. These stages are represented in the modern taxonomic sections of the genus Buxus. which allows us to infer their evolutionary advancement. The author points out the great antiquity of Buxus which certainly originated before the separation of Western Europe and North America, and he records two progressive extinctions of the European paleotropical elements of the genus, one west to east and the other north to south, as well as the establishment, since the Lower Oligocene, of the Eurasiatic Buxus complex.
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The Chinese province of Yunnan, bordered by the Tibeto‐Himalayan Region, has long been renowned for its high plant diversity. Understanding how this diversity arose is a focus in various research areas, such as botany, paleobotany, molecular phylogenetics and environmental biology. Paleoclimatic studies indicate that during the Neogene, Yunnan was warmer and wetter than today, with a weaker Asian monsoon climate. As temperature declined, precipitation decreased and the monsoon intensified plant diversity: some plant taxa disappeared (e.g., Cedrus, Sequoia), while numerous others flourished and diversi­ fied (e.g., Pedicularis, Rhododendron). These changes in plant diversity may also be associated with the topographic deforma­ tions that occurred as a result of the south‐eastern extrusion of the Tibeto‐Himalayan Region, including the uplift of mountains and the formation of deep valleys.
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Propagation processes of plate-scale faults through continental lithosphere are poorly documented. The North Anatolian Fault (NAF) is a continental right-lateral transform with striking evidence for propagation processes in the Marmara Sea pull-apart region. Earlier work (Armijo et al., 1999, https://doi.org/10.1130/0091-7613(1999)027<0267:WPOTNA>2.3.CO;2) suggests that in the Dardanelles, where the principal, northern branch of that fault (NNAF) enters into the Aegean: (1) a fold-thrust system has progressively developed above the NNAF fault tip, at the WSW corner of the Marmara Sea pull-apart. The main anticline formed there was sheared and its SW half laterally offset by ~70 km to the SW; (2) the timing of structure development appears correlated with sea level changes associated with the Messinian Salinity Crisis. Our new description of the Dardanelles (or Ganos-Gelibolu) fold-thrust system is based on structural mapping, field observations, and calcareous nannoplankton analyses to date key sedimentary units. Our results provide tight constraints on the main pulse of folding associated with propagation of the tip of the NNAF: it took place in the late Miocene to earliest Pliocene (5.60 to 5.04 Ma), before deposition of undeformed Pliocene marine sediments. The folding is mostly coeval with the Messinian Salinity Crisis and accommodated several kilometers of shortening at the fault tip. After full propagation of the NNAF up to the surface, the folded structure was sheared and right laterally offset, with an average 14 mm/year of slip rate during the past ~5 Myrs. A reconstruction of tectonic evolution suggests a flower structure nucleating and taking root at the tip of the fault.
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The Rifian Corridor was one of the Mediterranean–Atlantic seaways that progressively restricted and caused the Messinian Salinity Crisis (MSC). Many key questions concerning the controls on the onset, progression and termination of the MSC remain unanswered mainly because the evolution of these seaways is poorly constrained. Uncertainties about the age of restriction and closure of the Rifian Corridor hamper full understanding of the hydrological exchange through the MSC gateways: required connections to sustain transport of salt into the Mediterranean for the primary-lower gypsum and halite stages. Here we present integrated surface-subsurface palaeogeographic reconstructions of the Rifian Corridor with improved age-control. Information about age and timing of the closure have been derived from high-resolution biostratigraphy, palaeoenvironmental indicators, sediment transport directions, and the analysis of published onshore subsurface (core and seismic) datasets. We applied modern taxonomic concepts to revise the biostratigraphy of the Rifian Corridor and propose astronomically-tuned, minimum-maximum ages for its successions. Finally, we summarise the palaeogeographic evolution in four time slices corresponding to the middle Tortonian (10.57–8.37), late Tortonian (8.37–7.25 Ma), early Messinian (7.25–6.35 Ma), and late Messinian (6.35–5.33 Ma). Several successions record the closure of the corridor via a continuous marine to continental-lacustrine transition. The youngest dated marine sediments represent a good approximation of the age of seaway closure. The closure of the South Rifian Corridor is constrained to 7.1–6.9 Ma; that of the North Rifian Corridor is more uncertain and ranges from 7.35 to ca. 7 Ma. We conclude that the Rifian Corridor was already closed in the early Messinian and did not contribute to the restriction events that resulted in the MSC. Because the Betic Corridor is also closed by the early Messinian, the modern Gibraltar Straits remain the sole option in the Western Mediterranean as last Messinian seaway that was open during the MSC. Our results imply that the Gibraltar Straits could have been established as the exclusive Mediterranean-Atlantic portal already in the late Miocene, and therefore we suggest that future field and drilling campaigns should target the Alboran Sea and the Gibraltar region to investigate water exchange before and during the Messinian Salinity Crisis and its impact on Atlantic circulation and global climate.
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The early Eocene (ca. 56-47.8 Ma) was an interval of exceptional warmth with reduced pole-to-equator temperature gradients. Climate proxies indicate mean annual air temperatures (MATs) and sea-surface temperatures (SSTs) exceeding 8-18 °C and frost-free, mild winters in polar areas, features that have proven difficult to reproduce with the most elaborate climate models. A full appraisal of the early Eocene polar climate has been, however, limited by possible seasonal biases associated with geochemical proxies and the lack of data from the vast Eurasian Arctic. Here we present multiproxy data from lower-middle Eocene coastal plain sediments of the New Siberian Islands (Russia) showing that taxodioid Cupressaceae, palms, and the mangrove Avicennia grew in Arctic Siberia above 72°N under air temperatures averaging 16-21 °C annually and 5.5-14 °C in winter. Kaolinite contents are exceptionally high (up to 60% of clay assemblages) and comparable to those found in present-day subtropical soils formed under high mean annual precipitation (MAP > 1000 mm) and warm (MAT > 15 °C) conditions. The Avicennia pollen records the northernmost mangrove growth ever documented and indicates early Eocene SSTs exceeding 13 °C in winter and 18 °C in summer. Considering the high MAP estimated for Arctic Siberia and other pan-Arctic landmasses, we propose that the heat from warm river waters draining into the Arctic might have amplified early Eocene polar warmth. Our results provide the first climate constraints for the early Eocene of Arctic Siberia and support the view that most climate models underestimate polar warming in greenhouse conditions.