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Reliable reconstructions of tephrostratigraphy and emplacement mechanisms of Early to Middle Miocene volcaniclastic deposits across the Alpine-Mediterranean region may yield important clues as to the nature, spread, volume, magnitude and frequency of large silicic eruptions of the Carpathian-Pannonian Region. Here we report on a sequence of Middle Miocene volcaniclastic deposits intercalated with lacustrine strata from the Livno-Tomislavgrad Basin, part of the Dinaride Lake System. We applied a multi-proxy approach to elucidate their source, decipher their emplacement mechanism, and evaluate their basin-scale and regional correlativity. New high-precision zircon geochronology (~ 14.32 Ma) reveals their simultaneity with numerous volcaniclastic deposits (and their alteration products) widely spread across the Alpine-Mediterranean region. Additionally, their correlativity is confirmed at the scale of the Livno-Tomislavgrad Basin, based on similar lithostratigraphy, mineralogy and volcanic glass geochemistry. Newly obtained zircon Hf isotope data imply that Livno-Tomislavgrad Basin distal volcaniclastic deposits and ~ 14.36 Ma Harsány ignimbrite of the Carpathian-Pannonian Region had shared a parental eruptive center. However, different volcanic glass geochemistry, bolstered by the high-precision geochronology, suggests distinct eruption events, implying more frequent explosive volcanism of the Carpathian-Pannonian Region during Middle Miocene than previously recognized. We suggest that the ~ 14.32 Ma fine fallout tephra, deposited in the distal basin in the Dinarides (> 400 km from the source), was likely re-mobilized by water-driven hillside erosion from the extensive paleo-relief, and further transported via land-derived gravity flows. Upon entering the lake, the gravity flows likely transformed into subaqueous sediment density flows. These deposited ~ 1 to 7-m-thick overall graded volcaniclastic turbidites, thinning away from the presumed source of tephra re-mobilization. Although over-thickened, the ~ 14.32 Ma Livno-Tomislavgrad Basin volcaniclastic deposits can still serve as a reliable tephro- and tectono-stratigraphic markers due to their rapid mode of accumulation. Schematic illustration of the formation of studied ~14.32 Ma volcaniclastic successions of the SE Livno-Tomislavgrad Basin, Dinaride Lake System [ABSTRACT FROM AUTHOR]

Hasandağ volcano (Central Anatolia, Turkey) has recently underwent an increase in local seismicity and fumarolic activity since 2013. In the past, this volcano has produced multiple large explosive eruptions during the last million years. The Belbaşhanı Pumice is the product of a sub-Plinian to Plinian eruption dated at ~ 417 ± 20.5 ka (40Ar/39Ar). Here, we present a complete volcanological study including stratigraphy, glass chemistry, pumice morphology, geochronology, and eruption source parameters with the associated uncertainties, to characterize the Belbaşhanı Pumice eruption. The eruption involved a column of 18–29 km in height, with the main dispersal axis towards the northeast. A pumice layer up to ~ 17-m-thick accumulated in proximal deposits along the Belbaşhanı path, and up to 2-m-thick in medial-distal areas (~ 18 km northeast from the vent). The high and tubular vesicularity of the pumice clasts indicates that the Belbaşhanı eruption was predominantly magmatic. The bulk volume of the Belbaşhanı Pumice fallout deposit has been estimated as 0.5 and 8 km3 (with ~ 2 km3 being the mean value), which corresponds to Volcanic Explosivity Index (VEI) of at least 4 and up to 6. Both isopach and isopleth maps indicate that the volcanic vent may have been located at the intersection of the Tuz Gölü fault and Ulukışla caldera, within the Hasandağ volcanic complex. The glass composition of Belbaşhanı Pumice confirms that the eruption belongs to the Hasandağ magmatic system. The reconstruction of the Belbaşhanı Pumice eruption represents an essential baseline in providing volcanological constraints for further investigations of tephra fallout hazard assessment in Central Anatolia, especially considering that a new Plinian eruption cannot be ruled out at Hasandağ volcano in the future. The chemical and geochronological datasets presented here could aid in refining tephrochronological correlations, with the goal of synchronizing paleoenvironmental and paleoclimatic records alongside archaeological sites. [ABSTRACT FROM AUTHOR]

Small-to-moderate explosive eruptions involve VEIs ≤ 3, tephra volumes ≤ 0.1 km3 and often eject a significant amount of ash-sized pyroclastic material. This reduces the preservation potential of associated deposits and leads to an underrepresentation of these low- to mid-intensity explosive eruptions in long-term, frequency-magnitude datasets. Mt. Ruapehu is one of New Zealand’s most active volcanoes, having produced at least 32 small-to-moderate eruptions over the past 1800 years. The largest of these eruptions deposited the widespread T13-sequence and lasted several months to years. The cumulative deposit volume is estimated at 0.15 km3, thus being an order of magnitude larger than the average deposit volumes of the last 1800 years at Ruapehu. The sequence of pyroclastic fall deposits can be subdivided into six depositional sub-units representing at least five eruption phases of variable intensity and magnitude. The ash-lapilli sequence displays variable dispersal, deposit textures and pyroclast characteristics. While the initial phase is characterised by dispersal limited to the proximal 11 km and a tephra volume of 8.5 × 105 m3 (± 3%), the following high-intensity “peak” phase is estimated at 8.8 × 107 m3 (± 37.8%), representing about ⁓60% of the cumulative tephra volume. The combination of deposit characteristics with textural analysis of different types of juvenile clasts suggests that changes in eruption style and intensity were mainly controlled by shallow processes in the conduit, such as degassing and crystallisation and changes in conduit geometry. Multilobate, irregular dispersal patterns and laterally variable pyroclast assemblage indicate unsteady eruption conditions characterised by weak eruption plumes controlled by prevailing winds. This study testifies the complexity of tephra sequences associated with long-lasting, small-to-moderate eruptions, and describes the key eruption parameters that can be obtained through a detailed characterisation and identifies the main limitations related to the classification of these eruptive styles. [ABSTRACT FROM AUTHOR]

The Gumants River, rising on the eastern flank of the Mount Hagen stratovolcano, forms part of the headwater catchment of the Wahgi River in the central highlands of Papua New Guinea. The late Quaternary history of the catchment was shaped by a massive debris avalanche with an estimated volume >15 km3 that most likely occurred 400 ± 100 ka. The Upper Gumants River, which occupies about one-quarter of the 420 km2 catchment and underlain almost entirely by volcanic deposits including the avalanche, lahars and widespread airfall tephras that ceased falling ca 200 ka, once flowed directly to the Wahgi River through the Guga subcatchment rather than through the rest of the Gumants Basin. The Kuk Swamp part of the Guga catchment, intensively investigated for evidence of agriculture stretching back 10 ka, was added to the UNESCO World Heritage List in 2008. Nearly 40% of the 79 km2 of the Kugimi Basin is underlain by at least 30 m of swamp deposits with all but the uppermost few metres of the varied swamp and alluvial deposits beyond the range of radiocarbon dating. The Muga Basin forms nearly half of the Gumants catchment with about 50 km2 of swamp deposits and colluvial/alluvial sediments, which have been accumulating rapidly in the last few hundred years but are still underlain at a depth of a few metres by ancient sediments and, by inference, debris avalanche deposits that extend downvalley beyond the junction of the Gumants River with the Wahgi River. While there has been speculation for decades that the Wahgi River once flowed westward, it is now clear that the Gumants River has always flowed eastward, and it seems very likely that that is also true of the Wahgi River. A debris avalanche >15 km3 shaped major components of the Gumants and upper Wahgi valleys ca 400 ± 100 ka. Intensive investigations at the Kuk Swamp UNESCO World Heritage Site inform our knowledge of the larger Kugimi and Muga basins where sedimentary processes are more varied. For at least the last 35 ka, the rate of accumulation of thin tephra falls from the Bismarck Sea volcanoes 200–300 km to the northeast of the Kuk Swamp has exceeded the cumulative rate of erosion from the southern catchment draining to the Guga River. Although it has long been postulated that the Gumants and Wahgi rivers once flowed westward and possibly to the north coast of Papua New Guinea, this hypothesis now seems unlikely. [ABSTRACT FROM AUTHOR]

The cored succession of the Acerno basin, a tectonic palaeolake located in the southern Apennines (Italy), represents a key point of the Italian tephrostratigraphic network for the Quaternary. Trace element and isotope (87Sr/86Sr and 143Nd/144Nd) data have been acquired on bulk rock, glassy groundmass and separated minerals (feldspar and pyroxene phenocrysts) from twenty-one tephra layers, dated between ∼570 and 470 ka, embedded in the lacustrine sediments of the basin. The already available major element compositions have been here combined with the newly acquired data. The whole dataset provides a full geochemical characterization of the tephra that strengthens and improves previous attempts to identify their volcanic sources and potential correlatives. In this context, several previously proposed correlations among distal archives have been here confuted. The geochemical fingerprints highlight that the volcanic record preserved in the Acerno lacustrine succession can be attributed to the explosive activity of the Roccamonfina, Colli Albani, Sabatini, Pontian islands (Latium region, Central Italy) and the Neapolitan Volcanic Area (Campania region, South Italy), providing new insights to enhance the current knowledge on the Middle Pleistocene volcanic record in Italy. Moreover, tephra attributions suggest still unknown eruptive activity of such volcanoes during the Quaternary. From this perspective, our study testifies how difficult it is to precisely correlate different geological archives even in a very short time interval. Such a difficulty arises from a large number of volcanic events concentrated in a relatively short time span, with products of similar chemical composition, and from the incomplete characterization of the successions in proximal outcrops. A thorough reconstruction of the eruptive history of these volcanic complexes requires a wider and denser study of distal archives, alongside further investigations in proximal areas.

Between 38.5 ka cal BP and 32.4 ka cal BP, a dacitic Volcanic Explosivity Index 5 eruption at Misti volcano emplaced the Sacarosa tephra-fall deposit. Its biotite phenocrysts, fine grain size, scarce lithics, and abundant loose crystals characterize the deposit at locations sampled. The eruption's ~ 800 °C magma rose rapidly from ~ 10 km depth, culminating in a Plinian eruption which reached a mass eruption rate of 7.7 × 106–4.1 × 107 kg/s and emplaced about 3 km3 of tephra within tens of hours. The unit comprises two layers of subequal thickness separated by a diffuse contact with the upper distinguished by being slightly coarser and less well sorted than the lower. The deposit's coarser upper layer indicates either climactic conditions or a lesser degree of fragmentation during the latter half of the eruption. Strong winds distributed the deposit southwest of Misti, where it crops out over at least 800 km2 and drapes the present site of Arequipa with up to 100 cm of tephra. The Sacarosa deposit is the first among the Cayma stage deposits, a distinctive group of felsic, biotite-bearing units, to be carefully described and its eruption characterized. Several Cayma stage deposits were emplaced by voluminous explosive eruptions similar to the Sacarosa eruption, representing a ~ 8.9–15.5 ky interval of powerful eruptions. Such an explosive eruption today would threaten Arequipa's over 1,100,000 residents, many of whom live within the Sacarosa deposit's distribution. [ABSTRACT FROM AUTHOR]

Eighteen Middle–Upper Pleistocene (ca 200 ka) tephra units in the highlands of Papua New Guinea (PNG) are mapped and described. The study area is about 24 000 km2, extending from Tari in the west to Kainantu and the Kassam Pass in the east. It is estimated that at least 75 000 km2 of highland PNG received ≥50 cm tephra from various highland sources, and the total volume would have been well over 300 km3. Total tephra thicknesses near sources are >20 m, with thicknesses of individual units near source ranging from 1–2 to >4 m. Several units were deposited with coarse ash and lapilli basal layers that have been weathered to fine ash and clay sizes. Hagen, Giluwe and Yelia volcanoes are the main sources, with smaller centres near Giluwe and north of Hagen also producing mappable tephra units. One unit (Birip) was erupted about 40 ka, but most of the tephra units are 200 ka and older. Volumes of tephra suggest that many of the eruptions had volcanic explosivity indices of 4–6. On stable bedrock, tephras are present on slopes up to 35°, demonstrating the high stability of the tephra materials. Gaps in the tephra cover coincide with bedrock that weathers to unstable regolith where tephras did not accumulate; the tephra cover thus provides an indicator of bedrock stability. Mapped tephra units provide the potential for correlation of other Quaternary materials and can be used as widespread marker beds. The tephras are also important as the parent material for the dominant agricultural soils in the highlands. In the highlands of Papua New Guinea at least 75 000 km2 received >50 cm of tephra mainly from Hagen, Giluwe and Yelia volcanoes. This work extends knowledge of highland volcanic history, which will allow correlation of surfaces and events across the highlands. The tephras are important parent materials of soils that support highly productive agriculture in the highland valleys. The long-term stability of tephra-covered slopes maintains a soil cover for thousands, if not tens of thousands, of years. [ABSTRACT FROM AUTHOR]

[Display omitted] • Onset of Carpathian-Pannonian Region silicic volcanism is refined. • ∼18.1 and ∼ 17.3 Ma eruptions made regional ignimbrites and reached distal basins. • Complex temporal variabilities in mantle-crust interactions are indicated. The Carpathian-Pannonian Region (CPR) hosted some of the largest silicic volcanic eruptions in Europe during the Early and Middle Miocene, contemporaneously with major lithospheric thinning of the Pannonian Basin. This was recorded as an ignimbrite flare-up event from approximately 18.1–14.4 Ma. To gain in-depth perspectives on the eruption chronology, tephrostratigraphy, and petrogenesis at the onset of CPR silicic volcanism, we applied a multi-proxy approach to Lower Miocene rhyolitic ignimbrites and pyroclastic fall deposits from the northern CPR to the Dinaride Lake System. High-precision zircon U-Pb geochronology distinguished two Lower Miocene groups of volcaniclastic rocks at ∼ 18.1 Ma and ∼ 17.3 Ma. Based on combined tephrostratigraphic signatures we propose that the ∼ 18.1 Ma Kalnik and ∼ 17.3 Ma Eger eruptions produced widespread (intermediate to) large caldera-forming massive rhyolitic ignimbrites, deposited across northern and southwestern regions of the CPR. Due to easterly winds that carried volcanic ash hundreds of kilometers to the southwest, Eger eruption products also reached distal intra-montane Dinaride lacustrine basins, recorded as pyroclastic fall deposits. Heterogeneous major and trace elemental compositions of ∼ 18.1 Ma volcanic glass shards suggest that the Kalnik eruption was sourced from complex silicic magmatic systems, with simultaneous tapping of two discrete melt bodies during the eruption. The homogeneous geochemical composition of ∼ 17.3 Ma glasses is distinct from the older glasses. Integrated zircon and bulk glass Nd-Hf isotope compositions have a positive correlation, defining a regional mantle array, and are more radiogenic in the younger phase of volcanism. The recorded systematic isotopic change, moving from older more crustal signatures to younger more juvenile compositions, imply that during the period of lithospheric thinning of the Pannonian Basin the region underwent more complex variations in the interaction between metasomatized lithospheric mantle-derived magmas and various crustal components than previously recognized. [ABSTRACT FROM AUTHOR]

Abstract Mount Pelée (Martinique) is one of the most active volcanoes in the Lesser Antilles arc with more than 34 magmatic events in the last 24,000 years, including the deadliest eruption of the 20th century. The current volcanic hazard map used in the civil security plan puts the emphasis on the volcanic hazard close to the volcano. This map is however based on an incomplete eruptive history and does not take into account the variability of the expected source conditions (mass eruption rate, total erupted mass, and grain-size distribution) or the wind effect on ash dispersal. We propose here to refine the volcanic hazard map for tephra fallout by using the 2-D model of ash dispersal HAZMAP. We first simulate the maximum expected eruptive scenario at Mount Pelée (i.e., the P3 eruption) using a seasonal wind profile. Building upon the good agreement with field data, we compute probability maps based on this maximum expected scenario, which show that tephra fallout hazard could threaten not only areas close to the volcano but also the southern part of Martinique. We then use a comprehensive approach based on 16 eruptive scenarios that include new field constraints obtained in the recent years on the past Plinian eruptions of Mount Pelée volcano. Each eruptive scenario considers different values of total erupted mass and mass eruption rate, and is characterized by a given probability of occurrence estimated from the refined eruptive history of the volcano. The 1979-2019 meteorological ERA-5 database is used to further take into account the daily variability of winds. These new probability maps show that the area of probable total destruction is wider when considering the 16 scenarios compared to the maximum expected scenario. The southern part of Martinique, although less threatened than when considering the maximum expected scenario, would still be impacted both by tephra fallout and by its high dependence on the water and electrical network carried from the northern part of the island. Finally, we show that key infrastructures in Martinique (such as the international airport) have a non-negligible probability of being impacted by a future Plinian eruption of the Mount Pelée. These results provide strong arguments for and will support significant and timely reconceiving of the emergency procedures as the local authorities have now placed Mount Pelée volcano on alert level yellow (vigilance) based on increased seismicity and tremor-type signals.

It is essential to establish the timing of past sector collapse events at a volcanic edifice to evaluate not only the evolution of the volcanic system but also potential volcanic hazards. This can be done by determining the age of the collapse-generated debris avalanche deposits. However, without evidence of an associated magmatic eruption, it is impossible to recognize juvenile materials in these deposits. Thus, it is usually difficult to determine the precise age of sector collapse. Usu is a post-caldera volcano of the Toya Caldera (Hokkaido, Japan) and has been constructed since ca. 19–18 ka on top of the caldera-forming Toya pyroclastic flow deposits (Tpfl deposit: 106 ka). A sector collapse occurred after the formation of a stratovolcano edifice and produced the Zenkoji debris avalanche (ZDA) deposit with reported ages ranging from >20 to 6 ka. We investigated the tephrostratigraphy preserved in the soil above the ZDA deposit and in the surrounding area and recognized fine ash fall deposits at two locations, above and east of the ZDA deposit. The glass shards within these deposits were correlated with several tephra layers with the majority being derived from Tpfl deposits. Thus, these ash deposits should be considered reworked tephra. A considerable number of hummocks in the ZDA deposit were also composed of deformed and fragmented Tpfl deposits, which suggests that the ZDA bulldozed and partially incorporated the Tpfl deposit on the flank of the volcano. Deformation and fragmentation of the non-welded soft silicic Tpfl deposit during the transport and emplacement of the ZDA produced an accompanying ash cloud, which deposited the observed glassy, fine, ash fall units. Radiocarbon dating of soil samples directly below and above the reworked ash deposits allowed dating the sector collapse to ca. 8 ka. This age is much younger than previously proposed results. Based on our findings, the transport and emplacement mechanism of the sector collapse should be revised. Our study shows that reworked ash layers caused by the flow of a debris avalanche can be used as an indicator of the timing of a sector collapse of the volcano.

The exact spatial and temporal behaviour of rapid climate shifts during the Last Glacial–Interglacial Transition are still not entirely understood. In order to investigate these events, it is necessary to have detailed palaeoenvironmental reconstructions at geographically spread study sites combined with reliable correlations between them. Tephrochronology, i.e., using volcanic ash deposits in geological archives as a dating and correlation tool, offers opportunities to examine the timing of events across wider regional scales. This study aims to review the posited asynchrony of the Younger Dryas stadial in comparison with Greenland Stadial-1 by correlating new proxy data from southernmost Sweden to previous palaeoclimate reconstructions in Europe based on the presence of the Hässeldalen Tephra, the Vedde Ash, and the Laacher See Tephra. μ-XRF core-scanning data were projected using a recently published age–depth model based on these tephras and several radiocarbon dates, and compared to previous findings, including by adapting previous chronologies to the recently proposed earlier date of the Laacher See Tephra (13,006 ± 9 cal. a BP). Although the results to some extent support the idea of a more synchronous Younger Dryas event than previously assumed, this issue requires further high-resolution proxy studies to overcome limitations of temporal precision. [ABSTRACT FROM AUTHOR]

Active volcanoes in East Asia pose potential threats to the surrounding areas. The eruptive history of many of the Japanese volcanoes are well understood, but their dispersal pathways are often based on visible tephra. Additionally, other important volcanoes in the region still require a deeper understanding of their eruptive potential. Here, we explore the Holocene cryptotephra record preserved in a marine core 13PT‐P4 in the southwestern East Sea, in order to better reconstruct past eruptive events and their dispersal. Six widespread tephra layers are identified and correlated to their source volcanoes in S Korea (Ulleungdo), China/N Korea (Changbaishan) and Japan (Kikai), with their dispersal ranges updated. Our results rank the 13PT‐P4 sequence the most intensively tephra‐constrained Holocene record in the East Sea, which permits synchronization of this mid‐latitude archive with records in the Arctic and tropical regions. Terrestrially based tephra ages are used to constrain the marine reservoir effect and the age‐depth model of the record. The average reservoir age in the region is estimated to be 1150 ± 30 14C yr at ca. 7.3–5.6 cal ka BP and 1565 ± 30 14C yr at ca. 1.0 cal ka BP. These observed changes in reservoir age could indicate active upwelling at a regional scale. Additionally, we provide a detailed age estimate and glass geochemistry for a previously poorly understood eruption (U‐1) from the Ulleungdo volcano, thus refining its Holocene eruptive history. The U‐1 eruption is dated to 3354‐3080 cal yr BP (95.4%), and has glass composition that is distinct from other Ulleungdo tephras. Plain Language Summary: Explosive volcanic eruptions are one of the most important natural hazards in East Asia. The study of eruptive history and volcanic ash dispersal are the key to understand the behavior of certain volcanoes over time and to better identify the level of risk from different volcanoes. We studied the microscopic volcanic ash layers preserved in a marine core from the southwestern East Sea. Geochemical and stratigraphic evidence allow us to pinpoint the source volcanoes and eruptive events for these ash layers. The results indicate that several ash layers in the region are more widely dispersed than what we have learned from visible ash studies. We provide chronological and geochemical data for a previously poorly understood eruption from Ulleungdo volcano, S Korea, thus refining its Holocene eruptive history. We use terrestrial ages of the ash layers to aid the dating of the marine record and the assessment of marine reservoir effect. Using the identified ash layers, we can now synchronize the marine record with sedimentary archives in the Arctic and the tropical regions. This is also one of the first studies of microscopic volcanic ash layers in marine records in the region and shows the potential of this approach for future studies. Key Points: Widespread cryptotephra layers identified in the East Sea sediments permit hemispheric synchronization of sedimentary archivesHolocene eruptive history of the Ulleungdo volcano is refined and the U‐1 eruption is dated for the first time and geochemically characterizedSea‐land tephra correlations allow for the establishment of marine age models and the assessment of marine reservoir ages [ABSTRACT FROM AUTHOR]

During the past millennia, several eruptions have occurred within the La Fossa caldera on the island of Vulcano (Aeolian Islands, Italy), some being also described in historical documents dating back to Republican Roman times (first to second century BC). The absolute and relative timing of such activity, however, has remained poorly defined and controversial, due to contrasting ages provided by radiometric and unconventional palaeomagnetic methods. Here, we present a detailed reconstruction of the eruptive history focused on the ninth to fifteenth century AD period that occurred at both La Fossa cone and Vulcanello. This integrated approach involves tephrostratigraphy, standard palaeomagnetic methodology and radiocarbon dating. The new dataset confirms that the lavas exposed above sea level at Vulcanello were erupted between the tenth and eleventh century AD, and not between the first and second century BC as previously suggested. In this same time interval, La Fossa cone was characterized by long-lasting, shoshonitic, explosive activity followed by a discrete, sustained, rhyolitic explosive eruption. Between AD 1050 and 1300, activity was focused only on La Fossa cone, with alternating explosive and effusive eruptions that emplaced four rhyolitic and trachytic lava flows, resulting in significant growth of the cone. After the violent, phreatic event of the Breccia di Commenda (thirteenth century), the eruption continued with a substantial, long-lasting emission of fine ash until activity ceased. Magmatic explosive activity resumed at La Fossa cone at the beginning of the fifteenth century marking the onset of the Gran Cratere cycle. This phase lasted until the mid-sixteenth century and produced at least seven explosive eruptions of intermediate magma composition and a couple of lateral explosions (Forgia Vecchia I and II). During this time interval, a third cinder cone was emplaced at Vulcanello, and the activity produced the lava flows of Punta del Roveto and Valle dei Mostri. From the seventeenth to twentieth centuries, volcanic activity was concentrated at La Fossa cone, where it ended in 1890. This work confirms that Vulcanello island formed in Medieval times between the tenth and eleventh centuries. Moreover, between the tenth and mid-sixteenth centuries, La Fossa caldera was the site of at least 19 eruptions with an average eruption rate of one event every 34 years. This rate makes volcanic hazard at Vulcano higher than that suggested to date. [ABSTRACT FROM AUTHOR]

The significance of the southern Caucasus in understanding Pleistocene hominin expansions is well established. However, the palaeoenvironments in which Palaeolithic occupation of the region took place are presently poorly defined. The Hrazdan river valley, Armenian Highlands, contains a rich Palaeolithic record alongside Middle Pleistocene volcanic, fluvial and lacustrine strata, and thus offer exciting potential for palaeoenvironmental reconstruction. We present the first results of sedimentological, geochemical, tephrostratigraphical and biological (diatoms) study of the sequence of Bird Farm 1, located in the central part of the valley. These data show six phases of landscape development during the interval 440–200 ka. The sequence represents the first quantitative Pleistocene diatom record from the Armenian Highlands and the southern Caucasus, and indicates the persistence of a deep, stratified lacustrine system, with evidence for changing lake productivity that is tentatively linked to climate. Furthermore, major element chemical characterization of visible and crypto‐tephra horizons in the sequence enables the first stages of the development of a regional tephrostratigraphy. Together, the evidence from Bird Farm 1 demonstrates the importance of lacustrine archives in the region for palaeoenvironmental reconstruction and highlights the potential for linkages between archives on both a local and regional scale. [ABSTRACT FROM AUTHOR]

The Milos, Christiana‐Santorini‐Kolumbo (CSK) and Kos‐Yali‐Nisyros (KYN) volcanic complexes of the Aegean Volcanic Arc have repeatedly produced highly explosive eruptions from at least ∼360 ka into historic times and still show recent unrest. We present the marine tephra record from an array of 50, up to 7.4 m long, sediment cores along the arc collected in 2017 during RV Poseidon cruise POS513, which complements earlier work on distal to ultra‐distal eastern Mediterranean sediment cores. A unique set of glass‐shard trace element (LA‐ICPMS) compositions complements our major element (EMP) data on 220 primary ash layers and 40 terrestrial samples to support geochemical fingerprinting for correlations with 19 known tephras from all three volcanic complexes and with the 39 ka Campanian Ignimbrite from the Campi Flegrei, Italy. The correlations include 11 eruptions from CSK (Kameni, Kolumbo 1650, Minoan, Cape Riva, Cape Tripiti, Upper Scoriae 1 and 2, Middle Pumice, Cape Thera, Lower Pumice, Cape Therma 3). We identify a previously unknown widespread tephra from a plinian eruption on Milos (Firiplaka Tephra). Near the KYN we correlate marine tephras with the Kos Plateau Tuff, the Yali 1 and Yali 2 tephras, and the Upper and Lower Pumice on Nisyros. Between these two major tephras, we found two tephras from Nisyros not yet observed on land. The four Nisyros tephras form a systematic trend toward more evolved magma compositions. In the companion paper we use the tephrostratigraphic framework established here to constrain new eruption ages and magnitudes as a contribution to volcanic hazard assessment. Plain Language Summary: The Aegean Volcanic Arc comprises the Milos, Christiana‐Santorini‐Kolumbo and Kos‐Yali‐Nisyros volcanic complexes that present particularly high threats for humans and economy due to abundant highly explosive eruptions in the past. The systematic catalog of how eruption products are dispersed on the seafloor (marine tephras) with time provides information on the number and recurrence of eruptions, on their size, and intensities and is thus essential to quantitatively assess future volcanic hazards and risks. During RV Poseidon cruise POS513 in the Eastern Aegean Sea we recovered 50 sediment cores up to 7.4 m long. More than 220 tephra deposits (e.g., volcanic glass shards) from these eruptions were identified. Glass shard compositions from all layers were used for subsequent geochemical fingerprinting to correlate them with 19 known onshore Aegean eruptions as well as with the 39 ka Campanian Ignimbrite eruption from the Campi Flegrei, Italy. Correlations with 11 eruptions from Christiana‐Santorini‐Kolumbo are established. We identify a previously unknown widespread tephra from an eruption on Milos (Firiplaka Tephra). At the eastern region of the arc, we correlate 7 marine tephras with the Kos‐Yali‐Nisyros volcanic complex. Key Points: Marine tephrostratigraphy for the Aegean ArcChemical fingerprinting to correlate on and offshore tephras [ABSTRACT FROM AUTHOR]

Mount Pelée (Martinique) is one of the most active volcanoes in the Lesser Antilles arc with more than 34 magmatic events in the last 24,000 years, including the deadliest eruption of the 20th century. The current volcanic hazard map used in the civil security plan puts the emphasis on the volcanic hazard close to the volcano. This map is however based on an incomplete eruptive history and does not take into account the variability of the expected source conditions (mass eruption rate, total erupted mass, and grain-size distribution) or the wind effect on ash dispersal. We propose here to refine the volcanic hazard map for tephra fallout by using the 2-D model of ash dispersal HAZMAP. We first simulate the maximum expected eruptive scenario at Mount Pelée (i.e., the P3 eruption) using a seasonal wind profile. Building upon the good agreement with field data, we compute probability maps based on this maximum expected scenario, which show that tephra fallout hazard could threaten not only areas close to the volcano but also the southern part of Martinique. We then use a comprehensive approach based on 16 eruptive scenarios that include new field constraints obtained in the recent years on the past Plinian eruptions of Mount Pelée volcano. Each eruptive scenario considers different values of total erupted mass and mass eruption rate, and is characterized by a given probability of occurrence estimated from the refined eruptive history of the volcano. The 1979-2019 meteorological ERA-5 database is used to further take into account the daily variability of winds. These new probability maps show that the area of probable total destruction is wider when considering the 16 scenarios compared to the maximum expected scenario. The southern part of Martinique, although less threatened than when considering the maximum expected scenario, would still be impacted both by tephra fallout and by its high dependence on the water and electrical network carried from the northern part of the island. Finally, we show that key infrastructures in Martinique (such as the international airport) have a non-negligible probability of being impacted by a future Plinian eruption of the Mount Pelée. These results provide strong arguments for and will support significant and timely reconceiving of the emergency procedures as the local authorities have now placed Mount Pelée volcano on alert level yellow (vigilance) based on increased seismicity and tremor-type signals. [ABSTRACT FROM AUTHOR]

Abstract Sediments from the semi-enclosed Japan Sea are sensitive to paleoclimatic perturbations and they offer great opportunities for many regional and global paleoceanographic and paleoclimatic studies. These studies often require a robust chronology. However, due to rare preservation of calcareous microfossils and drastic changes in surface water salinity during glacial lowstands, the construction of a traditional oxygen isotope stratigraphy for Japan Sea sediments is often difficult. Here, we use sediments recovered at Integrated Ocean Drilling Program (IODP) Expedition 346 Site U1424 to build an integrated Pliocene-Pleistocene reference magnetostratigraphy and tephrostratigraphy for sedimentary sequences from the region. Rock magnetic experiments indicate that magnetic remanence of Site U1424 sediments are carried primarily by (titano)magnetite with small contributions from high coercivity minerals (e.g., hematite) and possibly iron sulphides (pyrrhotite and/or greigite). Dark-colored sediments appear to contain less (titano)magnetite probably due to reductive diagenesis under euxinic conditions. Natural remanent magnetization (NRM) of u-channel samples covering a continuous ~ 167.6 m sediment sequence at Site U1424 was repeatedly measured at 1 cm intervals before and after stepwise demagnetization. Despite lower NRM intensity in dark-colored sediments, NRM directional data from both dark- and light-colored sediments are considered suitable for the construction of magnetostratigraphy. Site U1424 sediments clearly recorded the majority of the polarity chrons and subchrons within the last ~ 4.89 Myr, with the Cobb Mountain subchron, the end of Kaena subchron, and the onset of Nunivak subchron less well preserved. Sixteen tephra layers from the site were sampled for chemical composition analyses and the results were correlated to reference tephrostratigraphy of the region. Ages of the identified tephras are consistent with and can be well integrated with the magnetostratigraphy. The resulting age model suggests that sedimentation rates at Site U1424 range between ~ 1.7 and 7.6 cm/kyr with an average of ~ 3.3 cm/kyr. The acquired magnetostratigraphy and tephrostratigraphy at Site U1424 provide a reference chronology that can be correlated with and transferred to other sediment sequences in the region to study paleoceanographic and paleoclimatic changes of the region as well as their links to other regional and global changes. Graphical abstract

Abstract The Milos, Christiana‐Santorini‐Kolumbo (CSK) and Kos‐Yali‐Nisyros (KYN) volcanic complexes of the Aegean Volcanic Arc have repeatedly produced highly explosive eruptions from at least ∼360 ka into historic times and still show recent unrest. We present the marine tephra record from an array of 50, up to 7.4 m long, sediment cores along the arc collected in 2017 during RV Poseidon cruise POS513, which complements earlier work on distal to ultra‐distal eastern Mediterranean sediment cores. A unique set of glass‐shard trace element (LA‐ICPMS) compositions complements our major element (EMP) data on 220 primary ash layers and 40 terrestrial samples to support geochemical fingerprinting for correlations with 19 known tephras from all three volcanic complexes and with the 39 ka Campanian Ignimbrite from the Campi Flegrei, Italy. The correlations include 11 eruptions from CSK (Kameni, Kolumbo 1650, Minoan, Cape Riva, Cape Tripiti, Upper Scoriae 1 and 2, Middle Pumice, Cape Thera, Lower Pumice, Cape Therma 3). We identify a previously unknown widespread tephra from a plinian eruption on Milos (Firiplaka Tephra). Near the KYN we correlate marine tephras with the Kos Plateau Tuff, the Yali 1 and Yali 2 tephras, and the Upper and Lower Pumice on Nisyros. Between these two major tephras, we found two tephras from Nisyros not yet observed on land. The four Nisyros tephras form a systematic trend toward more evolved magma compositions. In the companion paper we use the tephrostratigraphic framework established here to constrain new eruption ages and magnitudes as a contribution to volcanic hazard assessment.

Tephrochronology is of paramount importance in New Zealand where paleoclimate studies use ages of volcanic ash layers as chronological makers. Maar lakes in the Auckland Volcanic Field (AVF) are characterised by continuous sediment accumulation over extended periods of time (>10,000 years) providing outstanding archives for paleoclimate studies also containing distally-sourced known-age rhyolitic, andesitic and locally-sourced basaltic tephra. Using a multi-method age model for the sediment sequence from Ōrākei Basin (ca. 130,000 years) combining radiocarbon dating, tephrochronology, luminescence dating, and tuning of relative magnetic paleointensity, we present new ages, and test and refine the reliability of existing tephra ages for 14 basaltic, 18 andesitic and eight rhyolitic tephra horizons. Our results show overall strong agreement with previously published ages (except the new age derived for the Okareka tephra, here reported as 23,525 cal yr BP) but reduce the error ranges. Larger differences in tephra ages compared to previously published ages occur predominantly beyond the radiocarbon dating limit. The revised ages have potential implications for studies involving tephrochronology (sensu stricto), for volcanic eruption recurrence rates in the AVF and for the timing of climatic changes observed in northern New Zealand, such as a possibly cooler marine isotope stage (MIS) 5b than MIS4. [ABSTRACT FROM AUTHOR]

Understanding the temporal and spatial environmental response to past climate change during the Last Glacial-Interglacial Transition (LGIT, 16-8 ka) across Europe relies on precise chronologies for palaeoenvironmental records. Tephra layers (volcanic ash) are a powerful chronological tool to synchronise disparate records across the continent. Yet, some regions remain overlooked in terms of cryptotephra investigations. Building on earlier work at the same sites, we present the first complete LGIT high-resolution cryptotephra investigation of two lake records in the Carpathian Mountains in Romania, Lake Brazi and Lake Lia. Numerous volcanic glass shards have been recognised as originating from various volcanic regions, including: Iceland (Katla, Askja, and Torfajokull), Italy (Campi Flegrei, Ischia, Lipari, and Pantelleria), and central Anatolia (Acigol and Ericyes). In total, four distinct tephra horizons have now been identified in these records: 1) an LGIT Lipari tephra (11,515–12,885 cal BP, 95.4% range); 2) Askja-S (11,070–10,720 cal BP, 95.4% range); 3) an Early Holocene Lipari tephra,(12,590–10,845 cal BP, 95.4% range) and; 4) an Early Holocene Ischia tephra (11,120–10,740 cal BP, 95.4% range). The use of trace element analysis on selected cryptotephra layers provided additional important information in identifying volcanic source and facilitating correlations. These tephra layers, along with numerous other discrete cryptotephra layers, offer promise as significant future isochrons for comprehending the spatial and temporal fluctuations in past climate change throughout Europe and the Mediterranean area. This research has emphasized the significance of the Carpathian region in expanding the European and Mediterranean tephra lattice and establishing it as a keystone area within the framework. • Far-travelled volcanic shards found in Lakes Lia and Brazi, Romania. • Geochemical correlation to three main volcanic regions: Iceland, Italy and Anatolia. • Successful use of trace element analysis for validating volcanic origins. • Significance in discovering three new, dated cryptotephra layers. • Region crucial in wider European and Mediterranean tephrostratigraphic framework. [ABSTRACT FROM AUTHOR]

PROMETHEUS is a statistical tool that allows creating maps showing the probability of finding tephra deposits of different grain sizes, originating from eruptions of a specific volcanic source, at any location around the vent. It couples wind profiles at different heights in the Mediterranean area with terminal velocity of volcanic particles. The input parameters include the height of the eruption column (which characterizes the intensity of the eruption), wind statistics (directions and intensities), and tephra deposits of a selected grain size. In particular, we used the parameterizations provided by Costa et al. (2016) and performed simulations using the HAZMAP tephra dispersal model to determine the maximum reachable distances that tephra can cover under weak, medium, and strong wind conditions (e.g. 7, 30, and 70 m/s velocities at the tropopause) and with column heights of 10, 20, and 30 km, depositing of at least the loading corresponding to 0.1 mm (corresponding to cryptotephra). Three alternative configurations of the model are validated analyzing first the eruptive source of Somma Vesuvius, with the related explosive eruptions from 22 ka Pomici di Base to the 1944 eruption. A further validation is made by comparing the probabilistic maps with the tephrostratigraphy of known marine and terrestrial cores using standard test of proportions (binomial distributions) and the binary logistic regression model, statistically quantifying the effectiveness of the model against the tephrostratigraphy recorded within this time frame. Based on this validation, a preferred configuration of PROMETHEUS is selected. PROMETHEUS probability maps will guide the selection of sampling sites for specific tephra deposits and could also support the study of the completeness of overall eruption catalogs over time. • Probability maps allow us to determine how far a particular grain size of tephra can reach. • The easy reproducibility of the scripts and the related maps allows one to create probability maps in any place of interest. • These probability maps will allow us to understand which places are most affected by explosive volcanic eruptions with a given eruptive size. [ABSTRACT FROM AUTHOR]

The complex urban geology of the historic center of Naples is characterized by the emplacement of products from two adjoining volcanic areas that were reworked by alluvial and coastal processes. To expand the geologic knowledge of this densely populated area, multidisciplinary research was carried out on the recently drilled San Marcellino borehole, as part of a larger borehole collection project. Critical revision of 290 previously drilled sequences, and a complete set of tephrostratigraphic, sedimentologic, and paleoecologic data obtained on the San Marcellino stratigraphy, informed a hydrogeological conceptual model of water circulation and paleoenvironmental reconstruction of the city historic center. Both before and after the Neapolitan Yellow Tuff eruption, ca. 15 ka, the landscape was characterized by a marine to transitional paleoenvironment. This signifies a good balance between sea-level rise and volcaniclastic inputs, consisting of both primary and remobilized deposits in an area that is also subject to bradyseismic oscillations. Amongst the primary pyroclastic deposits, the products of an explosive event from Campi Flegrei about 16 ka, with an eastward-directed sustained-column phase, were recognized. Collectively, the multidisciplinary data obtained in this study favor the presence of a double-aquifer conceptual model, characterized by a volcanic and a marine-sedimentary aquifer. [ABSTRACT FROM AUTHOR]

The exact spatial and temporal behaviour of rapid climate shifts during the Last Glacial–Interglacial Transition are still not entirely understood. In order to investigate these events, it is necessary to have detailed palaeoenvironmental reconstructions at geographically spread study sites combined with reliable correlations between them. Tephrochronology, i.e., using volcanic ash deposits in geological archives as a dating and correlation tool, offers opportunities to examine the timing of events across wider regional scales. This study aims to review the posited asynchrony of the Younger Dryas stadial in comparison with Greenland Stadial-1 by correlating new proxy data from southernmost Sweden to previous palaeoclimate reconstructions in Europe based on the presence of the Hässeldalen Tephra, the Vedde Ash, and the Laacher See Tephra. μ-XRF core-scanning data were projected using a recently published age–depth model based on these tephras and several radiocarbon dates, and compared to previous findings, including by adapting previous chronologies to the recently proposed earlier date of the Laacher See Tephra (13,006 ± 9 cal. a BP). Although the results to some extent support the idea of a more synchronous Younger Dryas event than previously assumed, this issue requires further high-resolution proxy studies to overcome limitations of temporal precision.

Abstract Integrated Ocean Drilling Program Expedition 346 “Asian Monsoon” obtained sediment successions at seven sites in the Japan Sea (Sites U1422–U1427 and U1430) and at two closely located sites in the northern East China Sea (Sites U1428 and U1429). The Quaternary sediments of the Japan Sea are characterized by centimeter- to decimeter-scale dark–light alternations at all sites deeper than 500 m water depth. The sedimentary records from these sites allow an investigation of the regional environmental response to global climate change, including changes in the Asian Monsoon and eustatic sea level. However, the discontinuous occurrence of calcareous microfossils in the deep-sea sediments and their distinct isotope signature that deviates from standard marine δ18O records do not permit the development of a detailed stable isotope stratigraphy for Japan Sea sediments. Here, we present the tephrostratigraphy for the two southernmost sites drilled in the Japan Sea (Sites U1426 and U1427) and for one site drilled in the East China Sea (Site U1429) along with the benthic δ18O isotope stratigraphy for the shallower Site U1427 and the East China Sea Site U1429. Eighteen tephra layers can be correlated between sites using the major-element composition and morphology of volcanic glass shards, and the compositions of grains and heavy minerals. Tephra correlations show that negative δ18O peaks in the Japan Sea correspond to positive glacial maxima peaks in the East China Sea. Using this integrated stratigraphic approach, we establish an orbital-scale age model at Site U1427 for the past 1.1 Myr. The correlation of tephra layers between the shallower Site U1427 (330 m below sea level: mbsl) and the deeper Site U1426 (903 mbsl) in the southern Japan Sea provides the opportunity for further age constraints. Our results show that alternations in sediment color at Sites U1426 and U1427 can be correlated for the past 1.1 Myr with minor exceptions. Thus, the stable isotope stratigraphy established at the shallower Site U1427 can be correlated to Site U1426, and in turn to all sites drilled during Expedition 346, based on correlations of dark–light layering.

In the following paper, we apply digital mapping techniques and tephrostratigraphy to correlate marker horizons across the Whanganui Basin, culminating in a new 1:25,000 geological map of the central Rangitikei. This is achieved by (1) compilation of existing research, (2) correlation of major element glass shard datasets to known eruptive products and (3) completion of a three-year field survey. We update and refine existing stratigraphic correlations, focusing on two critical units within the basin succession; namely the Makirikiri Tuff (1.6 Ma) and Kaimatira Pumice Sand (1 Ma) formations. Okehu Group is proposed to cover all strata from Pakihikura to Potaka pumice. Rewa Pumice is placed within its own formation bridging the Makirikiri Tuff and Kaimatira Pumice Sand formations. Mapping and analysis facilitate placement of Coutts Creek Horizon within Rewa Formation. Sub-aerial surfaces and influxes of greywacke and volcaniclastic detritus from c. 1.6 Ma onward provide evidence for an alluvial plain developing at the foot of the uplifting, paleo-axial range. We suggest uplift in the paleo-axial range occurred contemporaneously with the onset of rhyolitic activity at Mangakino caldera (c. 1.6 Ma) so that the first influxes of fluvial conglomerate and volcaniclastics occur in close proximity within the eastern basin succession. [ABSTRACT FROM AUTHOR]

A comprehensive morphostratigraphic and chronological study of the complete set of Holocene tephras from Tafí and Santa María valleys (northwestern Argentina), including analyses of compositional characteristics, is presented. Five ash tephras are recognized: V0 (El Rincón), V1a (Carreras 1a ash), V1b (Carreras 1b ash), V2a (Carreras 2 ash), and V2b (El Paso 3 ash). Two of them (V1b and V2b) are described for the first time in the study area. The new 14C and accelerator mass spectrometry ages presented, along with the previously published information, allows for the establishment of a chronological framework. The V0 tephra was deposited in the Early Holocene (about 10,000 yr BP), V1a and V1b were deposited in the Middle Holocene (about 4200 and 3500 yr BP, respectively), and V2a and V2b were deposited in the Late Holocene (after about 800 yr BP). The mineralogical, textural, and geochemical characterizations of the five tephras suggest that their tephra provenance was mainly from the back-arc region. However, the determination of the exact source of each tephra requires more accurate high-resolution tephrochronological studies. At least five major eruptions affected the Tafí and Santa María valleys in the last 10,000 yr. [ABSTRACT FROM AUTHOR]

Databases facilitate the rapid access of crucial information, consequently these tools are vital to the various disciplines within the Earth sciences that study volcanic rocks. In the central Mediterranean, archives of data describing the bulk and glass compositions of volcanic rocks exist, but those resources are not structured as searchable databases or, if they are, they are too general to be useful for specific problems (e.g. correlation of tephra layers in the Tertiary-Quaternary stratigraphy). Here we present a new, open access database that contains information describing (mainly) mineral phases and (minor) glass compositions of distal and proximal deposits from the Miocene to the present day. The MedVolc-PH database can be searched using single or multiple queries, facilitating the correlation or study of deposit(s) with the requested characteristics. This manuscript describes the database scheme and highlights how the database can be queried through user-friendly examples of central Mediterranean tephra correlations. • MedVolc-PH includes age and compositions of mineral phases (mainly) and glass (minor) of Mediterranean volcanic deposits. • Currently MedVolc-PH encompasses information on Miocene to the present day proximal and distal volcanic deposits. • It can be searched using single or multiple queries, facilitating the correlation of deposit(s) with the requested features. • This manuscript describes the database scheme and highlights how the database can be queried through user-friendly examples. • MedVolch-PH is hosted on the server of "Dipartimento di Scienze della Terra e Geoambientali" of the Bari University (Italy). • It is an open database and it will be continuously updated with new published data. [ABSTRACT FROM AUTHOR]

Extensive and protracted volcanism in the Carpathian-Pannonian Region climaxed during the Early to Middle Miocene with series of major ignimbrite-forming eruptions with their products dispersed across the Alpine-Mediterranean Region. The spatial and temporal dispersion of these volcanic horizons make them potentially important stratigraphic markers throughout the region, allowing better understanding of temporal and spatial changes in depositional environments and paleoclimate. Several of these Middle Miocene volcaniclastic layers are preserved in stratigraphically and environmentally variable sedimentary facies on Mt. Medvednica, located in the North Croatian Basin. In order to decipher the age, depositional environment and provenance of two volcaniclastic horizons intercalated within Central Paratethys marine sediments on Mt. Medvednica, we applied an integrated approach of volcanological, geochronological, and paleontological analyses. New high-precision zircon geochronology and volcanic glass geochemistry data allow to distinguish two primary rhyolitic volcaniclastic horizons derived from distinct eruptions, "Plaz", and the "Bidrovec", dated at 14.937 ± 0.012 Ma and 14.835 ± 0.012 Ma. Distinguished mineralogical and geochemical data enabled the correlation of the older ("Plaz") horizon on Mt. Medvednica with the Demjén eruption, one of the six major Early–Middle Miocene ignimbrite-forming eruptions of the Carpathian-Pannonian Region. However, a correlation of the younger ("Bidrovec") horizon and assignment to a specific eruption could not be established due to a lack of compositional data from coeval eruption products throughout the region. The newly gathered data establishes both "Plaz" and "Bidrovec" pyroclastic deposits as valuable marker horizons for regional reconstructions, and enable a better understanding of the eruption chronology and tephrostratigraphy of the Carpathian-Pannonian Region. • Mt. Medvednica volcaniclastic horizons were emplaced at ∼14.94 Ma and ∼ 14.84 Ma. • Primary volcaniclastic deposits were deposited in Central Paratethys environments. • ∼14.94 Ma horizon can be related to Demjén eruption of the Carpathian-Pannonian Region. • ∼14.84 Ma horizon is coeval with several regionally spread volcaniclastic horizons. • Better understanding of the regional widespread eruption history and tephrostratigraphy is enabled. [ABSTRACT FROM AUTHOR]

The Campanian Volcanic Zone (CVZ) comprises multiple active volcanoes and includes the highly productive Campi Flegrei and Ischia caldera systems. These caldera volcanoes have produced probably the largest eruptions in Europe in the past 200 ka, such as the Monte Epomeo Green Tuff (MEGT; Ischia) at ca. 56 ka and the Campanian Ignimbrite (CI; Campi Flegrei) at ca. 40 ka, which form widespread isochrons across the Mediterranean region. These closely-spaced volcanic centres erupt phonolitic to trachytic glass compositions that are similar, and thus it can be challenging to correlate tephra deposits to specific volcanic sources. Here we present a detailed tephrostratigraphy for pre-CI eruption activity using the units preserved within a sequence at the coastal Acquamorta outcrop, on the western side of the CI caldera rim. Both the MEGT and CI units are present in the section, and they bracket twelve eruption units that were logged and sampled. New major and trace element glass chemistry data have been acquired for these Acquamorta tephra deposits. Three eruption deposits from Ischia and nine from Campi Flegrei are identified, which helps constrain the tempo of volcanic activity of these centres between the large caldera-forming eruptions. The three Ischia tephra deposits between the MEGT and the CI are indistinguishable based on both major and trace element glass chemistry and cannot be correlated to a specific or known eruption in this interval, such as the Schiappone tephra. The compositional variations between the Campi Flegrei eruptions reveal temporal shifts in the composition of the tephra deposits that reflect changes in the magmatic system prior to the CI eruption. These deposits indicate that there were at least nine eruptions at Campi Flegrei within 16 ka of the enormous CI eruption, and suggest that there was no significant period of repose before the caldera generating eruption. • Ischia and Campi Flegrei were very active between caldera-forming eruptions: twelve units identified between 56 ka and 40 ka. • Ischia tephras have similar glass compositions having implications for using them and the Schiappone tephra as marker layers. • The compositions of the nine Campi Flegrei tephras can be categorised into three glass chemistry groups. • Glass compositions become more evolved over time, extending toward a composition that is also present in the CI deposits. [ABSTRACT FROM AUTHOR]

Altered tephras (K-bentonites) are of great importance for calibration of the geologic time scale, for local, regional, and global correlations, and paleoenvironmental reconstructions. Thus, definitive identification of individual tephras is critical. Single crystal geochemistry has been used to differentiate tephra layers, and apatite is one of the phenocrysts commonly occurring in tephras that has been widely used. Here, we use existing and newly acquired analytical datasets (electron probe micro-analyzer [EPMA] data and laser ablation ICP-MS [LA-ICP-MS] data, respectively) of apatite in several Ordovician K-bentonites that were collected from localities about 1200 km apart (Minnesota/Iowa/Wisconsin and Alabama, United States) to test the use of machine-learning (ML) techniques to identify with confidence individual tephra layers. Our results show that the decision tree based on EPMA data uses the elemental concentration patterns of Mg, Mn, and Cl, consistent with previous studies that emphasizes the utility of these elements for distinguishing Ordovician K-bentonites. Differences in the experimental setups of the analyses, however, can lead to offsets in absolute elemental concentrations that can have a significant impact on the correct identification and correlation of individual K-bentonite beds. The ML model using LA-ICP-MS data was able to identify several K-bentonites in the southern Appalachians and establish links to K-bentonites samples from the Upper Mississippi Valley. Furthermore, the ML model identified individual layers of multiphase eruptions, thus illustrating very well the great potential of applying ML techniques to tephrochronology.

The 56 ka Monte Epomeo Green Tuff (MEGT) resulted from the largest volume explosive eruption from Ischia island (south Italy). Its tephra is one of the main stratigraphic markers of the central Mediterranean area. Despite its importance, a detailed characterisation of the petrography and mineral chemistry of MEGT is lacking. To fill this gap, we present detailed petrographic description and electron microprobe mineral chemistry data on samples collected on-land from the MEGT. Juvenile clasts include pumice, scoria, and obsidian fragments with porphyritic/glomeroporphyritic, vitrophyric, and fragmental textures. The porphyritic index is 13–40 vol.%, and phenocryst phases include alkali-feldspar, plagioclase, clinopyroxene, ferrian phlogopite, and titano-magnetite, in order of decreasing abundance; accessory phases include sphene, hydroxy-fluor-apatite, and rare edenite. Plagioclase varies from predominant andesine to subordinate oligoclase, whereas alkali-feldspar is more variable from sanidine to anorthoclase; quasi-pure sanidine commonly occurs as either rim or recrystallisation overgrowth of large phenocrysts due to hydrothermal alteration. Secondary minerals include veins and patches of carbonate minerals, Fe-Mn oxyhydroxides, clay minerals, and zeolites. Clinopyroxene is ferroan diopside (En45–29Fs7–27) and never reaches Na-rich compositions. This feature allows the discrimination of MEGT from aegirine-bearing, distal tephra layers erroneously attributed to MEGT, with implications for the areal distribution of Ischia explosive deposits.

The Olorgesailie Drilling Project and the related Hominin Sites and Paleolakes Drilling Project in East Africa were initiated to test hypotheses and models linking environmental change to hominin evolution by drilling lake basin sediments adjacent to important archeological and paleoanthropological sites. Drill core OLO12-1A recovered 139 m of sedimentary and volcaniclastic strata from the Koora paleolake basin, southern Kenya Rift, providing the opportunity to compare paleoenvironmental influences over the past million years with the parallel record exposed at the nearby Olorgesailie archeological site. To refine our ability to link core-to-outcrop paleoenvironmental records, we institute here a methodological framework for deriving a robust age model for the complex lithostratigraphy of OLO12-1A. Firstly, chronostratigraphic control points for the core were established based on 40Ar/39Ar ages from intercalated tephra deposits and a basal trachyte flow, as well as the stratigraphic position of the Brunhes-Matuyama geomagnetic reversal. This dataset was combined with the position and duration of paleosols, and analyzed using a new Bayesian algorithm for high-resolution age-depth modeling of hiatus-bearing stratigraphic sections. This model addresses three important aspects relevant to highly dynamic, non-linear depositional environments: 1) correcting for variable rates of deposition, 2) accommodating hiatuses, and 3) quantifying realistic age uncertainty with centimetric resolution. Our method is applicable to typical depositional systems in extensional rifts as well as to drill cores from other dynamic terrestrial or aquatic environments. We use the core age model and lithostratigraphy to examine the interconnectivity of the Koora Basin to adjacent areas and sources of volcanism. • Innovative age model based on new Pleistocene drill core record from south Kenya Rift. • Geochronology uses control points from tephra 40Ar/39Ar ages and magnetostratigraphy. • Bayesian algorithm corrects for variable rates of deposition and paleosol hiatuses. • Age model chronostratigraphy sets a new standard for calibrating drill core records. [ABSTRACT FROM AUTHOR]

Shallow-marine to fluvio-estuarine deposits in Pohangina Valley represent an underexplored portion of the Whanganui Basin, a globally significant archive of Quaternary climate change. To address this, we document environments of deposition through facies analysis, tephrostratigraphy and biostratigraphy. The marine shelf environment is characterised by fossiliferous mudstone containing marine Mollusca. Estuarine facies consist of pumiceous sandstone, tephra, lignite and carbonaceous mudstone. Volcaniclastic and tephra-fall deposits record seven eruptions from the Taupo Volcanic Zone between c. 1.6 and 0.9 Ma. We identify and define Awahou Tephra (new) (c. 1.03 Ma), through mapping and geochemical analysis of constituent glass shards. Progressive retreat of the sea (c. 1.6 Ma) is indicated by a change from shallow-marine to fluvio-estuarine sedimentation. An east–west drainage system developed (c. 1 Ma), including ponding near Woodville from which an early ancestor of the Manawatu River exited, establishing an antecedent path to the Tasman Sea across the uplifting paleo-axial range. [ABSTRACT FROM AUTHOR]

Large Magnitude (6–8) Late Quaternary Japanese volcanic eruptions are responsible for widespread ash (tephra) dispersals providing key isochrons suitable for the synchronisation and dating of palaeoclimate archives across East Asia, the NW Pacific and beyond. The transfer of geochronological information using these eruption deposits demands robust tephra correlations underpinned by detailed and precise volcanic glass geochemical data. Presented here is a major (electron microprobe; EMP) and trace element (Laser ablation inductively coupled plasma mass spectrometry; LA-ICP-MS) characterisation of near-source deposits from a series of large magnitude Japanese eruptions spanning approximately the last 150 ka. These data offer new insights into diagnostic compositional variations of the investigated volcanic sources spanning the Japanese islands. Whilst in the case of the highly productive Aso caldera (Kyushu), we are able to explore compositional variations through successive large magnitude eruptions (50–135 ka). These near-source volcanic glass data are used to validate and refine the visible tephrostratigraphy of the intensely dated Lake Suigetsu sedimentary record (SG06 core), Honshu Island, whilst also illustrating key tephrostratigraphic tie points to other East Asian palaeoclimate records (e.g. Lake Biwa). The identification of widespread Japanese tephrostratigraphic markers in the SG06 sediment record enables us to place chronological constraints on these ash dispersals, and consequently explosive volcanism at source volcanoes situated along the Kyushu Arc, including Kikai, Ata and Aso calderas. The proximal Aso-4 Ignimbrite (Magnitude 7.7) deposit is dated here by 40Ar/39Ar at 86.4 ± 1.1 ka (2σ), and provides a chronological anchor (SG06-4963) for the older sediments of the Lake Suigetsu record. Finally, trace element glass data verify visible ash fall layers derived from other compositionally distinct source regions of Japanese volcanism, including activity along the northern Izu-Bonin arc and North East Japan Arcs. These findings underline the Lake Suigetsu record as central node in the Japanese tephrostratigraphic framework. • Near-source and distal (Lake Suigetsu) characterisation of Late Quaternary widespread Japanese Tephrostratigraphic markers. • Grain-specific major and trace element volcanic glass analyses (EMP & LA-ICP-MS). • Chemical discrimination of Japanese volcanic source regions for the purposes of Tephrochronology. • Unlocking the Lake Suigetsu (SG06 core) visible tephra layers for reliable archive synchronisation. • Proximal 40Ar/39Ar age of 86.4 ± 1.1 ka (2σ) for the Magnitude 7.7 caldera forming Aso-4 eruption. [ABSTRACT FROM AUTHOR]

Barton Peninsula is an ice-free area located in the southwest corner of King George Island (South Shetland Islands, Antarctica). Following the Last Glacial Maximum, several geomorphological features developed in newly exposed ice-free terrain and their distribution provide insights about past environmental evolution of the area. Three moraine systems are indicative of three main glacial phases within the long-term glacial retreat, which also favoured the development of numerous lakes. Five of these lakes were cored to understand in greater detail the pattern of deglaciation through the study of lacustrine records. Radiocarbon dates from basal lacustrine sediments enabled the reconstruction of the chronology of Holocene glacial retreat. Tephra layers present in lake sediments provided additional independent age constraints on environmental changes based on geochemical and geochronological correlation with Deception Island-derived tephra. Shrinking of the Collins Glacier exposed the southern coastal fringe of Barton Peninsula at 8 cal ky BP. After a period of relative stability during the mid-Holocene, the ice cap started retreating northwards after 3.7 cal ky BP, confining some glaciers within valleys as shown by moraine systems. Lake sediments confirm a period of relative glacial stability during the last 2.4 cal ky BP. [ABSTRACT FROM AUTHOR]

Abstract Tephra deposits are used by many disciplines of the natural sciences, not only for gaining important insight into volcanism, but also for chronological purposes, especially the dating of sedimentary sequences throughout geological time. Use of these deposits as isochronous tie points relies on the ability to accurately correlate tephra from one site to another including more diffuse, distal sites, as well as to possibly identify the source eruption. However, the ability to uniquely identify tephra deposits, and thus correlate them with certainty, is not without its complications. Here we present a case study from North Island, New Zealand, to highlight the complications and intricacies of achieving robust tephra deposit correlations. We highlight three key issues including: 1) the large uncertainties associated with direct dating techniques for older (≥1 Ma) tephra horizons; 2) the lack of/or minimalist amount of published and accessible geochemical data; and 3) the lack of data pertaining to the source regions themselves. We report new age and geochemical data for tephra deposits from a region that has been the depositional site of many eruptions since at least 12 Ma. Of the tephra horizons sampled in this region, six contained sufficient zircons for fission-track dating. Ages of the horizons range from 1.4 to 5.7 Ma, in good agreement with previously assigned age constraints based on biostratigraphic and/or paleomagnetic markers. However, the precision of these ages (2σ uncertainties of ±0.4–1.6 Ma) is insufficient to correlate the tephra horizons to either their specific source (eruption event) or alternative tephra deposits using geochronology alone. Therefore, in addition to the new (and existing) age data, we present the results of major and trace element analysis of glass shards from 18 tephra horizons. For most horizons the geochemical signatures of the glass shards are internally homogeneous for both major and trace elements, suggesting a single source eruption. In a few cases, however, the tephra horizons exhibit heterogeneous geochemical signatures, which, when coupled with the deposit morphology, suggest evidence for reworking, post-depositional devitrification, and a more complex source history. We discuss correlation of the tephra horizons to onshore and offshore counterparts and also to source. Our results emphasise the importance of combining geochronological constraints with geochemical fingerprinting and additional parameters including stratigraphy to provide the most accurate correlations. As a result, we encourage the use of electronic storage files in publications to give access to full geochemical (including secondary standard data) and chronological datasets. This will not only allow complete characterisation of the tephra, but also facilitate rigorous statistical assessment to produce accurate correlation to other deposits in future studies. Highlights • Complications of tephrochronology highlighted. • Late Cenozoic rhyolitic tephra horizons identified and characterised from the Hawke's Bay region, New Zealand. • Methods of correlation of tephra deposits to other sites and to source are discussed. • The importance of geochemical data and geochronological data in making accurate correlations is discussed. [ABSTRACT FROM AUTHOR]

Abstract Re-examination of central Mediterranean paleoclimate archives on tephra layers indicates that three widely dispersed tephra layers occurred during the Bronze Age, namely Agnano Mt Spina from Campi Flegrei (ca. 4.4 cal ka BP), Avellino from Somma-Vesuvius (ca. 3.9 cal ka BP), and FL from Etna (ca. 3.3 cal ka BP). Stratigraphical correlations of selected archives using these tephra layers indicate that some records have severe chronological biases, posing important limitations to the use of these archives for defining the paleoclimate conditions during the Bronze Age. Regardless of the temporal mismatches, the Agnano Mt Spina tephra layer seems to have occurred at the beginning of a centennial scale period of climatic deterioration, while the Avellino tephra layer, taking place during a wetter period, seems to mark the end of this event. The dry event bounded by the two tephra layers seems to be correlated with the so-called "4.2 event". Instead, the FL tephra from Etna seems to herald a new climatic deterioration at ca. 3.3–3.2 cal ka BP. Although the general frame is still incomplete, these three tephra layers appear to play a fundamental role in synchronizing archives, and can lead to the definition of a detailed paleoclimatic framework of the Bronze Age in the central Mediterranean area. [ABSTRACT FROM AUTHOR]

The Taupo Volcanic Zone (TVZ) in North Island, New Zealand, is the on-land continuation of the Tonga-Kermadec arc formed in the Quaternary at the obliquely convergent boundary of the Pacific and Australian tectonic plates. The central TVZ is a region of intense silicic volcanism and active rifting with a very high heat flux. Within this zone is a dynamic landscape affected by a dense, active fault network, the Taupo Rift. In this rift, the Ngakuru graben hosts fossil hydrothermal systems in an area parallel to numerous active faults including the east strand of Whirinaki Fault that forms a major structure. Using various geoscientific techniques including mapping, stratigraphy, paleoseismic trenching, and tephrostratigraphy, in conjunction with LiDAR-derived DEMs, we reconstruct and date the fault's rupture history along with hydrothermal activity (including silica-sinter development) since c. 40,000 calendar years ago (40 cal. ka) at a site near Hossack Road called "Meade". Ages for Kawakawa (c. 25.4 cal. ka), Okareka (c. 21.8 cal. ka), Rotorua (c.15.6 cal. ka), Rotoma (c. 9.4 cal. ka), and Taupo (c. 1.7 cal. ka) tephras enabled us to date five identified fault rupture events using the Meade trench excavation. Slip rates of 2.66 ± 0.77 mm/yr (pre-Kawakawa tephra), 0.28 ± 0.04 mm/yr (between c. 25.4 ka and Taupo) and 0.51 ± 0.19 mm/yr (post-Taupo), and the recurrence interval of ∼5500 cal. yr during the last c. 25.4 cal. kyr, all correlate with events of similar ages determined from studies on other trenches on Whirinaki Fault. Intercalated with Tahuna tephra (c. 39.3 cal. ka) and additionally dated at c. 38.9 cal. ka using radiocarbon, the hydrothermal sinter began developing at the Meade site at c. 39 cal. ka and ceased by c. 21.8 cal. ka (marked by Okareka tephra). We examine the causative relationship between fault activity and the development of sinter by comparing the chronology of volcanic eruptions and fault rupturing events with that of sinter formation as recorded in three neighbouring sites, Mangatete, Matthews, and Fitzpatrick. The findings improve understanding of the complex rupture behaviour of faulting and provide evidence for relationships between tectonic and hydrothermal activities, which were additionally influenced by the impacts of climatic change and geomorphic processes on landscape evolution, within the late Quaternary period. The study also exemplifies the unique value of tephrochronology in helping to disentangle complex geological deposits and events in an extremely dynamic part of the Earth's surface (the Taupo Rift). • An active fault and hydrothermal sinters occur together in the dynamic Taupo Rift, TVZ. • We date the fault rupture history and hydrothermal activity ≤40 ka via tephrochronology. • Five ruptures occurred: pre-25.4 ka, 25.4–21.8 ka, 15.6–9.4 ka, 9.4–1.7 ka, post-1.7 ka. • Sinters were deposited 39–21.8 ka, relating partly to changes of location of heat source. • Landscape shaped by combination of fault and hydrothermal activity, LGM-climate change. [ABSTRACT FROM AUTHOR]

Abstract Precise chronologies that allow direct correlation of paleoclimate archives are a prerequisite for deciphering the spatiotemporal characteristics of short-term climate variability. Such chronologies can be established through the analysis of tephra layers that are preserved in the respective sedimentary archives. Here we explore the yet untapped tephrochronological potential of the Eastern Mediterranean region for the Middle Pleistocene, specifically for the interval spanning Marine Isotope Stages (MIS) 12–10 (460–335 ka). High-resolution cryptotephra analysis was carried out on peat cores spanning the MIS 12–10 interval that have been recovered from the iconic climate archive of Tenaghi Philippon, NE Greece. Eighteen primary cryptotephras were identified, and major- and trace-element analyses of single glass shards from all cryptotephras were performed in order to correlate them with their eruptive sources. The results suggest origins from both Italian and Aegean Arc volcanoes. Specifically, one cryptotephra layer could be firmly correlated with the Cape Therma 1 eruption from Santorini, which makes it the first distal tephra finding for this eruptive event. While eight further cryptotephras could be tentatively correlated with their volcanic or even eruptive sources, the provenance of another nine cryptotephras as yet remains unknown. The relatively large number of cryptotephras that could not be assigned to specific volcanic sources and eruptive events reflects the still considerable knowledge gap regarding the geochronology and geochemistry of proximal tephra deposits from the Middle Pleistocene of the Central and Eastern Mediterranean regions. Due to the lack of well-dated Middle Pleistocene eruptions, we provide age estimates for all cryptotephra layers identified in the MIS 12–10 interval at Tenaghi Philippon based on high-resolution pollen data from the same cores. While eight of the identified cryptotephras were deposited within MIS 12 (∼438–427 ka), one cryptotephra was deposited at the onset of MIS 11 (∼419 ka), five cryptotephras during the younger part of MIS 11 (∼391–367 ka), and four cryptotephras during MIS 10 (∼359–336 ka). The high number of cryptotephras from multiple sources as recorded in the MIS 12–10 interval at Tenaghi Philippon highlights the key role of this archive for linking tephrostratigraphic lattices for the Middle Pleistocene of the Central and Eastern Mediterranean regions. Highlights • 18 cryptotephra layers identified for the 460–335 ka interval at Tenaghi Philippon. • Major- and trace-element compositions reveal Italian and Aegean Arc sources. • One cryptotephra can be traced to the Santorini Cape Therma 1 eruption. • Nine cryptotephras originate from a yet unknown Eastern Mediterranean source. • Cryptotephra ages derived from orbitally tuned high-resolution pollen data. [ABSTRACT FROM AUTHOR]

Rhyolitic pyroclastic deposits, mostly ignimbrites (ash-and-pumice flow deposits) from plinian eruptions belonging to the early activity (> 2.5 Ma) of the Plio-Quaternary Monts Dore volcanic field (Massif central, France) are documented in order to provide lithofacies and compositional data that could serve as a rational basis for ignimbrite discrimination and tephrostratigraphic correlations. We define or redefine six major pyroclastic units (five ignimbrites and one pumice fallout deposit), based mainly on pumice texture and mineral assemblage. Pumices and quartz-hosted glass inclusions are rather uniform compositionally, being high-silica rhyolites with very low CaO, MgO and FeO contents. Juvenile mineral assemblages are K-feldspar ± quartz ± plagioclase, with rare biotite ± amphibole + accessory phases (mostly sphene, zircon, oxides, apatite). The feldspars, biotite and amphibole compositions of all units strongly overlap and poorly constrain ignimbrite discrimination. These data provide clues to some volcanological issues under debate in the Monts Dore volcanic field. The major rhyolitic pyroclastics found on the Monts Dore margins, e.g. the conspicuous « Grande Nappe » unit of previous authors, are here interpreted as stratigraphical units beneath those exposed in proximal areas, and concealed in the central structural depression (caldera) suggested by previous gravimetric studies. The poorly constrained caldera geometry should be envisioned as a compound, polygenic structure related to several ignimbrite eruptions spanning at least 350 ky, whose vent locations may have shifted with time. The very scarce Fe-Mg silicate phases, biotite and amphibole found in the pumices and ignimbrite matrices show complex compositional populations which can be explained only partly by xenocrystic contamination and require further petrological investigations.

Abstract The Kos-Nisyros-Yali volcanic region is one of the centers in the South Aegean Volcanic Arc to exhibit Holocene volcanic activity, with poorly dated thin tephra layers on Yali associated with Neolithic artifacts. This paper helps to resolve the age and character of early to mid - Holocene volcanism in the South Aegean Sea. It presents the lithostratigraphic record of seven newly recovered cores from this region at the SE termination of the South Aegean Volcanic Arc. The cores were scanned for magnetic susceptibility, split, logged and sampled at one centimeter resolution for carbonate content. Selected intervals were analyzed for grain size, organic carbon content, and feldspar content by XRD, in order to identify lithostratigraphic levels with enhanced volcanic minerals. Subsequently, textural and electron microprobe analyses of volcanic glass shards and pumice fragments were carried out on 20 samples. Chronology was inferred from the upper and lower limits of the S1 sapropel and from five AMS 14C dates on foraminifera. In several cores in the S1 interval, mixed volcanic glass types that compositionally correlate with the Nisyros Lower and Upper Pumice, Yali pumices and KPT suggest that the volcanic glass is reworked from previous deposits and transported by turbidity currents. Cores from deep water northeast and northwest of Yali have a single population of tephra at two or more horizons within S1 that geochemically resembles Holocene Yali–4 pumice on land. These beds likely represent air-fall ash that was dispersed at least 10 km from Yali, with ages of 8 and 10 ka. Moreover we report two or more tephra layers within S1 from the Kalymnos Basin that are not reworked and geochemically resemble Santorini tephra. This study thus confirms the occurrence of small early Holocene eruptions at Yali and provides possible evidence for early Holocene eruptions at Santorini. Highlights • A lithostratigraphic record of seven cores from Kos–Nisyros–Yali volcanic center • S1 sapropel constitutes a chronostratigraphic marker for the volcanic deposits. • Reworked volcanic glass shards of Nisyros, Yali and KPT origin traced within S1 • Cryptotephra of minor Santorini eruptions traced within S1 in Kalymnos Basin • Minor early Holocene eruptions on Yali island confirmed [ABSTRACT FROM AUTHOR]