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This study provides geological, geochemical, and chronological insight into the evolution of the Hachijo-jima volcanoes of the Izu Bonin arc. The regional Ata-Torihama tephra (Ata-Th; 0.24 Ma) and Kikai-Tozurahara tephra (K-Tz; 0.095 Ma) from Kyushu are intercalated within the voluminous proximal volcanic products. Our study combines detailed geologic mapping, tephrochronology, U-Pb zircon dating, and published drill core data from NEDO (1993) to evaluate the time transgressive 3-dimensional (thus 4-dimensional) structure of the dissected Mihara-yama volcano, the older of the two volcanoes on Hachijo-jima. The volcanic succession comprises terrestrial volcanic basement, marine volcaniclastic rocks, and terrestrial tuff intercalated with tholeiitic basalt and the regional calc-alkaline tephra layers. The un-dissected Hachijo-Fuji stratovolcano (tholeiitic basalt) overlies marine volcaniclastics abutting the northwestern paleo sea cliffs of Mihara-yama. Newly-described folding and normal faulting of the marine and overlying terrestrial volcaniclastic rocks suggests NW-SE shortening that may be associated with the collision of the Izu-Bonin arc with the Honshu arc. The proto Hachijo-jima volcano emerged above the sea > 0.24 Ma, and this date can be applied as a molecular biological calibration date for organisms on this island.

Southern South America, especially Patagonia, presents numerous glacial lakes holding proxies of past environmental and climate changes. This is useful to reconstruct past environmental changes, key for understanding Southern Hemisphere variability and the present. Our aim was to identify the volcanic and environmental impact that occurred during the last 700 year in Northern Patagonia (Argentina) using subfossil chironomids, organic matter content, and tephrochronology from short sediment cores of two lakes located between Los Alerces National Park and Esquel city. Both lakes have similar watershed characteristics and were affected by the same volcanic events, making them an excellent tool for study environmental changes. Although changes in chironomid assemblages were subtle along both cores, enviromental variations and faunal responses to volcanic ash (tephra) could be inferred. In the last 50 years, an increase of organic matter, chironomids typical of productive environments, and the presence of macrophytes, point towards an increase in lake productivity. Probably linked to the establishment of Esquel city and fisheries starting in 1966 AD. Four tephra were recorded along cores affecting chironomid abundance differently, showing that the effects of volcanic events are not unique onefold but are related to the characteristics of the ash, the effect of wind, rain, and/or macrophytes.

The accurate and precise reconstruction of Quaternary climate as well as the events that punctuate it is an important driver of the study of lake sediment archives. However, until recently lake sediment-based palaeoclimate reconstructions have largely concentrated on Northern Hemisphere lake sequences due to a scarcity of continuous and high-resolution lake sediment sequences from the Southern Hemisphere, especially from the southern mid-latitudes. In this context, the deep maar lakes of the Auckland Volcanic Field of northern New Zealand are significant as several contain continuous and well-laminated sediment sequences. Onepoto Basin potentially contains the longest temporal lake sediment record from the Auckland Volcanic Field (AVF), spanning from Marine Isotope Stage 6e (MIS 6e) to the early Holocene when lacustrine sedimentation was terminated by marine breach of the south-western crater tuff ring associated with post-glacial sea-level rise. The Onepoto record consists of two new, overlapping cores spanning ca. 73 m combined with archive material in a complete composite stratigraphy. Tephrochronology and 14C dating provide the fundamental chronological framework for the core, with magnetic relative palaeo-intensity variability downcore, and meteoric 10Be influx into the palaeolake to refine the chronology. The µ-XRF (micro X-ray fluorescence) downcore variability for the entirety of the lake sediment sequence has been established with measurement of a range of proxies for climate currently underway. This work will produce the first continuous record of the last 200 kyr of palaeoclimate from northern New Zealand to date.

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 ch...

It is generally accepted that the vent of the 3.6 ka Minoan eruption was situated in the water-filled Santorini caldera prior to the Minoan eruption. One should therefore expect to find huge quantities of pumice and ash on the inner side of the caldera walls, but there is only a relatively small amount preserved. An unexpected discovery of remnants of a synchronous pumice mantle of the Minoan eruption appears to solve this enigma. A lengthy period of erosion and the intensive quarrying of pumice for the construction of the Suez Canal (1859 to 1869) led to the removal of an enormous amount of material and information for generations of geologists. The synchronous pumice mantle covered the whole caldera wall from rim to sea level. Archaeological finds under the pumice mantle show that the caldera wall was accessible and inhabited in the Bronze Age. Furthermore, this discovery documents that only one Minoan eruption took place and that the so-called “Lower pumice” does not exist on Santorini.

In our research work, the central focus is upon the multi-proxy analysis of sediment core recovered in sebkha Mhabeul (southeastern Tunisia), provides the first high-resolution, continuous sedimentary record in the region, extending back to mid Holocene. The integration of sedimentary facies, elemental geochemistry and magnetic susceptibility, together with an age model based on tephrochronology, enable reconstruction of the main hydrological and climate changes in the region. Arid conditions, represented by thick gypsum interval at the bottom of Mh2 core occurred during Bronze Age. However, the period extending from Iron Age to the Present time is characterized by alternating episodes of higher effective moisture and severely arid climatic conditions. Magnetic and geochemical compositions provide information concerning changes of elemental and mineralogical compositions from flood events materials interrupted by thin deposits of aeolian origin. Indeed, six binary data consist of dominant silty fractions rich in heavy minerals and increasing with wadi-derived elements like Na2O/K2O and Na2O/Fe2O3. These wadi sediments are covered with sandy/silty Saharan aeolian input occurring commonly after rapid and short climate change towards drier conditions. These sandstorm events are known for increasing redox-sensitive elements Na2O/K2O.

Volcanic tuffs are important in determining the stratigraphic age of sedimentary sequences, which is closely related to the tectonic, sedimentological, geomorphological, palaeoclimatic, and palaeo-ecological evolution of the sequences. However, it may be difficult practically to identify tuffs in stratigraphic sections, especially when they are altered after deposition. In this study, a series of petrographic, mineralogical, and geochemical analyses was deployed in the tuff layers cropping out in the Lunpola Basin of the central Tibetan Plateau, which is a crucial site for studying the dynamics and processes of the Cenozoic uplift of the Tibetan Plateau and its environmental impacts. In these pyroclastic layers, authigenic analcime is the main volcanic glass alteration product. The analcime-bearing samples are Na-enriched, in contrast to the K-abundant magmatic rocks in the central Tibetan Plateau. The distribution patterns of the rare earth elements (REEs) of the bulk analcime-bearing samples are similar to those of the magmatic rocks but different from those of the analcime-poor sediments and analogues of well-mixed upper continental material (e.g. the upper continental crust and post-Archaean Australian average shales). The distinct distributions of Na and REEs among analcime-bearing samples, analcime-poor sediments, and volcanic rocks reveal that analcime formed both from alteration of volcanic material and from mixing processes with non-volcanic sediments. It is proposed, therefore, that the discrimination plot of Na2O/Al2O3-(La/Yb)Nmay be used to distinguish the analcime-related pyroclastic rocks from the basin sedimentary sequence, and thus it may provide a means of discriminating between various volcanic material and of supporting age dating by tephrochronology in the central Tibetan Plateau.

A 9.3-m-long lake sediment core from dune-impounded Lake Kai Iwi in Northland, New Zealand provides a nearly continuous record of environmental changes from multi-proxy organic, physical index, and µ-XRF elemental data sets. The chronology for the upper 3 m of the core was established by 210Pb, 14C and tephrochronology and includes Marine Isotope Stage (MIS) 1 (Holocene), MIS 2 and late MIS 3. From this well-dated section of the core stratigraphy we were able to infer the environmental proxies that respond to wind and/or precipitation during cool periods (MIS 2 and 4) and with the warm periods (MIS 1 and 5). Principal component analysis (PCA) and cluster analysis were performed on the µ-XRF elemental data set including elements common in lake sediments (P, S, Fe, Ti, K, Ca, and Si) and five ratios (Sr/Ca, Br/Cl, Mn/Fe, Ti/K, and Inc/coh) to identify patterns in the µ-XRF proxy data associated with environmental change manifesting as changes in precipitation and wind deposition. The PCA indicates that Component (PC)-1 represents detrital versus organic deposition, and PC-2 is associated with nutrient influx versus anoxic conditions in the lake. The cool periods of MIS 2 and 4 are apparent in the µ-XRF data as having increased detrital influx in the form of Sr/Ca from marine derived sediments from the exposed continental shelf during low sea level indicating cool and dry conditions. Warmer and wetter periods (MIS 1 and 5) are identified by increased Ti/K influx from precipitation runoff and increased organic productivity as shown by Inc/coh and total organic carbon. The Holocene warm equivalent conditions of MIS 5e are not represented in the lower part of the Lake Kai Iwi core stratigraphy consistent with an extrapolated basal age of 117 ± 8.5 ka BP.

Auckland Volcanic Field (AVF) is a basaltic intraplate volcanic field in North Island, New Zealand, upon which >1.6 million people live. Seismic velocity tomography and geochemistry suggest a prima...

co-auteur étranger; International audience; We use the tephrostratigraphic framework along the Aegean Volcanic Arc established in Part 1 of this contribution to determine hemipelagic sedimentation rates, calculate new tephra ages, and constrain the minimum magnitudes of (sub)plinian eruptions of the last 200 kyrs. Hemipelagic sedimentation rates range from ∼0.5 cm/kyr up to ∼40 cm/kyr and vary laterally as well as over time. Interpolation between dated tephras yields an eruption age of ∼37 ka for the Firiplaka tephra, showing that explosive volcanism on Milos is ∼24 kyrs younger than previously thought. The four marine Nisyros tephras (N1 to N4) identified in Part 1 (including the Upper (N1) and Lower (N4) Pumice) have ages of ∼57 ka, ∼63 ka, ∼69 ka, and ∼76 ka, respectively. Eruption ages for the Yali-1 and Yali-2 tephras are ∼55 ka and ∼34 ka, respectively. The Yali-2 tephra comprises two geochemically and laterally distinct marine facies. The southern facies is identical to the Yali-2 fall deposit on land but the western facies has slightly less evolved glass compositions. Overall, erupted plinian and co-ignimbrite fall tephra volumes range from

A new Late glacial – Holocene palaeoenvironmental record from Cerro Benitez (51°33′S 72°35′W), Seno Ultima Esperanza, is presented. A pollen and spore record, from a closed basin mire, provides insight into the dramatic landscape changes spanning the past ~16,000 years. AMS radiocarbon dating, supplemented by the application of tephrochronology, provides robust age constraint. Our record of landscape change is set alongside a summary of the archaeofaunal records from the suite of caves and rock shelters that surround Cerro Benitez. Our record begins c. 16.3 ka, sometime after glacier retreat from the area, and describes a treeless landscape favoured by large grazing animals. At c. 14.9 ka, southern beech trees began to migrate into the area, but the landscape remained open with sufficient open ground for grazers. At c. 12.0 ka there was a dramatic expansion of woodland, but the decline of large mammals appears to have started some ~700 years earlier and is coincident with the arrival of hunter-gatherers in the area c. 12.7 ka. However, there is no archaeological evidence for human induced mass killing events, and it is likely that Cerro Benitez was a marginal resource area for early hunters that fell in and out of favour as the landscape changed during the Holocene; initially, less favourable during the early Holocene dry period (c. 11.0–8.0 ka) and more in favour during the mid-to late Holocene, although increasingly supplemented by more distant (~5–10 km) materials, including marine resources from the Golfo Almirante Montt.

Highlights • Tephra are abundant in NE North America, with 36 unique units deposited between ∼14,000 and the present day. • Source volcanoes are in the Cascades, Alaska, Kamchatka, Kuriles and potentially Japan. • Updated Bayesian modelled ages are presented for key proximal correlative eruptions and newly described tephra. • The tephra link paleoenvironmental records from this region to the Far East, Greenland and Europe. • Correlated source eruption volumes vary widely; this alone cannot explain recorded ash distribution trends. Lakes and bogs in northeastern North America preserve tephra deposits sourced from multiple volcanic systems in the Northern Hemisphere. However, most studies of these deposits focus on specific Holocene intervals and the latest Pleistocene, providing snapshots rather than a full picture. We combine new data with previous work, supplemented by a broad review of the characteristics and ages of potential source regions and volcanoes, to develop the first composite tephrostratigraphic framework covering the last ∼14,000 years for this region. We report new cryptotephra records from three ombrotrophic peat bogs—Irwin Smith (Michigan), Bloomingdale (New York), and Sidney Bog (Maine)—as well as new analyses and age models from previously reported sites, Nordan's Pond Bog (Newfoundland) and Thin-Ice Pond (Nova Scotia). A new tephra (Iliinsky) from the NGRIP and GRIP ice cores is also presented as it can be correlated to new data from these terrestrial records and helps validate radiocarbon age models. We identify 21 new tephra in addition to the 15 already known, several of which cover the entire region – the White River Ash east, Newberry Pumice, Ruppert (NDN-230), and Mazama. For the first time we find Mount St. Helens Yn (ca. 3660 cal yr BP) and a set P tephra (∼3000–2550 cal yr BP), and confirm the presence of Jala Pumice from Volcan Ceboruco, Mexico, and KS1 from Ksudach volcano, Kamchatka. We describe new “ultra-distal” tephra, including the early Holocene KS2 eruption, and propose correlations to volcanoes Iliinsky and Shiveluch of Kamchatka, and Ushishir of the Kurile Islands. Not all of these tephra represent large eruptions, with several plausible correlations to sub-Plinian events. Using Bayesian age-modeling, we present new age estimates for the newly described tephra, for tephra with previously poor age control, and for several proximal correlatives. Overall, we demonstrate northeastern North America's importance for providing transcontinental linkages between paleoenvironmental records and providing insights into ash distribution from different styles and sizes of eruptions.

Late Pleistocene tephras derived by large explosive volcanic eruptions are widespread in the Mediterranean and surrounding areas. They are important isochronous markers in stratigraphic sections and therefore it is important to constrain their sources. We report here tephrochronology results using multiple criteria to characterize the volcanic products of the Late Pleistocene Ciomadul volcano in eastern-central Europe. This dacitic volcano had an explosive eruption stage between 57 and 30 ka. The specific petrological character (ash texture, occurrence of plagioclase and amphibole phenocrysts and their composition), the high-K calc-alkaline major element composition and particularly the distinct trace element characteristics provide a strong fingerprinting of the Ciomadul volcano. This can be used for correlating tephra and cryptotephra occurrences within this timeframe. Remarkably, during this time there were several volcanic eruptions produced tephras with similar glass major element composition. However, these tephras differ from Ciomadul ones by glass trace element abundances, ratios of strongly incompatible trace elements and distinctive mineral cargo that serve as discrimination tools. We used (U-Th)/He zircon dates combined with U-Th in-situ rim dates along with luminescence and radiocarbon dating to constrain the age of the explosive eruptions of Ciomadul that yielded distal tephra layers, but lack of identified proximal deposits.

Glass composition-based correlations of volcanic ash (tephra) traditionally rely on extensive manual plotting. Many previous statistical methods for testing correlations are limited by using geochemical means, masking diagnostic variability. We suggest that machine learning classifiers can expedite correlation, quickly narrowing the list of likely candidates using well-trained models. Eruptives from Alaska's Aleutian Arc-Alaska Peninsula and Wrangell volcanic field were used as a test environment for 11 supervised classification algorithms, trained on nearly 2000 electron probe microanalysis measurements of glass major oxides, representing 10 volcanic sources. Artificial neural networks and random forests were consistently among the top-performing learners (accuracy and kappa > 0.96). Their combination as an average ensemble effectively improves their performance. Using this combined model on tephras from Eklutna Lake, south-central Alaska, showed that predictions match traditional methods and can speed correlation. Although classifiers are useful tools, they should aid expert analysis, not replace it. The Eklutna Lake tephras are mostly from Redoubt Volcano. Besides tephras from known Holocene-active sources, Holocene tephra geochemically consistent with Pleistocene Emmons Lake Volcanic Center (Dawson tephra), but from a yet unknown source, is evident. These tephras are mostly anchored by a highly resolved varved chronology and represent new important regional stratigraphic markers.

The chemical compositions of tephra shards are widely utilised in a myriad of disciplines, including volcanology, petrology, tephrochronology, palaeoecology and climate studies. Previous research has raised concerns over the possible chemical alteration of microscopic (

Wudalianchi volcanic field (WDLC) is one of the youngest intracontinental monogenetic volcanic fields in China. The 1719–1721 CE Laoheishan-Huoshaoshan eruption, and the 1776 CE Laoheishan eruption are the latest eruptions in WDLC based on the local historical records. However, most of the recent explosive eruptive products around WDLC are attributed to the 1719–1721 CE Laoheishan-Huoshaoshan eruption while less attentions were paid on the 1776 CE Laoheishan eruption. There are two types of scoria fall deposits around Laoheishan volcano, i.e. the upper light grey high vesicular scoria deposit (US) and below dark low vesicular scoria deposit (BS). Most of the glass shards from US exhibit >4% Na2O while BS show 5%) content with trachyandesitic to tephriphonolitic in composition that can be clearly distinguished from those from other nearby volcanic regions, such as Nuomin (~150 km to Nangelaqiushan lake (NGLQ)), Arxan-Chaihe (~450 km to NGLQ), Longgang (~700 km to NGLQ) and Jingbohu (~550 km to NGLQ). A cryptotephra layer is clearly revealed as a distinct peak in magnetic susceptibility measurements from NGLQ ~ 8 km northwest to Laoheishan volcano. Glass composition of the cryptotephra layer recorded in NGLQ is similar to the proximal US around Laoheishan volcano. On basis of historical records and field observations, we ascribed US to the 1776 CE Laoheishan eruption and BS to the 1719–1721 CE Laoheishan-Huoshaoshan eruption. Consequently, historical records assigned a precise age (1776 CE) for the tephra recorded in NGLQ, and thus can be used to refine the age model of these lacustrine sediments.

Emerging lake sediment records are rapidly improving Iceland‘s Holocene tephra stratigraphy and chronology. Here, we expand upon these recent developments with a securely-dated tephrochronological record from the lake Haukadalsvatn in West Iceland. We capitalize on the existing paleomagnetic secular variation (PSV) age model, which uses 54 ties points to synchronize Haukadalsvatn‘s high-resolution lake sediment record to a well-dated PSV master chronology from North Iceland Shelf marine core MD99-2269. Major element composition permits the identification of 38 tephra layers over the last 10500 years. Of these tephra, 15 can be traced to tephra found on the Vestfirðir peninsula and represent a series of well-dated marker tephra for West and Northwest Iceland that feature precise geochemical fingerprints. Based on these premises, and in contrast to recent assertations, there is no firm evidence for the presence of the presumed Middle Holocene „Hekla O tephra” in West or Northwest Iceland. Despite their close geographical locations, comparison of Haukadalsvatn‘s tephra layer frequency record to that of Northwest Iceland‘s reveals different trends. This regional disparity is likely the result of predominately small eruptions that featured narrower ash plumes. We argue that Haukadalsvatn serves as an important template for the tephrochronology of West Iceland and for future studies investigating the tephra records in more distal regions of the northwest North Atlantic, such as Greenland.

In comparison with temperature reconstructions, New Zealand proxy records for paleo-precipitation are rare, despite the importance of precipitation in contemporary climate variability and for projected climate impacts. In this study, records of mid-late Holocene palaeomoisture variation were derived for two hydrologically separate ombrotrophic Restionaceae bogs in northern New Zealand, based on peat humification analysis. At each site, three cores were analysed for peat humification, facilitating both intra- and inter-site comparisons. Age models for the six sequences were developed using radiocarbon dating and tephrochronology. Twelve tephras (including six cryptotephras) were recognised, four of which were used to precisely link the two sites and to define start and end points for the records at 7027 ± 170 (Tuhua tephra) and 1718 ± 10 cal yr BP (Taupo tephra) (2σ-age ranges), respectively. We find individual differences between the six peat humification records at short-term timescales that are presumably due to local site factors, in particular changing vegetation and microtopography, or to changes in the composition of the material analysed. Stronger longer-term coherence is observed between all six records but is attributed to slow anaerobic decay over time because the implied trend towards wetter summers in the late Holocene cannot be corroborated by independent climate proxies. Despite these confounding factors, centennial scale shifts in bog surface wetness are a pervasive feature of all six records with varying degrees of overlap in time that show strong correspondence with El Nino-Southern Oscillation reconstructions from the eastern equatorial Pacific. These results indicate the potential for peat humification records from New Zealand's ombrotrophic bogs to elucidate past climate variability and also demonstrate the importance of developing multiple well-dated profiles from more than one site.

This paper presents a detailed record of volcanism extending back to ∼80 kyr BP for southern South America using the sediments of Laguna Potrok Aike (ICDP expedition 5022; Potrok Aike Maar Lake Sediment Archive Drilling Project - PASADO). Our analysis of tephra includes the morphology of glass, the mineral componentry, the abundance of glass-shards, lithics and minerals, and the composition of glass-shards in relation to the stratigraphy. Firstly, a reference database of glass compositions of known eruptions in the region was created to enable robust tephra correlations. This includes data published elsewhere, in addition to new glass-shard analyses of proximal tephra deposits from Hudson (eruption units H 1 and H 2 ), Aguilera (A 1 ), Reclus (R 1 , R 2-3 ), Mt Burney (MB 1 , MB 2 , MB x , MB 1910 ) and historical Lautaro/Viedma deposits. The analysis of the ninety-four tephra layers observed in the Laguna Potrok Aike sedimentary sequence reveals that twenty-five tephra deposits in the record are the result of primary fallout and are sourced from at least three different volcanoes in the Austral Andean Volcanic Zone (Mt Burney, Reclus, Lautaro/Viedma) and one in the southernmost Southern Volcanic Zone (Hudson). One new correlation to the widespread H 1 eruption from Hudson volcano at 8.7 (8.6–9.0) cal ka BP during the Quaternary is identified. The identification of sixty-five discrete deposits that were predominantly volcanic ashes (glass and minerals) with subtle characteristics of reworking (in addition to three likely reworked tephra, and one unknown layer) indicates that care must be taken in the analysis of both visible and invisible tephra layers to decipher their emplacement mechanisms.

Haruna volcano, located in central Japan, erupted the Hr-FA and Hr-FP tephras during a period of several decades around the 6th century. To estimate the precise age of the second eruption, we performed AMS radiocarbon dating on a charred wood trunk (29 rings) collected from a pyroclastic flow deposit of the Hr-FP, and obtained a year range of cal AD 424–444 (2σ) using 14C wiggle matching of seven dates with the IntCal13 dataset. However, this result is approximately 100 years older than the inferred calendar year from Sue pottery and Kofun (ancient tomb mound) chronologies and is also inconsistent with the stratigraphic relation of the Hr-FA and Hr-FP. For the 5−6th centuries when the Hr-FP might have erupted, 14C dating was performed on Japanese trees whose precise chronologies were established dendrochronologically. The 14C ages of the annual rings of these trees showed local offsets about 30 years older than those of IntCal13. This tendency has been observed in several studies on trees in Japan and is consistent with the results from the Japanese cedar tree. As a preliminary study, the Hr-FP data were wiggle matched with the existing local dataset for AD 340–545 obtained from one tree in central Japan. The year of the outermost annual ring of the sample tree collected in the Hr-FP tephra is estimated to be cal AD 538−559 (79.0% probability). This estimated age of the Hr-FP eruption is consistent with the archaeological chronology (Sue pottery and Kofun) and tephrochronology around Haruna volcano.

Palaeoclimate records in East Asia offer significant potential to further our understanding of monsoon dynamics and can serve as a link between North Atlantic and tropical climate systems. The sedimentary core from Lake Kushu, Rebun Island, provides the first high-resolution palaeoclimate record from northern Japan. In order for this regionally significant archive to be synchronised to other records, and to generate a more detailed Holocene tephra lattice for East Asia, we present the first cryptotephra stratigraphy for northern Japan using the Kushu RK12 core. The detailed RK12 tephrostratigraphy integrates local and far-travelled tephras originating from Japan, Russia, China/North Korea and most likely Indonesia. Five key cryptotephra layers have been identified, precisely dated and correlated to the specific eruptions or the source region (B-Tm tephra – Changbaishan volcano; SH#12 tephra – Shiveluch volcano; Ko-g tephra – Komagatake volcano; Ma-f ∼ j tephra – Mashu volcano and RK12-0819 tephra with possible Indonesian origin). These tephra horizons are very widely dispersed, providing opportunities to synchronise distant palaeoclimate records from the polar region, through high northern latitudes to the tropics, which facilitate interregional comparison of palaeoclimate and environmental data. In addition, a number of the geochemically analysed horizons contain other minor numbers of compositionally distinct glass, which can also be grouped and correlated to their source volcanoes. These minor analyses are of interest since they provide new insight into regional tephra dispersal (e.g., ash dispersal potential of Aira and Towada), and could suggest that there are other potential eruptions that have yet to be identified in the geological record (e.g., potential Changbaishan eruptions). The integrated Lake Kushu cryptotephra record extends the ash dispersal of several key tephra horizons in the region. The presence of the Shiveluch SH#12 tephra in Lake Kushu (ca. 1900 km away), documents the first example of a Russian tephra reaching the Japanese Archipelago. Furthermore, glass compositions suggest that the core could preserve an eruption event derived from Indonesia, highlighting the future possibility to significantly extend and interlink the tephra lattice across the entirety of Asia. This is an essential step for the understanding of how climate changes propagate over large geographical areas. Indeed, several of these tephra markers coincide with significant ecological changes reflected in the pollen proxy record at Lake Kushu. Using this high-resolution palaeoenvironmental record, we however find no significant ecological impact following the large late Holocene “Millennium Eruption” from Changbaishan, China/North Korea.

This article presents first tephrochronological data on the volcanic activity in the valley of the Jom-Bolok River (East Sayan Mountains, Siberia), which is the largest manifestation of the Holocene eruptions in Central Asia. The data results from our study of the proglacial Kaskadnoe-1 Lake situated near the Jom-Bolok basalt field. The lake sediments include a series of tephra-rich layers. Radiocarbon dating of the lake sediments provided a robust age model which allowed us to build timing of eruptions formed the Jom-Bolok volcanic field. We recognize two large phases of volcanism separated by almost 5 thousand years dormant phase. The first phase is traced back to ca. 14.3 cal ka BP and lasted until 6.3 cal ka BP. Ten clusters of microtephra layers in the sediments of the first phase show 300-800 years recurrence of the volcanic events weakening upward. The event of 14.3-13.3 cal ka BP probably represents the strongest eruptions of the Jom-Bolok. The second phase started ca. 1.6 cal ka BP and highly likely continues in our days. Its strongest eruptions occurred between 1.6 and 0.8 cal ka BP with periodicity of 200 years. This tephrostratigraphy shows a multiplicity of the Jom-Bolok volcanic events and amplifies the earlier built scheme resulted from investigations of the stratified basalts, pyroclasts and lake damming events.

This article presents first tephrochronological data on the volcanic activity in the valley of the Jom-Bolok River (East Sayan Mountains, Siberia), which is the largest manifestation of the Holocene eruptions in Central Asia. The data results from our study of the proglacial Kaskadnoe-1 Lake situated near the Jom-Bolok basalt field. The lake sediments include a series of tephra-rich layers. Radiocarbon dating of the lake sediments provided a robust age model which allowed us to build timing of eruptions formed the Jom-Bolok volcanic field. We recognize two large phases of volcanism separated by almost 5 thousand years dormant phase. The first phase is traced back to ca. 14.3 cal ka BP and lasted until 6.3 cal ka BP. Ten clusters of microtephra layers in the sediments of the first phase show 300–800 years recurrence of the volcanic events weakening upward. The event of 14.3–13.3 cal ka BP probably represents the strongest eruptions of the Jom-Bolok. The second phase started ca. 1.6 cal ka BP and highly likely continues in our days. Its strongest eruptions occurred between 1.6 and 0.8 cal ka BP with periodicity of 200 years. This tephrostratigraphy shows a multiplicity of the Jom-Bolok volcanic events and amplifies the earlier built scheme resulted from investigations of the stratified basalts, pyroclasts and lake damming events. Additionally, we indicate a possible influence of the Jom-Bolok volcanic activity on the regional and global climatic changes.

Three new tephras have been identified in Southeast Alaska. An 8-cm-thick black basaltic tephra with nine discrete normally graded beds is present in cores from a lake on Baker Island. The estimated age of the tephra is 13,492 ± 237 cal yr BP. Although similar in age to the MEd tephra from the adjacent Mt. Edgecumbe volcanic field, this tephra is geochemically distinct. Black basaltic tephras recovered from two additional sites in Southeast Alaska, Heceta Island and the Gulf of Esquibel, are also geochemically distinct from the MEd tephra. The age of the tephra from Heceta Island is 14,609 ± 343 cal yr BP. Whereas the tephras recovered from Baker Island/Heceta Island/Gulf of Esquibel are geochemically distinct from each other, similarities in the ages of these tephras and the MEd tephra suggest a shared eruptive trigger, possibly crustal unloading caused by retreat of the Cordilleran Ice Sheet. The submerged Addington volcanic field on the continental shelf, which may have been subaerially exposed during the late Pleistocene, is a possible source for the Southeast Alaska tephras.

Two correlated tephra deposits, each 13 cm thick in the Aisen region of southern Chile, one in a lacustrine sediment core from the Mallin el Toqui (MET) peat bog and another from a subaerial soil exposure ∼10 km to the west in the Rio Maniguales (RM) valley, preserve evidence for a large explosive eruption of Mentolat volcano, one of the five stratovolcanoes of the southernmost portion of the Andean Southern Volcanic Zone (SVZ). This eruption is constrained in age to ≥11,728 cal years BP by radiocarbon dating of organic matter from the MET sediment core and is termed the ∼11.7 ka MEN event. The two tephra deposits are identical and based on their petrology, bulk tephra, glass, and amphibole geochemical characteristics, are attributed to an eruption of Mentolat volcano. Both contain pumice lapilli with glass compositions that ranges from 59 to 76 wt. % SiO2, with medium to low-K2O calc-alkaline composition and trace element abundances similar to both lavas and other tephras derived from Mentolat. They have abundant amphibole, plagioclase, orthopyroxene, and clinopyroxene phenocrysts, with a smaller proportion of olivine and Fe-Ti oxides, and a minor amount of distinctive crustal xenoliths with both unfoliated and foliated textures. Amphiboles have low K2O (0.20–0.37 wt. %) and TiO2 (1.5–3.8 wt. %) and are similar geochemically to amphiboles from other Mentolat-derived tephra (K2O = 0.14–0.43 wt. % and TiO2 = 1.9–2.4 wt. %), but distinct from amphiboles in lavas and tephra derived from other volcanoes in the southernmost SSVZ including Cay (K2O = 0.47–0.55 wt. % and TiO2 = 2.4–3.1 wt. %) and Melimoyu (K2O = 0.39–0.52 wt. % and TiO2 = 2.8–4.5 wt. %). Amphiboles from the ∼11.7 ka MEN tephra formed over a broad range of pressures (154–406 MPa), temperatures (834-969 °C), and magma water contents (4.9–7.0 wt. %), which overlap with the physical-chemical conditions for the formation of amphiboles from other Mentolat-derived tephra. The two correlated tephra deposits, which are located ∼95 km southeast of Mentolat, are correlative with tephra of similar age identified in 12 other lacustrine sediment cores from the region, for which, based on their petrology and the geochemistry of their tephra glass and amphiboles, Mentolat is also the likely source volcano. This eruption produced approximately 1.8 km3 of bulk material with an estimated magnitude of 5.2. Mentolat has produced numerous (>18) explosive eruptions since glacial retreat from the region and future explosive eruptions from this center could potentially impact local population centers and the agricultural industry in southern Chile and Argentina.

International audience; The Southern Volcanic Zone of the Andes (∼33–46° S) is a very active volcanic zone with several volcanic centers recording recurrent historical activity (e.g. Llaima, Villarrica, Puyehue-Cordón Caulle, Osorno, Calbuco and Hudson). Tephrochronology is a valuable tool to help better understand the eruptive history of volcanic centers, essential for producing volcanic hazard maps. Additionally, tephrochronology can also be very useful to synchronize stratigraphic records of different nature such as paleoclimatological, paleoceanographical and archaeological records on land, lakes, ice and the ocean. Here we present a (crypto) tephrochronological record from two marine sediment cores retrieved in the Chilean continental margin at ∼41° S and ∼41.6° S. The records display continuous sedimentation since the late glacial, as robustly constrained by planktonic foraminifera δ18O and 14C dates. During this period, twenty three cryptotephras were identified as glass shard peaks together with two ∼25–30 cm–thick visible tephras (one in each core). The source of the (crypto) tephras was mainly constrained by major and trace element geochemistry of individual glass shards together with their stratigraphic position, since it is not possible to observe physical characteristics, such as color and grain size, when analyzing cryptotephras. From these, one cryptotephra was robustly correlated with the HW7 eruption from the Hudson volcano occurring in the Late Holocene at ∼1.5 cal ka BP; and the two visible tephra layers were identified as distant correlatives of the Lepué tephra originating from Michinmahuida volcano and occurring in the Deglaciation/Holocene transition at around 11 cal ka BP. Additionally, eight cryptotephra occurring at ∼3.6, 6.2, 7.0, 8.5, 9.6, 14.2, 15.9 and 18.2 cal ka BP were robustly identified as sourced from Michinmahuida volcano but where otherwise not correlated, providing novel evidence of pre Holocene activity of this volcanic center.

Volcanic ash layers are important markers for the chronostratigraphy of paleoclimate and paleoenvironmental archives at the southern tip of South America. However, this requires that tephras are well-dated. We report geochemical data from the MA1 stalagmite formed in a non-karst cave near Mt. Burney volcano in southernmost Patagonia (~53°S). High-resolution LA-ICP-MS analyses, SEM imagery, and NanoSIMS enable to identify volcanogenic signals during the last 4.5 kyrs BP from sub-annual trace element variations and tephra particles in distinct laminae. The new 230Th/U-chronology of MA1 provides precise dating of tephra from Mt. Burney (MB) and Aguilera (A) at 4216 +93/−193 yrs BP (MB2), 2291 ± 33 yrs BP (MB3), 853 +41/−60 yrs BP (MB4) and 2978 +91/−104 yrs BP (A1). This unique high-resolution record of MA1 holds potential to date further eruptions from Southern Andean volcanoes for the tephrochronology in this critical region, and potentially also large-volume explosive volcanism off South America.

Highlights: • A single Saksunarvatn Ash layer was detected in two varved lake cores from N-Germany. • The ash layers in the two cores are dated to 10,282 ± 45 and 10,264 ± 24 cal. BP. • Palynological and geochemical analysis were conducted in proximity of the ash layers. • Environmental disturbance, possibly linked to volcanism, predates the ash fallout. • Evidence for a ca. 15-year-long cooling is recognizable after tephra deposition. Abstract Estimating the environmental and societal impact of recent volcanic eruptions is a task aided by direct measurements and historical sources. Beyond the reach of first-hand accounts, our understanding of pre-historic volcanism is often hindered by dating uncertainties inherent to geological archives. Here, we minimize dating errors by analyzing the annually laminated sequences of two Central European lakes, Poggensee and Woseriner See. We focus on environmental transformations that occurred in the decades preceding and following the deposition of the Icelandic Saksunarvatn tephra, dated between ca. 10,300 and 10,200 cal. BP. As a first result, we provide two new independent age determinations for the ash layer detected in both sequences. Our estimates (10,264 ± 24 cal. BP at Poggensee and 10,282 ± 45 cal. BP at Woseriner See) place the age of this tephra deposit closer to Greenland estimates than to continental ones, possibly reducing the chronological gap between the multiple fallout events that characterize the Saksunarvatn Ash. A high resolution palaeoenvironmental characterization was carried out via pollen, thin sections and geochemical analysis. Both sequences show traces of a contemporaneous disturbance event dated to ca. 18 years before tephra deposition. In addition, environmental impact compatible with a cooling event is discernible for ca. 15 years following tephra deposition. While independent climate mechanisms can be responsible for the observed trends, we explicitly focus on exploring volcanic eruptions as a possible leading driver. A consistent agreement across all proxies is lacking in the pre-tephra record, yet sulfur enrichment and acidification processes allow us to suggest volcanism as a plausible trigger. Combined with the post-tephra cooling, the two sedimentary records depict a possible scenario of multi-decadal, continuous volcanic impact.

Highlights: • NW Pacific ice-rafted debris found further south than previously thought. • Largest iceberg events were comparable in magnitude to N Atlantic Heinrich Events. • Iceberg flux to ODP Site 1207 was episodic throughout the late Quaternary. • Kamchatka-Koryak bergs frequently reached south of the N Pacific Subarctic Front. • Ice-rafting and climate contrast sharply between the last two glacial periods. Abstract: The ice-rafted-debris (IRD) record of the open Northwest Pacific points towards the existence of substantial glacial ice on the Northeast Siberian coast during the late Quaternary. However, the scale and timing of glaciation and de-glaciation remains controversial due to the dearth of both onshore and offshore records. Existing IRD data suggests at least one event of dynamic and abrupt change during mid-late Marine Isotope Stage (MIS 3) which mimics the massive collapse of the Laurentide ice sheet during Heinrich Events. It is uncertain whether other events of this magnitude occurred during the late Quaternary. Here we present a ∼160,000 yr IRD series, planktic foraminiferal counts and an age model, derived from a benthic O curve, radiocarbon dates and tephrochronology, from core ODP 1207A (37.79°N, 162.75°E), revealing the presence of low but episodic flux of IRD. We conclude that glacial Northwest Pacific icebergs spread further south than previously thought, with icebergs emanating from Northeast Siberia being transported to the transition region between the subpolar and subtropical waters, south of the subarctic front during at least the Quaternary's last two glacial periods. The episodic nature of the 1207A IRD record during the last glacial, combined with coupled climate-iceberg modelling, suggests occasional times of much enhanced ice flux from the Kamchatka-Koryak coast, with other potential sources on the Sea of Okhotsk coast. These findings support the hypothesis of a variable but extensive ice mass during the last glacial over Northeast Siberia, particularly early in the last glacial period, behaving independently of North American and Eurasian ice masses. In strong contrast, IRD was absent during much of the penultimate glacial Marine Isotope Stage (MIS) 6 suggesting the possibility of very different Northeast Siberian ice coverage between the last two glacial periods.

Volcanic ash (tephra) horizons represent powerful chronological and stratigraphic markers: rapid and widespread deposition allows for correlation of geological records in time and space. Recent analytical advances enable identification of invisible ash (cryptotephra) up to thousands of kilometers from its volcanic source. This momentum has greatly expanded the reach and potential of tephrochronology: some deposits can now be traced across continents and oceans. However, the laborious laboratory procedures required to identify tephra horizons in geological archives hold back the pace of progress. By allowing the rapid visualization of ash at micrometer (µm) scales, computed tomography (CT) holds great promise to overcome these restrictions. In this study, we further demonstrate the potential of this tool for the tephra community with experimental results and applications on conventionally analyzed archives. A custom-made scanner helps us strike a balance between the convenience of whole-core medical scanners and the µm-resolution of micro-CT systems. Using basic image processing tools that can be readily mastered by tephrochronologists, we identified invisible horizons down to ∼500 shards in synthetic cores. In addition, procedures for the removal of image artifacts can be used to visualize other paleoenvironmental indicators such as bioturbation burrows, ice rafted debris or mineral dust. When applied on segments of manually counted natural archives, our approach captures cryptic glass shard maxima down to ∼300 shards/cm3. We also highlight the value of CT to help optimize sampling strategies by identifying micrometer-scale ash horizons that were not detected in shard count profiles. In conclusion, this work helps broaden the applicability of CT as a promising frontier in tephrochronology that can advance the field by optimizing the efficiency and accuracy of isochron detection.

Highlights • 14C-based Holocene chronology of explosive eruptions from Avachinsky group volcanoes. • Bulk rock and glass chemistry (single-shard microprobe and LA-ICP-MS data). • Two stages of Avachinsky volcano activity. • Volcanic glasses reflect temporal evolution of Avachinsky magma plumbing system> • Slab temperature increasing with depth causes difference between neighboring Kamchatka volcanoes. Abstract Avachinsky, Kozelsky, and Koryaksky volcanoes form one of the most volcanically active clusters in the Kamchatka volcanic arc and are located in close proximity of the cities of Petropavlovsk-Kamchatsky and Elizovo – the most populated area in Kamchatka. In this paper, we report a compilation of new and revised previously published data on the eruptive history of these volcanoes during the past 13.5 kyrs. We identify 217 explosive eruptions of these volcanoes, determine their ages using 207 radiocarbon dates and Bayesian statistical modeling, and characterize their tephra geochemically using major and trace element compositions of bulk samples (40 samples) and volcanic glass (75 samples). Avachinsky has been the most active during the Holocene time and had >150 explosive eruptions; Koryaksky produced ~60 eruptions; and Kozelsky had only two final eruptions in the early Holocene. Our new data confirm the onset of the Avachinsky postglacial activity at 11.3 cal ka BP and previously distinguished two major stages of Avachinsky Holocene eruptive history: stage I (8–3.8 cal ka BP) and stage II (3.8 cal ka BP – present). During stage I, eruptions were relatively rare, but they included at least six large pumice eruptions with tephra volumes exceeding 0.5 km3. Stage I tephras had low-K andesitic bulk compositions and low-K rhyolitic matrix glasses. The andesites likely sampled volatile-rich crystal mush from a long-lived magma chamber under Avachinsky volcano. The stage II started at ~3.8 cal ka BP with a powerful eruption and was related to the construction of the Young Cone inside the Avachinsky somma. The subsequent late Holocene eruptions were frequent, but most of them did not exceed the volume of 0.3 km3. The stage II tephras are mostly cindery basaltic andesites containing well-crystallized groundmasses of andesitic composition. These tephras originate from smaller, perhaps more shallow magmatic reservoirs, and their matrix glasses are likely products of in-situ crystallization of relatively mafic magmas on their ascent to the surface. Koryaksky volcano was mostly active in the early Holocene when Avachinsky was quiet. Koryaksky tephras had a relatively constant bulk medium-K andesitic composition during the Holocene. Thanks to characteristic compositions, high frequency, and well-constrained ages, tephras of Avachinsky and Koryaksky volcanoes can be used for high resolution dating of local sediments. Some eruptions of Avachinsky volcano reached volcanic explosivity index (VEI) 5 and produced widely dispersed tephras. These eruptions could have had global environmental effects, and their tephras can be used for the correlation of disparate sedimentary archives. Some Avachinsky and Koryaksky eruptions were closely spaced in time. However, their tephras are easily distinguished by respective low-K and medium-K compositions and by different trace element patterns, which imply compositionally different sources in the mantle wedge. We interpret these differences to reflect the increasing slab surface temperature and transition of slab component from a relatively low-temperature fluid-like phase under Avachinsky to more high-temperature and solute-rich supercritical fluid or melt under Koryaksky. The transition appears to be very sharp in Kamchatka, causing a large compositional shift in magmas just behind the volcanic front.

Distally deposited tephra from explosive volcanic eruptions can be a powerful tool for precise dating and correlation of sedimentary archives and landforms. However, the morphostratigraphic and chronological potential of ocean-rafted pumice has been under-utilized considering its long observational history and widespread distribution on modern and palaeo-shorelines around the world. Here we analyze the geochemical composition and elevation data of 60 samples of ocean-rafted pumice collected since 1958 from raised beaches on Svalbard. Comparison of pumice data with postglacial relative sea-level history suggests eight distinct pumice rafting events throughout the North Atlantic during the Middle and Late Holocene. Analyzed ocean-rafted pumice exhibit consistent silicic composition characteristic of deposits from Iceland’s volcanic system, Katla. Eruption-triggered jokulhlaups are key drivers of the transport of pumice from the Katla caldera to beyond the coast of Iceland and into the surface currents of the North Atlantic Ocean. Thus, the correlation of distinct, high-concentration pumice horizons from Katla deposited along raised Middle Holocene beach ridges in Svalbard further advocates for the persistence of the Mýrdalsjokull ice cap through the Holocene thermal maximum.

Following on the discovery (in 2011) of a layer of distal tephra from the Pomici di Avellino eruption (Somma-Vesuvius, EU5) in the Agro Pontino (southern Lazio, Italy), further detailed study of the Holocene sediment archives in this graben and in the nearby Fondi coastal basin showed that distal tephra from this EU5 eruption occurs as a rather continuous, conspicuous layer. Two other, less conspicuous tephra layers were found, identified as the earlier Astroni 6 eruption from the Campi Flegrei (Fondi basin) and the later AP2 eruption of the Somma-Vesuvius (Agro Pontino). The identification of the distal tephra layers rests upon a combination of criteria, including stratigraphy, macro characteristics, mineralogy, geochemical data on glass composition, Sr-isotopic ratios, and the known tephrochronology for the period concerned, i.e. between c. 2500 and 1000 BCE. 14C datings serve to constrain their age. No significant spatial variation in the characteristics of the main tephra layer (EU5) was observed, other than distinct fining with increasing distance from the vent. Based on a detailed palaeogeographical reconstruction, the occurrence and preservation of these tephra are explained by the local environmental conditions governing their preservation during this time span (the Central Italian Bronze Age), and by the later evolution of the area. The observations underpin that multiple corings are needed to fully assess whether sedimentary hiatuses exist in palaeorecords, based on cores from sediment archives. Lastly, our study shows that hazard evaluations for future eruptions by Campanian volcanoes should pay more attention to their potential impacts on distal areas.

Through a systematic integrated approach, which combined lithostratigraphic, geochronological and geochemical analyses of tephra from near-source sections of the peri-Tyrrhenian volcanoes and mid to distal settings, here we provide an improved tephrochronological framework for the Marine Isotope Stage 11c interglacial (MIS 11c, ∼425–395 ka) in the Central Mediterranean area. Specifically, we present the complete geochemical dataset and new high-precision 40Ar/39Ar ages of the previously poorly characterized earliest pyroclastic products of the Vico volcano (420–400 ka), including the Plinian eruptions of Vico α and Vico β and the immediately post-dating lower magnitude explosive events. Furthermore, we also provide new geochronological and geochemical data for the distal tephra layers preserved in the aggradational succession of the Tiber delta (San Paolo Formation), Roman area, which records sea level rise relating to the MIS 12 (glacial) to MIS 11 (interglacial) transition. Five pyroclastic units were recognized in Vico volcanic area, four out of which, Vico α, Vico β, Vico βtop (a minor eruption immediately following Vico β and temporally very close to it) and Vico δ were directly dated at 414.8 ± 2.2 ka, 406.5 ± 2.4 ka, 406.4 ± 2.0 ka and 399.7 ± 3.2 ka respectively (2σ analytical uncertainties). These new data allow a critical reappraisal of the previously claimed identifications of Vico tephra from mid-distal to ultra-distal successions (i.e., Vico-Sabatini volcanic districts, Roman San Paolo Formation and Castel di Guido archaeological site, Sulmona Basin, Valdarno and Lake Ohrid), which were unavoidably biased by the poor and incomplete geochemical and geochronological reference datasets previously available. Such an improvement of the tephrochronological framework brings great benefits to any future investigations (e.g., paleoclimatology, archaeology, active tectonic, volcanology) in the dispersal areas of the studied eruptions at the key point in time that is MIS 11.

We report the widespread extent of Toba volcanic glass shards in the Central Indian Ocean Basin. Investigation of four sediment cores (7o–17oS) revealed several shard-rich horizons (SRH) that provide the first detailed tephrochronology for volcanic glass shards in the CIOB. A comparative study of surface sediments floored with Youngest Toba Tuff (YTT), indicate that irrespective of the rate of sedimentation, YTT in the basin is restricted to a depth of

Volcanic ash deposits (tephra) in western Canada are instrumental in providing independent chronologic control for many archaeological and paleoenvironmental sites. In Alberta, tephra are a key chronologic tool in a region where radiocarbon dates are often unreliable because of the prevalence of carbonate-rich bedrock and other “old carbon” sources, such as coal. However, many studies using tephra for age control, particularly archaeological projects, identify tephra simply through field characteristics or light microscopy. In both Alberta and British Columbia, many radiocarbon dates that were used to date key tephra deposits were bulk conventional ages on peat and lake sediments, which are not always reliable. These factors have led to uncertainty in the age and number of Bridge River and Mount St. Helens (MSH) set Y tephra present in the region and incomplete distribution maps. New major-element geochemical analyses from archaeological and sedimentary sites across south-central Alberta, complemented by new analyses of tephra from British Columbia and Saskatchewan, refine the distribution of the Bridge River, MSH Yn and Mazama tephra. New geochemical data, radiocarbon dates, and a detailed overview of proximal MSH set Y stratigraphy and geochemistry show that only one MSH layer, Yn, is present in this region, rather than two MSH set Y tephra as previously suggested. Additionally, re-assessment of age data combined with new geochemical analyses confirm that there is also only one Bridge River tephra. A Bayesian modelled age estimate is determined for MSH Yn based on new AMS dates on the tephra and vetted existing conventional ages, providing a revised age estimate for MSH Yn of 3805–3535 cal BP (mean of 3660 cal BP).

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).

The Eemian was the last interglacial period (~130 to 115 ka BP) to precede the current interglacial. In Eastern Mediterranean marine sediments, it is marked by a well-developed and organic-rich “sapropel” layer (S5), which is thought to reflect an intensification and northward migration of the African monsoon rain belt over orbital timescales. However, despite the importance of these sediments, very little proxy-independent stratigraphic information is available to enable rigorous correlation of these sediments across the region. This paper presents the first detailed study of visible and non-visible (cryptotephra) layers found within these sediments at three marine coring sites: ODP Site 967B (Levantine Basin), KL51 (South East of Crete) and LC21 (Southern Aegean Sea). Major element analyses of the glass component were used to distinguish four distinct tephra events of Santorini (e.g., Vourvoulos eruption) and possible Anatolian provenance occurring during the formation of S5. Interpolation of core chronologies provides provisional eruption ages for the uppermost tephra (unknown Santorini, 121.8 ± 2.9 ka) and lowermost tephra (Anatolia or Kos/Yali/Nisyros, 126.4 ± 2.9 ka). These newly characterised tephra deposits have also been set into the regional tephrostratigraphy to illustrate the potential to precisely synchronise marine proxy records with their terrestrial counterparts, and also contribute to the establishment of a more detailed volcanic history of the Eastern Mediterranean.

Tephra from Icelandic volcanic eruptions is frequently dispersed to northern Europe, but so far tephra has not been detected in Finnish sedimentary records. We report the first finding of a cryptot ...

The Tengchong volcanoes in western Yunnan Province are some of the youngest volcanoes in China, and determining their eruption ages would further our understanding of their genesis and historical activity. In this study, the age of a late Quaternary eruption of Dayingshan volcano was obtained by dating organic-rich sediments that envelope a 5-cm-thick visible tephra layer found in the Yubi peat section. Compositionally, the purified glass shards extracted from the layer by density separation are calc-alkaline trachyandesite and trachyte/trachydacite, which is consistent with the composition of the Dayingshan lava. An age-depth model of the Yubi section was constructed from accelerator mass spectrometry (AMS) 14C dating of peat samples and Poisson models of deposition (P_sequence) functions, using OxCal with the IntCal 13 database. This yielded an age for the tephra layer of 13,642 ± 84 cal yr BP. A nearly identical tephra layer occurs in the Qinghai Crater Lake sediments. The Yubi tephra is now a reliable age and stratigraphic marker layer, useful for regional paleoclimate and tephrochronology research.

The chronology of over 50 tephra layers preserved in a lake sediment core from Laguna La Trapananda (LLT) in the southern portion of the Andean Southern Volcanic Zone (SSVZ), Chile, is constrained by new radiocarbon age determinations, which span the period from late Pleistocene glacial retreat to the late Holocene. The tephra are correlative with tephra previously described from other lake cores in the region and are attributed to explosive eruptions of the SSVZ volcanoes Mentolat, Hudson, Macá, and potentially Cay. The new age determinations are used to estimate the ages of the >50 tephra in the LLT core, as well as those from the other previously described lake cores in the area, by a Bayesian statistical method. The results constrain the frequency of explosive eruptions of the volcanic centers in the southernmost SSVZ. They indicate that there was essentially no increase in the rate of eruptions from late-glacial to recent times due to deglaciation. They also provide isochrones used to constrain the depositional histories of the small lacustrine systems within which they were deposited and they provide a tephrochronologic tool for other paleoclimatic, paleoecologic, archaeologic and tephrochronologic studies in central Patagonia.

We examined the radiocarbon (14C) reservoir effect in Lake Kutubu using tephrochronology and terrestrial plant material to deliver a precise age-depth profile and sedimentation rates for this lake. Based on the presence of two tephra horizons (Tibito and Olgaboli), we found a reservoir age offset in sediments of between 1490 and 228014C yr using the sediment ages derived from the lead-210 (210Pb) dating method. The live submerged biological samples collected exhibited a higher reservoir age offset than the sediment. This is most likely a result of delayed transport of “bomb”14C from the atmosphere to aquatic and sedimentary system. The14C reservoir effect increased with distance from the lake inlet and also decreased with depth. Dissolution of14C-depleted carbon from surrounding limestone and direct in-wash of old soil or vegetation remnants from the catchment are the most likely causes of the14C reservoir effect. Based on limestone areas mapped in Papua New Guinea, we indicate lakes which may be subject to a significant14C reservoir effect. The results of this study demonstrate the magnitude of the14C reservoir effect in lakes and provide insights to the correct interpretation of past environmental and archaeological events in PNG.

We present a record of late Holocene volcanic eruptions with elemental data for a sequence of sampled tephras from Lake Amatitlan in Highland Guatemala. Our tephrochronology is anchored by a Bayesian P_Sequence age-depth model based on multiple AMS radiocarbon dates. We compare our record against a previously published study from the same area to understand the record of volcanism and environmental changes. This work has implications for understanding the effects of climate and other environmental changes that may be related to the emission of volcanic aerosols at local, regional and global scales.

Tephrochronology facilitates the interpretation and correlation of terrestrial and marine paleoclimate records in and around Iceland. The Holocene tephra record on the Vestfirðir peninsula has until now been poorly known. Based on detailed analysis of major element chemistry, we present a holistic tephra stratigraphy and chronology (n = 30) generated from four lakes located on northeastern Vestfirðir. Key markers are Tv-3, the 10 ka Grimsvotn tephra series along with the Hekla VF, Katla EG, Hekla T, Hekla 4 (intermediate component) and Hekla 3 (intermediate component), Snaefellsjokull-1, Landnam (basalt and rhyolite), Katla 920, Hekla 1693 and Barðarbunga 1716 tephra layers. Notably, we also document two early Holocene intermediate tephra from the Hekla volcano, the oldest yet identified. Imperfections in the continuity of tephra records between lakes indicate gaps produced by either variable ash plume trajectories or periodic ice coverage (glacier or seasonal) of the lakes. The northernmost lake, Skorarvatn, archives three tephra layers consistent with the 10 ka Grimsvotn tephra layer series formed by eruptions in the same time frame as the well-known Saksunarvatn tephra from the Faroe Islands. Radiocarbon-dated macrofossils bounding Skorarvatn's upper and basal tephra layers from the 10 ka series indicate that they were produced by at least three large, successive eruptions from Grimsvotn over ∼240 years. The composite Vestfirðir tephra stratigraphy and chronology presented here will enable better age control and synchronization between paleoclimate records in the northern North Atlantic.

Soils have an important role as a reservoir of essential elements for forest ecosystems. Although previous chronosequence studies have determined accumulation rates of several elements in soils, they have not focused on sulfur (S), a secondary macronutrient. We investigated S accumulation rates in five volcanic soils, dated by the use of tephras from the following volcanoes: Mt. Komagatake (tephra Ko-a, 1929 CE), Mt. Tarumae (tephra Ta-a, 1739 CE), Mt. Fuji (tephra F-Ho, 1707 CE), Towada caldera (tephra To-a, 915 CE), and Mt. Haruna (tephra Hr-FP520, 520 CE). The soils were sampled from A horizons formed above the tephra layer, and total S and pedogenic minerals (Ald, Fed, Alo, and Feo) were analyzed to determine the relationships between their estimated pools and soil age. The fractionation of S by oxidation state was determined by S K-edge XANES analysis in constituents of soils from Mt. Komagatake and Mt. Haruna. Our results showed that the S accumulation rate was almost constant over the last millennium. To extend our analysis to longer soil formation times, we extrapolated the S accumulation–age relationship to 10 cal. ka and compared the resulting values with previously reported S data from horizons that likely developed during that time period in soils from Mt. Nantai dated by tephra Nt-S (14–15 cal. ka). The similarity of the extrapolated values to the Nantai soil values suggests that the S accumulation rate may have been constant since 10 cal. ka. In addition, the growth of the S pool with soil age was linearly proportional to the growth of pedogenic mineral pools. Sulfur isotope composition of soil total S depended not on soil age, but rather on the soil origin as indicated by location. The predominant oxidation state of the S fraction changed from reduced to oxidized with soil age during the Holocene. These results suggest that the constant S accumulation rate may reflect the variable influence of exogenous S sources as well as the association of S compounds with pedogenic minerals. Sulfur compounds may accumulate at a constant rate in Japanese volcanic soils as the result of biological transformation followed by retention of S in association with the pedogenic minerals.

Highlights • Cryptotephra study of a Holocene sedimentary record from the Chukchi Sea. • Major tephra concentration peak fingerprinted to the ∼3.6 ka Aniakchak eruption. • New electron microprobe and LA-ICP-MS glass data applicable for the Western Arctic. • Re-evaluation of the Aniakchak tephra volume. • Redeposited tephra shards map pathways of sediment transport. Abstract Developing chronologies for sediments in the Arctic Ocean and its continental margins is an important but challenging task. Tephrochronology is a promising tool for independent age control for Arctic marine sediments and here we present the results of a cryptotephra study of a Holocene sedimentary record from the Chukchi Sea. Volcanic glass shards were identified and quantified in sediment core HLY0501-01 and geochemically characterized with single-shard electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). This enabled us to reveal a continuous presence of glass shards with identifiable chemical compositions throughout the core. The major input of glasses into the sediments is geochemically fingerprinted to the ∼3.6 ka Aniakchak caldera II eruption (Alaska), which provides an important chronostratigraphic constraint for Holocene marine deposits in the Chukchi-Alaskan region and, potentially, farther away in the western Arctic Ocean. New findings of the Aniakchak II tephra permit a reevaluation of the eruption size and highlight the importance of this tephra as a hemispheric late Holocene marker. Other identified glasses likely originate from the late Pleistocene Dawson and Old Crow tephras while some cannot be correlated to certain eruptions. These are present in most of the analyzed samples, and form a continuous low-concentration background throughout the investigated record. A large proportion of these glasses are likely to have been reworked and brought to the depositional site by currents or other transportation agents, such as sea ice. Overall, our results demonstrate the potential for tephrochronology for improving and developing chronologies for Arctic Ocean marine records, however, at some sites reworking and redistribution of tephra may have a strong impact on the record of primary tephra deposition.

This article presents results of the study of tsunami deposits on the Avachinsky Bay coast, Kurile-Kamchatka island arc, NW Pacific. We used tephrochronology to assign ages to the tsunami deposits, to correlate them between excavations, and to restore paleo-shoreline positions. In addition to using established regional marker tephra, we establish a detailed tephrochronology for more local tephra from Avachinsky volcano. For the first time in this area, proximal to Kamchatka’s primary population, we reconstruct the vertical runup and horizontal inundation for 33 tsunamis recorded over the past ~ 4200 years, 5 of which are historical events − 1737, 1792, 1841, 1923 (Feb) and 1952. The runup heights for all 33 tsunamis range from 1.9 to 5.7 m, and inundation distances from 40 to 460 m. The average recurrence for historical events is ~ 56 years and for the entire study period ~ 133 years. The obtained data makes it possible to calculate frequencies of tsunamis by size, using reconstructed runup and inundation, which is crucial for tsunami hazard assessment and long-term tsunami forecasting. Considering all available data on the distribution of historical and paleo-tsunami heights along eastern Kamchatka, we conclude that the southern part of the Kamchatka subduction zone generates stronger tsunamis than its northern part. The observed differences could be associated with variations in the relative velocity and/or coupling between the downgoing Pacific Plate and Kamchatka.