Marine tephrochronology of the Mt. Edgecumbe Volcanic Field, Southeast Alaska, USA

The Mt. Edgecumbe Volcanic Field (MEVF), located on Kruzof Island near Sitka Sound in southeast Alaska, experienced a large multiple-stage eruption during the last glacial maximum (LGM)-Holocene transition that generated a regionally extensive series of compositionally similar rhyolite tephra horizons and a single well-dated dacite (MEd) tephra. Marine sediment cores collected from adjacent basins to the MEVF contain both tephra-fall and pyroclastic flow deposits that consist primarily of rhyolitic tephra and a minor dacitic tephra unit. The recovered dacite tephra correlates with the MEd tephra, whereas many of the rhyolitic tephras correlate with published MEVF rhyolites. Correlations were based on age constraints and major oxide compositions of glass shards. In addition to LGM-Holocene macroscopic tephra units, four marine cryptotephras were also identified. Three of these units appear to be derived from mid-Holocene MEVF activity, while the youngest cryptotephra corresponds well with the White River Ash eruption at ∼ 1147 cal yr BP. Furthermore, the sedimentology of the Sitka Sound marine core EW0408-40JC and high-resolution SWATH bathymetry both suggest that extensive pyroclastic flow deposits associated with the activity that generated the MEd tephra underlie Sitka Sound, and that any future MEVF activity may pose significant risk to local population centers.     

Glacier Peak,Washington: A potentially hazardous cascade volcano

Recent field studies of postglacial volcanic deposits at Glacier Peak indicate the volcano has erupted more often, more voluminously, and more recently than previously thought. These past eruptions produced pyroclastic flows, extensive lahars, and widely distributed tephra falls. Analysis of the magnitude of past eruptions and the distribution of volcanic sediments indicates that future eruptions at Glacier Peak as large as those of the last several thousand years would dramatically affect people and property downstream and downwind from the volcano. Pyroclastic flows and lateral blasts would primarily affect uninhabited valleys within a few tens of kilometers of the volcano. Lahars and floods constitute the major hazard to populated areas from future eruptions, and could affect areas at low elevation along valley floors and in the Puget lowland as far as 100 km downvalley west of the volcano. Air-fall tephra from future eruptions will probably be deposited primarily east of Glacier Peak because of prevailing westerly winds.     

Sedimentation and welding processes of dilute pyroclastic density currents and fallout during a large-scale silicic eruption, Kikai caldera, Japan

Sedimentation and welding processes of the high temperature dilute pyroclastic density currents and fallout erupted at 7.3 ka from the Kikai caldera are discussed based on the stratigraphy, texture, lithofacies characteristics, and components of the resulting deposits. The welded eruptive deposits, Unit B, were produced during the column collapse phase, following a large plinian eruption and preceding an ignimbrite eruption, and can be divided into two subunits, Units B_l and B_u. Unit B_l is primarily deposited in topographic depressions on proximal islands, and consists of multiple thin (< 1 m) flow units with stratified and cross-stratified facies with various degrees of welding. Each thin unit appears as a single aggradational unit, composed of a lower lithic-rich layer or pod and an upper welded pumice-rich layer. Lithic-rich parts are fines-depleted and are composed of altered country rock, fresh andesite lava, obsidian clasts with chilled margins, and boulders. The overlying Unit B_u shows densely welded stratified facies, composed of alternating lithic-rich and pumice-rich layers. The layers mantle lower units and are sometimes viscously deformed by ballistics. The sedimentary characteristics of Unit B_l such as welded stratified or cross-stratified facies indicate that high temperature dilute pyroclastic density currents were repeatedly generated from limited magma-water interactions. It is thought that dense brittle particles were segregated in a turbulent current and were immediately buried by deposition of hot, lighter pumice-rich particles, and that this process repeated many times. It is also suggested that the depositional temperature of eruptive materials was high and the eruptive style changed from a normal plinian eruption, through surge-generating explosions (Unit B_l), into an agglutinate-dominated fallout eruption (Unit B_u). On the basis of field data, welded pyroclastic surge deposits could be produced only under specific conditions, such as (1) rapid accumulation of pyroclastic particles sufficiently hot to weld instantaneously upon deposition, and (2) elastic particles' interactions with substrate deformation. These physical conditions may be achieved within high temperature and highly energetic pyroclastic density currents produced by large-scale explosive eruptions.     

Towards a comprehensive distal andesitic tephrostratigraphic framework for New Zealand based on eruptions from Egmont volcano

The chronology and glass composition of 43 andesitic tephra layers in palaeolake sediments in northern New Zealand provide the basis for a fine‐resolution tephrostratigraphy of the interval 10–70 cal. ka. Their ages are constrained by 14 interbedded, (mostly) well‐dated rhyolitic tephra layers. The andesitic tephra have the potential to subdivide time intervals (1–5 kyr) bracketed by well known rhyolitic layers, including periods of rapid climate change such as the last glacial–interglacial transition and the Younger Dryas. The source of the distal andesitic tephra is identified as Egmont volcano (some 270 km S‐SW) on the basis of glass shard composition. The tephra contain high‐K₂O (3–6 wt%) andesitic‐dacitic (SiO₂ = 60–73 wt%) glass, with commonly heterogeneous shard populations (2–10 wt% SiO₂). Within stratigraphic intervals of < 10 kyr, individual tephra layers can be distinguished on the basis of their SiO₂ and K₂O contents, and variability in these contents can also be a distinguishing characteristic. The tephra record greatly extends the dated pyroclastic and geochemical record of Egmont volcano, and demonstrates that the volcano has frequently produced widely dispersed tephra over the last 70 kyr at a generally constant rate. Copyright © 2005 John Wiley & Sons, Ltd.     

First evidence of a distal early Holocene ash layer in Eastern Mediterranean deep-sea sediments derived from the Anatolian volcanic province

A hitherto unknown distal volcanic ash layer has been detected in a sediment core recovered from the southeastern Levantine Sea (Eastern Mediterranean Sea). Radiometric, stratigraphic and sedimentological data show that the tephra, here termed as S1 tephra, was deposited between 8970 and 8690 cal yr BP. The high-silica rhyolitic composition excludes an origin from any known eruptions of the Italian, Aegean or Arabian volcanic provinces but suggests a prevailing Central Anatolian provenance. We compare the S1 tephra with proximal to medial-distal tephra deposits from well-known Mediterranean ash layers and ash fall deposits from the Central Anatolian volcanic field using electron probe microanalyses on volcanic glass shards and morphological analyses on ash particles. We postulate a correlation with the Early Holocene ‘Dikkart?n’ dome eruption of Erciyes Da? volcano (Cappadocia, Turkey). So far, no tephra of the Central Anatolian volcanic province has been detected in marine sediment archives in the Eastern Mediterranean region. The occurrence of the S1 tephra in the south-eastern part of the Levantine Sea indicates a wide dispersal of pyroclastic material from Erciyes Da? more than 600 km to the south and is therefore an important tephrostratigraphical marker in sediments of the easternmost Mediterranean Sea and the adjacent hinterland.     

Volcaniclastic resedimentation in distal fluvial basins induced by large-volume explosive volcanism: the Ebisutoge–Fukuda tephra, Plio-Pleistocene boundary, central Japan

The Ebisutoge–Fukuda tephra (Plio‐Pleistocene boundary, central Japan) has a well‐recorded eruptive style, history, magnitude and resedimentation styles, despite the absence of a correlative volcanic edifice. This tephra was ejected by an extremely large‐magnitude and complex volcanic eruption producing more than 400 km³ total volume of volcanic materials (volcanic explosivity index=7), which extended more than 300 km away from the probable eruption centre. Remobilization of these ejecta occurred progressively after the completion of a series of eruptions, resulting in thick resedimented volcaniclastic deposits in spatially separated fluvial basins, more than 100 km from the source. Facies analysis of resedimented volcaniclastic deposits was carried out in distal fluvial basins. The distal tephra (≈100–300 km from the source) comprises two different lithofacies, primary pyroclastic‐fall deposits and reworked volcaniclastic deposits. The resedimented volcaniclastic succession shows five distinct sedimentary facies, interpreted as debris‐flow deposits (facies A), hyperconcentrated flow deposits (facies B), channel‐fill deposits (facies C), floodplain deposits with abundant flood‐flow deposits (facies D) and floodplain deposits with rare flood deposits (facies E). Resedimented volcaniclastic materials at distal locations originated from unconsolidated deposits of a climactic, large ignimbrite‐forming eruption. Factors controlling inter‐ and intrabasinal facies changes are (1) temporal change of introduced volcaniclastic materials into the basin; (2) proximal–distal relationship; and (3) distribution pattern of pyroclastic‐flow deposits relative to drainage basins. Thus, studies of the Ebisutoge–Fukuda tephra have led to a depositional model of volcaniclastic resedimentation in distal areas after extremely large‐magnitude eruptions, an aspect of volcaniclastic deposits that has often been ignored or poorly understood.     

Characterization and correlation of the Hegawa-Kasamori 5 tephra,a widespread tephra aged c. 450 ka associated with large-scale pyroclastic flows from southern Kyushu,SW Japan

A Middle Pleistocene widespread tephra, defined here as Hegawa-Kasamori 5 tephra (Hgw-Ks5), has been newly recognized over a broad area of Japan. Large-scale pyroclastic flow deposits associated with co-ignimbrite ash fall deposits (CAFDs) of Hgw-Ks5 have been identified in the proximal southern Kyushu area, south-west Japan. Hgw-Ks5 possibly originated from the Aira caldera in southern Kyushu, and it is widely spread and intercalated with deposits of the Kasamori Formation, Honshu Island, more than 1000 km away from the source. In the north-west area of the Aira Caldera, the tephra is sparsely distributed in the form of non-welded ignimbrites, and is exposed stratigraphically above the well-known Kobayashi-Kasamori tephra. Hgw-Ks5 is characterized through petrographic features, major element geochemistry of glass shards, and refractive indices of orthopyroxene. The results of previous stratigraphic isotope studies indicate that the eruptive age of Hgw-Ks5 is 434–458 ka (Marine Isotope Stage 12). Assuming that the CAFDs originating from the Aira Caldera are distributed concentrically, the apparent volume of Hgw-Ks5, estimated from the area of distribution and CAFD thickness, is ~100 km³. Therefore, a volcanic explosivity index of 7 is assigned to the Hgw-Ks5 eruption.     

Long-runout pyroclastic surge on a Cretaceous alluvial plain, Republic of Korea

Pyroclastic surge is a dilute and turbulent flow of volcanic gas and tephra that is commonly generated during explosive volcanic eruptions and can threaten lives along its flow paths. Assessing its travel distance and delineating future volcanic hazards have therefore been major concerns of volcanologists. Historical eruptions show that most pyroclastic surges travel a few tens of kilometres or less from their sources. Aeolian or aquagene processes have therefore been evoked for the emplacement of supposed surge deposits much beyond this distance. Here we show that a Cretaceous tuff bed in Korea was emplaced by an exceptionally powerful pyroclastic surge that flowed as far as the most powerful pyroclastic flows that formed the low-aspect-ratio ignimbrites (LARI). This has significant implications for interpreting ancient volcanic eruptions and delineating volcanic hazards by pyroclastic surges, and casts intriguing questions on the eruption dynamics and physics of long-runout pyroclastic surges and their distinction from LARI-forming pyroclastic flows.     

Explosive rhyolite tuya formation: classic examples from Kerlingarfjöll,Iceland

Rhyolite eruptions in Iceland mostly take place at long-lived central volcanoes, examples of which are found associated with each of the present-day rift-zone ice caps. Subglacial eruptions at Kerlingarfjöll central volcano produced rhyolite tuyas that are notable for their exposures of early-erupted pyroclastic material. Observations from a number of these edifices are synthesised into a general model for explosive rhyolite tuya formation. Eruptions begin with violent phreatomagmatic explosions that generate massive tuff (mT), but the influence of water quickly declines, leading to the formation of massive lapilli-tuffs (mLT) containing magmatically-fragmented vesicular pumice and ash. These are deposited rapidly near the vent, probably by moist pyroclastic density currents, confined by ice but not within a meltwater lake. The explosive-effusive transition is controlled by the ascent rate and gas content of the magma. An unusual obsidian-rich massive lapilli-tuff lithofacies (omLT) is identified and interpreted as pyroclastic material that was intruded into gas-fluidised deposits at the explosive-effusive transition. The effusive phase of eruption involves the emplacement of intrusions and lava caps. Intrusions of lava into the early-erupted phreatomagmatic deposits are characterised by peperitic margins and the formation of hyaloclastite. Intrusions into stratigraphically higher levels of the pyroclastic material show more limited interaction with the host tephra and have microcrystalline cores. Large lava bodies with columnar-jointed margins cap the tuyas and have intrusive basal contacts with the tephras. The main influence of the ice is to confine the rhyolite eruptive products to immediately above the vent region. This is in contrast to subglacial basaltic tuya-forming eruptions, which are characterised by the formation of meltwater lakes, phreatomagmatic fragmentation and subaqueous deposition. The lack of meltwater storage may reduce the potential for large jökulhlaups.     

Intra-crater deposits of the Toga tuff ring, Oga Peninsula, NE Japan

The Toga tuff ring is a large, dissected tuff ring located on the modern shoreline of the Oga Peninsula, NE Japan. The crater measures 2 km by 2.4 km and the inner crater walls are inclined inward at 40–50° to form a funnel shape. Intra-crater beds are mainly composed of platy or blocky, non- to variably vesicular glass shards and pumice lapilli of K-rich rhyolite composition and dip inward at 10°–30° or less. A gravity model suggests they fill the downward-tapering conduit to a depth of 548 m below sea level. Fission-track dates from the intra-crater deposits indicate the age of the Toga tuff ring is ca. 420 ka, likely corresponding to a stage of global sea-level fall, MIS 12. Subsequent sea-level rise and marine transgression is inferred to have resulted in erosion of almost the entire outer tuff ring by post-eruptive wave action.The intra-crater deposit`s are exposed over a thickness of 50 m in the deeply incised crater floor. They comprise mainly monomictic tephra of phreatomagmatic origin and are similar in grain-size distribution and sedimentary structures to relatively high and low density turbidites, although the constituents, sparse block-sag structures, and multiple fluid-escape dikes suggest that they are the subaqueous equivalents of high- and low-density pyroclastic currents with similar grain-sizes and degree of grain-size sorting. Marine diatom frustules sparsely contained in the deposits suggest that the crater was likely open to the sea, enabling rapid access of seawater to the vent. Pyroclasts ejected through the water flowed back into the crater to form eruption-fed oscillatory or circular turbidity currents and were repeatedly recycled and variably abraded by subsequent explosions, while many juvenile pumice lapilli and ash grains were carried beyond the crater rim to form relatively dilute pyroclastic currents. The Toga example suggests that primary deposits emplaced in crater lakes are well sorted, graded and stratified with polymodal flow directions, sparse block-sags, and vesicular and fragile fragments that are more or less abraded by repeated explosions and recycling.     

Using scoria cones,lava lakes and tephra islands to understand the evolution of basaltic fissure eruptions

Basaltic fissure eruptions are the most common eruption type on Earth. They are characterised by linear lava fountains that construct pyroclastic cones and expansive lava flow fields. The histories of these eruptions can be notoriously difficult to interpret due to the geochemical homogeneity of the tephra, and due to the fact that many of the early deposits become buried during later stages of the eruption. Furthermore, observing the construction of the pyroclastic cones is inherently difficult and dangerous due to the presence of active lava fountains. However, glacial outbursts in the north of Iceland have dissected the products of a Holocene fissure eruption. Examination of the pyroclastic cones, tephra deposits and a solidified lava lake along the fissure has allowed us to elucidate the complex eruptive processes that occur during these eruptions.     

The ultimate summit eruption of Puy de Dôme volcano (Chaîne des Puys,French Massif Central) about 10,700 years ago

The Puy de Dôme volcano is a trachytic lava dome, about 11,000 y old. New pyroclastic layers originating from the volcano itself were discovered covering the summit and the flanks of the volcano. These pyroclastic layers do not fit with the previous interpretation, assuming a non-explosive dome-forming eruption. The tephra display pyroclastic surge features and exhibit fresh trachytic lapilli, basement lithics, allogeneous basaltic lava and clinker fragments requiring an open vent eruption. This ultimate eruption occurred after a period of rest, long enough for vegetation to develop on the volcano, as evidenced by carbonized plant fragments. Radiocarbon dating of some of these fragments gave an age of c.10,700 y also suggesting a significant rest duration.     

长白山天池地区全新世以来火山活动及其特征

长白山火山全新世规模最大的喷发活动发生在公元1199-1200年,即800年前的大爆发,被确定为普林尼或布里尼(Plinian)式喷发。这次大爆发形成体积巨大的、分布广泛的以空中降落堆积物为主的火山喷发碎屑堆积物,在长白山火山周围,远至日本都留下了地质记录。文章辨认并划分了这次大爆发火山碎屑物的成因类型:火山喷发空中降落堆积物(airfalltephra)、火山碎屑流(pyroclasticflow)状堆积物和火山泥流(lahar)堆积物,并且点、面结合,近、远和国内、国外兼顾,分析了这些火山碎屑物的主要特征、分布和相互关系,进而确定这些火山碎屑物分别属于两次普林尼式爆发。第1次(早期)普林尼式爆发称赤峰期,火山喷发模式为:普林尼式喷发柱(赤峰空落浮岩层)-火山碎屑流(长白山火山碎屑流层),随即主要由火山碎屑流诱发火山泥流(二道白河火山泥流层);第2次(晚期)普林尼式爆发称园池期,喷发模式为:普林尼式喷发柱(园池空落浮岩火山灰层)-火山碎屑流(冰场火山碎屑流层)。在层序上将气象站期碱流岩置于800年前大爆发火山碎屑物之下是正确的,其时代为晚更新世-全新世早期。     

长白山火山灾害及其对大型工程建设的影响

长白山火山是世界著名的活火山,历史时期有过多次喷发,有再次爆发的危险.长白山火山最大的一次爆发发生在公元1199-1200年,这次大爆发的火山灰最远到达距其1 000km远的日本北部.依据这次大爆发由火山喷发空中降落堆积物、火山碎屑流和火山泥流造成的巨大火山灾害,预测了长白山火山未来爆发火山灾害的类型、强度和范围,并编制了长白山火山未来爆发火山喷发空中降落堆积物灾害预测图、火山碎屑流灾害预测图和火山泥流灾害预测图.该研究可预防和减轻火山灾害,指导核电站等大型工程选址.     

当代火山喷发碎屑堆积物的研究进展及其主要类型

火山喷发碎屑堆积物主要分为：火山喷发空中降落堆积物、火山碎屑、流状堆积物、火山泥流堆积物和火山基浪堆积物。简述了这些火山碎屑堆积物的成因及主要特征。     

Middle to late Pleistocene record of explosive volcanic eruptions in marine sediments offshore Kamchatka (Meiji Rise,NW Pacific)

This paper presents the first detailed study of a late Pleistocene marine tephra sequence from the NW Pacific, downwind from the Kamchatka volcanic arc. Sediment core SO201-2-40, located on the Meiji Rise ~400 km offshore the peninsula, includes 25 tephras deposited within the last 215 ka. Volcanic glass from the tephras was characterized using single-shard electron microprobe analysis and laser ablation inductively coupled mass spectrometry. The age of tephras was derived from a new age model based on paleomagnetic and paleoclimate studies. Geochemical correlation of distal tephras to Kamchatkan pyroclastic deposits allowed the identification of tephras from the Karymsky, Gorely, Opala and Shiveluch eruptive centers. Three of these tephras were also correlated to other marine and terrestrial sites and hence are identified as the best markers for the north-west Pacific region. These are an early Holocene tephra from the Karymsky caldera (~8.7 ka) and two tephras falling into the Marine Isotope Stage (MIS) 6 glacial time: an MIS 6.4 tephra from Shiveluch (~141 ka) and the MIS 6.5 Rauchua tephra (~175 ka) from Karymsky. The data presented in this study can be used in paleovolcanological and paleoceanographic reconstructions.     

A New Multi-Mineral Age Reference Material for 40Ar/39Ar, (U-Th)/He and Fission Track Dating Methods: The Limberg t3 Tuff

The phonolitic Limberg t3 tephra (Kaiserstuhl Volcanic Complex, Germany) was previously dated by the conventional K/Ar method yielding inconsistent results. We have re-dated this tephra layer with three independent methods. Fission Track (FT) external detector analyses on single apatite crystals (16.8 ± 1.3 Ma, 2s) and (U-Th)/He measurements on titanite and apatite (16.5 ± 1.0 Ma, 2s and 16.8 ± 1.0 Ma, 2s, respectively) are in close agreement with laser Ar/Ar dates on incrementally heated single crystals of sanidine (16.3 ± 0.4 Ma, 2s). Due to very rapid cooling, the He, FT and Ar thermochronometers provide one single age representing the eruption event. The different minerals are characterised by favourable properties with respect to their chemical composition, grain size and shape. In particular for the t3 sanidine, homogeneity has been demonstrated by electron microprobe analysis and on a grain-to-grain and grain-internal scale by single crystal incremental laser heating. Based on the agreement between independent methods and the mineral yield of this unit, the Limberg t3 tephra is proposed as multi-method age reference material for single grain laser Ar/Ar, FT and (U-Th)/He dating.     

Tephrochronological study in the quaternary Val d’Agri intermontane basin (Southern Apennines,Italy)

In the south-eastern depocentre of the Val d’Agri basin (Southern Apennines), a volcanic ash layer crops out interbedded within poorly structured alluvial fan deposits of Late Pleistocene age. Textural, depositional and pedological features of this weathered layer suggest a primary deposition from a pyroclastic fall-out of volcanic ash. Chemical analyses of feldspars show an alkali trachytic composition and accessory minerals association allow to correlate this tephra layer with the regionally dispersed Y-7 marine tephra layer (Tufo Verde Epomeo eruption, Ischia volcano), dated at 56 ± 4 ka. The Val d’Agri tephra here described for the first time was deposited during MIS Stage 3. Its recovery and characterization permit to contribute to regional correlation of the Mediterranean climatic and volcanic events from marine to continental successions and to describe landscape evolution of the Southern Apennines during glacial–interglacial cycles.     

The Pyroclastic deposits of Mount Etna volcano,Sicily

Throughout most of its geological evolution Etna has been characterized by the eruption of lava flows of a predominantly hawaiitic composition, but within the stratigraphical record there are four major sequences of pyroclastic materials: the Acireale tephra and lahars (˜100000 B.P.); the ‘lower tephra’ and Milo lahars (both ˜26000 B.P.); the Biancavilla ignimbrites (15–15500 B.P.) and the ‘upper tephra’ (˜5000–6000 B.P.). This paper reports investigations carried out on these deposits in order to determine their stratigraphy, petrology, sedimentology, and likely origins. Whereas the Biancavilla ignimbrites were generated when a more evolved, gas-charged magma (benmoreite) was being produced by the volcano, the other suites of pyroclastic deposits were erupted from hawaiitic magmas—similar to those that have characterized the volcano during historical times. These deposits resulted from two processes: violent strombolian activity producing lapilli-rich. coarse, but well-sorted sediments, and hydrovolcanism when the mixing of water and magma in the conduit, brought about more violently explosive activity, giving rise to highly fragmented, poorly sorted, airfall tephra and lahars. Conditions favouring hydrovolcanism occurred at times in the volcano's history when palaeoenvironment and palaeogeography were conducive to the retention of large amounts of surface and subsurface water. Although climates favouring the retention of water at high levels on the volcano have occurred on many occasions in the history of the volcano, at ˜26.000 and ˜5000-6000 B.P. these occurred in conjunction with a construct of sufficient height and suitable configuration to allow storage of water and give rise to hydrovolcanic activity. The nature of the mechanisms responsible for the emplacement of these hydrovolcanic deposits is considered and it is concluded that airfall is the most probable process. Finally, the implications of this research for the assessment of hazard are reviewed.     

Mineral composition of tephra layers in the Quaternary deposits of the Sea of Okhotsk:: Heavy minerals associations and their geochemistry

Heavy mineral associations from tephra layers in the Quaternary deposits of the Sea of Okhotsk and their chemical characteristics were studied by various techniques. It was shown that such investigations may have a bearing on the problems of tephrostratigraphic correlation. We assessed the possibility of application of the mineral composition of distal tephra for identification and, in particular, estimation of the relation of tephras to the explosive volcanism of back-arc and frontal zones of island arcs. The investigation of the compositions of minerals and use of mineral geothermometers and geobarometers (two-pyroxene, magnetite–ilmenite, and amphibole) provided evidence on the physicochemical parameters of melt crystallization during the explosive volcanic eruptions that produced the distal tephra layers. It was established that the pyroclastic material of some tephra layers was supplied during explosive eruptions not only from shallow magma chambers but also from deeper and higher temperature reservoirs. Together with the geochemical signatures of volcanic glasses, the obtained results on mineral associations and the geochemistry of mineral inclusions are applicable for the comparative analysis and correlation of tephras from marine and continental sequences, as well as for the identification of explosive volcanic products in adjacent land areas.