Search

Historical eruptions of Veniaminof Volcano, Alaska have all occurred at a 300-m-high cinder cone within the icefilled caldera that characterizes the volcano. At least six of nineteen historical eruptions involved simultaneous explosive and effusive activity from separate vents. Eruptions in 1944, 1983–1984, 1993–1994, 2013, 2018 and 2021 included periods of explosive ash-producing Strombolian activity from summit vents and simultaneous nonexplosive effusion of lava from flank vents on either the southern or northeast sides of the cone. A T-junction conduit network is proposed to explain the simultaneous eruptive styles and as a mechanism for gas-magma segregation that must occur to produce the observed activity. Historical eruptions with simultaneous summit and flank activity produced slightly higher rising ash clouds compared to historical eruptions where simultaneous activity did not occur. This could be a consequence of the partitioning of more gas-charged magma into the vertical conduit of a T-junction conduit system.

An integrated stratigraphic, sedimentological, volcanological, and geochemical studies were conducted for the first time on the eruptive products of the Marssous volcano, Bahariya Depression, Western Desert, Egypt. The rarity of complex volcanological studies in the west Red Sea rift makes these investigated volcanoes important as they offer a clue to the style of volcanism, eruptive environment and magma genesis during magmatism complimentary to those areas extensively studied in the Arabian Peninsula toward Syria and Eastern Turkey. The Marssous volcano is small monogenetic scoria cone that shows a polyphase feeding system, consisting of unconformable superimposed characteristic effusive-to-explosive eruptive units, suggesting a wide spectrum of diverse eruptive styles through a complex feeder network. On the basis of the sedimentological characteristics, field relationships, lava flow textures and granulometric indicators, five volcanic units have been identified from the base to top as (1) coherent porphyritic massive basalts (Bpm), (2) stratified tuff beds (Unit 1), (3) crude-bedded lapilli tuff beds with bombs (Unit 2), (4) massive agglutinate beds (composed of spatter and fluidal bombs) formed by lava fountains (Unit 3), (5) porphyritic vesicular basalts (Bpv), and (6) subvolcanic feeder intrusions. The degree of vesicularity and the size of the clasts increase from thin Unit 1 (ash to lapilli) through more thick Unit 2 (lapilli-bomb) to Unit 3 (breadcrusted scoriaceous bomb) as an indicative of an increased magma flux and the high eruptive energy together with an enlarged of degassing fragmentation. There is consequently a progressive evolution from an initial Phreatomagmatic explosive stage followed an initial effusive event to dry magmatic explosive (Strombolian & Hawaiian) and effusive eruptive styles in the later. With eruption progression, the external water to fuel Phreatomagmatism was diminished relatively early in the eruptions giving way to accumulate a pyorclastic fall deposition of Strombolian to Hawaiian lava-fountain episodes together with effusive eruptions, all together forming the majority of the pyroclastic and effusive successions of Gabal Marssous. These eruptive phases have happened during a continuous deposition without any time pauses in a short period of time as a result of a single cone-forming eruptions. The Marssous volcano shares resemblances in terms of inferred eruption style and structures with other scoria cones elsewhere in the broad regional context such as North Africa, Mediterranean province, and Arabian Peninsula, and thus provides an outstanding field laboratory to explore scoria cones architecture and growth from a global perspective. This volcano event is a key tectono-stratigraphic marker for an early manifestation, coinciding with the initiation of Red Sea rifting opening.

Scoria cones are abundant in most volcanic fields on Earth, such as the Michoacán-Guanajuato Volcanic Field, in the central-western sector of the Trans-Mexican Volcanic Belt. However, there are few in-depth studies on their eruptive style and controlling factors, despite of their diversity in shape and composition which implies a wide range of hazards. Here, we present results of morphologic, stratigraphic, sedimentary, petrographic, and geochemical studies of the prominent Las Cabras scoria cone located west of the Zacapu lacustrine basin in the center of the Michoacán-Guanajuato Volcanic Field. This basaltic andesitic to andesitic volcano formed between 27 and 26 kyrs BP on the steep slopes (>10º) of the lava shield of El Tule volcano. Over time, its dominant eruptive style changed from Strombolian to effusive. Initial explosive activity built a 170-m-high scoria cone and deposited thick tephra fallout on the surrounding sloping terrain. Structures in the deposits indicate that early friable fine-grained tephra underwent significant erosion due to syn-eruptive heavy rain coupled with the sloping nature of the underlying ground. This erosion generated lahars that very likely reached the Zacapu lake based on the pre-eruptive topography. As the explosivity dropped, lava was emitted from the base of the cone first to the S and SE, forming a thick, viscous lobe that filled a pre-existing E-W valley. The flow direction then deviated to the N and NE, to form thinner, less-viscous lobes fed from the vent by an open-channel. The lavas are covered by hummocks made of agglutinates and bombs that indicate that the eruption terminated by catastrophic collapse of the SE sector of the cone, possibly triggered by the intrusion of magma within the cone, which destabilized its downslope segment. The sudden flank failure was potentially associated with a late effusive event and the hummocks may have been carried away by the lava surge. Whole-rock chemical variations and crystal disequilibrium textures point toward a complex magma feeding system, involving mixing and mingling between different magma batches. This study shows that the formation of scoria cones on a terrain with a marked slope (>10°) has profound impacts on the eruption dynamics and related hazards due to its effect on cone stability and ash erosion. It also evidences the erosive effect of syn-eruptive rain on fine-grained tephra, especially when deposited on a slope. Finally, it reveals the complex magmatic processes that may occur in the shallow plumbing system of monogenetic andesitic volcanoes, which could be particularly important in inland areas of continental arcs.

SUMMARYStudying the magnetic fabric in volcanic edifices, particularly lava flows from recent eruptions, allows us to understand the orientation distribution of the minerals related to the flow direction and properly characterize older and/or eroded flows. In this work, the magnetic fabric from recent (Quaternary) lava flows (slightly inclined in seven sites and plateau lavas in two sites), pyroclastic deposits (two sites from a scoria cone) and volcanic cones, domes and plugs (three sites) from Penguin and Bridgeman islands, located in the Bransfield backarc basin, are presented. The volcanism in the two islands is related to rifting occurring due to the opening of the Bransfield Strait, between the South Shetlands archipelago and the Antarctic Peninsula. The direction of flow of magmatic material is unknown. Rock magnetic analyses, low temperature measurements and electron microscope observations (back-scattered electron imaging and Energy Dispersive X-ray analyses) reveal a Ti-poor magnetite (and maghemite) as the main carrier of the magnetic fabric. Hematite may be present in some samples. Samples from the centre of the lavas reveal a magnetic lineation either parallel or imbricated with respect to the flow plane, whereas in the plateau lavas the magnetic lineation is contained within the subhorizontal plane except in vesicle-rich samples, where imbrication occurs. The magnetic lineation indicates a varied flow direction in Bridgeman Island with respect to the spreading Bransfield Basin axis. The flow direction in the plateau lavas on Penguin Island is deduced from the imbrication of the magnetic fabric in the more vesicular parts, suggesting a SE–NW flow. The volcanic domes are also imbricated with respect to an upward flow, and the bombs show scattered distribution.

February 18, 2021, a flank eruption started on the north-western slope of the Klyuchevskoy Volcano (Kamchatka, Russia). Cinder cone was formed at the altitude of 2 850 m above sea level, from which a lava flow was spreading north-west. Having moved 1.2 km downslope, the lava flow entered the Ehrmann Glacier, which resulted in the formation of huge mud-stone flows. The latter made their way further north-east along the Kruten’kaya River bed and reached the length of about 30 km. The eruption brought onto the surface high-aluminous basaltic andesites typical of the Klyuchevskoy Volcano. By March 21, the flank eruption ended. It has been named after G.S. Gorshkov, associate member of USSR Academy of Science, famous Russian volcanologist.

The gravity method is a method often used in geophysical exploration. According to recent technological developments, data acquisition has evolved by utilizing satellite data and modeling, one of which is GGMplus gravity data. In this study, GGMplus gravity data will be used to map the distribution of maar and cinder cones in the Gunung Lamongan Region. To obtain the optimal local anomaly results of gravity data, a combination of power spectrum analysis and upward continuation filtering methods is carried out.ABL data contours are sliced, gravity anomaly data from each slicing path is processed using FFT so that the wave number and power spectrum values are obtained as well as the relationship graph between the two.The power spectrum analysis method provides window width data that is used as information on determining the height of the upward continuation method.The ABL contour map in the Gunung Lamongan region shows a range of gravitational field values between -20 mGal to 50 mGal. High anomaly values indicate the existence of Mount Lamongan which is dominated by intrusive rocks. The subsurface structure of the Gunung Lamongan region is thought to consist of tuff, lava, volcanic breccia, and lava. The existence of maar and cinder cones in the Gunung Lamongan area can be mapped from the contours of the local anomaly. Local anomaly contours are obtained from ABL data by connecting the two methods of filtering i.e power spectrum analysis and upward continuation. There are 10 cinder cones and 8 maar visible on the local anomaly contour map.

The El Estribo Volcanic Complex, located to the south of Pátzcuaro Lake (Central Mexico), forms an elevation based on a shield volcano crowned by a cinder cone. Two debris avalanches, dated at 28,000 and 14,000 ybp, cover an area of 4 km2 with a typical hummocky topography. The zone is a state natural protected area with no previous studies of hazard and risk from mass movement processes. Herein, we present a detailed geomorphological map of the debris-avalanche area, scale 1:20,000. The approach applied used two hierarchical levels, geomorphological landscapes and landforms. The fault scarp was mapped using high-resolution digital elevation models obtained whit unmanned aerial vehicles (UAV) survey. We describe and characterized four main geomorphological units, 20 subunits, 66 hummocks, and the general drainage network. This map is a valuable tool to identify and quantify risks from mass movement processes.

Cenozoic geological evolution of New Zealand centres around the formation of Zealandia, a new continent that became detached from the eastern margin of Gondwana around 105 Ma. Spreading opened the ...

Lumajang merupakan salah satu kabupaten di Jawa Timur yang terdapat Kawasan Gunungapi Lamongan. Gunungapi Lamongan merupakan Gunungapi monogenesis muda yang tumbuh dari sesar pada puncaknya. Erupsi yang terjadi pada Gunungapi Lamongan tidak hanya pada gunung utama, tetapi juga membentuk kerucut parasit berjumlah sekitar 37 cinder cone dan 27 maar di sekitar gunung utama. Cinder cone dan Maar terbentuk ketika terjadinya kontak antara magma dan air sehingga menimbulkan erupsi freatomagmatik yang disertai dengan muntahan piroklastik dan aliran timbunan material. Penelitian ini berfokus pada pemetaan kawasan Gunungapi Lamongan bagian barat berdasarkan data anomali magnetik untuk mengetahui ada tidaknya aktivitas vulkanik di bawah permukaan Kawasan Gunungapi Lamongan. Berdasarkan analisis hasil penelitian, maka disimpulkan bahwa data anomali magnetik mengonfirmasi adanya suhu tinggi batuan bawah permukaan pada daerah selatan, barat, dan utara dari Gunungapi Lamongan di sekitar maar dan cinder cone yang diindikasikan dengan anomali magnetik negatif. Kata kunci: Gunungapi Lamongan, maar, cinder cone, anomali magnetik.

The Chaihe–Arxan volcanic field is situated in the Greater Khingan Range of northeastern China. The volcanic field consists of over 40 monogenetic cones. Yanshan is the youngest volcano in this area, with a reported age of 2 ky BP. The regions surrounding the volcano was subjected to a large fire in 2006, allowing researchers to determine the eruption history of the volcano. During a 2-week comprehensive field investigation, we found Yanshan volcano exhibits three types of eruption products: pyroclastic blanket, multi-crater scoria cone, and lava flow. The eruption process of this volcano has since concluded. Its eruption activity was initially ambiguous Strombolian eruption of the north crater, followed by sub-Plinian eruption of the east crater, and finally lava flow effusive events from the west crater. The Yanshan basalts are composed of trachybasalt and basalt. Geochemical analyses for major and trace elements suggest that the Yanshan basalts do not undergo significant crustal contamination but undergo olivine and pyroxene crystallization. Experimental melt calculations and the La/Yb versus Sm/Yb diagram indicate that the Yanshan basalts are derived from the melting of garnet peridotite. The Sm/Yb versus Na/Ti diagram illustrates that the initial melting depth beneath Yanshan is approximately 140 km, and the lithospheric thickness is approximately 70 km. These results support the existence of a high-temperature and fluid-rich plume at a depth of 10–12 km beneath the youngest volcanic chain where Yanshan is located, indicating the possibility of eruption of this volcano. Therefore, it is necessary to strengthen volcanic monitoring at Yanshan.

Studies synthesizing field work, numerical simulations, petrology, geochemistry and geophysical observations indicate that the compositional diversity of arc lavas results from evolution of mantle-derived magmas by mixing, assimilation and fractional crystallization. This evolution occurs within complexes called transcrustal magmatic systems. The mafic lower parts of such zones, called hot zones, are difficult to probe. However, a satellite vent near the stratovolcano Ruapehu in the southern Taupo Volcanic Zone (New Zealand) comprises materials that may originate from a hot zone. Magnesian andesites (Mg#60–65) from the Ohakune scoria cone contain primitive olivine (Fo85–91), high-Mg# clinopyroxene (Mg#81–88) and orthopyroxene (Mg#76–83), but lack plagioclase. Disequilibrium of Ohakune crystals and groundmass suggests that the crystal cargo of Ohakune andesites was scavenged from deeper and more primitive levels of the magmatic system. Mineral constraints on temperature and pressure indicate that the hot zone initially formed at mid- to lower-crustal pressures (3.5–7.0 ± 2.8 kbar). We interpret the mafic mineralogy and presence of disequilibrium features as evidence that these andesites and their crystal cargo are products of a hot zone in the middle to lower crust. Products of the hot zone may appear before products of the systems that form the bases of mature stratovolcanoes such as Ruapehu. Supplementary material: Details of petrography, geochemical and arc olivine data, and MELTS modelling data are available at https://doi.org/10.6084/m9.figshare.c.5494984

Recent subaerial volcanism at El Hierro Island (Canary Islands, Spain) consists of monogenetic volcanic fields. This volcanism generated cinder cones, tephra air-fall deposits, and lava flows. The lava flows reach several kilometres in length extending through shore platforms and, sometimes, penetrating under the sea level. The volcanic landforms of El Hierro convert it into a natural laboratory for topographic and morphometric modelling and lava flow simulations. We perform the modelling and simulation of the Montaña de Aguarijo eruption, a cinder cone at the NE rift. The associated lava flow channelled through a V-shaped ravine until reaching a cliff, where formed cascades. The flow spread at the cliff base over a platform before reaching the sea modifying the coastline. Different maps were designed to show the results, including the geomorphologic reconstruction of the area affected by this eruption and the lava flow simulations obtained with the Q-LavHA plugin. © 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group on behalf of Journal of Maps., Financial support was provided by Project LAJIAL (ref. PGC2018-101027-B-I00, MCIU/AEI/FEDER, EU). This study was carried out in the framework of the Research Consolidated Groups GEOVOL (Canary Islands Government, ULPGC) and GEOPAM (Generalitat de Catalunya, 2017 SGR 1494).

The accurate dating of prehistoric eruptions is essential for reconstructing volcanic sequences and for preparing volcanic-hazard assessments. The chronology of the eruptions of the Datong volcanic field (DVF) in eastern China has been debated for several decades, especially the start and end of volcanism. Loess sediments incorporated in explosive volcanic products have been described from the Dongpingshan scoria cone in the DVF. We conducted radiocarbon dating of the loess sediments, which produced an age of ~7300 cal yr BP for the Dongpingshan volcanic eruption. This result confirms the eruption of the DVF during the Holocene, and it provides important evidence for assessing volcanic hazards in this densely populated region. The Holocene age of the eruption indicates that DVF is dormant, contrary to previous studies which concluded that the DVF is extinct and that its volcanic eruptions ended at ~100 ka. In addition, this study documents a new method of dating Late Pleistocene to Holocene volcanic eruptions in and around the DVF, where loess sediments are widespread and may be preserved within volcanic products.

Clusters of small-volume volcanoes that individually may be defined as monogenetic, but have interlinked and interconnected plumbing systems, are used to be categorized as monogenetic volcanic fields (MVF). We argue that such volcanic clusters should be distinguished as separate type of volcanism, intermediate between monogenetic and polygenetic. The magma plumbing system structure of the MVF (its complexity and polymagmatic character) is the key argument for the potential separation of them in a classification. To avoid confusion caused by genetic meaning of the used words we suggest using a term “areal volcanism” or “areal volcanic fields” (AVF instead of MVF) as defining this special type of volcanic activity. Here we provide a review of the main characteristic features of one of the largest Holocene AVF, which is active now – the Tolbachik field of cinder cones in the southern part of Klyuchevskaya volcano group (Kamchatka), known in the literature as Tolbachinsky Dol. This paper is focused on the research of magma plumbing system. We consider structural, morphological, geological, geochemical and petrological data on the erupted basalts and their genesis. Specially planned seismic experiments made in 2010–2015 (seismic tomography and microseismic sounding) allowed modeling of the principal elements of the magma plumbing system of Tolbachik AVF. Analysis of the investigations made in this area shows that Tolbachik AVF has a complex, dynamic, variable magmatic feeding system, which can be visualized as a superposition of subvertical and sublateral magma conduits. The contrast composition of the erupted rocks is caused by their different, although genetically connected, magma sources and mixing processes. One of the long-lived eruptive centers of Tolbachik AVF is Plosky Tolbachik stratovolcano, which lost its independent activity and was captured by Tolbachik AVF in Holocene. The AVF formed rejuvenated volcanism using the feeding system of the stratovolcano like an “old anthill”. The magma plumbing system characteristics of Tolbachinsky Dol strongly support the idea of separation of AVF from monogenetic volcanism type in the classification.

La Poruna (21°53′S; 68°30′W) is a 140 m high scoria cone composed of pyroclastic material and an extensive basaltic-andesite to andesite lava flow that is up to 8 km in length. Automated mineralogical analysis describes a suite of porphyritic mafic samples, comprising olivine- and pyroxene-bearing rocks. Well-defined major element compositional trends, as well as trace and rare earth element characteristics (e.g. Sr/Y 96 ka) from San Pedro volcano exhibit similar isotopic characteristics, therefore evidence of similar magmatic processes. This new dataset clearly defines magma compositional changes during the La Poruna eruption (ca. 100 ka), revealing an increase in crustal contamination at shallow crustal levels for the younger San Pedro lavas (

A stratigraphic framework can be constructed through lithofacies description and interpretation. The application of this method in volcanic systems is a fundamental tool for understanding their evolution and eruptive dynamics and for establishing hazard assessments in active volcanic areas. This work presents and discusses a detailed stratigraphy of the Paredao Volcano, allowing the understanding of the lateral and vertical distribution of volcanic facies and the 3D geometry of the deposits, generating a model for the volcanism and discussing the erupting mechanisms. The Paredao Volcano is a scoria cone located in the southeast of Trindade Island and represents the youngest subaerial volcanic episode (Pleistocene) recorded in Brazil. Its stratigraphic organization indicates nephelinitic flows alternate with lapillistones and lapilli-tuffs of same composition at the base and a pyroclastic cone with nearly 200 m high above the sea level. Through lithofacies description and association 4 stratigraphic columns were constructed in scale 1:50, three of them at the Tartarugas beach (TRV-01, TRV-02, TRV-03) and the other one at the pyroclastic cone (TRV-04). The petrographic characterization of facies was carried through conventional optical microscopy. The stratigraphic analysis resulted in the distinction of seven lithofacies, divided into two coherent and five volcaniclastic (one autoclastic and four pyroclastic). The coherent lithofacies are of massive (Npm) and vesicular porphyritic nephelinite (Npv). Texturally, the lavas are holocrystalline and vesicular, composed by olivine phenocrysts in a very fine matrix of clinopyroxene, nepheline, zeolite and titanomagnetite, at times with phlogopite. The autoclastic lithofacies of nephelinitic breccia (Nb) is composed of fragments (2 mm–15 cm) of vesicular nephelinite and the pyroclastic ones are composed mainly of lapillitic scoria fragments with subordinate bombs and volcanic ash. The pyroclastic lithofacies are of massive lapillistone (Lm) and lapilli-breccia (LBm), planar stratified lapilli-tuff (LTp), and reverse grading lapillistone (Lrg). The lithofacies associations characterize ‘A’a, rubbly pahoehoe and pahoehoe flow types, distal and proximal pyroclastic deposits. The interpretation of the vertical and lateral facies distribution leads to the conclusion that the volcanism occurred with an initial phreatomagmatic stage, succeeded by a Strombolian stage (pyroclastic with primary fragments domain) and a final Hawaiian stage (lava flows domain).

The present study employs petrology, rock magnetics, and paleointensity on four lava flows (seven sites) of the El Jorullo volcano; a historical (1759–1766 AD) cinder cone in the Michoacan-Guanajuato Volcanic Field. El Jorullo lava flows cover an extensive area of ∼10.8 Km2, and a volume ∼0.35 Km3. Rock-magnetic experiments and microscopic observations reveal pseudo-single domain size Ti-poor titanomagnetite as the main carrier of magnetization in all sampled flows. Notably the calculated mean direction from all the sites show a slight westwards bias when compared against the secular variation global models. The mean paleo-direction for the El Jorullo historical eruption is: Dec = 2.5°, Inc = 37.5°, kappa = 214, α95 = 1.8, N = 31; the Virtual Geomagnetic Pole has Plat = 87° N, Plong = 307° E, Kappa = 260, A95 = 1.6; paleointensity data: 45.4 ± 3.6 μT; and Virtual Dipole Moment: 10.3 ± 1 × 1022 Am2. The paleodirections and the paleointensity values from these lava flows are well-constrained and reliable. These results allow to improve the accuracy and reliability of the global and regional secular variation models available for the last centuries.