Tectonic controls on geomorphology and spatial distribution of monogenetic volcanoes in the Central Southern Volcanic Zone of the Andes (Argentina)

Monogenetic volcanoes are among the most common volcanic landforms on Earth. The morphology and distribution of small volcanoes can provide important information about eruption dynamics and tectonics. The Southern Volcanic Zone of the Andes (CSVZ) comprises one of the most active magmatic regions on Earth. Characterized by the presence of polygenetic volcanoes and calderas in a complex tectonic setting, this region also hosts hundreds of small, back-arc monogenetic volcanoes. In this contribution, we apply a Geographic Information System (GIS) that combines imagery data and digital elevation models to establish the first comprehensive dataset of monogenetic volcanoes in the CSVZ (38° to 40° S), exploring their eruption dynamics and relationship to tectonic and structural processes. Combining spatial analysis and geomorphological observations, we identify the presence of 356 monogenetic volcanoes distributed into nine clusters, now grouped in the Zapala Volcanic Field (ZVF). The ZVF is marked by the predominance of cinder cones (80%) followed by phreatomagmatic volcanoes (20%), suggesting some influence of external water in the eruption dynamics. Generally, monogenetic vents present a clear association with local and regional lineaments, suggesting a strong structural control on the occurrence of the monogenetic deposits. The higher vent densities are observed in the southern Loncopué Though, an important extensional feature related to tearing of the subducted Nazca plate underneath the South American Plate. Morphometric parameters of cinder cones indicate variable stress orientations in the CSVZ that possibly result from the oblique tectonics in the region. From north to south, the maximum principal stress rotates from NE-SW to E-W and becomes progressively less constrained as it distances from the current magmatic arc. Based on the relative ages, we map the evolution of monogenetic volcanism through time. Our results suggest a waning in the monogenetic activity in ZVF over time. When compared to monogenetic fields in the Central Andes, the ZVF is marked by higher vent densities and number of phreatomagmatic landforms, with the absence of lava domes. This ultimately reflects the contrasting crustal structure and climate conditions of these two regions.

Pleistocene-Holocene Monogenetic Volcanism at Malko-Petropavlovsk Zone of Transverse Dislocations on Kamchatka: Geological Setting, Spatial, Geochemical Paticular Features and Potential Volcanic Hazards

Based on government statistical data ~80% of the local Kamchatkan population (~250 ka people) live in the major cities on the coastal line of Avacha Gulf . It is the main transport seaway to Kamchatka , and and important Asia - North America air transport corridor. The Avacha Gulf is located in the Malko-Petropavlovsk zone of transverse dislocations (MPZ) on the extension of deep transform fault on the boundary between various ly aged slabs. Most of monogenetic cinder cones chaotic distributed in relation to the trench and belong to the long-living rupture zones of MPZ. Some of the monogenetic volcanoes are parasitic cones on the slopes of Koryaksky and Avachinsky stratovolcanoes and related with their magma plumbing systems. We here present new results of the geochemical and isotopic stud ies of monogenetic volcanism in MPZ. Based on whole rock and trace element geochemistry, Sr-Nd-Pb isotopic ratios of monogenetic volcanism, ­­ magmas were shown to sample the enriched mantle source with dominance decompression melting without significant inputs of the slab`s components. Calculations of the P, T conditions suggest magma residence of monogenetic cinder cones on the Moho boundary. That correlates with the geophysical observation of crustal discontinuity under the MPZ. Monogenetic cinder cones have an active magma plumbing system because during the Holocene time were several periods of activations. Presented results show necessary install continuous monitoring of environment changing around the Avacha Gulf and more serious attention from government and science. A more detailed investigation of MPZ will help degrease potential risks of eruptions from monogenetic volcanoes for human and infrastructures.

TFgeotourism: A Project to Quantify, Highlight, and Promote the Volcanic Geoheritage and Geotourism in Tenerife (Canary Islands, Spain)

Volcanic landscapes offer a multitude of resources to the communities that live within them. However, the main attraction that volcanoes offer is associated with volcanic heritage and geotourism. The scope of this project is to create and promote emerging geotouristic products through the empowerment of volcano tourism and thus contribute to strengthening the economic and business fabric of the volcanic island of Tenerife (Spain). In Tenerife, this great geodiversity includes the stravolcanoes, shield volcanoes, calderas, cinder cones, maars, tuff cones and rings, and lava fields, all exposed beautifully in cliffs, ravines, beaches, deposits, etc. The main activities of the project associated with the documentation and quantification of the conservation values of the volcanic heritage are the following: production of a documentary on the volcanic geoheritage of Teide volcano, selection of the top 50 sites of geotouristic interest, creation of urban geotourism itineraries, recreation of the itinerary of Alexander von Humboldt, and creation of a web page for the project. This project will deliver an essential resource needed to diversify the leisure activities offered in Tenerife through the volcanic heritage and geotourism. It quantifies the best that Tenerife can uniquely offer and highlights it in a globally accessible and perpetual manner.

Evidence of active magmatic rifting at the Ma’Alalta volcanic field (Afar, Ethiopia)

During continental rifting, strain and magmatism are believed to localize to narrow magmatic segments, while the rift margin is progressively abandoned. We integrate volcanological, geochemical, petrological and seismic data from the Ma’Alalta volcanic field (MVF) near the western margin of Afar, to show that the MVF is an active magmatic segment. Magmatism in MVF initiated with lava flows and large-volume, caldera-forming ignimbrites from a central edifice. However, the most recent magmatic activity shifted towards mafic lava fields, cinder cones and obsidian-rich silicic domes erupted from vents aligned NNW-SSE, defining a ~ 35-km-long magmatic segment. Along the same area, a NNW-SSE alignment of earthquakes was recorded by two local seismic networks (2005–2009 and 2011–2013). The geochemistry of the mafic rocks is similar to those of nearby axial volcanoes. Inferred magma storage depth from mineral geobarometry shows that a shallow, silicic chamber existed at ~ 5-km depth below the stratovolcano, while a stacked plumbing system with at least three magma storage levels between 9 and 24 km depth fed the recent basalts. We interpret the wide set of observations from the MVF as evidence that the area is an active magmatic segment, showing that localised axial extension can be heavily offset towards the rift margin.

Tiny Volcanoes Are a Big Deal on Mars

Cinder cones and fissure vents provide clues about the evolution of the Red Planet’s mantle and crust.

Regional morphological division on Isidis Planitia on Mars

<p>       There are thousands of small cones on Isidis Planitia on Mars. The cones have diameters of 300–500 m and heights of ~30 m. Many cones form subparallel chains several kilometers in length. Their origin is discussed in many papers [1,2,3,4] however, the mechanism of their formation is not explained, nor the reason for their arrangement in subparallel chains. The cones may be: rootless cones, cinder cones, tuff cones, pingos, mud volcanoes etc. [4]. Some of chains have a characteristic furrow suggesting possibility of fissure volcanism.</p><p>       The prevalence of these chains indicates that large-scale processes are responsible for their formation. Their proper classification can help identify their origin and explain other large-scale processes on Isidis Planitia. There are a few works about statistics of cones  on Isidis Planitia e.g. [1,2,5]. However, we approached the problem in a different way. </p><p>        Our analysis indicates that the cones can be grouped in larger systems. We divided Isidis Planitia into several characteristic regions. There may be several types of cones in one of the distinguished regions. Our division is based on the following structures:</p><p>1.Chains of separate cones,</p><p>2.Chains of cones connected with each other,</p><p>3a. Chains of cones connected to the furrow through the center,</p><p>3b. Chains of cones connected to the furrow through the center with elongated, elliptical cones,</p><p>4. Chains of cones with the traces of flows,</p><p>5. Chains of irregular cones without calderas with a depression around the cones,</p><p>6a. Ridge arches without cones,</p><p>6b. Chains of cones on the ridges. </p><p>        We also paid attention to the orientation of the chains of cones. In most of our regions there are also groups of cones that do not form linear chains. Such group are named as "field of cones''</p><p>         Our current Isidis Planitia division includes 36 regions. We distinguished 11 regions with the predominant arrangement of arcs in the directions between ENE and ESE, 5 regions with the directions between WNW and WSW, 2 regions with the directions between NNE and NNW and 15 areas with the directions between SSE and SSW, 3 areas where the arcs of the cones form circles. In the rest of our regions there are no chains of cones.  </p><p>       We marked also sinuous ridges, cracks and serial depressions, occurring near craters, fields with polygonally cracked surface and quasi-circular depressions sQCDs - ghost craters [4].</p><p>Plan of future research: The next stage of our research is to explain the origin of the formation of each type of cone and their chains on Isidis Planitia.</p><p><strong>References:</strong></p><p>[1] Guidat, T., et al., (2015) Earth and Planet. Sci. Let . 411, 253-267. [2] Souček, O., et al., (2015) Earth and Planet. Sci. Let 426, 176-190.  [3] Gallinger, C.L. and Ghent, R. R., (2016) 40th Lunar and Planet. Sci. Conf. 1953. [4] Ghent, R. R., et al., (2012) Icarus 217, 1169-183. [5] Hiesinger H., et al., (2009)  47th Lunar and Planet. Sci. Conf. 2767.</p>

Upper crustal shear wave velocity and radial anisotropy beneath Jeju Island volcanoes from ambient noise tomography

Summary Jeju Island offshore of the southern Korean Peninsula is an isolated intraplate volcano formed by multiple basaltic eruptions from the Pleistocene (∼1.8 Ma) to the Holocene (∼3.7 ka). Due to the lack of available seismic data, magma structures at upper crustal depths of the island have not been clearly revealed. In this study, we imaged upper crustal isotropic and radial anisotropic structures beneath the island using ambient noise data from a temporary seismic network. A series of transdimensional hierarchical Bayesian inversions were performed to construct upper crustal (1–10 km) isotropic and anisotropic structures. Surface wave (Rayleigh and Love wave) group and phase velocity dispersion data were jointly inverted for 2–15 s. The results show that layers of negative anisotropy (VSH < VSV) are predominant at shallower (<2 km) and deeper (>5 km) depths, which was interpreted as reflecting dyke swarms responsible for the more than 400 cinder cones at the surface and the vertical plumbing systems supplying magma from deeper sources, respectively. Additionally, a layer with significantly positive radial anisotropy (VSH > VSV, up to 5 per cent) was found at middle depths (2–5 km), and was interpreted as horizontally aligned magma plumbing systems (e.g. sills) through comparisons with several other volcanoes worldwide. In comparison with the isotropic structure, the positive anisotropic layer was separated into upper and lower layers with locally neutral to slightly fast and slower shear wave velocities, respectively, beneath the largest central crater (Mt. Halla). Such a structure indicates that the cooled upper part of the magma plumbing systems formed within the horizontally developed sill complex, and is underlain by still-warm sill structures, potentially with a small fraction of melting. With dykes predominant above and below, the island-wide sill layer and locally high-temperature body at the center explain the evolution of the Jeju Island volcanoes by island-forming surface lava flows and central volcanic eruptions before and after the eruptions of cinder cones.

Geotourism Potential Of Phu Quy Island, Binh Thuan Province

Phu Quy island – Binh Thuan province, is 120 km southeast of Phan Thiet city, where the long – lasting destruction of waves, wind, and rain into oceanic volcanic materials formed four significant geomorphological heritages. These geomorphosites have scientific and additional values (cultural, aesthetic, and ecological values), of which mountain Cao Cat cinder cones deserves to be a South Central Coast geomorphosite; while mountain Cam volcano, Hang Cliff – Nho beach erosion coast and Tranh volcanic islet are proposed at a local level. The impressive cliffs exposed layers of coarse and steeply sloping sediments caused by blasting; erosion coastal terrain such as cliffs, rocky headlands, stacks, arch, islets, etc. all shapes and colors associated with landmarks such as Mong Tay tack, Gam inlet, Ban inlet, Xuong Ca headland, Phat inlet, Dried Squid pond, Den islet, Giua islet, Do islet... are outstanding scientific values. Furthermore, Sa Huynh cultural relics (2,500 – 3,000 years ago) discovered in mountain Cao Cat; Linh Son, and Linh Buu ancient pagodas; Phu Quy landscape viewpoints from mountain Cam Lighthouse or colorful coral reefs on Tranh islet... are additional values that increase the worth of Phu Quy island's geomorphosites. Interpreting the scientific and additional values of these geomorphosite with images, books, geometrically similar models, etc. would promote the geotourism – a niche of the sustainable tourism market that is developed along with Global Geoparks recognized by UNESCO.