scholarly journals Voluminous Storage and Rapid Magma Ascent Beneath La Palma Revealed by Seismic Tomography

2022 ◽  
Author(s):  
Luca D'Auria ◽  
Ivan Koulakov ◽  
Janire Prudencio ◽  
Ivan Cabrera-Perez ◽  
Jesus Ibanez ◽  
...  
Keyword(s):  
Oceanic Crust ◽  
Seismic Tomography ◽  
Magma Ascent ◽  
S Wave ◽  
La Palma ◽  
Plumbing Systems ◽  
Magma Sources ◽  
High Resolution Images ◽  
First Time ◽  
Crustal Magma

Abstract Seismic tomography provides a window into magmatic plumbing systems; however, obtaining sufficient data for ‘real-time’ imaging is challenging. Until now, syn-eruptive tomography has not been successfully demonstrated. For the first time, we obtained high-resolution images of Earth's interior during an ongoing volcanic eruption. We used data from 11,349 earthquakes, most of which during La Palma eruption (19 September-13 December, 2021), to perform travel-time seismic tomography. We present high-precision earthquake relocations and 3D distributions of P and S-wave velocities highlighting the geometry of magma sources. We identified three distinct structures: (1) a shallow localised region (< 3 km) of hydrothermal alteration; (2) spatially extensive, consolidated, oceanic crust extending to ~10 km depth and; (3) a large (> 400 km3) sub-crustal magma-filled rock volume intrusion extending from ~7 to 25 km depth. Our results suggest that this large magma reservoir feeds the La Palma eruption continuously for almost three months. Prior to eruption onset, magma ascended from ~10 km depth to the surface in < 7 days. In the upper 3 km, melt migration is along the western contact between consolidated oceanic crust and altered hydrothermal material. Similar structural weaknesses along the eastern contact could potentially cause new eruptive centres in the future.

Coupled dynamics of primordial and recycled heterogeneity in Earth's lower mantle, and their present-day seismic signatures

2021 ◽  
Author(s):  
Anna J. P. Gülcher ◽  
Maxim D. Ballmer ◽  
Paul J. Tackley
Keyword(s):  
Oceanic Crust ◽  
Seismic Tomography ◽  
Lower Mantle ◽  
Large Scale ◽  
Numerical Models ◽  
Global Scale ◽  
Physical Parameters ◽  
Compositional Heterogeneity ◽  
Seismic Velocities ◽  
S Wave

&lt;p&gt;The nature of compositional heterogeneity in Earth&amp;#8217;s lower mantle is a long-standing puzzle that can inform about the thermochemical evolution and dynamics of our planet. On relatively small scales (&lt;1km), streaks of recycled oceanic crust (ROC) and lithosphere are distributed and stirred throughout the mantle, creating a &amp;#8220;marble cake&amp;#8221; mantle. On larger scales (10s-100s of km), compositional heterogeneity may be preserved by delayed mixing of this marble cake with either intrinsically-dense or -strong materials of e.g. primordial origin. Intrinsically-dense materials may accumulate as piles at the core-mantle boundary, while intrinsically viscous (e.g., enhanced in the strong mineral MgSiO&lt;sub&gt;3&amp;#160;&lt;/sub&gt;bridgmanite) may survive as blobs in the mid-mantle for large timescales (i.e., as plums in the mantle &amp;#8220;plum pudding&amp;#8221;). So far, only few, if any, studies have quantified mantle dynamics in the presence of different types of heterogeneity with distinct physical properties.&lt;br&gt;&lt;br&gt;Here, we use 2D numerical models of global-scale mantle convection to investigate the coupled evolution and mixing of (intrinsically-dense) recycled and (intrinsically-strong) primordial material. We explore the effects of ancient compositional layering of the mantle, as motivated by magma-ocean solidification studies, and the physical parameters of the primordial material. Over a wide parameter range, primordial and recycled heterogeneity is predicted to coexist with each other. Primordial material usually survives as mid-to-large scale blobs in the mid-mantle, and this preservation is largely independent on the initial primordial-material volume. In turn, recycled oceanic crust (ROC) persists as piles at the base of the mantle and as small streaks everywhere else. The robust coexistence between recycled and primordial materials in the models indicate that the modern mantle may be in a hybrid state between the &amp;#8220;marble cake&amp;#8221; and &amp;#8220;plum pudding&amp;#8221; styles.&lt;br&gt;&lt;br&gt;Finally, we put our model predictions in context with geochemical studies on early Earth dynamics as well as seismic discoveries of present-day lower-mantle heterogeneity. For the latter, we calculate synthetic seismic velocities from output model fields, and compare these synthetics to tomography models, taking into account the limited resolution of seismic tomography. Because of the competing effects of compositional and thermal anomalies on S-wave velocities, it is difficult to identify mid-mantle bridgmanitic domains in seismic tomography images. This result suggests that, if present, bridgmanitic domains in the mid-mantle may be &amp;#8220;hidden&amp;#8221; from seismic tomographic studies, and other approaches are needed to establish the presence/absence of these domains in the present-day deep Earth.&lt;/p&gt;

Seismic tomography model reveals mantle magma sources of recent volcanic activity at El Hierro Island (Canary Islands, Spain)

2014 ◽  
Vol 199 (3) ◽  
pp. 1739-1750 ◽  
Author(s):  
Araceli García-Yeguas ◽  
Jesús M. Ibáñez ◽  
Ivan Koulakov ◽  
Andrey Jakovlev ◽  
M. Carmen Romero-Ruiz ◽  
...  
Keyword(s):  
Canary Islands ◽  
Volcanic Activity ◽  
Seismic Tomography ◽  
Recent Volcanic Activity ◽  
El Hierro ◽  
Magma Sources ◽  
Mantle Magma

Imaging the crustal magma sources beneath Mauna Loa and Kilauea volcanoes, Hawaii

Geology ◽  
1997 ◽  
Vol 25 (10) ◽  
pp. 867 ◽  
Author(s):  
Paul G. Okubo ◽  
Harley M. Benz ◽  
Bernard A. Chouet
Keyword(s):  
Mauna Loa ◽  
Magma Sources ◽  
Crustal Magma

scholarly journals Contribution to the Knowledge of the Genus Proceratium Roger (Hymenoptera: Formicidae: Proceratiinae) in the New World

Sociobiology ◽  
2019 ◽  
Vol 66 (4) ◽  
pp. 551
Author(s):  
Itanna Oliveira Fernandes ◽  
Jacques Hubert Charles Delabie ◽  
Fernando Castiblanco Fernández
Keyword(s):  
High Resolution ◽  
South America ◽  
New Record ◽  
New World ◽  
Distribution Data ◽  
Caribbean Islands ◽  
The World ◽  
High Resolution Images ◽  
South Of Brazil ◽  
First Time

The genus Proceratium Roger comprises rare ants that are irregularly distributed in tropical and temperate regions of the world. Despite this global distribution, these ants are rarely collected, likely due to their cryptobiotic lifestyle. In the New World, the genus comprises 22 known species distributed from Southern Canada to the South of Brazil, and in some Caribbean islands. The taxonomy of the genus Proceratium is here updated for South America. We describe P. amazonicum sp. nov, from Rondônia state and provide distribution data for P. brasiliense, P. convexipes, and P. silaceum. We also present, for the first time, high-resolution images of the P. colombicum type and P. ecuadoriense, and provide a new record of P. micrommatum from Peru, and comment about its morphological variation and distribution. A key for the workers of the P. micrommatum clade is also provided. The species we describe belongs to P. micrommatum clade and represents the second species recorded from Brazil after 60 years, since only P. brasiliense was known previously in the country.

Halimeda incrassata (Bryopsidales, Chlorophyta) reaches the Canary Islands: mid- and deep-water meadows in the eastern subtropical Atlantic Ocean

2018 ◽  
Vol 61 (2) ◽  
pp. 103-110 ◽  
Author(s):  
Carlos Sangil ◽  
Laura Martín-García ◽  
Julio Afonso-Carrillo ◽  
Jacinto Barquín ◽  
Marta Sansón
Keyword(s):  
Atlantic Ocean ◽  
Canary Islands ◽  
Deep Water ◽  
Population Coverage ◽  
Isolated Populations ◽  
La Palma ◽  
Soft Bottoms ◽  
The Caribbean ◽  
Marine Flora ◽  
First Time

AbstractExtensive offshore meadows ofHalimeda incrassataare documented for the first time in sandy bottoms of La Palma, Canary Islands.Halimeda incrassataforms dense sublittoral assemblages between 20 and 55 m, but isolated populations occur down to 65 m depth. This species currently spreads over an area of 9.14 ha. Population coverage varies with depth, with the highest values at 35–40 m and an average cover of 62.34%. The calcified segments ofH. incrassataact as a stable substratum in these soft bottoms for the growth of other macroalgae, such as the rhodophytesLophocladia trichocladosandCottoniella filamentosa. Specimens reach lengths of up to 10 cm, shorter than individuals from the Caribbean. Although it is difficult to ascertain whether this species is a recent introduction, there is evidence of a correlation between the increase in population coverage and recent ocean warming, constituting another example of the tropicalization of the marine flora of this region.

scholarly journals First nearly complete skull of Gallotia auaritae (lower-middle Pleistocene, Squamata, Gallotiinae) and a morphological phylogenetic analysis of the genus Gallotia

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Penélope Cruzado-Caballero ◽  
Carolina Castillo Ruiz ◽  
Arnau Bolet ◽  
Juan Ramón Colmenero ◽  
Julio De la Nuez ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Cranial Morphology ◽  
Middle Pleistocene ◽  
Phylogenetic Position ◽  
Fossil Species ◽  
La Palma ◽  
Computed Microtomography ◽  
X Ray Computed ◽  
Cranial Osteology ◽  
First Time

Abstract The Canary Islands are an Atlantic archipelago known for its high number of endemic species. Among the most known endemic vertebrate species are the giant lizards of the genus Gallotia. We describe the cranial osteology of the first almost complete and articulated fossil skull of the taxon Gallotia auaritae, recovered from the lower-middle Pleistocene of the La Palma island. In this work, X-ray computed microtomography images were used to perform an exhaustive phylogenetic analysis where most of the extant and fossil species of the genus Gallotia were included for first time. This analysis recovered a monophyletic Gallotia clade with similar topology to that of molecular analyses. The newly described specimen shares some characters with the group formed by G. bravoana, G. intermedia and G. simonyi, G. auaritae, and its position is compatible with a referral to the latter. Our study adds new important data to the poorly known cranial morphology of G. auaritae, and the phylogenetic analysis reveals an unexpected power of resolution to obtain a morphology-based phylogeny for the genus Gallotia, for inferring the phylogenetic position of extinct species and for helping in the identification of fossil specimens.

scholarly journals Velocity and density characteristics of subducted oceanic crust and the origin of lower-mantle heterogeneities

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Wenzhong Wang ◽  
Yinhan Xu ◽  
Daoyuan Sun ◽  
Sidao Ni ◽  
Renata Wentzcovitch ◽  
...  
Keyword(s):  
Phase Transition ◽  
Oceanic Crust ◽  
Seismic Tomography ◽  
Lower Mantle ◽  
Shear Velocity ◽  
Calcium Ferrite ◽  
Velocity Anomaly ◽  
Mantle Heterogeneities ◽  
Subducted Oceanic Crust ◽  
Low Shear

AbstractSeismic heterogeneities detected in the lower mantle were proposed to be related to subducted oceanic crust. However, the velocity and density of subducted oceanic crust at lower-mantle conditions remain unknown. Here, we report ab initio results for the elastic properties of calcium ferrite‐type phases and determine the velocities and density of oceanic crust along different mantle geotherms. We find that the subducted oceanic crust shows a large negative shear velocity anomaly at the phase boundary between stishovite and CaCl2-type silica, which is highly consistent with the feature of mid-mantle scatterers. After this phase transition in silica, subducted oceanic crust will be visible as high-velocity heterogeneities as imaged by seismic tomography. This study suggests that the presence of subducted oceanic crust could provide good explanations for some lower-mantle seismic heterogeneities with different length scales except large low shear velocity provinces (LLSVPs).

scholarly journals Inside the volcano: Three-dimensional magmatic architecture of a buried shield volcano

Geology ◽  
2020 ◽  
Author(s):  
Faye Walker ◽  
Nick Schofield ◽  
John Millett ◽  
Dave Jolley ◽  
Simon Holford ◽  
...  
Keyword(s):  
Gravity Data ◽  
Three Dimensional ◽  
Shield Volcano ◽  
Plumbing System ◽  
Magma Chambers ◽  
Volcanic Plumbing System ◽  
Volcanic Conduit ◽  
Plumbing Systems ◽  
Dimensional Reconstruction ◽  
First Time

The nature and growth of magmatic plumbing systems are of fundamental importance to igneous geology. Traditionally, magma chambers have been viewed as rapidly emplaced bodies of molten rock or partially crystallized “magma mush” connected to the surface by a narrow cylindrical conduit (referred to as the “balloon-and-straw” model). Recent data suggest, however, that magma chambers beneath volcanoes are formed incrementally through amalgamation of smaller intrusions. Here we present the first high-resolution three-dimensional reconstruction of an ancient volcanic plumbing system as a large laccolithic complex. By integrating seismic reflection and gravity data, we show that the ~200 km3 laccolith appears to have formed through partial amalgamation of smaller intrusions. The complex appears to have fed both surface volcanism and an extensive sill network beneath the volcanic edifice. Numerous sills are imaged within the volcanic conduit, indicating that magma stalled at various levels during its ascent. Our results reveal for the first time the entire multicomponent plumbing system within a large ancient shield volcano.

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