scholarly journals Isotopic evolution of prehistoric magma sources of Mt. Etna, Sicily: Insights from the Valle Del Bove

2021 ◽  
Vol 176 (7) ◽  
Author(s):  
P. D. Kempton ◽  
A. Spence ◽  
H. Downes ◽  
J. Blichert-Toft ◽  
J. G. Bryce ◽  
...  
Keyword(s):  
Isotopic Signature ◽  
Mount Etna ◽  
Magma Source ◽  
Spinel Lherzolite ◽  
Isotopic Evolution ◽  
Ne Sicily ◽  
Magma Sources ◽  
Mt Etna ◽  
Geochemical Variations ◽  
Tectonic Position

AbstractMount Etna in NE Sicily occupies an unusual tectonic position in the convergence zone between the African and Eurasian plates, near the Quaternary subduction-related Aeolian arc and above the down-going Ionian oceanic slab. Magmatic evolution broadly involves a transition from an early tholeiitic phase (~ 500 ka) to the current alkaline phase. Most geochemical investigations have focussed on either historic (> 130-years old) or recent (< 130-years old) eruptions of Mt. Etna or on the ancient basal lavas (ca. 500 ka). In this study, we have analysed and modelled the petrogenesis of alkalic lavas from the southern wall of the Valle del Bove, which represent a time span of Mt. Etna’s prehistoric magmatic activity from ~ 85 to ~ 4 ka. They exhibit geochemical variations that distinguish them as six separate lithostratigraphic and volcanic units. Isotopic data (143Nd/144Nd = 0.51283–0.51291; 87Sr/86Sr = 0.70332–0.70363; 176Hf/177Hf = 0.28288–0.28298; 206Pb/204Pb = 19.76–20.03) indicate changes in the magma source during the ~ 80 kyr of activity that do not follow the previously observed temporal trend. The oldest analysed Valle del Bove unit (Salifizio-1) erupted basaltic trachyandesites with variations in 143Nd/144Nd and 87Sr/86Sr ratios indicating a magma source remarkably similar to that of recent Etna eruptions, while four of the five subsequent units have isotopic compositions resembling those of historic Etna magmas. All five magma batches are considered to be derived from melting of a mixture of spinel lherzolite and pyroxenite (± garnet). In contrast, the sixth unit, the main Piano Provenzana formation (~ 42–30 ka), includes the most evolved trachyandesitic lavas (58–62 wt% SiO2) and exhibits notably lower 176Hf/177Hf, 143Nd/144Nd, and 206Pb/204Pb ratios than the other prehistoric Valle del Bove units. This isotopic signature has not yet been observed in any other samples from Mt. Etna and we suggest that the parental melts of the trachyandesites were derived predominantly from ancient pyroxenite in the mantle source of Etna.

scholarly journals Correction to: Isotopic evolution of prehistoric magma sources of Mt. Etna, Sicily: Insights from the Valle Del Bove

2021 ◽  
Vol 176 (9) ◽  
Author(s):  
P. D. Kempton ◽  
A. Spence ◽  
H. Downes ◽  
J. Blichert-Toft ◽  
J. G. Bryce ◽  
...  
Keyword(s):  
Isotopic Evolution ◽  
Magma Sources ◽  
Mt Etna

scholarly journals Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary: Was mélange melting involved?

Geosphere ◽  
2021 ◽  
Author(s):  
Antonio Castro ◽  
Carmen Rodriguez ◽  
Carlos Fernández ◽  
Eugenio Aragón ◽  
Manuel Francisco Pereira ◽  
...  
Keyword(s):  
Magma Source ◽  
Isotopic Ratios ◽  
Secular Evolution ◽  
The North ◽  
Secular Variations ◽  
Magma Sources ◽  
Geochemical Variations ◽  
Subduction Erosion ◽  
Ultramafic Cumulates ◽  
Trench Sediments

This study of Sr-Nd initial isotopic ratios of plutons from the North Patagonian batholith (Argentina and Chile) revealed that a secular evolution spanning 180 m.y., from the Jurassic to Neogene, can be established in terms of magma sources, which in turn are correlated with changes in the tectonic regime. The provenance and composition of end-member components in the source of magmas are represented by the Sr-Nd initial isotopic ratios (87Sr/86Sr and 143Nd/144Nd) of the plutonic rocks. Our results support the interpretation that source composition was determined by incorporation of varied crustal materials and trench sediments via subduction erosion and sediment subduction into a subduction channel mélange. Subsequent melting of subducted mélanges at mantle depths and eventual reaction with the ultramafic mantle are proposed as the main causes of batholith magma generation, which was favored during periods of fast convergence and high obliquity between the involved plates. We propose that a parental diorite (= andesite) precursor arrived at the lower arc crust, where it underwent fractionation to yield the silicic melts (granodiorites and granites) that formed the batholiths. The diorite precursor could have been in turn fractionated from a more mafic melt of basaltic andesite composition, which was formed within the mantle by complete reaction of the bulk mélanges and the peridotite. Our proposal follows model predictions on the formation of mélange diapirs that carry fertile subducted materials into hot regions of the suprasubduction mantle wedge, where mafic parental magmas of batholiths originate. This model not only accounts for the secular geochemical variations of Andean batholiths, but it also avoids a fundamental paradox of the classical basalt model: the absence of ultramafic cumulates in the lower arc crust and in the continental crust in general.

scholarly journals Geochemical Variation of Miocene Basalts within Shikoku Basin: Magma Source Compositions and Geodynamic Implications

Minerals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 25
Author(s):  
Shuang-Shuang Chen ◽  
Tong Hou ◽  
Jia-Qi Liu ◽  
Zhao-Chong Zhang
Keyword(s):  
Japan Sea ◽  
Isotopic Signature ◽  
Magma Source ◽  
Isotopic Compositions ◽  
Enriched Mantle ◽  
Shikoku Basin ◽  
Depleted Mantle ◽  
Parece Vela Basin ◽  
Back Arc ◽  
Ocean Ridge

Shikoku Basin is unique as being located within a trench-ridge-trench triple junction. Here, we report mineral compositions, major, trace-element, and Sr-Nd-Pb isotopic compositions of bulk-rocks from Sites C0012 (>18.9 Ma) and 1173 (13–15 Ma) of the Shikoku Basin. Samples from Sites C0012 and 1173 are tholeiitic in composition and display relative depletion in light rare earth elements (REEs) and enrichment in heavy REEs, generally similar to normal mid-ocean ridge basalts (N-MORB). Specifically, Site C0012 samples display more pronounced positive anomalies in Rb, Ba, K, Pb and Sr, and negative anomalies in Th, U, Nb, and Ta, as well as negative Nb relative to La and Th. Site 1173 basalts have relatively uniform Sr-Nd-Pb isotopic compositions, close to the end member of depleted mantle, while Site C0012 samples show slightly enriched Sr-Nd-Pb isotopic signature, indicating a possible involvement of enriched mantle 1 (EM1) and EM2 sources, which could be attributed to the metasomatism of the fluids released from the dehydrated subduction slab, but with the little involvement of subducted slab-derived sedimentary component. Additionally, the Shikoku Basin record the formation of the back-arc basin was a mantle conversion process from an island arc to a typical MORB. The formation of the Shikoku Basin is different from that of the adjacent Japan Sea and Parece Vela Basin, mainly in terms of the metasomatized subduction-related components, the nature of mantle source, and partial melting processes.

scholarly journals Combining High- and Low-Rate Geodetic Data Analysis for Unveiling Rapid Magma Transfer Feeding a Sequence of Violent Summit Paroxysms at Etna in Late 2015

2021 ◽  
Vol 11 (10) ◽  
pp. 4630
Author(s):  
Alessandro Bonforte ◽  
Flavio Cannavò ◽  
Salvatore Gambino ◽  
Francesco Guglielmino
Keyword(s):  
Ground Deformation ◽  
High Rate ◽  
Rate Data ◽  
Scale Analysis ◽  
Feeding System ◽  
Magma Sources ◽  
Mt Etna ◽  
Multi Temporal ◽  
Gnss Measurements ◽  
Low Rate

We propose a multi-temporal-scale analysis of ground deformation data using both high-rate tilt and GNSS measurements and the DInSAR and daily GNSS solutions in order to investigate a sequence of four paroxysmal episodes of the Voragine crater occurring in December 2015 at Mt. Etna (Italy). The analysis aimed at inferring the magma sources feeding a sequence of very violent eruptions, in order to understand the dynamics and to image the shallow feeding system of the volcano that enabled such a rapid magma accumulation and discharge. The high-rate data allowed us to constrain the sources responsible for the fast and violent dynamics of each paroxysm, while the cumulated deformation measured by DInSAR and daily GNSS solutions, over a period of 12 days encompassing the entire eruptive sequence, also showed the deeper part of the source involved in the considered period, where magma was stored. We defined the dynamics and rates of the magma transfer, with a middle-depth storage of gas-rich magma that charges, more or less continuously, a shallower level where magma stops temporarily, accumulating pressure due to the gas exsolution. This machine-gun-like mechanism could represent a general conceptual model for similar events at Etna and at all volcanoes.

Geology and geochemistry of pillow basalt in the Huilvshan region (west Junggar, China): implications for magma source and tectonic setting

2018 ◽  
Vol 55 (12) ◽  
pp. 1339-1353
Author(s):  
Huichao Zhang ◽  
Yongfeng Zhu
Keyword(s):  
Tectonic Setting ◽  
Weighted Average ◽  
Early Carboniferous ◽  
Tectonic Activity ◽  
Chromian Spinel ◽  
Magma Source ◽  
Spinel Lherzolite ◽  
Pillow Basalt ◽  
Depleted Mantle ◽  
West Junggar

Geological characteristics and geochemical analyses are reported for the early Carboniferous pillow basalt in the Huilvshan region (west Junggar, Northwest China), with the aim to indicate its petrogenesis, magma source characteristics, and tectonic implication. This pillow basalt consists of clinopyroxene and plagioclase with trace amounts of magnetite, apatite, and chromian spinel. It is tholeiitic in composition with low concentrations of Na2O + K2O (1.52–4.74 wt.%). Similar to the N-MORB, the samples of this pillow basalt have nearly flat chondrite-normalized REE patterns ((La/Yb)N = 0.87–1.47) with insignificant Eu anomalies (Eu/Eu* = 0.84–1.18), and show no obvious enrichments of LILEs and insignificant depletions in HFSEs. Petrology and geochemical characteristics suggest that this pillow basalt is the product of MORB-like magma derived from a depleted mantle corresponding to ≤4% partial melting of spinel lherzolite. SIMS analysis of the zircons separated from tuff interlayered with basalt gives a weighted average U–Pb age of 328 ± 3 Ma (MSWD = 1.4), which represents the magma eruption time in the Huilvshan region. From these observations, in combination with the previous work, we conclude that an extensional tectonic regime dominated the tectonic activity of west Junggar during early Carboniferous.

Deploying and operating an Absolute Quantum Gravimeter on the summit of Mount Etna volcano

2021 ◽  
Author(s):  
Daniele Carbone ◽  
Laura Antoni-Micollier ◽  
Filippo Greco ◽  
Jean Lautier-Gaud ◽  
Danilo Contrafatto ◽  
...  
Keyword(s):  
Gravity Data ◽  
Volcanic Tremor ◽  
Mount Etna ◽  
Quality Data ◽  
Etna Volcano ◽  
High Quality ◽  
Absolute Gravimetry ◽  
Superconducting Gravimeters ◽  
Mt Etna ◽  
Absolute Quantum

&lt;p&gt;The NEWTON-g project [1] proposes a paradigm shift in terrain gravimetry to overcome the limitations imposed by currently available instrumentation. The project targets the development of an innovative gravity imager and the field-test of the new instrumentation through the deployment at Mount Etna volcano (Italy). The gravity imager consists in an array of MEMS-based relative gravimeters anchored on an Absolute Quantum Gravimeter [2].&lt;br&gt;The Absolute Quantum Gravimeter (AQG) is an industry-grade gravimeter measuring g with laser-cooled atoms [3]. Within the NEWTON-g project, an enhanced version of the AQG (AQGB03) has been developed, which is able to produce high-quality data against strong volcanic tremor at the installation site.&lt;br&gt;After reviewing the key principles of the AQG, we present the deployment of the AQGB03 at the Pizzi Deneri (PDN) Volcanological Observatory (North flank of Mt. Etna; 2800 m elevation; 2.5 km from the summit active craters), which was completed in summer 2020. We then show the demonstrated measurement performances of the AQG, in terms of sensitivity and stability. In particular, we report on a reproducible sensitivity to gravity at a level of 1 &amp;#956;Gal, even during intense volcanic activity.&lt;br&gt;We also discuss how the time series acquired by AQGB03 at PDN compares with measurements from superconducting gravimeters already installed at Mount Etna. In particular, the significant &amp;#160;correlation with gravity data collected at sites 5 to 9 km away from PDN proves that effects due to bulk mass sources, likely related to volcanic processes, are predominant over possible local and/or instrumental artifacts.&lt;br&gt;This work demonstrates the feasibility to operate a free-falling quantum gravimeter in the field, both as a transportable turn-key device and as a drift-free monitoring device, able to provide high-quality continuous measurements under harsh environmental conditions. It paves the way to a wider use of absolute gravimetry for geophysical monitoring.&lt;/p&gt;&lt;p&gt;[1] www.newton-g.com&lt;/p&gt;&lt;p&gt;[2] D. Carbone et al., &amp;#8220;The NEWTON-g Gravity Imager: Toward New Paradigms for Terrain Gravimetry&amp;#8221;, Front. Earth Sci. 8:573396 (2020)&lt;/p&gt;&lt;p&gt;[3] V. M&amp;#233;noret et al., &quot;Gravity measurements below 10&amp;#8722;9 g with a transportable absolute quantum gravimeter&quot;, Nature Scientific Reports, vol.&amp;#160;8,&amp;#160;12300 (2018)&lt;/p&gt;

scholarly journals Late Cenozoic Uguumur and Bod-Uul Volcanic Centers in Northern Mongolia: Mineralogy, Geochemistry, and Magma Sources

Minerals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 612
Author(s):  
Alexander Perepelov ◽  
Mikhail Kuzmin ◽  
Svetlana Tsypukova ◽  
Yuri Shcherbakov ◽  
Sergey Dril ◽  
...  
Keyword(s):  
Basaltic Magma ◽  
Magma Source ◽  
Depth Range ◽  
Late Cenozoic ◽  
Central Mongolia ◽  
Cenozoic Volcanism ◽  
Northern Mongolia ◽  
Magma Sources ◽  
Response To Stress ◽  
Isotope Systematics

The paper presents new data on mineralogy, geochemistry, and Sr-Nd-Pb isotope systematics of Late Cenozoic eruption products of Uguumur and Bod-Uul volcanoes in the Tesiingol field of Northern Mongolia, with implications for the magma generation conditions, magma sources, and geodynamic causes of volcanism. The lavas and pyroclastics of the two volcanic centers are composed of basanite, phonotephrite, basaltic trachyandesite, and trachyandesite, which enclose spinel and garnet peridotite and garnet-bearing pyroxenite xenoliths; megacrysts of Na-sanidine, Ca-Na pyroxene, ilmenite, and almandine-grossular-pyrope garnets; and carbonate phases. The rocks are enriched in LILE and HFSE, show strongly fractioned REE spectra, and are relatively depleted in U and Th. The low contents of U and Th in Late Cenozoic volcanics from Northern and Central Mongolia represent the composition of a magma source. The presence of carbonate phases in subliquidus minerals and mantle rocks indicates that carbon-bearing fluids were important agents in metasomatism of subcontinental lithospheric mantle. The silicate-carbonate melts were apparently released from eclogitizied slabs during the Paleo-Asian and Mongol-Okhotsk subduction. The parent alkali-basaltic magma may be derived as a result from partial melting of Grt-bearing pyroxenite or eclogite-like material or carobantized peridotite. The sources of alkali-basaltic magmas from the Northern and Central Mongolia plot different isotope trends corresponding to two different provinces. The isotope signatures of megacrysts are similar to those of studied volcanic centers rocks. The P-T conditions inferred for the crystallization of pyroxene and garnet megacrysts correspond to a depth range from the Grt-Sp phase transition to the lower crust. Late Cenozoic volcanism in Northern and Central Mongolia may be a response to stress propagation and gravity instability in the mantle associated with the India-Asia collision.

Understanding the role of accessory minerals in the Sm-Nd isotopic evolution of ancient rocks: An in-situ LA-(MC)-ICP-MS approach

2020 ◽  
Author(s):  
Johannes Hammerli
Keyword(s):  
Hf Isotope ◽  
Nd Isotope ◽  
Accessory Minerals ◽  
Icp Ms ◽  
Isotopic Evolution ◽  
Magma Sources ◽  
Mantle Reservoir ◽  
Isotope System

&lt;p&gt;The long-lived radiogenic isotope systems Lu-Hf and Sm-Nd have been widely used by geochemists to study magma sources and crustal residential times of (igneous) rocks in order to understand how early crust formed and to model the production rate and volume of continental crust on global and regional-scales during the last ~4.4 Ga. However, while throughout most of Earth&amp;#8217;s history Nd and Hf isotope signatures in terrestrial rocks are well correlated due to their very similar geochemical behavior, some of Earth&amp;#8217;s oldest rocks show an apparent inconsistency in their Nd and Hf isotope signatures. While Hf isotopes in early Archean rocks are generally (near) chondritic, Nd isotope signatures can be distinctly super- or sub-chondritic. The super-chondritic Nd isotope values in Eoarchean samples would suggest that these rocks are derived from a mantle reservoir depleted by prior crust extraction. The chondritic Hf isotope values, on the other hand, support a mantle source from which no significant volume of crust had been extracted. While a range of different processes, some of them speculative, might explain this Hf-Nd isotope paradox, recent research [1, 2] has shown that relatively simple, post-magmatic, open-system processes can explain decoupling of the typically correlative Hf-Nd isotope signatures. This talk will focus on the importance of identifying Nd-bearing accessory minerals in (Archean) rocks to understand how the Sm-Nd isotope system is controlled and how in situ isotope and trace element analyses by LA-(MC)-ICP-MS in combination with detailed petrographic observations help to understand when and via which processes the two isotope systems become decoupled. Reconstructing the isotopic evolution of the different isotope systems since formation of the protoliths has important implications for our understanding of early crust formation and questions some of the proposed current models for early crust extraction from the mantle.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;[1] Hammerli et al. (2019) Chem. Geol 2; [2] Fisher et al. (2020) EPSL&lt;/p&gt;

Mount Etna and the 1971 eruption - Some consideration on the magma of the 1971 eruption

1973 ◽  
Vol 274 (1238) ◽  
pp. 37-43 ◽  
Keyword(s):  
Mount Etna ◽  
Magma Column ◽  
Mt Etna

Lava samples, collected periodically during the 1971 eruption of Mt Etna, have been analysed. A certain evolution of their composition has been observed: the first lavas are phonolitic tephrites, while the last ones are mugearites. This evolution can be explained by assuming a pneumatolytic differentiation in the uppermost parts of the magma column and a subtraction of femic phenocrysts by gravitational differentiation in its deeper parts, where the last products originated. Furthermore, the analyses of the 1971 lavas are compared with all available data of ancient products of this complex volcano and, particularly, with those of its historical eruptions.

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