scholarly journals How to reconstruct the geometry of a Middle Triassic feeding system: clues from clinopyroxene textures in lava flows from Cima Pape (Southern Alps, Italy)

2020 ◽  
Author(s):  
Federico Casetta ◽  
Pier Paolo Giacomoni ◽  
Nicolò Nardini ◽  
Massimo Coltorti
Keyword(s):  
Middle Triassic ◽  
Sedimentary Cover ◽  
Great Majority ◽  
Southern Alps ◽  
Lava Flows ◽  
Physical Parameters ◽  
Feeding System ◽  
Plumbing Systems ◽  
Mt Etna ◽  
Active Volcanoes

<p>Ancient volcano-plutonic complexes can record the evolution of single- or multi-pulse plumbing systems and thus can be used as proxy to investigate the magma dynamics beneath active volcanoes. The exceptional state of conservation of the Middle Triassic Cima Pape complex (Dolomitic Area, Southern Alps) makes it an ideal snapshot of a ~238 Ma old feeding system of a dominantly effusive volcano. It is composed of a 50 to 300 metres thick gabbroic to monzodioritic sill intruded in the sedimentary cover and overlaid by its volcanic counterpart, made up of basaltic to trachyandesitic lavas and pillow breccias. A detailed investigation of the textural and compositional features of clinopyroxene phenocrysts in the volcanites revealed that complex dynamic processes took place in the feeding system beneath the Cima Pape “volcano”. Although some crystals have normal homogeneous or simple-zoned texture, with Mg# [MgO/(MgO+FeO<sub>tot</sub>) mol%] ranging between 71 and 77 (type 1 clinopyroxene), the great majority of them is typified by a peculiar texture, characterized by the occurrence of intermediate high-Mg# (80-84, up to 90), high-Cr<sub>2</sub>O<sub>3</sub> (up to 1.0 wt%) and low-TiO<sub>2</sub> (down to 0.1 wt%) bands (type 2 clinopyroxene). These overgrowths, crystallized between low-Mg# cores and rims, likely indicate that the feeding system was affected by frequent mixing between mafic inputs and differentiated batches. An overview of the main textural/geochemical features of clinopyroxene in effusive and intrusive products was put forward in the present study to reconstruct the main chemico-physical parameters and evolution of the feeding systems beneath the Middle Triassic volcanoes of the Dolomitic Area. Afterwards, these results will be used to advance some speculations about the processes recorded by clinopyroxene crystals in lava flows from active volcanoes, such as Stromboli and/or Mt. Etna.</p>

Magma ascent, ponding and mixing in a Middle Triassic plumbing system: clues from clinopyroxene chemical-textural features in the Cima Pape volcano-plutonic complex (Southern Alps, Italy)

2021 ◽  
Author(s):  
Nicolò Nardini ◽  
Federico Casetta ◽  
Pier Paolo Giacomoni ◽  
Massimo Coltorti
Keyword(s):  
Middle Triassic ◽  
Planetary Science ◽  
Southern Alps ◽  
Magma Ascent ◽  
Stromboli Volcano ◽  
Plumbing System ◽  
Ne Italy ◽  
Plumbing Systems ◽  
Convex Upward ◽  
Multiple Pulses

<p>Zoned crystals play a fundamental role in modern volcanology as a key to unravel the geometry and the dynamics of plumbing systems. Ancient volcano-plutonic complexes, nowadays exposed at the surface, can sometimes preserve textural-chemical record of such dynamics inside their constituting mineral phases. This is the case of the Cima Pape Middle Triassic complex (Dolomites, Southern Alps), which is composed by a 50 to 300 metres thick gabbroic to monzodioritic sill overlaid by basaltic to trachyandesitic volcanites with high Porphyricity Index (P.I. 43-48 %).</p><p>Volcanites contain a large number of concentric-zoned clinopyroxenes, while intrusive rocks are mostly made up of homogeneous and unzoned crystals. In volcanites, the typical clinopyroxene zoning pattern consists of one or more high-Mg# and high Cr<sub>2</sub>O<sub>3</sub> bands (Mg# 84-91; Cr<sub>2</sub>O<sub>3</sub> up to 1.2 wt%) with variable thickness, formed between cores and rims with relatively lower Mg# and Cr contents (Mg# 70-77; Cr<sub>2</sub>O<sub>3</sub> <0.1 wt%). Chondrite-normalized incompatible element patterns of low-Mg# portions show Nb, Ta, Sr, Zr and Ti negative anomalies and Th-U positive peaks, while high-Mg# bands have a generally more depleted patterns maintaining similar profile. REE patterns in both high-Mg# and low-Mg# domains have a convex-upward shape and La/Yb<sub>N</sub> from 1.3 to 2.1. Thermobarometric calculations reveal that the high-Mg# bands were in equilibrium with a more primitive, hotter and more H<sub>2</sub>O depleted melt (Mg# = 65-70; T = 1130-1150°C; H<sub>2</sub>O = 2.1-2.6 wt%) than cores and rims, which likely formed in a colder, H<sub>2</sub>O-rich evolved melt (Mg# = 43-45; T = 1035-1075°C; H<sub>2</sub>O = 2.6-3.8 wt%). According to our model, a first crystallization stage in a high crystallinity (P.I. almost 50%) “mush-type” system led to the formation of low-Mg# clinopyroxenes (Mg# 70-77) at P of 2-4 kbar. The ascent of one or multiple pulses of primitive, hot, and H<sub>2</sub>O-poor basaltic magmas (Casetta et al., 2020) in the shallower portions of the plumbing system led to the formation of the high-Mg# bands. Later on, re-equilibration of clinopyroxene with the post-mixing melt system resulted in the formation of the low-Mg# rims. Cima Pape products have many textural-chemical similarities with those reported at the active Stromboli volcano, suggesting that they were formed through similar dynamics at comparable T-P conditions (Petrone et al., 2018; Di Stefano et al., 2020). The peculiarity of clinopyroxene texture in Cima Pape rocks allowed us to study the processes occurred in the plumbing system beneath an ancient volcano and offered the opportunity to test the approaches/models currently adopted for active systems.</p><p> </p><p>Casetta, F., et al., 2020. The Variscan subduction inheritance in the Southern Alps Sub-Continental Lithospheric Mantle: Clues from the Middle Triassic shoshonitic magmatism of the Dolomites (NE Italy). Lithos, 105856.</p><p>Di Stefano, F., et al., 2020. Mush cannibalism and disruption recorded by clinopyroxene phenocrysts at Stromboli volcano: New insights from recent 2003–2017 activity. Lithos, 360–361.</p><p>Petrone, C. M., et al., 2018. Rapid mixing and short storage timescale in the magma dynamics of a steady-state volcano. Earth and Planetary Science Letters, 492, 206–221.</p>

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.

Chemical-physical constraints of the 2015 eruptive activity of Mt. Etna: new insights from thermo-barometry and geochemistry of olivine-hosted melt inclusions

2021 ◽  
Author(s):  
Pier Paolo Giacomoni ◽  
Federico Casetta ◽  
Virginia Valenti ◽  
Carmelo Ferlito ◽  
Gabriele Lanzafame ◽  
...  
Keyword(s):  
Melt Inclusions ◽  
New South ◽  
Basalt Magma ◽  
Feeding System ◽  
Physical Constraints ◽  
Eruptive Event ◽  
North East ◽  
Central Crater ◽  
Mt Etna ◽  
Crystallization Conditions

<p>The concomitant activation off all four summit craters of Mt. Etna during the December 2015 eruptive event allow us to investigate the chemical-physical crystallization conditions and magma dynamics in the shallower portion of the open-conduit feeding system. In this study, we discuss new petrological, geochemical and thermo-barometric data as well as the composition of major element and volatile content (H<sub>2</sub>O, CO<sub>2</sub>, F, Cl and S) of olivine-hosted melt inclusions from the explosive and effusive products emitted during the December 2015 eruptive event.</p><p>Results and rhyolite-MELTS thermodynamic modelling of mineral phase stability highlight the relatively shallow crystal equilibrium depth prior to the eruption ranging from 400-500 MPa for Central Crater and North East Crater, up to 200 MPa below the New South East Crater. The study of high-pressure and high-temperature homogenized olivine-hosted melt inclusions allowed us to identify the composition of the almost primary alkali-basalt magma (11.8 wt% MgO) containing up to 4.9 wt% and 8151 ppm of H<sub>2</sub>O and CO<sub>2 </sub>respectively. The results, together with those already reported for the previous paroxystic events of the 2011-2012 (Giacomoni et al., 2018), reinforce the model of a vertically extended feeding system and highlight that the activity at the New South East Crater was fed by a magma residing at significant shallower depth with respect to Central Craters and North East Crater, although all conduits are fed by a common deep (P = 530-440 MPa) basic magmatic refilling. Plagioclase stability model and dissolution and resorption textures confirm its dependence on H<sub>2</sub>O content, thus suggesting that further studies on the effect that flushing from fluids with different H<sub>2</sub>O/CO<sub>2</sub> ratio are needed in order to understand the eruption triggering mechanisms of paroxystic fountaining.</p><p> </p><p><strong>References</strong></p><p>Giacomoni P., Coltorti M., Mollo S., Ferlito C., Braiato M., Scarlato P. 2018. The 2011-2012 paroxysmal eruptions at Mt. Etna volcano: Insights on the vertically zoned plumbing system. JVGR 349, 370-391.</p>

The anisian (middle triassic) carbonate bank of Camorelli (Lombardy, Southern Alps)

Facies ◽  
1989 ◽  
Vol 21 (1) ◽  
pp. 41-56 ◽  
Author(s):  
Maurizio Gaetani ◽  
Marta Gorza
Keyword(s):  
Middle Triassic ◽  
Southern Alps ◽  
Carbonate Bank

scholarly journals Investigating the reasons for the failure of palaeointensity experiments: a study on historical lava flows from Mt. Etna (Italy)

2002 ◽  
Vol 149 (1) ◽  
pp. 44-63 ◽  
Author(s):  
Manuel Calvo ◽  
Michel Prévot ◽  
Mireille Perrin ◽  
Janna Riisager
Keyword(s):  
Lava Flows ◽  
Mt Etna

scholarly journals Middle Triassic trachytic lava flows associated with coeval dyke swarm in the North Patagonian Massif: A postorogenic magmatism related to extensional collapse of the Gondwanide orogen

2017 ◽  
Vol 75 ◽  
pp. 134-143 ◽  
Author(s):  
Santiago N. González ◽  
Gerson A. Greco ◽  
Ana M. Sato ◽  
Eduardo J. Llambías ◽  
Miguel A.S. Basei ◽  
...  
Keyword(s):  
Middle Triassic ◽  
Lava Flows ◽  
Dyke Swarm ◽  
The North ◽  
Extensional Collapse

Freboldia carinii sp. nov. from the Middle Triassic Brembana Valley (Esino Limestone, Southern Alps, Italy) – possibly the oldest known holoplanktonic gastropod

2020 ◽  
Vol 298 (1) ◽  
pp. 9-15
Author(s):  
Vittorio Pieroni ◽  
Alexander Nützel
Keyword(s):  
Life Style ◽  
Thin Shell ◽  
Type Species ◽  
Middle Triassic ◽  
Canadian Arctic ◽  
Southern Alps ◽  
Early Jurassic ◽  
Ellesmere Island ◽  
Gastropod Species ◽  
Mass Occurrence

A monospecific mass occurrence of the new gastropod species Freboldia carinii sp. nov. is described from the Middle Triassic Esino Limestone of the Brembana Valley, Southern Alps, Italy. It is the second species assigned to the genus Freboldia that was initially described from the Early Jurassic of Ellesmere Island, Canadian Arctic. This gastropod is unusual in being planispiral and inflated with a nearly bilateral symmetrical shape and in having a very thin shell. Like the Canadian type species of Freboldia, the new Triassic species is interpreted as a possibly holoplanktonic gastropod. If true, it would be the oldest known example of this life style in Gastropoda.

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