The circum-Mediterranean anorogenic Cenozoic igneous province

We present a kinematic, self-adaptive, numerical model to describe the down-flow thermal and rheological evolution of channel-contained lava. As our control volume of lava advances down a channel it cools and crystallizes, an increasingly thick and extensive surface crust grows, and its heat budget and rheology evolve. By estimating down-flow heat and velocity loss, our model calculates the point at which the control volume becomes stationary, giving the maximum distance lava flowing in the channel can extend. Modeled effusion rates, velocities, widths, surface crust parameters, heat budget, cooling, temperature, crystallinity, viscosity, and yield strength all compare well with field data collected during eruptions at Mauna Loa, Kĩlauea, and Etna. Modeled lengths of 25–27, 2.5–5.7, and 0.59–0.83 km compare with measured lengths of 25–27, 4, and 0.75 km for the three flows, respectively. Over proximal flow portions we calculate cooling, crystallization, viscosity, and yield strength of 1–10°C km–1, 0.001–0.01 volume fraction km–1, 103–104 Pa s, and 10–3–102 Pa, respectively. At the flow front, cooling, crystallization, viscosity, and yield strength increase to >100°C km–1, 0.1 volume fraction km–1, 106–107 Pa s, and 103–104 Pa, respectively, all of which combine to cause the lava to stop flowing. Our model presents a means of (a) analyzing lava flow thermo-rheological relationships; (b) identifying important factors in determining how far a channel-fed flow can extend; (c) assessing lava flow hazard; and (d) reconstructing flow regimes at prehistoric, unobserved, or remote flows.

FLOWGO: a kinematic thermo-rheological model for lava flowing in a channel

Combining SO2 plume emissions from Mt Etna in 1975-1995 with the magma S content suggests that between 35 and 59 km 3 of basalt were degassed for sulfur over two decades, only 10-20% of which actually extruded Except during extensive lava outbreak (1992), the SO2 flux was mostly supplied by endogenous degassing of non-erupted basalt, replaced at a time-averaged rate of 45-8 m3/s The unerupted degassed magma cannot be accomodated by the upper plumbing system (whose maximum capacity is estimated at 06 km3), nor by simple intrusive growth of the volcanic pile Being denser than undegassed melt, most of it was probably removed by gravitational convection in subvolcanic feeders Ultimately, part of this degassed magma may solidify within the crust, contributing to the accretion of a wide 'plutonic' complex, >_3 times larger than the volcano itself, that has grown within its sedimentary basement the largest dataset for a volcano worldwide The measurements were intermittent from 1975 to 1987 [Allard et al, 1991, and references therein] but routineous since then [Caltabiano et al, 1994; Allard et al, 1994a; Bruno et al, 1994, 1996] The SO2 flux was found to vary within a main range from _<1000 tons/day (t/d) during low passive fuming to 10000-12000 t/d during high Strombolian activity (95% of data) A few peaks at over 20000 t/d occurred during lava-fountaining paroxysms in 1990-1991 (03 % of data) However, high fluxes without Table Sulfur Output and Magma Degassing Budget of Etna, 1975-1995 Year SO2 output Degassed magma (tons) (106 m 3)

https://hal.archives-ouvertes.fr/hal-03356875/document

Endogenous magma degassing and storage at Mount Etna

https://www.higp.hawaii.edu/~wright/jvgr102.pdf

Effusion rate trends at Etna and Krafla and their implications for eruptive mechanisms

The size distributions of crystals of olivine, plagioclase and oxides of the 1991/93 eruption at Mt. Etna (Italy) are analyzed. The simultaneous collection of this information for different minerals gives precious insight into the cooling history of lavas. Three distinct episodes are detectable: a storage of the magma in a deep reservoir, characterized by nearly constant and low nucleation and growth rates (near to equilibrium); an ascent phase, with an ever increasing nucleation rate related to volatile exsolution; and finally a quenching phase. In addition to geochemical and geophysical evidence, the similarity of the crystal size distributions of the present eruption with those of previous ones of this century makes it possible to exclude that crystal size distributions of Etnean lavas are due to mixing of different populations. This strongly suggests that the main features of the volcano feeding system have not changed despite observed variations in the magma output rates.

Effects of magma storage and ascent on the kinetics of crystal growth

The long-standing 1991-1993 Mt. Etna eruption: petrography and geochemistry of lavas

Les inclusions vitreuses des ilmenites, apatites et quartz des sediments phosphates de Tunisie; temoignages d'un volcanisme alcalin d'age Paleocene superieur a Eocene

La Galite Archipelago (Tunisia, North Africa): new geological data and insights for geodynamic evolution of the Maghrebian Chain (African-European plate boundary)

The Beni M'hira meteorite fell on January 8, 2001 in southeastern Tunisia. This is only the fifth observed fall from Tunisia. On the basis of mineralogical, petrographic, and geochemical data, the stone can be classified as an L6 chondrite of shock stage S5.

/pdf/beni-m-hira-a-new-chondritic-l6-meteorite-fall-from-tunisia-3kfa6vb42l.pdf

R. Clocchiatti

Papers

The long-standing 1991-1993 Mt. Etna eruption: petrography and geochemistry of lavas

Les inclusions vitreuses des ilmenites, apatites et quartz des sediments phosphates de Tunisie; temoignages d'un volcanisme alcalin d'age Paleocene superieur a Eocene

La Galite Archipelago (Tunisia, North Africa): new geological data and insights for geodynamic evolution of the Maghrebian Chain (African-European plate boundary)

Beni M'hira: A new chondritic (L6) meteorite fall from Tunisia

Sur les roches pyroclastiques au Nord du Dacht-e-Nawar (Afghanistan); les quartz et leurs inclusions vitreuses