Petrography and geochemistry of achnelithic tephra from Las Herrerías Volcano (Calatrava volcanic field, Spain): Formation of nephelinitic achneliths and post-depositional glass alteration

Tracking the behaviour of persistently degassing volcanoes using noble gas analysis of Pele's hairs and tears: A case study of the Masaya volcano (Nicaragua)

“…ImageJ software (Abramoff et al, 2004) was used for image processing allowing the calculation of the sample vesicularitythe ratio between the area covered by vesicles and the total area of the sample. This method has been used to characterise internal morphological features, vesicularity and vesicle size of Pele's hairs and tears (Porritt et al, 2012;Carracedo-Sánchez et al, 2016;Cannata et al, 2019) and is comparable to results obtained when 2D microscope observations have been combined with vesicularity calculation derived from bulk density measurements (Porritt et al, 2012) and from 3D image analysis performed by synchrotron radiation X-ray computed microtomography (Cannata et al, 2019).…”

“…Pele's hairs and tears are millimetre sized glassy vesiculate pyroclasts derived from the fast-quenching of low-viscosity magmas erupted during lava-fountain Strombolian and Hawaiian eruptions of many basaltic volcanoes (e.g., Carracedo-Sánchez et al, 2016 and references therein). Several studies have investigated their morphological features (e.g., Duffield et al, 1977;Moune et al 2007, Porritt et al, 2012Carracedo-Sánchez et al, 2016;Cannata et al, 2019), petrography and geochemical compositions (Moune et al, 2007;Cannata et al, 2012;Porritt et al, 2012;Carracedo-Sánchez et al, 2016) and formation processes (Shimozuru, 1994;Zimanowski et al, 1997;Moune et al, 2007;Porritt et al, 2012), but little attention has been paid to the use of these particles as tracers of magmatic processes (Villemant, 2009). Pele's hairs and tears have been observed worldwide but they are specifically associated with the activity of persistently degassing basaltic volcanoes (e.g., Hawaii, Etna, Masaya, Erta' Ale, Villarica).…”

Melt stripping and agglutination of pyroclasts during the explosive eruption of low viscosity magmas

“…Figure 6 shows a juvenile pyroclast from the same fallout deposit at IHV; multiple droplets are observed sticking to the surface of the pyroclast, indicating that agglutination processes are widespread and not unique to the olivine cored pyroclasts. Furthermore, the agglutination of droplets onto surfaces has been observed on pyroclasts and crystals from the IHV NE volcano 46 , on nephelinitic achneliths 77 , lunar impact ejecta 78 , and clasts produced during nuclear accidents 79 and nuclear weapons tests 80 . The regime diagram (Fig.…”

Zeolite Crystal Growth Generations During Diagenetic and Hydrothermal Processes- Case Study of Lacustrine Volcaniclastics, Abu Treifiya Area, Cairo-Suez Road, Egypt

“…2c). These tephra deposits may be subaerial similar to that associated with fire fountain scoria in Strombolian and Hawaiian style volcanism, or of hydrovolcanic explosion origin of Cannata, et al (2012) and Carracedo-Sánchez et al (2016). The volcaniclastic sequences are often overlain by fluvial sandstones and lacustrine carbonates.…”

“…The lithic fragments are similar to but finer (0.5-2mm) than that described in the hyaloclastite breccia. This unit is characterized by the presence of variably sized and elongated palagonitized achneliths, corresponding to type two of Carracedo-Sánchez et al (2016). They are characterized by hyalocrystalline texture with light brown and highly vesicular glassy mesostasis (sideromelane) and cored by plagioclase or olivine phenocrysts (Fig.…”