A large Nb–Ta ore deposit was found in the Yushishan leptynite west Qilian Orogenic Belt (QOB). Based on a field geological survey and using Mineral Liberation Analyser (MLA, including scanning electron microscopy (SEM) energy-dispersive spectrometer (EDS)) methods, eight Nb minerals (fergusonite, polycrase, columbite, Nb-rutile, aeschynite, pyrochlore, microlite, ilmenorutile) were to occur le...

Mafic volcanism accounts for 80% of magmas erupted on Earth. Although the majority these eruptions are effusive to Strombolian and fountain-fed, large explosive mafic do occur. This work uses deposits pyroclast textures from 12.6 ka Curacautín ignimbrite eruption Llaima volcano constrain conditions that drove this extrapolate findings provide insights into promote large-volume, elsewhere. The (...

A prerequisite in refining volcanic hazard at explosive volcanoes is a better quantification of the timescales syn-eruptive processes, such as magma degassing and crystallization prior to eruption. To this aim, new data on matrices (microlites, residual glasses, bubbles) pumice, scoria, dense clasts erupted during AD 1530 andesitic eruption La Soufrière Guadeloupe are combined with published fr...

Unlike their silicic counterparts, mafic eruptions are known for being on the low-end of explosivity spectrum with eruption styles commonly ranging from effusive to Hawaiian fire fountaining. However, there increasing discoveries large Plinian eruptions, sometimes generating ignimbrites, suggesting that this phenomenon might not be so uncommon. So, what processes lead a magma fragment violently...

Abstract In 1999–2001, Guagua Pichincha volcano, Ecuador, produced a series of cyclic explosive and effusive eruptions. Rock samples, including dense blocks pumiceous clasts collected during the eruption sequence, ballistic bombs later from crater floor, provide information about magma storage, ascent, decompression, degassing, repressurization, regassing prior to eruption. Pairs Fe-Ti oxides i...

In December 2018, an unusually large intra- and extra-caldera eruption took place at Ambrym volcano (Vanuatu). The drained the volcano’s five active lava lakes terminated, least momentarily, surface activity that had been ongoing for decades to hundreds of years, sustaining largest recorded persistent degassing on planet. Here, we investigate mechanisms dynamics this major eruption. We use elem...

Environmental context Nitrate (NO3−) and ammonium (NH4+) are the most important soil nitrogen forms for plant growth. However, conventional extraction techniques may introduce artefacts affecting measurement of plant-available N concentrations following sampling sample preparation processes. This is first study DGT technique being used to measure NO3-N NH4-N in a wide range soils, compared with...

Understanding the relationship between degassing, crystallization processes and eruption style is a central goal in volcanology, particular how these modulate magnitude timing of cyclical Vulcanian explosions intermediate magmas. To investigate influence variations crystal micro-textures on magma rheology dynamics, we conducted high-temperature (940°C) uniaxial compression experiments at condit...

Laboratory experiments investigating syn-eruptive crystallization are fundamental for interpreting crystal and vesicle textures in pyroclasts. Previous have advanced our understanding by varying decompression cooling pathways, volatile components, melt composition. However, they largely failed to produce the high number densities seen many cryptodome dome samples. This is feasibly due relativel...