Search results for "LCA"

Active alkaline traps to determine acidic-gas ratios in volcanic plumes: Sampling techniques and analytical methods

2014

In situ measurements have been the basis for monitoring volcanic gas emissions for many years and—being complemented by remote sensing techniques—still play an important role to date. Con- cerning in situ techniques for sampling a dilute plume, an increase in accuracy and a reduction of detection limits are still necessary for most gases (e.g., CO2, SO2, HCl, HF, HBr, HI). In this work, the Raschig-Tube tech- nique (RT) is modified and utilized for application on volcanic plumes. The theoretical and experimental absorption properties of the RT and the Drechsel bottle (DB) setups are characterized and both are applied simultaneously to the well-established Filter packs technique (FP) in the …

Evolution of Early Metazoa: Phylogenetic Status of the Hexactinellida Within the Phylum of Porifera (Sponges)

1998

The evolution of the Metazoa from their protozoan ancestors is one of the greatest puzzles of phylogeny (Willmer 1994; Cavalier-Smith et al. 1996). The emergence of multicellular animals has been explained by two major theories: the syncytial theory (Hadzi 1963) - origin from a multinucleated ciliate - and the colonial theory (Haeckel 1868) - origin from a colonial flagellate - both of which assume a di(poly)phyletic origin of the Metazoa. Numerous attempts to resolve whether the Metazoa are of mono- or polyphyletic origin have sought evidence from a wide variety of developmental and morphological data such as body symmetry, type of development (protostome vs. deuterostome), type of body ca…

Volatile dilution during magma injections and implications for volcano explosivity

2016

Magma reservoirs underneath volcanoes grow through episodic emplacement of magma batches. These pulsed magma injections can substantially alter the physical state of the resident magma by changing its temperature, pressure, composition, and volatile content. Here we examine plagioclase phenocrysts in pumice from the 2014 Plinian eruption of Kelud (Indonesia) that record the progressive capture of small melt inclusions within concentric growth zones during crystallization inside a magma reservoir. High-spatial-resolution Raman spectroscopic measurements reveal the concentration of dissolved H2O within the melt inclusions, and provide insights into melt-volatile behavior at the single crystal…

Tertiary maars of the Hocheifel Volcanic Field, Germany

2008

In the Hocheifel only three maars are known. The Eckfeld Maar, filled with Eocene lacustrine sediments, is located at the southern boundary of the volcanic field, where the Tertiary peneplain has been eroded only slightly. The ages of the Jungferweiher Maar in the southeast and the Dottingen Maar in the northeast of the Tertiary Hocheifel Volcanic Field (THVF) are unknown and their timing within the THVF is uncertain. In contrast to the surrounding area, the central part of the THVF is deeply eroded. Here, six large diatremes (>600 m) were identified in the area of Kelberg with one exception. So far, no relics of crater sediments have been found within the large diatremes. They probably rep…

Responsorio de S. Diego de Alcalá

El full orlat Grav. xil. enmarcat de: "San Diego de Alcala", flanquejat per ornaments tip Text a dues col. separades per doble filet

Gozos a San Diego de Alcala de Henares, venerado por sus Congregantes y Devotos en el Real Convento de nuestro Padre San Francisco de Valencia.

El full orlat Grav. xil. enmarcat de "San Diego de Alcala", flanquejat per gerros amb flors Text del goig a tres col. separades per filets

Gozos a San Diego de Alcalá de Henares, venerado por sus Congregantes y Devotos en el Real Convento de nuestro Padre San Francisco de Valencia.

El full orlat Grav. xil. enmarcat de "San Diego de Alcala", flanquejat per gerros amb flors Text del goig a tres col. separades per filets

Gozos, a San Diego de Alcala de Henares, venerado en el Convento de N. P. S. Francisco de Valencia, para sus Congregantes, y Devotos.

El full orlat Grav. xil. enmarcat de "S. Diego de Alcala", flanquejat per símbols amb fletxa, corona i S Text del goig a tres col. separades per bandes

Vida, muerte y milagros de S. Diego de Alcala : en otaua rima

Esc. a la port Capll. orn

The role of melt-fracture degassing in defusing explosive rhyolite eruptions at volcán Chaitén

2012

Explosive volcanic eruptions of silicic magma often evolve towards non-explosive emissions of lava. The mechanisms underlying this transition remain unclear, however, a widely cited idea holds that shear-induced magma fragmentation plays a critical role by fostering volatile loss from fragmentary magma and through ash-filled cracks termed tuffisite. We test this hypothesis by measuring H2O concentrations within glassy tuffisite from the 2008–2011 rhyolitic eruption at volcan Chaiten, Chile. We show that while H2O concentrations decrease next to tuffisite veins and at the margins of obsidian fragments, the depletions cannot account for the disparity in H2O between explosively and effusively …