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Melt inclusions (MI) are considered the best tool available for determining the pre-eruptive volatile contents of magmas. H2O and CO2 concentrations of the glass phase in MI are commonly used both as a barometer and to track magma degassing behavior during ascent due to the strong pressure dependence of H2O and CO2 solubilities in silicate melts. The often unstated and sometimes overlooked requirement for this method to be valid is that the glass phase in the MI must represent the composition of the melt that was trapped at depth in the volcanic plumbing system. However, melt inclusions commonly contain a vapor bubble that formed after trapping owing to differential shrinkage of the melt compared to the host crystal, and/or crystallization at the inclusion-host interface. Such bubbles may contain a substantial portion of volatiles, such as CO2, that were originally dissolved in the melt. In this study, we determined the contribution of CO2 in the vapor bubble to the overall CO2 content of MI based on quantitative Raman analysis of the vapor bubbles in MI from the 1959 Kilauea Iki (Hawaii), 1960 Kapoho (Hawaii), 1974 Fuego volcano (Guatemala), and 1977 Seguam Island (Alaska) eruptions. We found that the bubbles typically contain 40 to 90% of the total CO2 in the MI. Reconstructing the original CO2 content by adding the CO2 in the bubble back into the melt results in an increase in CO2 concentration by as much as an order of magnitude (thousands of parts per million). Reconstructed CO2 concentrations correspond to trapping pressures that are significantly greater than one would predict based on analysis of the volatiles in the glass alone. Trapping depths can be as much as 10 km deeper than estimates that ignore the CO2 in the bubble. In addition to CO2 in the vapor bubbles, many MI showed the presence of a carbonate mineral phase. Failure to recognize the carbonate during petrographic examination or analysis of the glass and to include its contained CO2 when reconstructing the CO2 content of the originally trapped melt will introduce additional errors into the calculated volatile budget. Our results emphasize that accurate determination of the pre-eruptive volatile content of melts based on analysis of melt inclusions must consider the volatiles contained in the bubble (and carbonates, if present). This can be accomplished either by analysis of the bubble and the glass followed by mass-balance reconstruction of the original volatile content of the melt, or by re-homogenization of the MI prior to conducting microanalysis of the quenched, glassy MI. [ABSTRACT FROM AUTHOR]

The Rutgers University Central American geochemical dataset focuses on the active volcanoes related to the Cocos-Caribbean convergent plate boundary that extends from Guatemala to Costa Rica in Central America. The RU prefix signifies that the data and samples are primarily from the long-term Central American research project started at Dartmouth College in 1970 and continued at Rutgers University from 1974 to the present. The database is decidedly uneven because of the impressive improvement of analytical techniques over the span of data collection. Further complications arose because most of the sampling and analysis were part of the educational process for many different undergraduate and graduate students using different types of instruments. This note presents, as a reasonably coherent whole, geochemical data and metadata for about 1400 samples collected by at least 40 students and colleagues. Many unpublished Sr, Nd, and Pb isotopic ratios are included here but most of the new data are metadata that provide greatly improved descriptions of the tectonic settings, locations, and status of the samples as well as estimates of data quality. [ABSTRACT FROM AUTHOR]

The Rutgers University Central American geochemical dataset focuses on the active volcanoes related to the Cocos-Caribbean convergent plate boundary that extends from Guatemala to Costa Rica in Central America. The RU prefix signifies that the data and samples are primarily from the long-term Central American research project started at Dartmouth College in 1970 and continued at Rutgers University from 1974 to the present. The database is decidedly uneven because of the impressive improvement of analytical techniques over the span of data collection. Further complications arose because most of the sampling and analysis were part of the educational process for many different undergraduate and graduate students using different types of instruments. This note presents, as a reasonably coherent whole, geochemical data and metadata for about 1400 samples collected by at least 40 students and colleagues. Many unpublished Sr, Nd, and Pb isotopic ratios are included here but most of the new data are metadata that provide greatly improved descriptions of the tectonic settings, locations, and status of the samples as well as estimates of data quality. [ABSTRACT FROM AUTHOR]

Abstract: The volcanic record of western Nicaragua documents a significant lull in volcanic activity that has persisted from the late Miocene (~7Ma) to the formation of the modern volcanic front around 350ka. This study fills this gap for the first time with samples collected in Northwest Nicaragua between Cosigüina and San Cristóbal volcanoes and with samples collected from the Nicaraguan Depression. We found two previously unknown volcanic units ranging from 3.6 to 1.3Ma and the improved volcanic record allows us to reconstruct the geochemical evolution of the Nicaraguan arc. U/Th values increased by nearly threefold since the Miocene following the “carbonate crash” at 10Ma, when dominantly carbonate sediment deposition shifted toward hemipelagic sediment deposition. This transition was thought to be abrupt, however our new data show that it took place gradually over the last 7Ma. Northwest Nicaragua is a particularly interesting case study because it contains Middle Miocene volcanism on either side of the Nicaraguan Depression, the Coyol Formation (25–7Ma) to the East and the Tamarindo Formation (14.7–11.7Ma) to the West. The presence of Mid Miocene volcanism on either side of the Nicaraguan Depression has led to the hypothesis that the two coeval units, currently separated by ~100km, were once connected and have since been separated by extension. Here, we present data suggesting that the Tamarindo and Coyol are geochemically distinct and therefore cannot be considered part of the same unit. [Copyright &y& Elsevier]

Six to five Myr. old continental-arc shoshonites and other high-K igneous rocks crop out among the summits of the Talamanca Cordillera, Central America. These rocks fill a previously assumed volcanic gap in eastern Costa Rica, showing that the Late Miocene-Pliocene magmatic arc was almost continuous along the current Talamanca Cordillera. Their trace element compositions (e.g., Sr ~ 1700 ppm at Rb ~ 120 ppm concentrations) together with fractional crystallization modeling, and isotopic signatures suggest a genesis related to subduction processes rather than lower crustal melting. Here we present a comprehensive geochemical study that integrates Monte Carlo simulations of trace element geochemistry and isotopic evidence in order to explain the origin of these highly enriched igneous rocks. The trace element budget of the Talamanca arc rocks requires the input of an incompatible element-enriched component, similar in composition to the Cocos Island Province (Pacific Ocean). We interpret the presence of this component to be the result of slab melting of subducted seamounts. Our model suggests that in southern Central American, contribution of OIB-related seamounts is a critical step for the generation of continental crust-like rock compositions. • A juvenile continental arc fills a Late Neogene gap between Costa Rica and Panama. • This suite includes shoshonitic lavas highly enriched in incompatible elements. • Their trace element budgets require a melt component from subducted seamounts. [ABSTRACT FROM AUTHOR]

Damage and destruction caused by the 2021 eruption of the Tajogaite volcano on La Palma was unprecedented relative to other historical eruptions of the last century (1909, 1949, 1971, 2011) in the Canary Islands. The devastation caused by the eruption was not a result of eruption magnitude, which was only marginally larger than other historical events, but instead an increasing vulnerability due to population growth and increasing rural land use on the slopes of the volcanically active Cumbre Vieja Ridge. Since future eruptions along the Cumbre Vieja are inevitable, it is imperative that actions are taken to ensure the safety of the island's growing population. While civil protection and emergency services managed to avert loss of life from direct volcanic impacts in 2021, loss of property for many people in the affected area remains a grave issue and requires targeted measures to safeguard against human suffering from similar future events. [ABSTRACT FROM AUTHOR]

Major and trace element abundances, including highly siderophile elements, and 187Os and 182W isotopic compositions were determined for ca. 89 Ma mafic and ultramafic rocks from the islands of Gorgona (Colombia) and Curaçao (Dutch Caribbean). The volcanic systems of both islands were likely associated with a mantle plume that generated the Caribbean Large Igneous Provence. The major and lithophile trace element characteristics of the rocks examined are consistent with the results of prior studies, and indicate derivation from both a chemically highly-depleted mantle component, and an enriched, or less highly-depleted mantle component. Highly siderophile element abundances for these rocks are generally similar to rocks with comparable MgO globally, indicating that the major source components were not substantially enriched or depleted in these elements. Rhenium-Os isotopic systematics of most rocks of both islands indicate derivation from a mantle source with an initial 187Os/188Os ratio between that of the contemporaneous average depleted mid-ocean ridge mantle and bulk silicate Earth. The composition may reflect either an average lower mantle signature, or global-scale Os isotopic heterogeneity in the upper mantle. Some of the basalts, as well as two of the komatiites, are characterized by calculated initial 187Os/188Os ratios 10–15 % higher than the chondritic reference. These more radiogenic Os isotopic compositions do not correlate with major or trace element systematics, and indicate a mantle source component that was most likely produced by either sulfide metasomatism or ancient Re/Os fractionation. Tungsten-182 isotopic compositions measured for rocks from both islands are characterized by variable μ182W values ranging from modern bulk silicate Earth-like to strongly negative values. The μ182W values do not correlate with major/trace element abundances or initial 187Os/188Os compositions. As with some modern ocean island basalt systems, however, the lowest μ182W value (−53) measured, for a Gorgona olivine gabbro, corresponds with the highest 3He/4He previously measured from the suite (15.8 R/R A). Given the lack of correlation with other chemical/isotopic compositions, the mantle component characterized by negative μ182W and possibly high 3He/4He is most parsimoniously explained to have formed as a result of isotopic equilibration between the mantle and core at the core-mantle boundary. [ABSTRACT FROM AUTHOR]

Rare earth elements (REE) are essential ingredients of sustainable energy technologies, but separation of individual REE is one of the hardest problems in chemistry today. Biosorption, where molecules adsorb to the surface of biological materials, offers a sustainable alternative to environmentally harmful solvent extractions currently used for separation of rare earth elements (REE). The REE-biosorption capability of some microorganisms allows for REE separations that, under specialized conditions, are already competitive with solvent extractions, suggesting that genetic engineering could allow it to leapfrog existing technologies. To identify targets for genomic improvement we screened 3,373 mutants from the whole genome knockout collection of the known REE-biosorbing microorganism Shewanella oneidensis MR-1. We found 130 genes that increased biosorption of the middle REE europium, and 112 that reduced it. We verified biosorption changes from the screen for a mixed solution of three REE (La, Eu, Yb) using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) in solution conditions with a range of ionic strengths and REE concentrations. We identified 18 gene ontologies and 13 gene operons that make up key systems that affect biosorption. We found, among other things, that disruptions of a key regulatory component of the arc system (hptA), which regulates cellular response to anoxic environments and polysaccharide biosynthesis related genes (wbpQ, wbnJ, SO_3183) consistently increase biosorption across all our solution conditions. Our largest total biosorption change comes from our SO_4685, a capsular polysaccharide (CPS) synthesis gene, disruption of which results in an up to 79% increase in biosorption; and nusA, a transcriptional termination/anti-termination protein, disruption of which results in an up to 35% decrease in biosorption. Knockouts of glnA, pyrD, and SO_3183 produce small but significant increases (≈ 1%) in relative biosorption affinity for ytterbium over lanthanum in multiple solution conditions tested, while many other genes we explored have more complex binding affinity changes. Modeling suggests that while these changes to lanthanide biosorption selectivity are small, they could already reduce the length of repeated enrichment process by up to 27%. This broad exploratory study begins to elucidate how genetics affect REE-biosorption by S. oneidensis, suggests new areas of investigation for better mechanistic understanding of the membrane chemistry involved in REE binding, and offer potential targets for improving biosorption and separation of REE by genetic engineering. [ABSTRACT FROM AUTHOR]