Background/Overview: Most differentiated rocky worlds in our Solar System have mantles of olivine, pyroxene, spinel, and calcic plagioclase (or equivalent high-pressure phase assemblages). Earth’s mantle peridotite and similar rocks in other silicate planets and asteroids normally melt to form basaltic magma, komatiite, or other olivinenormative melts. Details of planetary mantle compositions a...

When a volcano erupts, the geological process that results often releases devastating amounts of energy from beneath the planet’s surface through volcanic flows. such flows are classified into two categories: well-known lava flows when the eruption is effusive, and pyroclastic flows when it is explosive. Explosive eruptions, like the ancient events at Mount Vesuvius in Italy and the modern ones...

[1] Bathymetry data collected with a multibeam echo sounder around Pico Island, Azores (Portugal), reveal a remarkable series of lava flows on the island’s shelf with a variety of pristine structures that suggest how lava behaves on entering water. Many flows are dendritic in plan view, some with channels and tumuli. Dendritic geometries are interpreted to arise from flow fronts repeatedly arre...

Introduction: Defining the mineralogy and composition of martian mantle source regions has proved to be a difficult task because: (1) the martian sample set does not include samples of the mantle, and (2) many of the samples are either cumulates or are highly fractionated and therefore not in equilibrium with the mantle. Despite these complexities, isotopic evidence suggests that Mars had a mag...

We present an oxygen isotope and petrologic study of four voluminous, zoned ash-flow sheets of the Southwestern Nevada Volcanic Field (SWNVF): Topopah Spring (TS, .1200 km3, 12.8 Ma), Tiva Canyon (TC, 1000 km3, 12.7 Ma), Rainier Mesa (RM, 1200 km3, 11.6 Ma), and Ammonia Tanks (AT, 900 km3, 11.45 Ma). The d18O values of quartz, sanidine, sphene, magnetite, and zircons in rhyolites and latites of...

Explosive volcanic eruption requires that magma fragments into discrete parcels. Silicic magma can fragment through brittle failure or other processes that depend on the viscoelasticity of the melt. Owing to the low viscosity of basaltic magmas, however, the fragmentation mechanism must be different and will be governed by fluid mechanics alone. We perform a series of decompression experiments ...

The present-day inclination of the Moon reflects the entire history of its thermal and orbital evolution. The Moon likely possessed a global magma ocean following the Moon-forming impact. In this work, we develop a coupled thermal-orbital evolution model that takes into account obliquity tidal heating in the lunar magma ocean. Dissipation in the magma ocean is so effective that it results in ra...

We report the oxygen isotope composition of olivine and orthopyroxene phenocrysts in lavas from the main magma types at Mt Shasta and Medicine Lake Volcanoes: primitive high-alumina olivine tholeiite (HAOT), basaltic andesites (BA), primitive magnesian andesites (PMA), and dacites. The most primitive HAOT (MgO [ 9 wt%) from Mt. Shasta has olivine dO (dOOl) values of 5.9–6.1%, which are about 1%...

An integrated study involving whole-rock and Sr–Nd–Hf isotope geochemistry and zircon geochronology and trace element combined with detailed field investigation was carried out for the composite Meiwu batholith in the West Qinling orogenic belt of central China to probe the origins of its compositional diversity and its emplacement history. The batholith is composed of quartz diorite, granodior...

By left magma-$e$-magma, I mean a set containingthe fixed element $e$, and equipped by two binary operations "$cdot$", $odot$ with the property $eodot (xcdot y)=eodot(xodot y)$, namelyleft $e$-join law. So, $(X,cdot,e,odot)$ is a left magma-$e$-magmaif and only if $(X,cdot)$, $(X,odot)$ are magmas (groupoids), $ein X$ and the left $e$-join law holds.Right (and two-sided) magma-$e$-magmas are de...