Compositional Diversity of Rocky Exoplanets

To test whether exoplanets are similar to Earth, knowledge of their host star composition is essential. Stellar elemental abundances and planetary orbital data show that of the ~5,000 known minerals, exoplanetary silicate mantles contain mostly olivine, orthopyroxene, and clinopyroxene, ± quartz and magnesiowüstite at the extremes, while wholly exotic mineralogies are unlikely. Understanding the geology of exoplanets requires a better marriage of geological insights to astronomical data. The study of exoplanets is like a mirror: it reflects our incomplete understanding of Earth and neighboring planets. New geological/planetary experiments, informed by exoplanet studies, are needed for effective progress.

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v13n1 Supplement — Putirka “Methods and Further Reading”

Back to Main Article Methods and Further Reading by Keith Putirka  Supplement to the February 2017 (v13n1) issue of Elements. Disclaimer: this table was not reviewed by Elements nor were its contents verified. DOWNLOAD: Methods and Further Reading (PDF) Methods Calculating Clinopyroxene and Amphibole Pressures Clinopyroxene pressure and temperature estimates use Eqns. P1 and T2 of…

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Down the Crater: Where Magmas are Stored and Why They Erupt

Magmas are erupted from a wide range of depths. Olivine compositions, for example, indicate magma storage in the lower crust and upper mantle, while clinopyroxene and amphibole record middle to upper crust storage. Pre-eruptive magmas also often cool by 100–300 °C, frequently at middle–upper crust depths, indicating clogged, ephemeral volcanic pathways. These coolings imply that mafic recharge is not a sufficient cause for eruption and that crystallization-induced vapor saturation is a more proximal eruption trigger. But an improved understanding of eruption mechanisms require precise identifications of what are herein termed “ultimate”, “proximal,” and “immediate” causes of eruption.

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