The steep crest of the Sierra Nevada, Califor-nia, near Onion Valley, exposes natural cross sections through a mafic intrusive complex that formed as part of the Mesozoic Sierra Nevada batholith. Sheeted sills of hornblende gabbro to hornblende diorite, individually as thick as 1.5 m, form the upper 200 to 300 m of the complex. Thicker, multiply-injected sills, as well as mafic stocks, lie unde...

The Mont Shefford alkaline complex of southern Quebec contains mafic rocks and both silica-oversatwated and -undersaturated syenites. Chemical and isotopic studies examine the relationship of the various lithologies. Isotopic, major, and trace-element compositions are consistent with derivation of all Iithologies from a common mafic paren! some of which evolved to a syenitic itage by fractional...

Abstract The eruption activity of Shinmoedake in the Kirishima volcanic group Japan resumed 2017–18, following a quiet period during 2011–17. Subplinian eruptions preceded lava effusion 2011; however, no subplinian occurred 2017–18. Petrological studies and melt inclusion analyses were conducted to investigate ascent degassing magma understand cause different styles. Chemical analysis inclusion...

The Terra Nova Intrusive Complex (TNIC) in northern Victoria Land, Antarctica, results from widespread magmatism during the Early Paleozoic Ross Orogeny. According to field relationships, geochemistry, and geochronology data, part of TNIC comprises Browning Unit (BIU), which is associated with an arc crustal melting including migmatization Wilson Metamorphic Complex, later Campbell (CIU), attri...

The most frequent and voluminous eruptive Kurasawa, 1983], (4) partial melting of the lower crust products at Mount St. Helens are dacitic in composition, [e.g., Grant et al., 1984; Reid and Cole, 1983], and (5) although a wide variety of magma types (basalt to formation of compositional gradients in response to rhyodacite) is represented. To address the petrogenesis of convective and diffusive...