Compositional Diversity of Late Cenozoic Basalts in a Transect Across the Southern Washington Cascades: Implications for Subduction Zone Magmatism

Major volcanoes of the Southern Washington Cascades (SWC) include the large Quaternary stratovolcanoes of Mount St. Helens (MSH) and Mount Adams (MA) and the Indian Heaven (IH) and Simcoe Mountain (SIM) volcanic fields. There are significant differences among these volcanic centers in terms of their composition and evolutionary history. The stratovolcanoes consist largely of andesitic to dacitic lavas and pyroclastics with minor basalt flows. IH consists dominantly of basaltic with minor andesite lavas, all erupted from monogenetic rift and cinder cone vents. SIM has a poorly exposed andesite to rhyolite core but mainly consists of basaltic lavas erupted from numerous widely dispersed vents; it has the morphology of a shield volcano. Distribution of mafic lavas across the SWC is related to north‐northwest trending faults and fissure zones that indicate a significant component of east–west extension within the area. There is overlap in eruptive history for the areas studied, but it appears that peak activity was progressively older (MSH (Ka), IH (mostl

E0 Transitions and the Depopulation of SD Bands

We present the results of calculations showing that E0 transitions may successfully compete with other types of electromagnetic transitions in the decay out of SD bands

M1 and E2 transition rates from core-excited states in semi-magic 94Ru

Lifetimes of high-spin states have been measured in the semi-magic (N= 50) nucleus 94Ru. Excited states in 94Ru were populated in the 58Ni(40Ca, 4p)94Ru* fusion-evaporation reaction at the Grand Accélérateur National d’Ions Lourds (GANIL) accelerator complex. DSAM lifetime analysis was performed on the Doppler broadened line shapes in energy spectra obtained from γ-rays emitted while the residual nuclei were slowing down in a thick 6mg/cm^2 metallic 58Ni target. In total eight excited-state lifetimes in the angular momentum range I= (13 - 20) ℏ have been measured, five of which were determined for the first time. The corresponding B(M1) and B(E2) reduced transition strengths are discussed within the framework of large-scale shell model calculations to study the contribution of different particle-hole configurations, in particular for analyzing contributions from core-excited configurations