Origin of andradite in the Quaternary volcanic Andahua Group, Central Volcanic Zone, Peruvian Andes

Geochemical Constraints on the Origin of Volcanic Rocks from the Andean Northern Volcanic Zone, Ecuador

Whole-rock geochemical data on basaltic to rhyolitic samples from 12 volcanic centers are used to constrain the role of continental crust in the genesis of magmas formed beneath the anomalously wide subduction-related volcanic arc in Ecuador. Relatively homogeneous, mantle-like, isotopic compositions across the arc imply that the parental magmas in Ecuador were produced largely within the mantl...

An InSAR-based survey of volcanic deformation in the central Andes

[1] We extend an earlier interferometric synthetic aperture radar (InSAR) survey covering about 900 remote volcanos of the central Andes (14 –27 S) between the years 1992 and 2002. Our survey reveals broad (10s of km), roughly axisymmetric deformation at 4 volcanic centers: two stratovolcanoes are inflating (Uturuncu, Bolivia, and Hualca Hualca, Peru); another source of inflation on the border ...

Hydrothermal Origin of Smectite in Volcanic Ash

Abstraet--Smectite and fine-grained quartz were separated from 6 volcanic ash samples collected in Japan from Shinmoe-dake Volcano, southern Kyushu, and Mt. Usu Volcano, southern Hokkaido. Oxygen isotope ratios of smectite in the volcanic ash range from +6,9 to + 12.9 per mill (%o), which are comparable to the values of smectite (~lsO = +6.5 and +9.4%0) from currently active geothermal fields. ...

Surveying Volcanic Arcs with Satellite Radar Interferometry: The Central Andes, Kamchatka, and Beyond

Satellite Interferometric Synthetic Aperture Radar (InSAR) permits both synoptic and detailed surveys of mag-matic activity in volcanic arcs. To illustrate this capability, we summarize here the results of an extended study of inferred magmatic activity in the central Figure 1. Interferometric coherence (a measure of the quality of the Interferometric Synthetic Aperture Radar, or InSAR, measure...

Quaternary Volcanism Along the Volcanic Front in Northeast Japan