Introduction: A great deal has been learned about the composition of the martian surface using orbital and in-situ spectroscopy. Significant advancements have been made possible by recent measurements from the Thermal Emission Spectrometer (TES), Thermal Emission Imaging System (THEMIS), Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA), Miniature Thermal Emission Spectr...

The El'gygytgyn impact structure in Chukutka, Arctic Russia, is the only impact crater currently known on Earth that was formed in mostly acid volcanic rocks (mainly of rhyolitic, with some andesitic and dacitic, compositions). In addition, because of its depth, it has provided an excellent sediment trap that records paleoclimatic information for the 3.6 Myr since its formation. For these two m...

Cayambe Volcano is an ice-capped, 5,790 m high, andesitic-dacitic volcanic complex, located on the equator in Eastern Cordillera of Ecuadorian Andes. An eruption at would pose considerable hazards to surrounding communities and a nationally significant agricultural industry. Although only historically documented was 1785, it remains persistently restless long-period (LP) seismicity has been con...

Most of the largest volcanoes in México are located at the frontal part of the Trans-Mexican Volcanic Belt and in other isolated areas. This chapter considers some of these volcanoes: Colima, Nevado de Toluca, Popocatépetl, Pico de Orizaba (Citlaltépetl), and Tacaná. El Chichón volcano is also considered within this group because of its catastrophic eruption in 1982. The volcanic edifi ce of th...

Water is an important volatile component in andesitic eruptions and deep-seated andesitic magma chambers. We report an investigation of H2O speciation and diffusion by dehydrating haploandesitic melts containing 62.5 wt.% water at 743–873 K and 100 MPa in cold-seal pressure vessels. FTIR microspectroscopy was utilized to measure species [molecular H2O (H2Om) and hydroxyl group (OH)] and total H...

A suite of tholeiitic picrites from eight of the younger (<2 Ma) Hawaiian shield volcanoes provides new information about the compositions of primitive magmas and source components in the Hawaiian plume. Olivine and bulk rock compositions show that parental melts at Hawaiian volcanoes have at least 13–17% MgO and 3⁄410% Al2O3. The picrites have bulk compositions ranging from 14 to 30% MgO, and ...

the late eocene-early oligocene sarnowsar granitic rocks and many dacitic to rhyolitic dykesintruded in metamorphosed and metasomatized shale, sandstone, calcite and dolomite marbles andvolcaniclastic and pyroclastic rocks. as a result several million tons of iron ores formed within carbonaterocks in the sangan area. the sarnowsar granitic rocks are mainly granite to granodiorite, metaluminous,...

Vesicle cylinders are vertical pipes filled with bubbles and residual melt that differentiate from diktytaxitic basalt flows during crystallization. They grow from about 0.25 m above the base of the flow to the bottom of the chilled flow top. Field relations limit their growth to the period between cessation of lava movement and deep penetration of columnar joints. Basalts containing vesicle cy...