The 18-km-diameter El’gygytgyn crater is located on the Chukotka peninsula, northeastern Russia. It represents the only currently known impact structure formed in siliceous volcanics, including tuffs. The impact melt rocks and target rocks provide an excellent opportunity to study shock metamorphism of volcanic rocks. The shockinduced changes observed in porphyritic volcanic rocks from El’gygyt...

The Yellowstone Plateau volcanic field, the site of some of the largest known silicic volcanic eruptions, is the present location of NE-migrating hotspot volcanic activity. Most volcanic rocks in the Yellowstone caldera (0.6 Ma), which formed in response to the climactic eruption of 1000 km3 of Lava Creek Tuff (LCT), have unusually low oxygen isotope ratios. Ion microprobe analysis of both U^Pb...

The rocks of the Wadi Umm Gheig/El-Shush area in the central Eastern Desert of Egypt form part of the Nubian Shield, a component of the Neoproterozoic Pan-African Orogeny. The rocks have been divided into three units: (i) low-grade metamorphosed rocks, which consist of metavolcanic rocks interleaved with slices of ophiolitic melange; (ii) high-grade metamorphic rocks, which consist of syn-tecto...

 Igneous Rocks form from the solidification of molten rock. Intrusive igneous rocks are composed of crystals that are large enough to be seen with the naked eye because these rocks cooled slowly, deep within the Earth thereby allowing time for the crystals to grow. In contrast, extrusive (volcanic) igneous rocks cool very quickly after they erupt from a volcano, and so are composed of microsco...

introduction mesgar iron occurrence is located in northwestern part of the central iran, 115 km south of zanjan. although there is a sequence of volcanic-pyroclastic rocks accompanied by iron mineralization, no detailed works had been conducted in the area. the present paper provides an overview of the geological framework, the mineralization characteristics, and the results of geochemical stud...

in taleghan, olivine basalt-basaltic andesite dykes as part of tertiary mamgmatic activities in central and western alborz zone, intruded into both karaj formation and late eocene-oligocene volcanic rocks. these dykes have similar geochemical characteristic which suggest that they are originated from a common source. on the primitive mantle normalized spider diagram, the dykes are characterized...

Major systems of northwesterly, northerly, and northeasterly trending recurrilig fractures or faults controlled emplacement of various units of the Iron Mask batholith. The batholith was emplaced in a high level volcanic to subvolcanic environment, comagmatic with Nicola volcanic rocks and coeval with part of the upper Nicola succession. The batholith intruded volcanic and sedimentary rocks of ...