Most Hawaiian basaltic shield volcanoes are capped by moderately to strongly evolved alkalic lavas (MgO < 4.5 wt. %). On M auna Kea Volcano the cap is dominantly composed of hawaiite with minor mugearite. Although these lavas contain dunite and gabbroic xenoliths, they are nearly aphyric with rare olivine and plagioclase phenocrysts and xenocrysts. The hawaiites are nearly homogeneous in radiog...

New U-Th-Pb zircon data (SIMS) from three intrusive phases of the Palaeoproterozoic Viterliden intrusion in the western Skellefte District, central Fennoscandian Shield, dates igneous emplacement in a narrow time interval at about 1.89 Ga. A locally occurring quartz-plagioclase porphyritic tonalite, here dated at 1889± 3 Ma, is considered the youngest of the intrusive units, based on the new ag...

The volcanic rocks of the Kaban dacite, which is subject study, are located in Olur (Erzurum) region eastern Sakarya zone. This zone divided into four tectonic slices as Hopa-Borçka zone, Artvin Yusufeli Tortum and Erzurum Kars Ophiolite from north to south, east Eastern pontides, investigated within Olur-Tortum These represented by dacites rhyolites study area. Petrographically, it observed fi...

This thesis compiles two distinct studies that both document the control of microstructures on rock seismic properties. The first part deals with the development of crystallographic preferred orientations (CPO) in the uppermost mantle associated with melt/fluid-rock interactions, recorded in peridotites xenoliths from the Japan sea back-arc basin. The microstructural and geochemical characteris...

Axial melt lenses sandwiched between the lower oceanic crust and the sheeted dike sequences at fast-spreading mid-ocean ridges are assumed to be the major magma source of oceanic crust accretion. According to the widely discussed "gabbro glacier" model, the formation of the lower oceanic crust requires efficient cooling of the axial melt lens, leading to partial crystallization and crystal-melt...