Some anorthite bearing basic volcanic rocks in Japan

An albite-anorthite assemblage in low-grade amphibolite facies rocks

Poikiloblastic amphibole schists from an ophiolite series in the vicinity of the Tertiary Bergell granite contain the assemblage albite (An 0)-anorthite (An 95), actinolite-pargasite, together with clinozoisite. TEM illustrates how large andesine crystals with a periodic APB (anti-phase boundaries) structure of e plagioclase change over a few hundred angstroms to pure albite and pure PT anorthi...

Investigation of mineral chemistry, thermobarometry and fuzzy equilibrium of the basic Plio-Quaternary volcanic rocks in NE Varzeghan

1- Introduction The studied area is situated in northeast Varzeghan in East Azerbaijan Province. In the classification of the structural unites of Iran, this area is a part of Ahar-Arasbaran magmatic arc. The Cenozoic magmatism in the Ahar–Arasbaran region started in the Eocene with an intensive volcanic activity that produced widespread basic to felsic rocks and continued in the Oligo-Miocene...

Generalized Titanomagnetite in Hawaiian Volcanic Rocks'

A ferromagnetic oxide mineral with spinel structure was separated from Hawaiian volcanic rocks ranging from basalt to trachyte . The chemical compositions of all the specimens have been arranged on an oxygen reaction line, and can safely be interpreted as the result of a process of either oxidation or reduction of material with composition on or near this line. In the trachyte the mineral was f...

Groundwater in Sedimentary, Metamorphic and Volcanic Rocks

Petrology and Geochemistry of Boninite Series Volcanic Rocks, Chichi-jima, Bonin Islands, Japan

An Eocene submarine boninite series volcanic center is exposed on the island of Chichi-jima, Bonin Islands, Japan. Five rock types, boninite, bronzite andesite, dacite, quartz dacite, and rhyolite, were distinguished within the boninite volcanic sequence on the basis of petrographic and geochemical observations. Boninite lavas contain high magnesium, nickel, and chromium contents indicative of ...