نتایج جستجو برای: dacite
تعداد نتایج: 251 فیلتر نتایج به سال:
Eocene intermediate to felsic subvolcanic rocks of the Torud-Ahmad Abad magmatic belt (TAMB), in northern part Central Iran zone, are exposed between Torud and Ahmad regions South-Southeast Shahrood. These igneous include hypabyssal dacite, trachyte, andesite, trachy-andesite, basaltic andesite; they mainly composed phenocrysts microcrystalline groundmass pyroxene, amphibole, plagioclase, with ...
We report a combined conventional Mössbauer and synchrotron Nuclear Resonant Inelastic X-ray Scattering (NRIXS) study of series basalt, andesite, dacite, rhyolite glasses at temperatures ranging from 5 to 1223 K. These were synthesized under controlled oxygen fugacities span wide range Fe3+/Fetot ratios. As expected theory, we find that in these glasses, the inverse Lamb-Mössbauer factor (the r...
Continental arc volcanism generates a wide diversity of magma compositions, but the tempos compositional variation are unclear. Here, we investigate 7-million year record volcanic ash layers in Cretaceous Eagle Ford Group, which was deposited Western Interior Seaway western North America. Low oxygen conditions prevented significant bioturbation, allowing for preservation hundreds thin form bent...
Discussions continue about whether Middle Eocene magmatism in the Eastern Pontides is associated with collision or subduction. This paper presents new whole-rock geochemistry, Sr-Nd isotopic and 40Ar-39Ar age data for volcanic rocks from Bayburt area of (NE Turkey) to investigate their sources evolutionary history. The 40Ar–39Ar ages reveal that these erupted between 44.6 ± 0.1 Ma 43.5 Ma, with...
A large number of intermediate basic volcanic rocks and porphyry Cu-Mo deposits as well volcanic-hosted magnetite deposit have been recently discovered in the Xilekuduk area. However, no reports concerning petrogenesis age or their relationship with mineralization published to date. The purpose this study was make up for absence previous studies on Devonian activities area confirm between two s...
West Junggar is a key area for understanding intra-oceanic plate subduction and the final closure of Ocean. Knowledge Carboniferous tectonic evolution Ocean region required framework accretionary processes in Junggar, Central Asian Orogenic Belt. A series Early volcanic intrusive rocks, namely, basaltic andesite, dacite, diorite, occur Mayile southern northwestern China. Our new LA-ICPMS zircon...
This study investigates petrology and major, minor, and rare earth elements geochemistry of East Iranian Eocene–Oligocene volcanic rocks in Sistan suture zone, to examine their petrogenesis and magma evolution. The volcanic rocks include andesite, trachy-andesite, dacite and rhyolite. These calc-alkaline rocks of high-K series are enriched in Large Ion Lithophile Elements of Rb and Ba a...
Sahand volcanic rocks, with Plio-Quaternery age, is located southeast Tabriz in the northwest part of Central Iran. These rocks are mainly composed of pyroclastics (tuff and ignimberite) and lava flows (rhyolite, rhyodacite, dacite and andesite) that unconformably cover the Miocene sedimentary formations. The major constituent minerals include plagioclase and hornblende which are surrounded by ...
The Cheshmeh Zagh area is located on Khorasan Razavi Province, the southern parts of the Sabzevar zone, which is one of the most important metallogeny zones of Iran. Lithologically, the area includes a variety of Late Cretaceous volcanic rocks (dacite to basalt), intrusions (gabbro to synogranite), Oligo-Miocene sedimentary rocks, and Quaternary sediments. Alteration zones of propylitic, chlori...
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