نتایج جستجو برای: collision volcanic rocks
تعداد نتایج: 81746 فیلتر نتایج به سال:
The pyroclastic rocks of "The Crater", South Island, New Zealand belong to the Miocene, alkaline basaltic Dunedin Volcanic Group and represent an individual eruptive center with possible multiple vents. Three pyroclastic units have been separated at the study area based on textural and compositional features as well as their stratigraphic positions. The central part of The Crater comprises basa...
Arousan -e- Kaboudan area, located about 115 km northeast of Nain (south of Choupanan), is part of Central Iran (Yazad block). The Eocene volcanic rocks of the area are composed of lavas and pyroclastic rocks. The lavas can be divided into acidic (rhyodacite) and relatively basic-basic (trachyandesite, mugearite and hawaiite) rocks. The textures of these rocks are trachytic, hyaloporphyritic an...
In north to northeast of Baft city, south Kerman, various outcrops of volcanic rocks, belong to Uromieh-Dokhtar magmatic belt, are observed. This region in Kerman Province situated in east of Dehaj – Sarduiye magmatic belt. Most of volcanic sequences in this area are andesite, andesite-basalt, dacite, and a few basalt and rhyolite with Eocene age that interlayered with pyroclastic and volcano s...
In southeast of Bardsir (Kerman Province), there is a volcanic complex belongs to Uromieh-Dokhtar volcanic belt.This complex mainly contains basaltic-andesite and basalt lava flows with the Eocene age, alternative with pyroclastic rocks. Petrographic evidences include zoning, sieve texture and rounded crystal in plagioclase and pyroxene phenocrysts disequilibrium conditions between crystals and...
Around The Karik village, east of Meiduk mine, Eocene volcanic rocks (andesitic basalt, andesite, dacite and rhyolite) and pyroclastic rocks (agglomerate and tuff) are exposed. These rocks are cut by several andesitic dikes. The major textures in the volcanic rocks are porphyritic and flow textures. The minerals such as plagioclase, alkali feldspar, quartz, pyroxene, amphibole, biotite and opaq...
The Qinzhou Bay-Hangzhou Bay joint belt is a significant tectonic zone between the Yangtze and Cathaysian plates, where plentiful hydrothermal siliceous rocks are generated. Here, the authors studied the distribution of the siliceous rocks in the whole tectonic zone, which indicated that the tensional setting was facilitating the development of siliceous rocks of hydrothermal genesis. According...
Early Cambrian volcanic rocks of the Posht-e Badam tectonic block in Central Iran which is hydrothermally altered to green color rocks, hosts the Kiruna-type Iron Oxide-Apatite (IOA) mineralization in Anomaly 10 of Sechahun deposit. Geochemically, these volcanic rocks are classified as high-potassium calc-alkaline and mainly consist of rhyolite and trachyandesite. These rocks are important for ...
The Nam Pat Group of the Nam Pat Basin, Uttaradit Province, Thailand is situated in the Nan Suture Zone. Two contrasting tectonic framework models of the Nan Suture have previously been proposed: as a main Paleo-Tethyan suture and as a remnant of a closed back-arc basin. The goal of this study is to analyze the tectonic framework of the Nan Suture and reevaluate the existing tectonic models. Th...
U-Pb and Ar/Ar dates from the Talladega belt, southernmost Appalachians, provide insight into the timing and nature of pre-Alleghanian tectonism in this region. Low-grade metasedimentary rocks of the Talladega belt represent the outermost preserved portions of the southern Laurentian margin, thus recording the earliest orogenic events that affected the margin, in addition to later overprinting ...
Along the Isthmus of Panama 23 paleomagnetic sites were sampled in order to determine preliminary block rotations and paleolatitudinal movements. The lithology selected for this research corresponds to volcanic and sedimentary rocks with ages ranging from Upper Cretaceous to Pleistocene. Counterclockwise vertical axis rotations were uncovered in Paleocene and Oligocene units separated by a sini...
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