نتایج جستجو برای: lava rocks
تعداد نتایج: 24704 فیلتر نتایج به سال:
Pillow lava rims from the Mesoarchean Barberton Greenstone Belt in South Africa contain micrometer-scale mineralized tubes that provide evidence of submarine microbial activity during the early history of Earth. The tubes formed during microbial etching of glass along fractures, as seen in pillow lavas from recent oceanic crust. The margins of the tubes contain organic carbon, and many of the p...
The studied area is located about 35 KM north-west of Rafsanjan (Kerman Province) and belongs to Hezar volcanic complex (in Uromieh-Dokhtar volcanic belt) and consists of Eocene folded lava flows (basalt, basaltic andesite, andesite) and pyroclastic rocks. Plagioclase phenocrysts show evidences of disequilibrium textures such as sieve texture, resorption and oscillatory zoning. These features c...
The study area is situated within the Lut Block 50 Km northeast of Ferdows. The oldest exposed rocks are Cretaceous limestone. Kerman conglomerate cover the limestone. Dacite-rhyodacite lava and pyroclastic rocks erupted over Kerman conglomerate. Volcanic activities took place at different time in Tertiary. The composition ranges between trachyandesite, andesite, andesite-basalt and rhyolitic ...
The alkaline and stratoid volcanic rocks of Separdeh district (NE Qazvin), located on the central Albroz zone, are underlain conformably by Early Cretaceous limestones of Tizkuh Formation. These rocks are texturally homogenous and very fine-grained and characterized by microphenocrysts and microliths of plagioclase, pyroxene, olivine, apatite and opaque set in a hyaline matrix. However, few pyr...
Trachyandesitic rocks in the Ab-e-Torsh region, western Qazvin, have considerable thickness and extensive outcrops (>200 Km2) that form parts of the Alborz Paleogene volcanic belt. These rocks that can be correlated with the upper member of the Karaj formation, are subaerial eruptions with lava flows and some lava domes. Geochemically, these are classified as shoshonitic series. Occurrence of s...
The Deh-Sard area IS located about 90 km south of 8aft in the Kerman province, situated in southern part of Sanandaj-Sirjan zone. It consists of interm ittent lava flows (basalt, basaltic andes ite and trachyandesite), pyroclastic rocks (various types of tu ffs and paloebereccias) and sedimentary rocks (lime stones and shales) of Jurassic age. The Deh-Sard lava flows are essentially compo...
The eruptive unrests of active volcanoes are always associated to the emission of molten rocks at temperatures between 900-1500K, and to power releases typically above 10 Watts. Such high-temperature, surface volcanic features present overall moderate size, spanning in width between a few tens of meters (small active lava flows) and several hundred meters (large active lava flows, molten lava l...
[1] The Hawaiian-Emperor seamount chain is the ‘‘type’’ example of an age-progressive, hot spotgenerated intraplate volcanic lineament. However, our current knowledge of the age distribution within this province is based largely on radiometric ages determined several decades ago. Improvements in instrumentation, sample preparation methods, and new material obtained by recent drilling warrant 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 ...
about 50 Km northwest of Bardeskan, Eocene volcanic and volcano sedimentary rocks of magmatic belt of north central Iran structural zone are host of Abri copper deposit. Volcanic rocks dominantly have andesitic, basalt and andesitic basalt composition, and manifested such as submarine lava flows, brecciated lavas in the present of water (agglomerate), or ash and fragmented volcanic rocks (tuffi...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید