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Earth Systems and Cycles
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Igneous rocks form from the cooling and solidification of magmas, most of which originate deep in Earth. Magmas, and thus igneous rocks, originate by whole or partial melting of a parent rock. The elements silicon and oxygen dominate almost all magmas. Depending on the depth in Earth, typical magmas have temperatures between 700 °C and 1300 °C (1300 °F to 2400 °F). If a magma cools and solidifies underground, the result is an intrusive (also called plutonic) igneous rock. If a magma reaches the surface, it becomes lava and will cool to form an extrusive (also called volcanic) rock. Some extrusive rocks form from lava flows, but if an eruption is very explosive, magmas may become airborne fragmental material, including fine ash and sometimes coarser material, which settles to produce air-fall volcanic rocks.
Magmatism and Magmatic Rocks
Published in Aurèle Parriaux, Geology, 2018
In contrast to plutonic rocks, volcanic rocks are not widely used in industry, except for basalt, which is traditionally used as building stone, and some lavas used for roofing slabs. Today, volcanic rocks are used primarily for light aggregate. Because they contain amorphous silica, the risk of alkali reaction must be taken into account (see § 5.2.1.1). Pozzolans are important in the cement industry because they react with low-temperature calcium hydroxide in the presence of water to create very stable hydrated compounds. The resulting cement is very resistant over the long term.
Magmatism and Magmatic Rocks
Published in Aurèle Parriaux, Geology, 2018
Magmatic rocks result from the solidification of magma either at depth (plutonic rocks) or at the surface (volcanic rocks). Plutonic rocks are completely crystallized, massive and solid. Volcanic rocks are microcrystalline or amorphous, massive and hard (lavas) or powdery (pyroclastic rocks) depending on the type of eruption. Magmatic rocks form at oceanic ridges, in subduction zones or through lithospheric plates. Their composition is directly influenced by the tectonic environment in which they occur.
Zircon U–Pb age, whole-rock geochemistry and Nd–Sr–Pb isotope constraints on petrogenesis of the Eocene Zajkan gabbro–monzogranite intrusion, Tarom-Hashtjin magmatic belt, NW Iran
Published in Australian Journal of Earth Sciences, 2022
M. A. A. Mokhtari, H. Kouhestani, K. Z. Qin
In the Zajkan area, the major geological units are Eocene volcanic–volcaniclastic rocks (>2000 m in thickness; Hosseiny et al., 2016) that were intruded by the Zajkan intrusion (Figure 2). Volcanic rocks are andesite, trachyandesite and porphyritic andesite with local olivine basalt, andesitic basalt and rhyodacite lava flows (Hosseiny et al., 2016; Kouhestani et al., 2019a, 2019b). Andesites and trachyandesites comprise plagioclase, hornblende and biotite phenocrysts within fine-grained groundmass. Porphyritic andesite is composed of centimetre-sized plagioclase phenocrysts along with hornblende and minor small clinopyroxene phenocrysts set in a fine-grained to glassy matrix (Hosseiny et al., 2016). The olivine basalts consist of olivine, plagioclase, and clinopyroxene phenocrysts set in an intersertal and fine-grained groundmass (Hosseiny et al.,2016). Andesitic basalts show a porphyritic texture and consist principally of distinctive zoned phenocrysts of plagioclase and pyroxene (Hosseiny et al., 2016). The rhyodacite lavas are composed of largely plagioclase, sanidine, and quartz phenocrysts and rare biotite with a porphyritic texture (Hosseiny et al., 2016). The volcaniclastic strata is mainly tuff (i.e. crystal tuff, crystal lithic tuff, lapilli tuff, and tuff breccia), ignimbrite, agglomerate, sandy tuff and tuffaceous sandstone, with minor conglomerate intercalations (Hosseiny et al., 2016).
Enchasing anthropogenic element trackers for evidence of long-term atmospheric depositions in mine environs
Published in Journal of Environmental Science and Health, Part A, 2019
Biljana Balabanova, Trajče Stafilov, Robert Šajn
The investigated area covers Bregalnica river basin (N: 41°27′-42°09′ and E: 22°55′-23°01′) (Fig. 1). This area lies on the two main tectonic units – the Serbian-Macedonian massive and the Vardar zone.[25] The polyphasal Neogene deformations through the insignificant movements associated with the volcanic activities had direct influence on the gradual formation of the reefs and the formation of deposits in the existing basins. The oldest volcanic rocks occur in the areas of Bučim, Damjan, the Borov Dol district and in the zone of Toranica, Sasa, Delčevo, and Pehčevo.[25] The origin of these oldest volcanic rocks is related to the Oligocene – the early Miocene period. Volcanic rocks are categorized as follows: andesite, latite, quartz-latite, dacite. Volcanism appears sequentially and, in several phases, forming sub-volcanic areas. On the other hand, the pyroclastites are most frequently found in the Kratovo-Zletovo volcanic area, where the dacites and andesites are the oldest formations. Generalized geology of the area is produced based on the data provided by Rakićević et al.[26] and the geological map is presented in Figure 2.
Study on ecological adaptability of traditional village construction in Hainan volcanic areas
Published in Journal of Asian Architecture and Building Engineering, 2023
Chulin Chen, Yuchen She, Qianxin Chen, Sufang Liu
Volcanic rocks are formed by cooling and condensing magma from volcanic eruptions. There is a wide distribution of volcanic rocks in Hainan volcanic areas, and the most common type is basalt. The rock is mainly composed of silica, calcium, magnesium, sodium and other mineral trace elements. It has the characteristics of lightweight, weathering resistance and corrosion resistance, and has good adaptability to humid and rainy environments. Besides, the natural holes of volcanic rock have good permeability, which can infiltrate and exchange the indoor and outdoor air in hot weather, so as to reduce the indoor temperature, adjust the air humidity and improve the indoor environment.