Search results
Results from the WOW.Com Content Network
In geology, felsic is a modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz. [1] It is contrasted with mafic rocks, which are richer in magnesium and iron. Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium ...
Felsite is a very fine-grained volcanic rock that may or may not contain larger crystals. Felsite is a field term for a light-colored rock that typically requires petrographic examination or chemical analysis for more precise definition. Color is generally white through light gray, or red to tan and may include any color except dark gray, green ...
The Pliocene ( / ˈplaɪ.əsiːn, ˈplaɪ.oʊ -/ PLY-ə-seen, PLY-oh-; [6][7] also Pleiocene) [8] is the epoch in the geologic time scale that extends from 5.33 to 2.58 [9] million years ago (Ma). It is the second and most recent epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the ...
Archean felsic volcanic rocks are felsic volcanic rocks that were formed in the Archean Eon (4 to 2.5 billion years ago). [2] The term "felsic" means that the rocks have silica content of 62–78%. [3] Given that the Earth formed at ~4.5 billion year ago, [4] Archean felsic volcanic rocks provide clues on the Earth's first volcanic activities ...
Felsic or silicic magmas have a silica content greater than 63%. They include rhyolite and dacite magmas. With such a high silica content, these magmas are extremely viscous, ranging from 10 8 cP (10 5 Pa⋅s) for hot rhyolite magma at 1,200 °C (2,190 °F) to 10 11 cP (10 8 Pa⋅s) for cool rhyolite magma at 800 °C (1,470 °F). [ 21 ]
Organic geochemistry, the study of the role of processes and compounds that are derived from living or once-living organisms. [13] Photogeochemistry is the study of light-induced chemical reactions that occur or may occur among natural components of the Earth's surface. [14]
Pages in category "Felsic rocks" The following 9 pages are in this category, out of 9 total. This list may not reflect recent changes. A. Adakite; Aplite; Appinite;
A 900,000‑year‑long period of quiescence followed after the felsic shield-building stage, during which time erosion ate away at the shield's gentle slopes. This quiescence was followed by a mafic capping stage between 2.2 and 0.8 million years ago, but renewed activity might have occurred in the last 340,000 years.