Which has a more mafic composition rhyolite or basalt

A central area focused on South and Middle Sister is composed of more evolved (andesite to rhyolite) and relatively young volcanic rocks that are surrounded by mafic (basalt to andesite) volcanoes. North Sister is part of this so-called mafic periphery and is almost entirely older than eruptive products of the other two Sisters. The more mafic mineral, the more fluent the magma. In other words, basalt-rich magma is more flowing and felsic-rich magma is more viscous. So, the mafic composition increase the flow of magma.

Jun 23, 2019 · All the three rocks, rhyolite, andesite and basalt are extrusive igneous rocks formed by volcanic eruptions. Rhyolite is an extrusive igneous rock that has nearly the same composition as granite. It contains more silica. Rhyolite is the volcanic equivalent of granite. c. which has a more mafic composition? d. which has a greater percentage of biotite in it? e. which contains quartz? 13. name a felsic, intrusive rock. b) Rhyolite is a Grey, white, light black rock, while Basalt is Black, Brown, Light to Dark Grey. Rhyolite appears to be banded while the apperance of...

Rhyolite magmas can be produced by igneous differentiation of a more mafic (silica-poor) magma, through fractional crystallization or by assimilation Obsidian is usually of rhyolitic composition, and it has been used for tools since prehistoric times.[37] Obsidian scalpels have been investigated for use...A flood basalt is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Common mafic rocks include basalt, diabase and gabbro. In a general sense, it is the intermediate type between basalt and rhyolite, and ranges from 57 to 63% silicon dioxide (SiO 2 ) as illustrated in TAS diagrams.

Basalt generally has a composition of 45–55 wt% SiO 2, 2–6 wt% total alkalis, 0.5–2.0 wt% TiO 2, 5–14 wt% FeO and 14 wt% or more Al 2 O 3. Contents of CaO are commonly near 10 wt%, those of MgO commonly in the range 5 to 12 wt%. This page intentionally left blank IGNEOUS ROCKS: A CLASSIFICATION AND GLOSSARY OF TERMS Decades of field and microscope studies and more recent quantitative geo- chemical analyses have resulted in a vast, and sometimes overwhelming...