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Because of these mixing mechanisms, lavas may have different compositions but similar appearances, or similar compositions with different appearances. [3] The eruption that produced the Chaos Crags consisted of more than 90% mixed magma, [ 12 ] and likely resulted from the interaction of felsic and mafic magmas.
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, diabase and gabbro. Mafic rocks often also contain calcium -rich varieties of plagioclase ...
Mechanism of formation. Bimodal volcanism is normally explained as a result of partial melting of the crust, creating granitic magmas, during the emplacement of large volumes of relatively hot basaltic magma from a mantle source. The two magma types then form separate magma chambers giving rise to periodic eruption of both types of lava. [7][8]
Magma that cools slowly within a magma chamber usually ends up forming bodies of plutonic rocks such as gabbro, diorite and granite, depending upon the composition of the magma. Alternatively, if the magma is erupted it forms volcanic rocks such as basalt , andesite and rhyolite (the extrusive equivalents of gabbro, diorite and granite ...
Calabozos lies between two different types of volcanism—to its north, andesite and rhyolite are the primary constituents of lava while its southern neighbors are composed of more mafic andesite and basalt. It is mainly basaltic andesite and rhyodacite that make up Calabozos, forming a calcalkilic suite rich with potassium.
The Lassen volcanic center is fed by two magma chambers, one calc-alkaline reservoir common to the rest of the Cascade Volcanoes, and the other a smaller volume of low-potassium olivine tholeiitic basalt associated with the Basin and Range province. [9] Within the region, most if not all of the volcanic rock has erupted in the past 3 million ...
A chain of volcanoes is created as the lithosphere moves over the source of magma. In geology, hotspots (or hot spots) are volcanic locales thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle. [1] Examples include the Hawaii, Iceland, and Yellowstone hotspots. A hotspot's position on the Earth's ...
Magmatism. Geological map showing the Gangdese batholith, which is a product of magmatic activity about 100 million years ago. Magmatism is the emplacement of magma within and at the surface of the outer layers of a terrestrial planet, which solidifies as igneous rocks. It does so through magmatic activity or igneous activity, the production ...