What shape does basaltic lava form?
Shield volcanoes
Shield volcanoes Where a volcano produces low viscosity, runny lava, it spreads far from the source and forms a volcano with gentle slopes: a shield volcano. Most shield volcanoes are formed from fluid, basaltic lava flows. Mauna Kea and Mauna Loa are shield volcanoes.
What does basaltic lava look like?
Basalt is erupted at temperatures between 1100 to 1250 ° C. Volcanic rock (or lava) that characteristically is dark in color (gray to black), contains 45 to 53 percent silica, and is rich in iron and magnesium. Basaltic lavas are more fluid than andesites or dacites, which contain more silica.
What is basaltic lava called?
Basaltic lava is another term for mafic lava. Mafic lava is molten rock that is enriched in iron and magnesium and low in silica.
What are the 4 types of lava?
Because of the role of silica in determining viscosity and because many other properties of a lava (such as its temperature) are observed to correlate with silica content, silicate lavas are divided into four chemical types based on silica content: felsic, intermediate, mafic, and ultramafic.
Is basaltic lava thick or thin?
They are relatively thin (1-2 m) and very fluid with low viscosities. They advance downslope in a sort of smooth “rolling motion.” The front of the flow usually advances as a thin (< 20 cm) glowing lobe that will chill and crust over after 1-2 meters of flow.
What type of volcano has basaltic magma?
Shield volcanoes are formed by basaltic magma, typically above a mantle plume, whereas the stratovolcanoes (sometimes referred to as composite volcanoes) are formed by andesitic/rhyolitic magma.
What does basaltic lava cool into?
Pahoehoe can take several different forms. As the smooth lava surface cools to turns to a dark gray color and becomes less fluid and more viscous, behaving more like a plastic substance than a truly liquid substance.
What are the characteristics of basaltic magma?
Basaltic magma is high in iron, magnesium, and calcium but low in potassium and sodium. It ranges in temperature from about 1000oC to 1200oC (1832oF to 2192oF). Andesitic magma has moderate amounts of these minerals, with a temperature range from about 800oC to 1000oC (1472oF to 1832oF).
What are the types of basaltic lava?
Lavas, particularly basaltic ones, come in two primary types: pahoehoe (pronounced ‘paw-hoey-hoey”) and aa (pronounced “ah-ah”). Both names, like a number of volcanological terms, are of Hawaiian origin.
What are the two types of basaltic lava flows?
Basaltic lava generally takes two distinct forms known by the Hawaiian terms pahoehoe and aa. Pahoehoe has a smooth wavy surface that resembles twisted rope. It advances by extruding molten toes of lava beneath a thin, flexible crust. As it travels pahoehoe lava often changes to blocky flows called aa.
What is the difference between andesitic and basaltic lava?
Both lavas are formed at different plate boundaries which is why they have different silica contents: the basaltic lava forms from the hot mantle material at constructive plate boundaries and hotspots whereas the andesitic lava forms at destructive plate boundaries from melting crust.
