What is the difference between basaltic and andesitic 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).
Is basaltic magma more viscous than andesitic?
Andesitic lava is an example of a high viscosity lava whereas balastic lava has a low viscosity, so is more runny. High silica content in the andesitic lava contributes to causing this high viscosity and low silica content in the basaltic lava means it is of a lower viscosity.
Is basaltic magma hotter than andesitic magma?
Since andesitic lava has a lower level of aluminum and silica in its composition it is normally hotter with a range of 750-950° C. The last type of lava is mafic lava or basaltic lava. This is one of the hottest types of lava coming out at temperatures exceed 950 degrees Celsius.
How are basalt and andesite different How are they alike?
Whereas basalt forms a’a and pahoehoe surface forms, andesite generally produces blocky lava. Here, the surface contains smooth-sided, angular fragments (blocks) that are not as splintery or vesicular as a’a lava fragments. The blocky nature of these flows is attributed to the higher viscosity of andesite.
When compared to andesitic lavas what characteristics of basaltic lavas will be shown?
In more humid areas, the basalt has a reddish color because of the breakdown of the iron minerals to make rust. In contrast to basaltic lava flows, andesitic lava flows have a higher SiO2 content of 52–62%, which makes the lava more viscous.
Why is basalt less viscous?
Basalt is a hard, black volcanic rock with less than about 52 weight percent silica (SiO2). Because of basalt’s low silica content, it has a low viscosity (resistance to flow).
What type of magma is the hottest?
mafic
The hottest lava around today is deemed “mafic,” a type that contains mineral compositions that ensure it melts at the highest temperatures. At the moment, Kilauea, the active volcano on Hawaii, takes the ticket.
Which kind of magma is hotter basaltic or rhyolitic?
Temperature of magmas is difficult to measure (due to the danger involved), but laboratory measurement and limited field observation indicate that the eruption temperature of various magmas is as follows: Basaltic magma – 1000 to 1200oC. Andesitic magma – 800 to 1000oC. Rhyolitic magma – 650 to 800oC.
How basaltic magma is formed?
Basaltic magmas are formed by exceeding the melting point of the mantle either by adding heat, changing its composition, or decreasing its pressure. The majority of volcanism on earth can be traced back to beginning in the mantle, which is why basaltic lavas are so abundant.
How are basalt different from andesite?
It has less than 20% quartz and 10% feldspathoid by volume, with at least 65% of the feldspar in the rock consisting of plagioclase. This places andesite in the basalt/andesite field of the QAPF diagram. Andesite is further distinguished from basalt by its silica content of over 52%.
What are the compositional differences between andesite and basalt?
In contrast, here’s a basalt, which is much lower in silica and much higher in iron and magnesium, so it looks much darker. So an andesite has got a composition which is somewhere between the two in terms of its silica and magnesium.
Is basaltic magma viscous?
Viscosity of Magmas Thus, basaltic magmas tend to be fairly fluid (low viscosity), but their viscosity is still 10,000 to 100,0000 times more viscous than water. Rhyolitic magmas tend to have even higher viscosity, ranging between 1 million and 100 million times more viscous than water.
Does basaltic magma have low gas content?
The amount of gas in a magma is also related to the chemical composition of the magma. Rhyolitic magmas usually have higher gas contents than basaltic magmas.
Which is more viscous basaltic or granitic magma?
i) In general > silica content, > viscosity of magma, believed to result from tendency of complex silica anions to form long chains of molecules before crystallization begins. Thus granitic magmas are more viscous than basaltic magmas.
What is basaltic magma?
Basaltic magma is formed by the partial melting of mantle rocks. Basaltic lava is high in iron, magnesium, and calcium but low in potassium and sodium. Fluid basalt flows can extend tens of kilometers from an erupting vent. Basaltic lavas are relatively thin and are very fluid when erupted.
What is the viscosity of andesitic magma?
Andesitic magmas, in particular, have a wide range of magma viscosities, from 102 to 107 Pa s, which is due to a wide range in phenocryst contents from 0 (phenocryst‐free andesitic melt) to ∼50 vol % (50 vol % rhyolitic melt + 50 vol % phenocrysts).
How does andesitic magma form?
Andesitic magma is formed through wet partial melting of the mantle. The mantle under the ocean has contact with water. When subduction, or continental plates pulling away from one another, occurs, the mantle will heat up and water is pushed into it.
Is andesitic magma viscous?
Is andesite less dense than basalt?
Sedimentary rocks (and granite), which are rich in quartz and feldspar, tend to be less dense than volcanic rocks….Rock Densities.
| Rock | Density |
|---|---|
| Andesite | 2.5–2.8 |
| Basalt | 2.8–3.0 |
| Coal | 1.1–1.4 |
| Diabase | 2.6–3.0 |
What is the difference between basaltic and rhyolitic lava?
Basaltic lava is formed from magma that is low in silica. This makes for a more fluid magma that allows gas bubbles to expand on the way up to the surface, preventing sudden explosive activity. Rhyolitic and Andesitic lavas are formed from silica-rich magma that is very viscous.
What is the difference between andesitic magma and rhyolitic magma?
Dacitic magma is at the upper end when it comes to both silica content and temperature, and is closer in temperature and composition to Andesitic magmas, while Rhyolitic magma tends to be the cooler and thicker of the two.
What is the difference between andesitic and rhyolitic eruptions?
Lastly, andesitic eruptions have some viscosity in the lava flow Andesitic lava can be found in the Andes and other North American mountains. It is high in the rock andesite, which is the most common volcanic rock after basalt. It has course crystals. Andesitic lava flows more readily than rhyolitic lava, but not as easily as basaltic.
What is the viscosity of basaltic magma?
Because of the relatively low silica content and high temperature, Basaltic magmas have the lowest viscosity of all magma types, meaning that they are ‘thinner’ and more free-flowing – although it is still usually between 15,000 and 100,000 times less fluid (or free-flowing) than water.