What magma is the most abundant type of erupted at oceanic spreading centers?
Basalt is the most common magma erupted along oceanic rift systems.
Which kind of volcanism is typical of mid ocean ridges?
MID-OCEAN RIDGES, NEAR-RIDGE SEAMOUNTS, HOT SPOT VOLCANOES, CALIFORNIA MARGIN SEAMOUNTS – Basaltic volcanism in the deep oceans has long been thought to consist of quietly effusive discharge of lava to form pillow, lobate, and sheet flows.
Which kind of eruptive activity is most likely to be highly explosive quizlet?
Which kind of eruptive activity is most likely to be highly explosive? Fissure eruptions feeding lava to flood basalt accumulations.
Which kind of eruptive activity is highly explosive?
5. Which kind of eruptive activity is most likely to be highly explosive? Eruptions of big, continental margin, composite cones or stratovolcanoes. Lava flows from a large shield volcano on an oceanic island.
Which type of magma will produce the least explosive volcanic eruption quizlet?
A magma with low silica (<45%) will be runny and so the eruption will not be explosive.
What type of volcanic material indicates an eruption under water?
Lava flows produced by eruptions under water are called pillow lavas. If the viscosity is high, but the gas content is low, then the lava will pile up over the vent to produce a lava dome or volcanic dome.
What type of magma is created at mid-ocean ridge quizlet?
How is magma produced at Mid-Ocean Ridges and at Hot Spots? Magma with mafic composition erupts 1) basaltic lavas. As it cools and crystallizes the intermediate point takes away elements changing the composition to andesitic. Remaining melt is enriched with silica (felsic).
What is basaltic magma?
Basaltic (or mafic) magma predominates in nonexplosive volcanic eruptions. It is a high-temperature magma (1,200 °C (about 2,200 °F)) characterized by flowing lava, and it is made up of about 45–55 percent silica (SiO2) by weight.
Which magma type erupts most violently?
A Plinian eruption is the most explosive of the eruption types.
Which type of magma will produce the most explosive volcanic eruption?
andesitic to rhyolitic magmas Explosive eruptions are favored by high gas content & high viscosity magmas (andesitic to rhyolitic magmas). The explosive bursting of bubbles fragments the magma into clots of liquid that cool as they fall through the air.
What is the most explosive type of magma?
Lavas and pyroclastics are usually andesitic to rhyolitic in composition. Due to the higher viscosity of magmas erupted from these volcanoes, they are usually more explosive than shield volcanoes.
Which of the following magma types has the highest 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 type of magma would you expect to produce the most explosive volcanic eruption?
Explosive eruptions are favored by high gas content & high viscosity magmas (andesitic to rhyolitic magmas). The explosive bursting of bubbles fragments the magma into clots of liquid that cool as they fall through the air.
Which type of magma has the highest eruptive temperature?
CONTROLS ON EXPLOSIVITY
| SiO2 | MAGMA TYPE | TEMPERATURE (centigrade) |
|---|---|---|
| ~50% | mafic | ~1100 |
| ~60% | intermediate | ~1000 |
| ~70% | felsic | ~800 |
What is the source of magma at mid-ocean ridges quizlet?
A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. This uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary.
How is magma produced along a spreading center quizlet?
Decompression melting is the process that generates great volumes of magma through melting peridotite at spreading centers.
Where is andesitic magma found?
Granitic, or rhyolitic, magmas and andesitic magmas are generated at convergent plate boundaries where the oceanic lithosphere (the outer layer of Earth composed of the crust and upper mantle) is subducted so that its edge is positioned below the edge of the continental plate or another oceanic plate.
What is mafic magma?
Describes magma that contains lower amounts of silica and is generally less viscous and less gas-rich than silicic magma. Tends to erupt effusively, as lava flows. Includes andesites (57-63 percent SiO2), basaltic andesites (53-57 percent SiO2), and basalts (47-53 percent SiO2).
Which magma type erupts most violently quizlet?
Rhyolitic– Highest Viscosity (thickest), causes the most violent explosive eruptions.
Which type of magma forms at the mid ocean ridges or at hot spots under the ocean crust and is high in iron and magnesium but is low in silica?
basalt The basalt of the oceanic crust formed at mid-oceanic ridges, so it is known as "MORB" – Mid-Ocean Ridge Basalt.
What magma types produce explosive and effusive eruptions?
Overview. There are two major groupings of eruptions: effusive and explosive. Effusive eruption differs from explosive eruption, wherein magma is violently fragmented and rapidly expelled from a volcano. Effusive eruptions are most common in basaltic magmas, but they also occur in intermediate and felsic magmas.
Which magma composition is most explosive?
CONTROLS ON EXPLOSIVITY
| SiO2 | MAGMA TYPE | ERUPTION STYLE |
|---|---|---|
| ~50% | mafic | nonexplosive |
| ~60% | intermediate | intermediate |
| ~70% | felsic | explosive |
What is the source of magma for seafloor spreading quizlet?
What is the source of magma for seafloor spreading? Occurs along crests of oceanic ridges where hot mantle rock rises to replace material that has shifted horizontally.
How does magma form at an oceanic oceanic convergence boundary aka a subduction zone with two oceanic plates )?
When the oceanic plate is subducted due to partial melting of the asthenosphere magma with an andesitic composition is formed. The magma formed is less dense than the surrounding material so it rises to the surface to form a magmatic arc on the edge of the continent which the oceanic plate is subducted under.
Where is rhyolitic magma found?
Rhyolite has been found on islands far from land, but such oceanic occurrences are rare. The tholeiitic magmas erupted at volcanic ocean islands, such as Iceland, can sometimes differentiate all the way to rhyolite, and about 8% of the volcanic rock in Iceland is rhyolite.
What is felsic magma?
Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. Felsic magma or lava is higher in viscosity than mafic magma/lava. Felsic rocks are usually light in color and have specific gravities less than 3.
Which type of magma is known for the most violent eruptions?
andesitic Explosive eruptions are favored by high gas content and high viscosity (andesitic to rhyolitic magmas).
What type of magma is most erupted to form shield volcanoes?
basalt Magma Composition Shield volcanoes are usually basalt but can be constructed of mostly andesitic lava flows. Mauna Loa and Kīlauea erupt almost exclusively basaltic lavas.
What type of eruption is mafic magma?
The adjacent Magma Comparison table summarizes properties of the two basic magma types. Mafic magma produces high volume, slow moving, effusive eruptions….
| MAGMA COMPARISON | ||
|---|---|---|
| Property | Mafic Magma | Felsic Magma |
| Formation Temp. | higher | lower |
| Example of Rock | basalt | andesite |
| Eruption Type | effusive | explosive |
How is magma produced along a spreading center?
Along mid-ocean ridges (also called spreading centers), tectonic plates are moving apart. Molten rock rises from Earth's mantle into the gap between the separating plates and produces extensive lava flows. Along oceanic trenches, tectonic plates are colliding so that one plate is descending below another plate.