What type of lava erupts at divergent boundaries?
Shield volcanoes are produced at divergent plate boundaries and intraplate. Cinder cones are made of small fragments of a variety of compositions usually from a single eruption. They are found with composite and shield volcanoes.
How is magma formed at divergent boundaries?
This reduction in overlying pressure, or decompression, enables the mantle rock to melt and form magma. Decompression melting often occurs at divergent boundaries, where tectonic plates separate. The rifting movement causes the buoyant magma below to rise and fill the space of lower pressure.
What type of plate boundary produces the most lava?
Sometimes, the plates collide with one another or move apart. Volcanoes are most common in these geologically active boundaries. The two types of plate boundaries that are most likely to produce volcanic activity are divergent plate boundaries and convergent plate boundaries.
What type of lava is erupted at convergent plate boundaries?
Composite volcanoes are common along convergent plate boundary. When a tectonic plate subducts, it melts. This creates the thick magma needed for these eruptions.
What happens to magma at divergent boundaries?
What happens to magma at divergent boundaries? it rises to the surface and cools to form new ocean lithosphere.
What is viscous lava?
Lava viscosity determines the kind of volcanic activity that takes place when the lava is erupted. The greater the viscosity, the greater the tendency for eruptions to be explosive rather than effusive. As a result, most lava flows on Earth, Mars, and Venus are composed of basalt lava.
What type of magma would form at the convergent boundary and what forms at divergent boundary?
Felsic and intermediate magmas and rocks tend to form at ocean–continent or ocean–ocean convergent boundaries, or where hot spots are found on land, and mafic magmas form in divergent plate boundaries and hot spots in the ocean.
What forms at a divergent boundary?
A divergent plate boundary often forms a mountain chain known as a ridge. This feature forms as magma escapes into the space between the spreading tectonic plates.
What type of magma is found at convergent boundaries?
generation. 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 formed at divergent boundary?
A divergent plate boundary often forms a mountain chain known as a ridge. This feature forms as magma escapes into the space between the spreading tectonic plates.
What is basaltic lava?
Basaltic lava is another term for mafic lava. Mafic lava is molten rock that is enriched in iron and magnesium and low in silica. When mafic lava cools on the earth's surface, it forms basalt, which is why mafic lava is commonly called 'basaltic lava.
Is basaltic lava viscous?
A basaltic lava flow has a low viscosity due to its low SiO2 content. Eruptions associated with basaltic lava usually are not explosive due to the low silica and gas content. Gases escape more easily when silica content is low. Because of the low viscosity, basaltic lava flows spread out, forming extensive layers.
What happens at a divergent plate boundary?
Divergent (Spreading):This is where two plates move away from each other. Molten rock from the mantle erupts along the opening, forming new crust. The earthquakes that occur along these zones, called spreading centers, are relatively small.
What happens when plates diverge?
The plates diverge and this causes the construction of new rock. It happens when two tectonic plates pull apart and rock from the mantle rises up through the opening to form new surface rock when it cools. It happens at the start of a new ocean and continues at the mid-ocean ridge while the ocean is opening.
Where is andesitic lava found?
the Andes Mountains Andesites erupt at temperatures between 900 and 1100 ° C. Facts: The word andesite is derived from the Andes Mountains, located along the western edge of South America, where andesite rock is common.
What are 3 things that are formed at a divergent boundary?
Effects that are found at a divergent boundary between oceanic plates include: a submarine mountain range such as the Mid-Atlantic Ridge; volcanic activity in the form of fissure eruptions; shallow earthquake activity; creation of new seafloor and a widening ocean basin.
What landforms could be formed from divergent plate boundaries?
Answer and Explanation: Two landforms that are created from divergent boundaries are rift valleys and mid-oceanic ridges.
Where does pahoehoe lava form?
Pahoehoe is a smooth, ropy lava, common on the Hawaiian islands.
What is andesitic lava?
Andesite is a gray to black volcanic rock with between about 52 and 63 weight percent silica (SiO2). Andesites contain crystals composed primarily of plagioclase feldspar and one or more of the minerals pyroxene (clinopyroxene and orthopyroxene) and lesser amounts of hornblende.
What is granitic lava?
Granitic magmas are very different from basaltic magmas. They have about 20 percent more silica, and the minerals in granite (mica, amphibole) have a lot of water in their crystal structures. Granitic magmas are mostly exclusive to regions of continental crust.
What forms when a divergent boundary occurs on land?
Divergent boundaries within continents initially produce rifts, which eventually become rift valleys. Most active divergent plate boundaries occur between oceanic plates and exist as mid-oceanic ridges.
Where is rhyolitic lava 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 occurs at divergent plate boundaries?
Divergent boundaries occur along spreading centers where plates are moving apart and new crust is created by magma pushing up from the mantle. Picture two giant conveyor belts, facing each other but slowly moving in opposite directions as they transport newly formed oceanic crust away from the ridge crest.
What do divergent boundary create?
A divergent boundary occurs when two tectonic plates move away from each other. Along these boundaries, earthquakes are common and magma (molten rock) rises from the Earth's mantle to the surface, solidifying to create new oceanic crust. The Mid-Atlantic Ridge is an example of divergent plate boundaries.
What is the difference between pahoehoe and aa lava?
Pahoehoe is a smooth, ropy lava, common on the Hawaiian islands. 'A'a is a more chunky and thick flow, that is most commonly associated with composite volcano eruptions. 'A'a lava flows are also called clinkers, because of their rough and jagged appearance.
What is ropy lava?
Definition of ropy lava : lava marked with wrinkles resembling rope : pahoehoe.
What is rhyolitic lava?
Rhyolitic lavas are viscous and tend to form thick blocky lava flows or steep-sided piles of lava called lava domes. Rhyolite magmas tend to erupt explosively, commonly also producing abundant ash and pumice.
How is andesitic lava formed?
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.
What plate boundary causes volcanoes?
Plates rip apart at a divergent plate boundary, causing volcanic activity and shallow earthquakes; and. At a convergent plate boundary, one plate dives or “subducts” beneath the other, resulting in a variety of earthquakes and a line of volcanoes on the overriding plate.
How is pahoehoe lava formed?
Pahoehoe forms when lava flows more slowly. Under these circumstances, a well-developed skin can form which inhibits heat loss. When a tear in the skin does form, it is readily healed. Both magma discharge rate and the steepness of the slope over which the lava flows affect the flow rate.