What generally happens when magma encounters thick continental crust quizlet?
What generally happens when subduction-derived magma encounters thick continental crust? The magma interacts with the crust, forming felsic or intermediate compositions.
What happens when subduction-derived magma encounters overlying crust?
Describe what happens when subduction-derived magma encounters overlying crust. Mafic or intermediate magma formed from partial melting of the mantle is slowed by thick continental crust. The magma heats the surrounding rocks, causing partial melting, and produces felsic or intermediate magma.
When magma plumes hot spots encounter the oceanic crust they spread out along the boundary?
Magma can travel in regions where tectonic forces have newly fractured solid rocks. Magma can travel upward as rocks above magma chambers collapse. When magma plumes(hot spots) encounter the oceanic crust, they spread out along the boundary.
Why does magma tend to have a more felsic intermediate composition at volcanic sites associated with oceanic continental subduction?
They tend to occur along oceanic-to-oceanic or oceanic-to-continental boundaries because of subduction zones. They tend to be made of felsic to intermediate rock and the viscosity of the lava means that eruptions tend to be explosive.
What is the main cause of melting along subduction zones?
In a subduction zone (like the Cascades or the Andes), where an oceanic plate slides down under another plate, that downgoing slab releases its water as it heats up. That water then rises up into the mantle above it, causing it to melt at a lower temperature and, bam!
How is magma generated along subduction zones?
Magma is produced in subduction zones by melting of the oceanic crust of the subducting plate. The depth at which melting takes place in subduction zones is about: More crystal fractionation and significant crustal contamination.
How is magma created in a subduction zone?
As the denser tectonic plate subducts, or sinks below, or the less-dense tectonic plate, hot rock from below can intrude into the cooler plate above. This process transfers heat and creates magma. Over millions of years, the magma in this subduction zone can create a series of active volcanoes known as a volcanic arc.
How is magma created in a subduction zone quizlet?
Magma is produced in subduction zones by melting of the oceanic crust of the subducting plate.
What happens when rising mantle magma encounters felsic rocks as it rises through the continental crust?
As ultramafic magmas encounter the felsic rocks of the continental crust, they cause the most felsic minerals in those felsic rocks (the ones with the lowest melting point) to melt. Thus, felsic material is added to the magma as mafic material is lost to fractional crystalization.
Do hotspots occur under continental crust?
Most hotspot volcanoes are basaltic (e.g., Hawaii, Tahiti). As a result, they are less explosive than subduction zone volcanoes, in which water is trapped under the overriding plate. Where hotspots occur in continental regions, basaltic magma rises through the continental crust, which melts to form rhyolites.
What type of volcanic eruption happen when the magma is thicker and more vicious that made the gases difficult to escape?
Explosive eruptions Explosive eruptions generally involve magma that is more viscous and has a higher gas content. Such magma is often shattered into pyroclastic fragments by explosive gas expansion during an eruption. Volcanic eruptions may fall into six major types: Icelandic, Hawaiian, Strombolian, Vulcanian, Pelean, and Plinian.
What happens if magma is too viscous to rise through the crust to erupt at the surface?
If the magma is too viscous to rise to the surface it will become stuck in the crust to create intrusive igneous rocks.
What happens at a subduction zone?
Subduction zones are plate tectonic boundaries where two plates converge, and one plate is thrust beneath the other. This process results in geohazards, such as earthquakes and volcanoes.
How is magma formed in subduction zones?
Magma is produced in subduction zones by melting of the oceanic crust of the subducting plate. The depth at which melting takes place in subduction zones is about: More crystal fractionation and significant crustal contamination.
What happens when subduction occurs?
These plates collide, slide past, and move apart from each other. Where they collide and one plate is thrust beneath another (a subduction zone), the most powerful earthquakes, tsunamis, volcanic eruptions, and landslides occur.
What will happen to the continents as the magma pushes them?
Hot magma rises to the crust's surface, cracks develop in the ocean floor, and the magma pushes up and out to form mid-ocean ridges. Mid-ocean ridges or spreading centers are fault lines where two tectonic plates are moving away from each other.
Why does magma form at subduction zones?
As a tectonic plate slides into the mantle, the hotter layer beneath Earth's crust, the heating releases fluids trapped in the plate. These fluids, such as seawater and carbon dioxide, rise into the upper plate and can partially melt the overlying crust, forming magma.
How is magma created in the subduction zone?
As the denser tectonic plate subducts, or sinks below, or the less-dense tectonic plate, hot rock from below can intrude into the cooler plate above. This process transfers heat and creates magma. Over millions of years, the magma in this subduction zone can create a series of active volcanoes known as a volcanic arc.
What happens to the dissolved gasses in magma as the magma rises toward Earth’s surface?
Magma contains dissolved gases which provide the driving force that causes most volcanic eruptions. As magma rises towards the surface and pressure decreases gases are released from the liquid portion of the magma (melt) and continue to travel upward and are eventually released into the atmosphere.
How is magma formed at subduction point?
As the denser tectonic plate subducts, or sinks below, or the less-dense tectonic plate, hot rock from below can intrude into the cooler plate above. This process transfers heat and creates magma. Over millions of years, the magma in this subduction zone can create a series of active volcanoes known as a volcanic arc.
What type of landforms does subduction cause?
Various formations such as mountain ranges, islands, and trenches are caused by subduction and the volcanoes and earthquakes it triggers. In addition to causing earthquakes, subduction can also trigger tsunamis.
How does subduction at convergent plate boundaries lead to the formation of volcanoes?
As the sinking plate moves deeper into the mantle, fluids are released from the rock causing the overlying mantle to partially melt. The new magma (molten rock) rises and may erupt violently to form volcanoes, often building arcs of islands along the convergent boundary.
What type of volcanic eruption occurs when magma gets in contact with water resulting in the emission of pyroclastic materials?
phreatic eruptions Volcanic eruptions arise through three main mechanisms: Gas release under decompression, causing magmatic eruptions. Ejection of entrained particles during steam eruptions, causing phreatic eruptions. Thermal contraction from chilling on contact with water, causing phreatomagmatic eruptions.
Which of the following characteristics of magma affect the explosiveness of volcanic eruption?
Viscosity, together with the amount of gas dissolved in magma, can determine the explosivity of the eruption. More viscous magma with volatiles is more explosive than less viscous magma, where gases can bubble out relatively easily.
What will be the implications if a magma is too viscous?
A low-viscosity magma, like basalt, will allow the escaping gases to migrate rapidly through the magma and escape to the surface. However, if the magma is viscous, like rhyolite, its high polymerization will impede the upward mobility of the gas bubbles.
What will happen when an oceanic crust and a continental crust converge on one another?
When oceanic crust converges with continental crust, the denser oceanic plate plunges beneath the continental plate. This process, called subduction, occurs at the oceanic trenches. The entire region is known as a subduction zone. Subduction zones have a lot of intense earthquakes and volcanic eruptions.
What happens at a subduction zone quizlet?
The region where an oceanic plate sinks down into the asthenosphere at a convergent boundary, between continental and oceanic plates. Where two plates are moving apart, magma comes up to create new crust. A geologic feature in the seafloor produced by the descending plate during subduction.
What happens during a subduction?
Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the heavier plate dives beneath the second plate and sinks into the mantle.
What happens when oceanic crust collides with continental crust at a plate boundary?
When an oceanic plate converges with a continental plate, the oceanic crust will always subduct under the continental crust; this is because oceanic crust is naturally denser. Convergent boundaries are commonly associated with larger earthquakes and higher volcanic activity.
What features form as subduction produces magma?
Volcanic arcs form parallel to subduction zones. As one plate descends under another plate, it heats up and becomes magma. The magma will rise through the crust until it reaches the surface. This magma creates a chain of volcanoes or a volcanic arc near the boundary of the top plate.