eoTutor: Nature of Volcanic Eruptions The movement of magma from great depths to the surface is largely influenced by th

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Eotutor Nature Of Volcanic Eruptions The Movement Of Magma From Great Depths To The Surface Is Largely Influenced By Th 1 (61.58 KiB) Viewed 205 times

Eotutor Nature Of Volcanic Eruptions The Movement Of Magma From Great Depths To The Surface Is Largely Influenced By Th 2 (30.33 KiB) Viewed 205 times

eoTutor: Nature of Volcanic Eruptions The movement of magma from great depths to the surface is largely influenced by the composition of the magma. This is because different magma compositions have different densities. Magma density changes as it passes through Earth's layers. In general, it can be assumed that magma at a shallower depth is less dense than magma at a greater depth The depth of the magma reflects the relative density of (1) a crust layer, and (2) magma body. In general, the relative density of magma and the layer where they are found can be summarized as follows. A magma with a density less than a layer will rise through and above the layer A magma with a density greater than a layer will sink through and below the layer. The sequence of events that drives the movement of magma due to composition and density differences are summarized below. Refer to the illustration below as you read the following steps: 1. Most magmas originate in the upper part of the asthenosphere, a hot layer where partial melting of solid mantle materials results in magma with a matic composition. Because this magma is less dense than the lower lithosphere, it will begin to rise through the lithosphere. 2. Eventually the magma will reach a point where its density is higher than that of the upper lithosphere and/or crust (note that the crust is siliceous in composition). so it will begin to pond into a large magma chamber rather than rising further. 3. As the ponded magma begins to cool, its composition changes; high-density minerals with relatively low sillica content crystallize first, leaving the remaining magma in the chamber with a more intermediate or feisic composition. 4. This lower-density, silica-rich magma can then rise further through the crust until it reaches a point closer to the surface and forms another magma chamber 5. Degassing of volatiles from this magma chamber is what drives a volcanic eruption. Atmosphere Upper Lithosphere/Crust -Lower Lithosphere Asthenosphere Vent Condkat- Crust hosphere Asthenosphere E3 E3
Considering how magma composition and temperature change as it rises toward the surface, categorize each of the magmas described below in terms of their position within the lithosphere and uppermost asthenosphere. Drag the appropriate items into their respective bine. View Available Hint(a) Reset Help Magns with greatest ic content Mage with density less than the lower thosphere but higher than the crust Magma with density equal to or less than the crust Magma undergoing partial crystallization of high-density minerals Magma underg degassing during anuption Magma with the highest temperature Asthenosphere Upper Lithosphere/Crust Lower Lithosphere