Asked by brittney klann on Jul 16, 2024
Verified
What generally happens when subduction-derived magma encounters thick continental crust?
A) most magma reaches the surface with minor modification
B) the magma solidifies in sheeted dikes with a composition of basalt
C) the magma interacts with the crust, forming felsic or intermediate compositions
D) the oceanic crust melts
Subduction-Derived Magma
Magma that is generated in subduction zones when one tectonic plate moves under another, melting due to high pressure and temperature.
Continental Crust
The layer of igneous, sedimentary, and metamorphic rocks that forms the continents and the areas of shallow seabed close to their shores.
Felsic Composition
Rocks rich in silica and aluminum, characterized by lighter minerals like quartz and feldspar.
- Understand the connection between magma types (felsic, mafic) and volcanic structures.
- Clarify the sequence of processes leading to the emergence and transformation of magma, including the role of partial melting and differentiation within magma.
- Recognize the significance of water in the formation of magma, especially in subduction zones.
Verified Answer
AK
Aliya KabdiyevaJul 18, 2024
Final Answer :
C
Explanation :
When subduction-derived magma encounters thick continental crust, it typically interacts with the crustal material. This interaction often results in the magma evolving into more felsic or intermediate compositions due to processes like assimilation, where the magma incorporates elements of the continental crust, and fractional crystallization, where different minerals crystallize out of the magma at different temperatures, changing its composition.
Learning Objectives
- Understand the connection between magma types (felsic, mafic) and volcanic structures.
- Clarify the sequence of processes leading to the emergence and transformation of magma, including the role of partial melting and differentiation within magma.
- Recognize the significance of water in the formation of magma, especially in subduction zones.