question 45\n2 pts\nwhich of the following igneous rock textures indicates the slowest cooling…

question 45\n2 pts\nwhich of the following igneous rock textures indicates the slowest cooling rate?\npyroclastic\nporphyritic\nglassy\nphaneritic\naphanitic\nquestion 46\n2 pts\nwhich of the following describes the formation of the oceanic lithospheric mantle?\nsediment scraped from subducting oceanic lithosphere accumulates in the accretionary prism.\ndecompression melting of ultramafic asthenosphere produces mafic magma which cools to form mafic rocks.\nflux melting in the asthenosphere produces magmas which cool at the base of the crust.\ngradual cooling of the uppermost mantle beneath oceanic crust.

question 45\n2 pts\nwhich of the following igneous rock textures indicates the slowest cooling rate?\npyroclastic\nporphyritic\nglassy\nphaneritic\naphanitic\nquestion 46\n2 pts\nwhich of the following describes the formation of the oceanic lithospheric mantle?\nsediment scraped from subducting oceanic lithosphere accumulates in the accretionary prism.\ndecompression melting of ultramafic asthenosphere produces mafic magma which cools to form mafic rocks.\nflux melting in the asthenosphere produces magmas which cool at the base of the crust.\ngradual cooling of the uppermost mantle beneath oceanic crust.

Answer

Brief Explanations:

  • For Question 45: Phaneritic igneous rocks have large - sized crystals which form when magma cools slowly deep within the Earth's crust, allowing enough time for the crystals to grow.
  • For Question 46: The oceanic lithospheric mantle is formed by the decompression melting of ultramafic asthenosphere which produces mafic magma that cools to form mafic rocks.

Answer:

Question 45: Phaneritic Question 46: Decompression melting of ultramafic asthenosphere produces mafic magma which cools to form mafic rocks.