In general, which of the statements below best describe what happens in terms of composition as crystallization proceeds down the Bowen's reaction series (shown in the figure)?
A)The early-formed silicates are enriched in iron and magnesium, resulting in such rocks as andesite and granite. As crystallization proceeds, the later-formed silicates are enriched in sodium, potassium, and silicon, resulting in peridotite and basalt.
B)The early-formed carbonates are enriched in calcium and carbonate, resulting in such rocks as limestone. As crystallization proceeds, the later-formed carbonates are enriched in fossils, resulting in fossiliferous limestone and coquina.
C)The early-formed silicates are enriched in iron and magnesium, resulting in such rocks as peridotite and basalt. As crystallization proceeds, the later-formed silicates are enriched in sodium, potassium, and silicon, resulting in andesite and granite.
D)The early-formed silicates are enriched in sodium, potassium, and silicon, resulting in such rocks as peridotite and basalt. As crystallization proceeds, the later-formed silicates are enriched in iron and magnesium, resulting in andesite and granite.

Question

In general, which of the statements below best describe what happens in terms of composition as crystallization proceeds down the Bowen's reaction series (shown in the figure)?
A)The early-formed silicates are enriched in iron and magnesium, resulting in such rocks as andesite and granite. As crystallization proceeds, the later-formed silicates are enriched in sodium, potassium, and silicon, resulting in peridotite and basalt. 
B)The early-formed carbonates are enriched in calcium and carbonate, resulting in such rocks as limestone. As crystallization proceeds, the later-formed carbonates are enriched in fossils, resulting in fossiliferous limestone and coquina. 
C)The early-formed silicates are enriched in iron and magnesium, resulting in such rocks as peridotite and basalt. As crystallization proceeds, the later-formed silicates are enriched in sodium, potassium, and silicon, resulting in andesite and granite. 
D)The early-formed silicates are enriched in sodium, potassium, and silicon, resulting in such rocks as peridotite and basalt. As crystallization proceeds, the later-formed silicates are enriched in iron and magnesium, resulting in andesite and granite.

Quizplus · Accepted Answer

The Bowen's reaction series shows the sequence in which silicate minerals crystallize as magma cools and changes composition. The series starts with the early-formed mafic minerals high in iron and magnesium, such as olivine and pyroxene, which lead to rocks like peridotite and basalt. As crystallization proceeds, the later-formed felsic minerals, rich in sodium, potassium, and silicon, such as feldspar and quartz, are enriched, resulting in rocks like andesite and granite. Therefore, option C is the best choice as it correctly describes the trend in composition as crystallization proceeds down the Bowen's reaction series.

In General, Which of the Statements Below Best Describe What