IGNEOUS PETROLOGY — Model that explains sequences of igneous rocks. Which conceptual model best explains how different igneous rocks form from a cooling magma by systematic mineral crystallization sequences?

Introduction / Context:As magma cools, minerals crystallize in a predictable order. This order controls the evolving composition of the remaining melt and thus the rock types produced. Understanding this sequence is foundational in igneous petrology.

Given Data / Assumptions:

• The question seeks the model for mineral crystallization order and resulting rock varieties.
• We compare broad Earth-system cycles with a specific igneous model.
• No equations are needed; it is a conceptual recall item.

Concept / Approach:Bowen’s reaction series depicts discontinuous and continuous branches: olivine → pyroxene → amphibole → biotite (discontinuous), and plagioclase evolving from Ca-rich to Na-rich (continuous). As crystallization proceeds, magma composition shifts from mafic to felsic, explaining basalt, andesite, dacite, and rhyolite generation pathways.

Step-by-Step Solution:Identify the need: a crystallization-order model.Recall Bowen’s series as the specific petrologic diagram for this purpose.Contrast with the rock cycle, which is a high-level transformation loop among igneous, sedimentary, and metamorphic rocks.Select Bowen’s reaction series.

Verification / Alternative check:Introductory geology textbooks universally present Bowen’s series to explain fractional crystallization and the derivation of igneous rock suites.

Why Other Options Are Wrong:Rock cycle — too general; not a crystallization sequence model.Both are similar — false; they address different scales.None — incorrect since a well-known model exists.Plate-tectonic cycle — addresses crustal recycling, not mineral order.

Common Pitfalls:Confusing broad Earth cycles with specific igneous processes. The keyword is “crystallization sequence.”

Final Answer:Bowen's reaction series