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EnglandGeologyQuick questions
Module 2: Foundations in geology - Minerals and rocks
Quick questions on Bowen's reaction series and magma differentiation: crystallisation order and fractional crystallisation - OCR A-Level Geology
4short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What are the two branches?Show answer
Below where the branches meet, the lowest-temperature minerals crystallise in order: potassium feldspar, then muscovite, then quartz. So olivine and calcium-rich plagioclase form first (high temperature, silica-poor), and quartz forms last (low temperature, silica-rich).
What is q1?Show answer
Name the four minerals of the discontinuous branch of Bowen's reaction series, in order of crystallisation. [2 marks]
What is q2?Show answer
Explain what is meant by fractional crystallisation. [2 marks]
What is q3?Show answer
State how the silica content of a residual magma changes as early mafic minerals are removed, and why. [2 marks]
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