What This Document Is
This is a detailed exploration of igneous rock differentiation, a core concept within petrology. It delves into the processes that create the diverse suite of igneous rocks found in various geological settings – from volcanic islands and single intrusions to extensive continental formations. The material focuses heavily on crystal fractionation as a primary driver of these changes, and examines real-world examples of this process occurring within layered mafic intrusions. It builds upon foundational knowledge of igneous rock composition and mineralogy.
Why This Document Matters
This resource is invaluable for students in introductory petrology courses seeking a deeper understanding of how magmas evolve. It’s particularly helpful when studying the formation of complex igneous bodies and interpreting the relationships between different rock types within a given igneous province. Geosciences students preparing for fieldwork or advanced study in igneous petrology will find this a strong foundation. It’s best used *after* gaining a basic understanding of Bowen’s Reaction Series and common igneous mineral compositions.
Common Limitations or Challenges
This material focuses specifically on differentiation processes and does not provide a comprehensive overview of all igneous rock types or their initial formation. It assumes a foundational understanding of igneous textures and mineral identification. While several specific geological locations are referenced, detailed regional geological context beyond their relevance to differentiation is not included. It does not cover all possible differentiation mechanisms, prioritizing crystal fractionation.
What This Document Provides
* An overview of igneous rock suites and the concept of parental and daughter magmas.
* Discussion of how changes in magma composition can be visualized and interpreted using specific types of diagrams.
* Detailed examination of crystal fractionation, including the physical principles governing crystal settling.
* In-depth study of layered mafic intrusions as natural laboratories for observing fractionation.
* Analysis of specific geological examples, including the Skaergaard intrusion, and the evidence they provide for differentiation processes.
* Exploration of textural features indicative of crystal fractionation, such as cumulus textures and sedimentary-like layering.
