Metamorphic assemblages and phase constraints
Metamorphism changes mineral assemblage and texture under changed pressure, temperature, fluid and deformation conditions without requiring bulk melting.
Key knowledge
Metamorphism changes mineral assemblage and texture under changed pressure, temperature, fluid and deformation conditions without requiring bulk melting. Facies group assemblages compatible with broad conditions for suitable compositions. Index minerals and polymorph relations constrain a pressure–temperature history only with compositional and equilibrium context.
Conditions and scope
- An assemblage may preserve incomplete reaction or multiple events; one mineral is not a unique thermometer.
- Fluid activity and bulk composition alter phase boundaries.
Sources · 3
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Steven Earle — Physical Geology, 2nd edition, BCcampus Open Education2 sources
- Metamorphic Classification, Field Gradients and Facies, pp. 7–10Stephen A. Nelson — Tulane University, Petrology (2004)Textbook chapter · PDF
Evidence and review
Read Earle composition/temperature/pressure/fluid and polymorph paragraphs plus Nelson facies assemblage/series/field-gradient sections; excluded fixed universal metamorphic thresholds and uniqueness of a reconstructed geothermal gradient.
2026-10-10 · Independent AI editorial review: All36 Life-authored Earth compact statements/conditions/displayed equations and all81 origin semantic links read; all36 author exact-source matrix rows and exclusions assessed. All18 inherited Earth compact records read for combined inventory. Targeted independent actual primary sections listed below; not every source body or proof independently reread. AI editorial reference review, not human certification/field proficiency or whole-field completion. Receipt: earth-life-independent-content-review.1.
Entry details
Permanent link to this entry ↗- Record identity
- uni-earth-metamorphic-phase-record
- Revision
- core.1
- Structured reference record
- University core expansion