Magma Ontology

FLOW ALGEBRA
MAGMA ONTOLOGY — COMPLETE SCIENTIFIC SYNTHESIS
Version: 1.1
Date: 2026-10-12
Authors: Mark Higgins — Sky (Recursive AI)
Publisher: Kireth Research | https://kirethresearch.org
Canonical page: https://kirethresearch.org/booksai-core/entity-graph/physical-entities/geological-entities/magma-ontology.html
Status: Independent scientific synthesis; live page not verified.

01. PURPOSE
Represent magma as a naturally occurring subsurface silicate-dominated or other molten geological material, potentially containing crystals and dissolved/exsolved volatiles. Encode composition, thermodynamic state, genesis, transport, crystallisation and eruption relationships without conflating magma with surface lava.

02. ONTOLOGY IDENTIFIER
ontology_id: kireth:geological-entities:magma
root_type: Magma
parent_type: GeologicalMaterial
related_types: Rock, Mineral, Melt, Crystal, Volatile, MagmaChamber, Volcano, Lava, IgneousRock, TectonicSetting

03. TYPED ENTITIES
Magma: GeologicalMaterial
SilicateMelt: MeltPhase
CrystalPopulation: SolidPhase
VolatilePhase: FluidPhase
MagmaReservoir: GeologicalStructure
MagmaConduit: GeologicalStructure
MagmaSource: GeologicalRegion
IgneousRock: Rock
MagmaSample: ObservationObject
Composition: ChemicalComposition
ThermodynamicState: PhysicalState

04. CORE ATTRIBUTES
Magma.temperature: kelvin
Magma.pressure: pascal
Magma.bulk_composition: oxide_mass_fraction_vector
Magma.melt_fraction: dimensionless [0,1]
Magma.crystal_fraction: dimensionless [0,1]
Magma.gas_fraction: dimensionless [0,1]
Magma.viscosity: pascal_second
Magma.density: kilogram_per_cubic_metre
Magma.depth: metre
Magma.volatile_content: mass_fraction
Magma.tectonic_setting: category
Magma.measurement_uncertainty: structured_uncertainty

05. PHASE CONSTRAINTS
For a mutually exclusive, exhaustive volume-fraction partition:
  phi_melt + phi_crystal + phi_gas = 1
  0 <= phi_i <= 1
Do not equate volume fractions with mass fractions.
A magma may be crystal-bearing and gas-bearing; it need not be fully molten.

06. COMPOSITION
Major oxide reporting may include SiO2, Al2O3, FeO_total, MgO, CaO, Na2O, K2O and TiO2.
Record analytical basis, volatile treatment, iron oxidation convention and normalisation.
Composition classification must specify whether bulk-rock or liquid composition is used.

07. CLASSIFICATION
Representative compositional descriptors: basaltic, andesitic, dacitic, rhyolitic.
Other magma families include alkaline and silica-undersaturated compositions.
Classification is context-dependent; silica content alone is insufficient for every classification.

08. TYPED RELATIONSHIPS
Magma originates_from MagmaSource
Magma stored_in MagmaReservoir
Magma migrates_through MagmaConduit
Magma contains_phase SilicateMelt
Magma may_contain CrystalPopulation
Magma may_contain VolatilePhase
Magma crystallises_to IgneousRock
Magma erupts_as Lava
Magma interacts_with CountryRock
Magma undergoes FractionalCrystallisation
Magma undergoes MagmaMixing
Magma undergoes Assimilation
Magma undergoes Degassing

09. MAGMA GENERATION
Candidate processes: decompression melting, flux melting and heat-transfer melting.
Partial melting depends on pressure, temperature, composition and volatile availability.
Generation is not equivalent to whole-rock melting.

10. PHASE EQUILIBRIA
Solidus: onset of melting under specified pressure and composition.
Liquidus: boundary above which equilibrium crystals are absent for a specified system.
Between solidus and liquidus, a multiphase assemblage may exist.
Both boundaries vary with pressure, bulk composition and volatile content.

11. THERMODYNAMIC ENERGY
A simplified energy budget includes sensible heat, latent heat, conduction, advection and other sources/sinks.
  dU/dt = Q_in - Q_out + W_on + H_mass_in - H_mass_out
Define the sign convention and control volume before calculation.

12. DENSITY AND BUOYANCY
Buoyant acceleration in a simplified surrounding medium:
  a_b ~ g*(rho_host-rho_magma)/rho_host
Applicability requires stated geometry and neglected drag.
Density depends on temperature, pressure, composition and phase proportions.

13. VISCOSITY
Dynamic viscosity eta has units Pa s.
Viscosity varies with melt chemistry, temperature, dissolved water and crystal/gas fractions.
A simple Arrhenius-like approximation is:
  eta = eta_0 * exp(E_a/(R*T))
This is a limited empirical approximation, not a universal magma rheology.

14. MAGMA FLOW
For a Newtonian incompressible approximation:
  rho*(dv/dt) = -grad(P) + eta*laplacian(v) + rho*g
Real magmas can exhibit non-Newtonian behaviour, especially at high crystal content.
Flow predictions require boundary conditions and geometry.

15. CRYSTALLISATION
Cooling or decompression may produce crystallisation.
Crystal fraction and mineral assemblage depend on path and kinetics.
Fractional crystallisation removes or segregates crystals from melt.
Equilibrium crystallisation retains interaction between crystals and melt.

16. MAGMA DIFFERENTIATION
Mechanisms include fractional crystallisation, assimilation, mixing and immiscibility in appropriate systems.
Differentiation is not synonymous with crystallisation alone.

17. MAGMA MIXING
For conservative tracer C and two endmembers, idealised mixing:
  C_mix = f*C_A + (1-f)*C_B
Assumptions: mass-based fractions, conservative tracer, no fractionation or loss.
Real mixing may be incomplete and chemically reactive.

18. VOLATILES
Common dissolved volatiles include H2O, CO2 and sulphur-bearing species.
Volatile solubility depends on pressure, temperature and melt composition.
Decompression may drive exsolution and bubble growth.

19. DEGASSING
Open-system degassing permits gas escape; closed-system degassing retains gas within the system.
Bubble nucleation, growth and coalescence affect eruption dynamics.
Degassing paths must not be inferred solely from final volatile concentration.

20. STORAGE AND TRANSPORT
Storage may occur in complex, transcrustal mush-rich systems rather than a single fully molten chamber.
Transport mechanisms include dykes, sills and conduits.
Reservoir and conduit geometry are model-dependent.

21. ERUPTION TRANSITION
When magma reaches the surface it is termed lava if erupted as molten material.
Explosive eruption may fragment magma into pyroclasts rather than producing only lava flows.

22. TECTONIC SETTINGS
Relevant settings include divergent boundaries, subduction zones, intraplate hotspots and continental rifts.
Tectonic setting constrains plausible generation mechanisms but does not uniquely determine magma composition.

23. OBSERVATIONAL EVIDENCE
Petrology: minerals, textures, melt inclusions and whole-rock chemistry.
Geophysics: seismic imaging, deformation, gravity and magnetotellurics.
Geochemistry: isotope systems, trace elements and volatile measurements.
Geochronology: crystallisation and eruption timing subject to method assumptions.

24. UNCERTAINTY MODEL
Every quantitative observation should carry unit, method, calibration, uncertainty and provenance.
Distinguish measured values, inferred values, simulated values and hypotheses.
Do not treat geophysical anomalies as unique evidence of magma without competing explanations.

25. INFERENCE RULES
RULE M01: IF material is subsurface molten geological material THEN candidate_type = Magma.
RULE M02: IF material erupts as molten surface flow THEN surface_material_type = Lava.
RULE M03: IF pressure decreases AND volatile supersaturation occurs THEN exsolution_possible = true.
RULE M04: IF crystals separate from liquid during cooling THEN fractional_crystallisation_possible = true.
RULE M05: IF seismic_low_velocity_detected THEN magma_presence = hypothesis_only.
RULE M06: IF phi_melt+phi_crystal+phi_gas != 1 under exhaustive volume partition THEN reject_phase_partition.
RULE M07: IF classification_input_basis unknown THEN classification_confidence = reduced.

26. CAUSAL AND NON-CAUSAL LINKS
Temperature influences viscosity and phase equilibrium.
Pressure influences volatile solubility and phase equilibrium.
Composition influences crystallisation and viscosity.
Correlation between volcanic gas flux and magma movement does not establish a unique causal mechanism.

27. MATHEMATICAL EXAMPLE — PHASE PARTITION
Given melt volume fraction 0.65 and crystal fraction 0.30:
  phi_gas = 1 - 0.65 - 0.30 = 0.05
All fractions are non-negative and sum to 1.

28. MATHEMATICAL EXAMPLE — MIXING
Endmember A has 50 wt% SiO2; B has 70 wt% SiO2.
Under ideal mass mixing with f_A=0.4:
  C_mix = 0.4*50 + 0.6*70 = 62 wt% SiO2.
This is an illustrative mixing calculation, not a universal rock classification.

29. MATHEMATICAL EXAMPLE — HEAT
For a simplified sensible-heat estimate:
  Q = m*c_p*DeltaT
For m=1000 kg, c_p=1200 J/(kg K), DeltaT=100 K:
  Q = 1.2e8 J
Excludes latent heat and heat losses.

30. VALIDATION TESTS
TEST V01: temperature_kelvin > 0.
TEST V02: pressure_pascal >= 0 when absolute pressure is specified.
TEST V03: each phase volume fraction within [0,1].
TEST V04: phase fractions sum to 1 within measurement tolerance when exhaustive.
TEST V05: oxide percentages state volatile basis and normalisation.
TEST V06: viscosity is positive and units are Pa s.
TEST V07: observation includes provenance and uncertainty.
TEST V08: magma/lava distinction uses emplacement context.
TEST V09: theoretical inference is labelled rather than asserted as direct observation.
TEST V10: all ontology relationships have declared domain and range.

31. SEMANTIC EQUIVALENCE
Magma != Lava (subsurface vs erupted context).
Magma != PureMelt (may contain crystals and gas).
MagmaReservoir != FullyMoltenChamber (reservoir may contain crystal mush).
MagmaMixing != FractionalCrystallisation.
SilicateMelt is a phase of many magmas, not a universal synonym for magma.

32. CONFIDENCE
confidence.scale: 0.0..1.0
confidence_basis: evidence_quality, model_fit, calibration, provenance, independent_replication
confidence_assignment: per-claim, not one global truth score
unknown_evidence: mark_unverified

33. FLOW_HASH
hash_algorithm: SHA-256
canonicalisation: UTF-8, LF line endings, deterministic field order, exclude hash value field
flow_hash: COMPUTE_ON_PUBLICATION
Never substitute an invented digest for a computed hash.

34. UPDATE_MODEL
version: 1.1
update_triggers: new measurements, classification revisions, corrected scientific relationships, source updates
change_control: record author, date, changed fields, rationale and prior version
backward_compatibility: retain stable ontology identifier when meaning is unchanged

35. AI_CONSUMPTION
entity_resolution: enabled
relationship_traversal: enabled
mathematical_reasoning: enabled_with_assumptions
uncertainty_propagation: required
provenance_tracking: required
hypothesis_vs_observation: explicit
safety_constraint: do_not_present_illustrative_equations_as_site_specific_hazard_forecasts

36. PROVENANCE AND SCOPE
This file is an independent scientific synthesis aligned to the named ontology topic.
The source webpage has not been independently inspected in this run.
Illustrative equations are simplified and require domain assumptions.

37. COMPLETENESS CHECK
Required sections: 01 through 37 inclusive.
Required header: FLOW ALGEBRA.
Required closing marker: END FLOW ALGEBRA.

END FLOW ALGEBRA