magma
Enable an AI agent to recognise magma, assess its physical and chemical state, and judge which observations, interpretations or interventions its evidence supports.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
Researched by: Codex + Grok
Purpose and description
Enable an AI agent to recognise magma, assess its physical and chemical state, and judge which observations, interpretations or interventions its evidence supports.
Magma is molten silicate rock generated by partial melting of Earth's (or other planetary) mantle or crust, a multiphase mixture of melt, crystals, and volatiles that remains subsurface until eruption converts it to lava or pyroclastic products.
It can be Classify a candidate occurrence as magma or retain an unresolved identification with explicit evidence gaps.; Compare measured and inferred magma states while preserving their spatial, temporal and analytical bases.; Assess plausible melt, crystal and gas movement under specified conditions.; Evaluate conditional responses to cooling, decompression, mixing or volatile loss.; Select observations or sample analyses that discriminate between competing state interpretations.; Identify when emergence or complete solidification requires linking to a neighbouring material model..
Distinguishing features
Establish whether rock-derived liquid is present; high temperature or a molten appearance alone does not establish magma.
Establish whether the material is beneath the surface; record emergence as a boundary with the neighbouring lava model.
Distinguish a melt-bearing assemblage from fully solidified igneous rock, retaining uncertainty where melt presence is inferred.
Distinguish silicate or other rock melt from an aqueous hydrothermal fluid, including cases where both coexist.
Distinguish the magma material from the chamber, lens, fracture or conduit that contains it.
Scope
+ Identification and boundaries of a magma occurrence or parcel
+ Composition of the melt and associated crystals and gas
+ Temperature, pressure and phase proportions
+ Rheological state, segregation and capacity for movement
+ Cooling, crystallisation, mixing, volatile exsolution and decompression
+ Evidence and uncertainty connecting observations to inferred magma state
- Lava flows and their surface emplacement after magma emerges
- Fully solidified igneous rocks and their subsequent alteration
- Volcanoes, conduits and reservoirs as geological structures
- Regional tectonic processes and mantle source systems
- Hydrothermal fluids and groundwater outside the magma
- Eruption hazard zoning, exposure and emergency response
Characteristics
- Occurrence and reference time
- Location, spatial extent, reference time and containing geological feature Prevents observations from different magma bodies or stages being treated as one state.
- Melt composition
- Major components in wt%; trace components in ppm; analytical and normalisation basis stated Supports compositional identification and interpretation of phase behaviour.
- Bulk magma composition
- Composition of melt, crystals and gas together, with included phases and calculation basis stated Distinguishes the whole assemblage from its liquid component.
- Temperature
- °C or K, with uncertainty, method and reference time Constrains phase state and interpretations of crystallisation and mobility.
- Pressure
- MPa, with uncertainty and pressure type stated Constrains phase equilibria and volatile behaviour without treating depth as a direct measurement.
- Phase proportions
- Melt, crystal and gas fractions on an explicit mass or volume basis Describes the assemblage and supports assessment of its mechanical state.
- Crystal assemblage and texture
- Mineral identities, crystal size distribution, shape, zoning and connectivity Helps distinguish suspended crystals from a load-bearing framework and constrains process history.
- Volatile inventory and partitioning
- Species-specific dissolved concentrations and exsolved gas amounts, with phase and units stated Separates volatile abundance from gas already present and available to escape.
- Effective rheology
- Apparent viscosity in Pa·s and, where supported, yield stress in Pa; temperature and deformation conditions stated Supports conditional estimates of deformation and transport.
- Melt and gas connectivity
- Connected, isolated, mixed or unresolved for each phase at a stated scale Constrains whether liquid or gas can move independently of the crystal assemblage.
- Process trajectory
- Evidence-supported cooling, heating, crystallising, remelting, mixing, decompressing or unresolved Separates a snapshot from the direction of change relevant to future behaviour.
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 11 findings · 21 questions.
Magma identity and boundaries Establishes which melt-bearing material is being modelled and where its identity begins and ends.
A magma parcel, a partly molten region and a magma reservoir are different modelling subjects.
Material identification
Tests whether the subject is subsurface rock melt with associated phases.
Evidence of rock melt
Records the basis for identifying a rock-derived liquid rather than hot solid rock or aqueous fluid.
- What observation or inference establishes that rock melt is present? definition
- Could the same evidence instead represent hot solid rock or hydrothermal fluid? boundary
Spatial and material continuity
Defines the represented parcel or occurrence and its transitions to neighbouring subjects.
Represented magma unit
Makes the chosen extent and persistence of the magma subject explicit.
- Does this record follow a material parcel or describe material occupying a fixed region at a stated time? definition
- Where does emergence, complete solidification or separation of a phase require a linked record? boundary
Composition and phase inventory Separates the chemistry of the liquid from the composition and proportions of the whole magma.
Whole-rock, glass, crystal and gas observations cannot be substituted for one another without interpretation.
Chemical basis
Identifies which material each compositional observation represents.
Melt versus bulk chemistry
Records analytical basis and the relationship between sampled components and the modelled magma.
- Does each analysis describe liquid, quenched glass, individual crystals or the bulk assemblage? measurement
- What sampling, alteration or reconstruction steps affect its interpretation as magma composition? provenance
Coexisting phases
Describes crystals and gas alongside the liquid at the relevant state.
Phase abundances and identities
Captures phase amounts without confusing mass fractions, volume fractions or observations from different stages.
- Which minerals and gas species coexist with the melt, and what are their estimated proportions? measurement
- On what fraction basis and at what pressure, temperature and time were these proportions determined? measurement
Thermal and volatile state Connects temperature and pressure with phase stability and volatile partitioning.
Composition alone does not establish whether magma is crystallising, gas-bearing or capable of further exsolution.
Pressure and temperature constraints
Records the conditions represented by measurements and reconstructions.
State estimate validity
Distinguishes current conditions from conditions preserved by earlier mineral or melt records.
- What temperature and pressure ranges are supported, and by which measurements or calibrations? measurement
- Do these estimates represent the current magma, an earlier equilibration stage or several unresolved stages? provenance
Volatile partition and release
Separates dissolved volatiles, exsolved gas and gas already lost from the subject.
Dissolved and exsolved inventory
Captures the evidence needed to evaluate volatile redistribution under changing conditions.
- What volatile amounts remain dissolved, occur as gas or have escaped, and which amounts are unresolved? measurement
- Under a specified pressure or temperature change, what evidence supports further exsolution or gas dissolution? action
Magma mobility and segregation Describes deformation of the assemblage and movement of its constituent phases.
The presence of melt does not by itself establish that the whole magma can flow or that melt and gas can escape.
Assemblage rheology
Relates effective mechanical behaviour to liquid properties, crystals, bubbles and imposed deformation.
Conditional flow behaviour
Records rheological estimates together with the conditions under which they apply.
- What effective viscosity or yield behaviour is supported at the stated temperature, phase fractions and deformation rate? measurement
- Under the specified driving stress, can the assemblage deform or move, and what remains uncertain? action
Phase connectivity and separation
Examines independent migration of melt, crystals and gas.
Connected transport pathways
Distinguishes movement of the bulk magma from segregation through or within it.
- Are melt and gas connected at the relevant scale, and is there evidence for a supporting crystal framework? measurement
- Which phases could separate under the proposed conditions, and what connectivity evidence supports that assessment? action
Magma evolution and evidence Connects observations to competing histories and conditional future changes.
A magma state may preserve several episodes, so an agent must distinguish observed features from process interpretations.
Process history
Organises evidence for changes in composition, phase state and material exchange.
Competing evolution paths
Tests explanations involving crystallisation, recharge, mixing, assimilation or decompression.
- Which observations support the proposed process sequence, and which alternative sequences also fit? provenance
- What material or heat exchange across the magma boundary must each interpretation account for? boundary
Decision-relevant observations
Identifies evidence needed before a state interpretation can support a proposed action.
Resolve magma state ambiguity
Connects unresolved magma properties to targeted observations and conditional assessments.
- Which observation or analysis would best distinguish the competing interpretations of melt fraction, volatile state or mobility? action
- What additional evidence is required before using this magma record to assess a proposed sampling or physical intervention? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Kinds and varieties
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Basaltic (mafic) magma
- Andesitic (intermediate) magma
- Dacitic magma
- Rhyolitic (felsic) magma
- Ultramafic (komatiitic/picritic) magma
- Carbonatite magma
- Phonolitic/alkaline magma
- Sulfur-rich/immiscible sulfide magma
- Which of these kinds and varieties hold for the sense of magma this model covers, and on what evidence? provenance
Sources
- Magma, Lava, Lava Flows, Lava Lakes, and Lava Tubes - Official USGS distinction of magma as subsurface molten rock versus lava at the surface, and the melt-crystal-gas mixture.
What the second pass must settle
- What operational boundary should this registry use between magma, crystal mush and rock containing only a small amount of partial melt?
- Should non-silicate magmas share this model through compositional categories, or require specialised extensions?
- How should the model preserve parcel identity when magma mixes, splits or exchanges crystals and gas?
- Which methods can constrain present melt fraction, pressure and volatile inventory for a particular occurrence, and at what spatial resolution?
- What evidence and uncertainty limits are required before inferred rheology or volatile behaviour can support a specific intervention?