| 1. Domain | 1.1 Scope of the Domain | Boundaries | The range of phenomena the science includes and excludes. | Studies the chemical composition, reactions, distributions, and cycles of elements and isotopes within the Earth and other planetary bodies. Includes mineral–fluid interactions, rock chemistry, aqueous geochemistry, isotope geochemistry, redox systems, and global geochemical cycles. Excludes purely physical processes unless tied to chemical behavior. |
| | Scale | The spatial, temporal, or organizational level at which the science operates (e.g., quantum, cellular, social, cosmic). | Operates from atomic bonding and electronic structure → mineral chemistry → rock-scale reactions → basin-scale fluid flow → crust/mantle geochemical cycles → whole-planet chemical evolution. Time scales from seconds (reaction kinetics) to billions of years (planetary differentiation). |
| 1.2 Ontological Commitments | Entities | The kinds of things assumed to exist within the domain (particles, organisms, agents, fields, etc.). | Elements, isotopes, ions, minerals, fluids, melts, gases, complexes, colloids, organic molecules, geochemical reservoirs, phases, interfaces, chemical species, defects, dissolution/precipitation sites. |
| | Properties | The fundamental attributes these entities possess (mass, charge, genotype, preference, etc.). | Concentration, activity, pH, Eh, ionic strength, solubility, diffusivity, partition coefficients, isotope ratios, binding energies, redox state, thermodynamic potentials (G, μ), equilibrium constants, reaction rates. |
| | Categories | The basic ontological types used to classify domain elements (substances, processes, relations, structures). | Geochemical reservoirs (crust, mantle, hydrosphere, atmosphere, biosphere), geochemical processes (weathering, precipitation, adsorption, oxidation, reduction), isotope systems (radiogenic/stable), mineral groups, fluid types, chemical facies. |
| 1.3 State-Variables | Variables | The measurable or definable properties that describe system conditions. | Temperature, pressure, concentration, activity coefficients, pH, redox potential, partial pressures (CO₂, O₂, H₂), fluid composition, mineral modes, isotope ratios, chemical gradients, saturation indices. |
| | Parameterization | How variables encode and represent the system’s state. | States encoded by thermodynamic variables (G, μ, K), activity–activity diagrams, phase diagrams, Eh–pH diagrams, partitioning equations (Kd, D), isotope fractionation factors, mass-balance equations, chemical speciation models. |
| 1.4 Admissible Idealizations | Simplifications | Conceptual reductions used to make the domain tractable (point masses, rational agents, perfect gases). | Ideal solutions, dilute solutions, constant activity coefficients, equilibrium assumptions, closed-system behavior, homogeneous fluids, ignoring kinetic barriers, linearizing non-linear relations, neglecting minor species. |
| | Validity Conditions | The limits and contexts in which idealizations hold or break down. | Valid for dilute systems, slow-changing environments, high-temperature equilibrium, simple mineral–fluid systems; breaks down in concentrated brines, kinetic regimes, multi-component fluids, biological mediation, rapid transients, heterogeneous materials. |
| 1.5 Domain Assumptions | Structural Assumptions | Background ontological stances such as determinism, continuity, randomness, discreteness. | Chemical behavior follows thermodynamic and kinetic laws; elemental distributions reflect equilibrium/kinetic controls; isotope ratios record sources and processes; geochemical systems evolve through reactions and transport. |
| | Implicit Commitments | Unstated but necessary assumptions that shape the field’s conceptual structure. | Assumes composition is measurable, reactions are definable, mass balance applies, thermodynamic data are transferable, and chemical signals are preserved and interpretable within geologic contexts. |
| 1.6 Internal Coherence Requirements | Consistency | The demand that domain concepts do not contradict one another. | Requires consistency among mineral chemistry, fluid chemistry, isotope ratios, thermodynamic predictions, reaction-path models, and mass-balance constraints. |
| | Compatibility | The requirement that entities, variables, and assumptions fit together into a unified descriptive framework. | Must align with mineralogy, petrology, hydrology, tectonics, thermodynamics, biology (biogeochemistry), and planetary science within an integrated Earth chemical system. |
| 2. Evidence Layer | 2.1 Observable Phenomena | Observables | The aspects of the domain that can produce detectable signals accessible to measurement. | Elemental concentrations, isotope ratios, mineral compositions, fluid chemistry (pH, Eh, ions), precipitation/dissolution textures, alteration halos, weathering profiles, gas fluxes, adsorption signals, redox gradients, speciation patterns. |
| | Detection Limits | The boundaries of what can be resolved or sensed by current instruments or methods. | Limited by instrument sensitivity, matrix effects, low-abundance elements/isotopes, detection thresholds of ICP-MS/LA-ICP-MS, spectral overlaps in XRF, limits of pH/Eh probes, small sample volumes, contamination, unstable species. |
| 2.2 Measurement Systems | Units | Standardized quantifications (meters, seconds, volts, decibels, dollars, etc.) necessary for consistent comparison. | Concentration (ppm, ppb, wt%), isotope ratios (e.g., ⁸⁷Sr/⁸⁶Sr), pH, Eh (mV), ionic strength, speciation percentages, partial pressures (atm), thermodynamic constants (K), activity coefficients, fluxes (mol/m²/s). |
| | Instruments | Devices and tools (microscopes, spectrometers, sensors, surveys, detectors) used to produce measurements. | ICP-MS, LA-ICP-MS, ICP-OES, TIMS, SIMS, XRF, SEM-EDS, TEM, IR/Raman spectrometers, ion chromatographs, mass spectrometers (radiogenic/stable isotopes), titration systems, microprobes, gas analyzers, pH/Eh electrodes. |
| 2.3 Operational Definitions | Definitions | Terms defined by specific measurement procedures, ensuring empirical clarity. | Concentration defined by calibrated standards; isotope ratios defined relative to international reference materials; pH/Eh defined by electrode response; saturation state defined by IAP/K; speciation defined by equilibrium calculation methods. |
| | Procedures | The explicit steps required to perform a measurement in a reproducible way. | Sample digestion, filtration, acidification, chromatographic separation, isotope spike addition, standard calibration, blank correction, instrumental drift correction, chemical speciation modeling, titration protocols. |
| 2.4 Data Acquisition | Protocols | Formal processes for gathering data under controlled or standardized conditions. | Multi-step sample prep → analytical runs → replicate measurements; in situ micro-analyses; solution chemistry sampling; sequential fluid sampling; time-series chemical monitoring; mineral/grain-specific analysis via microbeam techniques. |
| | Sampling | Rules determining which subset of the domain is measured and how representative it is. | Multi-depth sampling, replicate fluid/rock samples, spatial grids, grain-specific spots, stratigraphic/temporal sampling, sampling across weathering gradients, multi-phase separation (fluid/solid/gas), contamination-controlled sampling. |
| 2.5 Data Character & Format | Data Types | The form raw evidence takes (time series, spectra, images, counts, qualitative records). | Elemental tables, isotope ratio tables, spectra (XRF, ICP-MS, IR/Raman), concentration–depth profiles, Eh–pH curves, time-series chemistry, speciation diagrams, mass-balance spreadsheets, chromatograms, calibration curves. |
| | Resolution | The granularity or precision with which data is captured. | Determined by instrument precision, spectral resolution, mass resolution (TIMS/SIMS), spatial resolution of microbeam instruments, sampling interval, chemical stability, and noise levels of electrodes or sensors. |
| 2.6 Reliability & Calibration | Calibration | Adjustment procedures ensuring instruments produce accurate results. | Internal/external standards, drift correction, blank subtraction, calibration curves, isotopic standardization (e.g., NBS, IAEA), electrode calibration (pH/Eh), instrument tuning, matrix-correction procedures. |
| | Error Characterization | Identification and quantification of noise, uncertainty, bias, and measurement error. | Chemical contamination, matrix effects, drift, instrumental noise, isotope fractionation during prep, detection-limit issues, standard miscalibration, improper sample digestion, carryover, beam damage in microanalysis, speciation-model uncertainty. |
| 3. Structural Layer | 3.1 Patterns & Regularities | Laws / Relations | Stable, repeatable patterns governing how observables behave across conditions. | Chemical reactions obey thermodynamic laws (ΔG, K); isotope fractionation follows temperature-dependent laws; element distribution follows partition coefficients; redox reactions follow Eh–pH stability relations; weathering follows predictable mobility sequences; incompatible/compatible elements follow systematic igneous differentiation trends; Rayleigh fractionation governs trace-element evolution. |
| | Invariants | Quantities or properties that remain constant under transformations (symmetries, conservation laws). | Conserved mass in closed systems; invariant isotope-decay laws (e.g., half-lives); fixed stoichiometries of minerals; stable ionic radii controls on substitution; invariant redox trends for given environments; consistent mineral–fluid partitioning for specific P–T–X conditions. |
| 3.2 Causal Architecture | Mechanisms | Underlying processes or structures that produce the observed regularities. | Dissolution/precipitation, adsorption/desorption, ion exchange, oxidation/reduction, hydrolysis, complexation, diffusion, advection, precipitation/crystallization, volatilization, isotope decay, fractionation, mineral transformation, speciation shifts driven by pH–Eh changes. |
| | Pathways | Organized sequences of interactions forming a causal chain or network. | Weathering → solute release → transport → precipitation → burial; melt generation → fractional crystallization → assimilation/mixing; hydrothermal fluid circulation → alteration → mineral deposition; isotope decay chains; redox-driven reaction networks; fluid–rock reaction paths. |
| 3.3 Theoretical Vocabulary | Concepts | Core terms that encode the domain’s structure (force, gene, equilibrium, field). | Activity, fugacity, equilibrium constant (K), Gibbs free energy (ΔG), partition coefficient (Kd, D), ionic strength, coordination, solubility product (Ksp), fractionation factor (α), mass balance, reaction path, buffering, saturation index (SI), complexation. |
| | Classifications | Taxonomies, categories, or typologies that organize entities and relations. | Aqueous geochemical facies, redox environments, isotope systems (radiogenic/stable), weathering regimes (congruent/incongruent), hydrothermal systems, igneous trace-element groups (LILE, HFSE, REE), fluid types (meteoric, magmatic, metamorphic). |
| 3.4 Formal Representations | Equations | Mathematical constructs expressing laws, relations, or mechanisms. | ΔG = ΔH − TΔS; mass-action equations; K = exp(−ΔG/RT); Nernst equation; Eh–pH relations; rate laws (e.g., −dA/dt = kAⁿ); partitioning equations; isotope fractionation equations; diffusion equations (Fick’s laws); mass-balance equations; Rayleigh fractionation formula. |
| | Models | Structured representations—mathematical, computational, or conceptual—used to predict and explain phenomena. | Thermodynamic models (PHREEQC, Geochemist’s Workbench), speciation models, reaction-path models, isotope-evolution models, fluid–rock interaction models, melt-evolution models, weathering models, adsorption surface-complexation models. |
| 3.5 Idealized Structures | Simplified Models | Purposeful abstractions that capture essential dynamics while omitting irrelevant detail. | Ideal solutions, dilute aqueous chemistry, equilibrium-only reactions, constant temperature/pressure, closed systems, no kinetic barriers, homogeneous mineral surfaces, ignoring biological effects, linear adsorption or reaction laws. |
| | Limit Conditions | Regimes where specific models or approximations hold (classical vs. quantum, linear vs. nonlinear). | Break down in concentrated brines, mixed fluids, kinetic regimes, strong biological mediation, high P–T gradients, far-from-equilibrium systems, heterogeneous minerals, multiphase systems, strong colloidal or organic interactions. |
| 3.6 Integrative Frameworks | Unifying Theories | Higher-order structures that connect disparate laws or mechanisms under a coherent whole. | Integration of thermodynamics, kinetics, transport, isotope systematics, mineral chemistry, and fluid chemistry to explain Earth’s chemical evolution; links atomic-scale processes → mineral assemblages → rock chemistry → global geochemical cycles. |
| | Interdisciplinary Links | Points where the theory connects to adjacent sciences or larger explanatory systems. | Intersects with petrology, hydrology, biogeochemistry, environmental science, oceanography, atmospheric chemistry, mineral physics, tectonics, and planetary geochemistry. |
| 4. Method Layer | 4.1 Inquiry Design | Experimental Design | Structured plans for manipulating variables to test causal claims. | Controlling temperature, pressure, pH, Eh, ionic strength, fluid composition, mineral surface area, reaction time, and flow regime in laboratory experiments to test hypotheses on dissolution, precipitation, redox reactions, isotope fractionation, and fluid–rock interaction. |
| | Observational Design | Systematic approaches for gathering non-manipulated data (surveys, field studies, natural experiments). | Monitoring natural geochemical gradients, weathering fronts, hydrothermal alteration zones, groundwater chemistry, soil profiles, gas emissions, and isotope distributions without imposing artificial perturbations. |
| 4.2 Testing & Validation | Hypothesis Testing | Procedures for evaluating whether evidence supports or contradicts specific claims. | Comparing predicted element ratios, isotope signatures, saturation states, mineral stability fields, speciation patterns, reaction paths, and partition coefficients with experimental results, field data, and thermodynamic calculations. |
| | Replication | The requirement that results be independently reproducible under similar conditions. | Repeating solution analyses, isotope measurements, mineral chemistry runs, titrations, reaction-path experiments, column-flow tests, field sampling campaigns, and speciation modeling calculations across independent batches and instruments. |
| 4.3 Inference & Evaluation | Statistical Inference | Rules for drawing conclusions from noisy or incomplete data. | Calculating uncertainties in concentrations, isotope ratios, saturation indices, rate constants, activity coefficients, partitioning factors, and regression-based relationships; performing mixing calculations and error-propagation analyses. |
| | Model Comparison | Criteria (fit, simplicity, predictive accuracy, robustness) used to evaluate competing models. | Evaluating competing thermodynamic databases, kinetic rate laws, surface-complexation models, fluid–rock reaction models, isotope-evolution models, and weathering or adsorption models using fit, predictive skill, and parsimony. |
| 4.4 Error Management | Error Analysis | Identification and quantification of random and systematic errors. | Identifying contamination, matrix effects, calibration drift, instrument noise, incomplete digestion, isotope fractionation during prep, sample-loss effects, surface-area uncertainties, unstable species, and equilibrium/kinetic misapplication. |
| | Bias Control | Methods for minimizing subjective, instrumental, or procedural biases. | Using blanks and standards, randomizing sample order, maintaining clean-lab procedures, cross-checking with independent techniques, correcting matrix effects, verifying digestion completeness, and performing independent replicates. |
| 4.5 Adjudication & Revision | Peer Scrutiny | Collective evaluation of claims through critique, review, and debate. | Independent evaluation of chemical/isotopic datasets, thermodynamic assumptions, reaction-path interpretations, database choices, mass-balance results, and model fits by multiple investigators or labs. |
| | Theory Revision | Procedures for modifying, replacing, or discarding models based on new evidence. | Updating rate laws, refining thermodynamic constants, correcting reaction-path models, revising isotope-fractionation factors, adjusting speciation assumptions, and incorporating contradictory experimental or field evidence. |
| 4.6 Integrity Conditions | Transparency | Requirements to disclose methods, data, assumptions, and limitations. | Full reporting of sample preparation steps, digestions, calibrations, analytical conditions, instrument settings, modeling assumptions, uncertainty treatment, data exclusions, and reference material information. |
| | Ethical Standards | Norms ensuring responsible conduct in experimentation, data handling, and publication. | Honest reporting of analytical uncertainty, contamination issues, negative results, incomplete reactions, and compliance with environmental, safety, and data-integrity standards; responsible handling of hazardous chemicals. |