Friday, 24 April, 2026
Geochemical Reference Databases
All comparisons in the Prospection module rely on the isotopes_reference.db database, a standalone SQLite file separate from your sample database. This page describes its exact content and explains how to query it.
Full Database Inventory
| Table | Content | No. of Entries |
|---|---|---|
| isotope_systems | 9 isotope systems (symbol, notation, element). | 9 |
| geological_contexts | 28 contexts: 15 deposit types (VHMS, SEDEX, PORPHYRY, MVT, IOCG…), 8 fluid sources, 5 rock types. | 28 |
| reference_signatures | Signatures by system and context. Full coverage of the 28 contexts for all 9 systems. | 255 |
| named_deposits | Named deposits with multi-element fingerprints and GPS coordinates. | 25 |
| regional_baselines | Baselines for 14 European geological regions. Systems covered: δ34S (13 regions), Isotopic Pb (up to 8 regions), δ18O (2), δ7Li (3). | 59 |
| fractionation_factors | 31 pairs: 7 δ34S, 7 δ18O, 5 δ7Li, 4 δ13C, 3 δD, 3 δ11B. | 31 |
| pb_evolution_models | SK75 (2-stage) + ZD81 (mantle, lower crust, upper crust, orogene). | 6 |
| kerogen_maturity | 18 stages covering types I, II, IIS, III, IV and "mixed" with Ro, Tmax, δ13C, δD ranges. | 18 |
| kinetic_isotope | 9 kinetic processes: BSR (2 variants), TSR, methanogenesis, δD and δ18O evaporation, Li-clay precipitation, B-calcite precipitation, UV photolysis (MIF-S). | 9 |
| mif_sulfur | 8 entries Δ33S / Δ36S: Archean VHMS, Archean shales, Archean orogenic gold, Paleoproterozoic VHMS, modern hydrothermal vents. | 8 |
| fluid_inclusions | 12 context/fluid associations with Th, Tm ice, salinity, pressure, depth, fluid δ18O and δD. | 12 |
| ree_signatures | 14 normalized REE profiles. | 14 |
| deposit_fluids | 9 deposit fluid entries (T, pressure, δ18O, δD). | 9 |
| sorption_li_b | 9 Kd coefficients for Li and B sorption on clays (smectite, illite, kaolinite, gibbsite, calcite). | 9 |
| publications | Bibliographic references (DOI, authors, journal, year). | 121 |
Deposit Types Represented in named_deposits
| Code | Type | No. of Deposits | Examples |
|---|---|---|---|
| VHMS | Volcanogenic Massive Sulfides | 5 | Kidd Creek, Flin Flon, Neves-Corvo, Rio Tinto, IPB (representative) |
| PORPHYRY | Porphyry Cu(-Mo, Au) | 3 | Escondida, Chuquicamata, Bingham Canyon |
| PEGMATITE_LI | Lithium Pegmatite | 3 | Greenbushes, Manono-Kitotolo, Cinovec/Zinnwald |
| BRINE_SALAR | Salar Brine | 3 | Atacama, Uyuni, Arizaro |
| CLAY_LI | Lithium Clay | 3 | Jadar, Emili/Bacanora, Thacker Pass |
| SEDEX | Sedimentary Exhalative (Zn, Pb) | 3 | McArthur River (HYC), Red Dog, Sullivan |
| OROGENIC_GOLD | Orogenic Gold | 2 | Kalgoorlie, Muruntau |
| BRINE_GEOTHERM | Geothermal Brine | 1 | Salton Sea Geothermal Field |
| IOCG | Iron Oxide Copper Gold | 1 | Olympic Dam |
| MVT | Mississippi Valley Type (Pb, Zn) | 1 | Rhenish MVT Deposits (Bleiberg, Mechernich) |
Fractionation Factors - Validity Ranges
The 31 pairs are categorized by system. Here are the valid temperature ranges for the most frequently used pairs:
| Pair | System | Valid T (°C) | Δ @ 200 °C | Δ @ 300 °C |
|---|---|---|---|---|
| SO₄aq–H₂Saq | δ34S | 100–600 | +28.3 ‰ | +19.1 ‰ |
| pyrite–galena (geotherm.) | δ34S | 150–500 | +4.6 ‰ | +3.1 ‰ |
| pyrite–H₂Saq | δ34S | 100–600 | +1.8 ‰ | +1.2 ‰ |
| quartz–H₂O (geotherm.) | δ18O | 200–600 | +11.7 ‰ | +6.9 ‰ |
| calcite–H₂O (geotherm.) | δ18O | 0–350 | +5.7 ‰ | −1.0 ‰ |
| CO₂–CH₄ (geotherm.) | δ13C | 0–700 | +50.9 ‰ | +34.7 ‰ |
| fluid–muscovite | δ7Li | 25–500 | +8.5 ‰ | +5.6 ‰ |
| fluid–smectite | δ7Li | 5–100 | +9.1 ‰ | +7.1 ‰ |
| aqueous B3–B4 | δ11B | 0–100 | +1.4 ‰ | +3.1 ‰ |
Accessing Reference Data via API
| Endpoint | Result | Useful Parameters |
|---|---|---|
| GET /api/prospection/reference/deposits | 25 named deposits | deposit_type, country, commodity |
| GET /api/prospection/reference/baselines | 59 baselines | region, isotope_system |
| GET /api/prospection/reference/signatures | 255 signatures | isotope_system, context_code, confidence |
| GET /api/prospection/reference/contexts | 28 geological contexts | category (deposit_type / fluid_source / rock_type) |
| GET /api/prospection/fractionation?t_c=250 | Δ calculated at 250 °C | system (e.g., delta34S), pair (e.g., SO4aq-H2Saq) |
On the /fractionation endpoint, if the requested temperature exceeds a pair's valid range, the response includes in_range: false. Extrapolation is calculated but must be interpreted with caution—especially beyond 600 °C for sulfur pairs.
Bibliographic Sources
The 121 compiled references cover publications from 1975 (Stacey & Kramers) to 2024. Primary journals represented include: Economic Geology, Geochimica et Cosmochimica Acta, Chemical Geology, Ore Geology Reviews, Applied Geochemistry, and Scientific Reports.
To report an inaccurate value or suggest a missing reference, contact me via email at colin.ferrari@isofind.tech.