C. Analyses - ufarrell/sgp_phase2 GitHub Wiki

Analytes

The diagram below summarizes the count of individual results for each category of analytes. Categories are based on those used on our search website (http://sgp-search.io/).

Analytical Metadata

We store information in the database about

  • the lab where analyses are run
  • the instruments used
  • the dates of the analyses
  • the person running the experiment
  • the person providing the data, especially if the data is unpublished

These categories are variably populated depending on the source of the data (see A. Database Description).

map of labs

34% of all data and 81% of SGP-entered data are associated with a lab. Those with the most results are commercial laboratories, where large amounts of elemental data tend to be generated for each sample.

University labs, by count of results (top ten).

Institution Count Results
Stanford University 45855
Arizona State University 21293
University of Maryland 16084
University of Cincinnati 13701
University of California, Riverside 12677
McGill University 12213
Virginia Polytechnic Institute and State University 9438
Harvard University 8874
University of Texas Permian Basin 8869
Yale University 8603

Commercial labs/Geological Surveys/Analytical Centers by count of results (top ten)

Institution Count Results
Bureau Veritas Minerals Laboratories 615055
Intertek-Genalysis Laboratory 138800
SGS 90910
Activation Laboratories Ltd. (Actlabs) 49371
AGAT Laboratories 32419
Chemostrat 29601
LabWest Minerals Analysis Pty Ltd. 28995
Geological Survey of Canada, Calgary 19354
Pôle Spectrométrie Océan 16249
GeoMark Research, Ltd., Texas 13444

Analytical Methods

The diagram below illustrates the proportion of individual results for each analytical method. Some methods have been simplified/concatenated for clarity. See here for a full list of analytical methods.

FSP = Ferrozine Spectrophotometry, NAA includes NAA, INAA and DNAA, Pyrol. includes SRA (source rock analysis), REP (Rock Eval pyrolysis, Vinci Technologies), and HAWK (Hydrocarbon Analysis With Kinetics, Wildcat Technologies). CALC/STOICH includes all calculated data (e.g. TC-TIC for organic carbon), and results calculated by stoichiometry (e.g. Fe-py after CRS).

Preparation Methods

The first step in most geochemical analyses is to crush and powder the rock. This is usually accomplished in several stages:

  • Initial reduction into small pieces using a rock saw or hammer. This step often specifically includes the removal of weathered surfaces.
  • Further reduction in size (in some cases) using e.g. a jaw crusher.
  • Ground to a powder using a either a mill/shatterbox, or by hand with a mortar and pestle.

In some studies a microdrill is used in order to target specific mineral phases, or avoid areas of alteration. In rare cases no crushing is required e.g. XRF on a polished rock surface.

The material used in this process can impact the geochemical measurements. In the SGP database it is usually the final grinding step that is recorded (e.g. Alumina (ceramic) ball mill). In the case of steel, note that it is most often 'hardened' steel of some kind that is used. The exact material is sometimes specified (e.g. chrome, carbon), but most are lumped together simply as steel.

Note that sometimes pieces of the same hand sample are crushed in different ways, and therefore one sample can be associated with multiple preparation types. Samples with a long history associated with multiple studies can be difficult to trace - therefore some samples may be associated with a preparation type for some analyses and have no preparation type for others, if it was not clear whether the same powder was used.

The following diagram summarizes the proportion of results in the database grouped by material, the full dictionary can be found here.

Experimental Methods

This category describes any experimental methods applied before a sample is analyzed - for example, acid digestion before ICP:MS.

Creating unique, simple, yet informative codes, is particularly challenging in this case. As a result this dictionary has been extensively revised since Phase 1, prompted partly by the addition of new carbonate and metal isotope data, and based on discussions with collaborators most familiar with the data.

Further revision is anticipated as we continue these discussions and add new kinds of data. While we aim to maintain stability in our dictionary terms, improving data quality is the first priority — so users should be aware that this dictionary in particular may not remain static.

The aim is to create codes which summarize essential steps, in particular if there is some debate over the relative strength of one method over another. Creating codes for newer, less established methods is generally the most difficult, as small variations in procedure are tested by different researchers. Where possible method papers, which set out all the key steps in detail, are linked to the code in the database (e.g. Poulton and Canfield, 2005 is linked to SeqA, B and C for iron speciation).

The codes are designed to be somewhat human-readable, and they are used in a modular way - the same code is used again if it is part of a longer protocol.

Standardized separators are used:

  • Sequential steps are separated by an underscore. Example: CB_MA3 (combustion/ashing followed by a three-acid digestion).
  • Details about a single step are enclosed in brackets and presented in a fixed order. Example: HCl(0.5N/24h/hot) (acid treatment with hot 0.5N HCl for 24 hours).
  • Multiple components of a single step are separated by a slash. Example: HCl/HNO3 (two-acid digestion using HCl and HNO3).

The experimental method dictionary has three columns (based on the schema from the British Geological Survey): the experimental_method_code, experimental_method_translation and experimental_method_desc. Each is slightly more detailed than the last. The code and translation are available on the website.

The sections below summarise methods based on the categories on the website. The tables are based around experimental methods which tend to be most specific to each category (whereas the analytical methods are more likely to be used across different groupings). Analytes and analytical method codes are grouped by category and then by experimental code, and usually sorted by number of results within a given category (the approach varies slightly depending what makes most sense for a given category).

These summaries are based on the studies that are included in SGP Phase 2, and therefore are not intended as a complete review or recommendation of methods, but rather to give a sense of the data currently available.

Commonly cited papers are subjectively taken from the methods sections of published papers, where we see the same citation turning up frequently - we note these are based on frequency and do not represent any suggestion/endorsement of a specific methodological approach.

Where SGP Proxy Primers are available, they are linked to the relevant section - these provide a detailed review of proxy use.

Reference standards for isotopic measurements refer to the standards currently associated with data in the SGP database; note these may not represent all standards commonly used in the broader field.

Iron and Sulfur

Commonly cited method papers

Notes

In SGP the overwhelming majority of sequential iron/targeted iron extractions are done using the method of Poulton and Canfield 2005, (SeqA, SeqB, SeqC), along with pyrite-iron measurements sensu Canfield et al. 1986 (CRS).

In 2025, after the addition of “-carb” analytes (see Carbonate Proxies below) the analyte codes for sequentially extracted iron were changed to Fe-carb(seq), Fe-ox(seq), Fe-mag(seq), to avoid confusion between Fe-carb from SeqA method and Fe-carb from a light leach.

Published FeHR, FeHR/FeT and Fe-py/FeHR are stored in the proxy table. On the website, the presented values are calculated based on the component parts in the first instance (e.g. highly-reactive iron FeHR = Fe-carb(seq) + Fe-ox(seq) + Fe-mag(seq) + Fe-py) and published values are used if components are not available.

For total iron see Elements section below.

Some studies have modified the SeqA method for Fe-carb extraction by time or temperature. In one case carbonate iron is defined based on the cold HCl method of Raiswell. Similarly, there is one modification of SeqB by time (6h instead of 2h).

Note that Pyrite-iron, pyrite, total sulfur and pyrite-sulfur are sometimes ambiguously named in tables and/or not mentioned in the methods e.g. tables with “pyrite” or “py” in a header where the value is for “Fe-py”, or a column for sulfur but no discussion of method, such that it could be S-py by CRS, or S measured along with carbon/other elements. Sometimes, therefore, an assumption has been made based on circumstantial evidence.

For discussion of CAS (carbonate-associated sulfate) methods see papers by Gill et al. 2008, and Wotte et al. 2012. Variations include repetition of the NaCl leach step, and the addition (or not) of bleach. In some cases CAS is determined stoichiometrically from the mass of the BaSO4 precipitate. In other cases SO4 is measured with ICP:MS or along with isotopes using EA-IRMS. S-org and S-SO4 values are mostly sourced from the USGS-NGDB database, with no associated methods.

The reference standard for sulfur isotopes is Vienna-Cañon Diablo Troilite (VCDT).

Proxy Primer

Dr. Maya Gomes, Sulfur Isotopes: https://www.youtube.com/watch?v=5nbf9JtEVlU

analyte(s) count_res code translation ana_method(s)
Iron
Fe-carb(seq) 15741 SeqA Sodium acetate extraction, 48hr, 50degC (Poulton and Canfield 2005) AAS, FSP, ICP:ES, ICP:MS, N/A, Q-ICP:MS, QQQ-ICP:MS
Fe-carb(seq) 135 SeqA(24h) Sodium acetate extraction, 24hr AAS, Q-ICP:MS
Fe-carb(seq) 59 SeqA(RoomTemp) Sodium acetate extraction, 48hr, room temperature ICP:MS
Fe-ox(seq) 15613 SeqB Sodium dithionite extraction, 2hr (Poulton and Canfield 2005) AAS, FSP, ICP:ES, ICP:MS, N/A, Q-ICP:MS, QQQ-ICP:MS
Fe-ox(seq) 201 SeqB(6h) Sodium dithionite extraction, 6hr AAS
Fe-mag(seq) 15719 SeqC Ammonium oxalate extraction, 6hr (Poulton and Canfield 2005) AAS, FSP, ICP:ES, ICP:MS, N/A, Q-ICP:MS, QQQ-ICP:MS
Fe-py 15273 CRS Chromous chloride reduction (Canfield et al. 1986) EA-CF-IRMS, STOICH
Fe-py 5 Lord1982 Pyrite sensu Lord 1982 ICP:ES
Fe-py 38 CB Combustion/ashing STOICH
Fe-AVS 10 AVS_HCl(6N/hot)_SnCl2 Hot 6N HCl acid-volatile sulfur extraction (Rice et al. 1993) STOICH
Fe-AVS 22 AVS_HCl(6N) 6N HCl distillation for acid volatile sulfur STOICH
Fe-HCl, Fe-py 698 HCl(12N/1min/boil) Boiling 12N HCl for 1min (Berner 1970) AAS, CAT, FSP, ICP:MS, N/A
Fe-AVS, Fe-HCl, Fe-py 282 NULL NULL CS-EA, N/A
Sulfur
CAS 226 NaCl(rep)/HCl/BaCl2 NaCl (repeated leaches), HCl, BaCl2 (Wotte et al. 2012) EA-CF-IRMS, EA-IRMS, ICP:MS, STOICH
CAS 101 NaCl/HCl/BaCl2 NaCl (single leach), HCl, BaCl2 STOICH
CAS 94 NaCl/NaOCl/HCl NaCl and NaOCl(bleach), HCl Q-ICP:MS
CAS 69 NaCl/NaOCl/HCl/BaCl2 NaCl and NaOCl(bleach), HCl, BaCl2 STOICH
AVS, S_ORG, S_SO4 1087 NULL NULL N/A, TS-NAVS
Sulfur Isotopes
DELTA_S34_PY 6965 CRS Chromous chloride reduction (Canfield et al. 1986) CF-IRMS, EA-CF-IRMS, EA-IRMS, IRMS, N/A
DELTA_S34 420 HCl(decarb) Decarbonization with HCl EA-IRMS
DELTA_S34 71 CB Combustion/ashing EA-IRMS
DELTA_S34_CAS 245 NaCl(rep)/HCl/BaCl2 NaCl (repeated leaches), HCl, BaCl2 (Wotte et al. 2012) EA-CF-IRMS, EA-IRMS
DELTA_S34_CAS 194 NaCl/NaOCl/HCl/BaCl2 NaCl and NaOCl(bleach), HCl, BaCl2 EA-IRMS
DELTA_S34_CAS, DELTA_S34_GYP 72 NaCl/HCl/BaCl2 NaCl (single leach), HCl, BaCl2 EA-IRMS
DELTA_S34_CAS 11 NaOCl/HCl/BaCl2 NaOCl(bleach), HCl, BaCl2 (summary in Gill et al. 2008) IRMS
DELTA_S34_OBS 66 SeqOBS Sequential sulfur extraction AVS/CRS/CB/BaCl2 EA-IRMS
DELTA_S34, DELTA_S34_CAS, DELTA_S34_PY 1188 NULL NULL EA-CF-IRMS, EA-IRMS, IRMS, N/A

Carbon

Notes

Total organic carbon (TOC) is most commonly determined by elemental analysis (EA, CS-EA, or CHNS-EA - most specify LECO) after removal of carbonate with an acid treatment (usually HCl).

In some cases the acid type is not specified, although HCl is most likely used - these cases are coded as "Decarb" only. A proportion of TOC measurements were determined by EA, without any acid treatment - note that, in at least some of these cases, it is quite possible that an acid treatment was used but not specifically mentioned. In particular, this applies to a subset of USGS-CMIBS data which has the following method:

"Forms of carbon and forms of sulfur by infrared detection after combustion; acid digestion may precede combustion for all but total C and total S".

This method is considered to be the equivalent to the SGP method of CS-EA. In SGP the combustion is considered an integral part of the CS-EA process, and not coded separately.

If TOC is determined by difference (Total Carbon - Total Inorganic Carbon) no experimental step is included.

Some CMIBS data comes with the following method description: "Total carbon, carbonate carbon and organic carbon by an unspecified detection method after combustion; acid digestion may precede combustion for all but total C and total S". These have the experimental method "CB" and no analytical method.

Total Inorganic Carbon (TIC) is usually determined by difference (Total Carbon - Total Organic Carbon), by acid treatment and mass-loss/gravimetry (see also "Carbonate" in the next section), or by coulometry. Some TIC values have an acid experimental method "HCl(decarb)" and EA as the analytical method - note this is for direct EA with an acidification module (rather than HCl(decarb) and mass loss/stoichiometry).

Programmed pyrolysis data are most commonly analyzed using Rock Eval (Vinci Technologies), with some by HAWK (Wildcat Technologies) or Source Rock Analysis (Weatherford Labs TPH-TOC Workstation). A small minority of studies had no reported methods for programmed pyrolysis analytes, and Rock Eval was assumed based on circumstantial evidence (including factors such as the location of the analysis and the age of the study - Rock Eval being more likely for older studies).

The reference standard for carbon isotopes is Vienna Pee Dee Belemnite (VPDB).

Proxy Primer

Dr. Alex Zumberge, Programmed Pyrolysis (Rock Eval) https://www.youtube.com/watch?v=7yz0gi-rXL4

Dr. Selva Marroquin, Carbon isotopes and chemostratigraphy https://www.youtube.com/watch?v=xXdYWXP6hxU

analyte(s) count_res code translation ana_method(s)
TOC 28601 NULL NULL COUL, CS-EA, EA, EA-CF-IRMS, EA-IRMS, HAWK, N/A, REP, SRA, TC-TIC
TOC 16951 HCl(decarb) Decarbonated with HCl CHNS-EA, CS-EA, EA, EA-CF-IRMS, EA-IRMS, IR, IRMS, N/A
TOC 3039 Decarb Decarbonated (no details provided, likely HCl or AcOH) CS-EA, EA-CF-IRMS, EA-IRMS, REP
TOC 701 WO_H2SO4 Wet oxidation with H2SO4 (CMIBS method) GRAV
TOC 383 CB Combustion/ashing CHNS-EA, COUL, N/A, TC
TOC 202 HCl(decarb)_MA2b Decarbonated with HCl, HCl/HF EA
TOC 130 500deg Heated to 500degC LOI
TOC 128 Acid_CB Acidified before Dumas combustion technique VD
TOC 70 H2SO3 Sulfurous acid EA-CF-IRMS
TOC 26 MA3 HNO3/HCl/HF CS-EA
TOC 12 Digest Unspecified digestion (CMIBS method) ICP:MS
TIC 13574 NULL NULL COUL, CS-EA, EA, EA-IRMS, HAWK, N/A, TC-TOC, TTR, VOL
TIC 1521 HCl(decarb) Decarbonated with HCl CS-EA, IR, ML
TIC 726 H3PO4 Phosphoric acid CS-EA, EA, IRMS
TIC 360 Decarb Decarbonated (no details provided, likely HCl or AcOH) COUL, CS-EA, EA, ML
TIC 313 HClO4 Perchloric acid COUL, COUL_TT
TIC 97 CB Combustion/ashing EA, N/A
C 12669 NULL NULL CS-EA, EA, EA-IRMS, GRAV, GRAV_FLUX, IR, N/A, REP
C 12420 CB Combustion/ashing CHNS-EA, COUL, CS-EA, IR, N/A, TC
C 6 Digest Unspecified digestion (CMIBS method) WC
Organic carbon isotopes
DELTA_C13_ORG 10204 HCl(decarb) Decarbonated with HCl CF-IRMS, EA-CF-IRMS, EA-IRMS, IRMS
DELTA_C13_ORG 2178 NULL NULL EA-CF-IRMS, EA-IRMS, IRMS, N/A
DELTA_C13_ORG 704 Decarb Decarbonated (no details provided) EA-CF-IRMS, EA-IRMS
DELTA_C13_ORG 160 HCl(decarb)_MA2b Decarbonated with HCl, HCl/HF IRMS
DELTA_C13_ORG 104 MA2b HCl/HF EA-IRMS
DELTA_C13_ORG 79 H2SO3 Sulfurous acid EA-CF-IRMS
Rock Eval Pyrolysis/HAWK/Source Rock Analysis
S1, S2, S3, Tmax 26029 NULL NULL HAWK, REP, SRA, N/A
S1, S2, S3, Tmax 7875 Decarb Decarbonated (no details provided) REP

Carbonate proxies

In Phase 2, new analytes with the subscript "_carb" were added to accommodate carbonate data from a light acid leach, specifically targeting metals in the carbonate crystal lattice. These analyses usually involve a single-acid leach of various strengths. Some protocols used a relatively strong acid (e.g., a 6N HCl) which may leach elements from clay or detrital minerals compared to a lighter leach, but that are philosophically targeting the carbonate fraction. The acid strength is a key part of the experimental code in this instance (by contrast, see Elements, where strong acids are assumed).

Carbonate is sometimes short-handed as 'CaCO3' in data tables, even where methods used clearly could be extracting other carbonate types (iron carbonate, dolomite etc.). On the SGP website these are all presented as 'Carbonate'.

Outliers include 1) 'CaCO3' with a four-acid digest - CMIBS data, results from Lewis_2010 with the method "Major and minor elements by inductively coupled plasma-atomic emission spectrometry after digestion with HF-HCl-HNO3-HClO4; Fe2O3 by computation FeTO3 less FeO". 2) CaCO3 from Stüecken et al after SeqA method: "Calcium and Mg concentrations in the acetic acid fraction were used to determine the relative abundances of CaCO3 and MgCO3 end members in the samples".

The overwhelming majority of carbonate-carbon and oxygen isotopes are determined by IRMS with an associated carbonate preparation device (e.g. Kiel III, Gasbench, NuCarb etc.) using phosphoric acid (H3PO4).

The reference standard for carbonate-carbon and -oxygen isotopes is Vienna Pee Dee Belemnite (VPDB).

Cerium anomalies

Commonly cited method papers

Cerium anomalies are reported in SGP as published and currently do not distinguish between calculation methods (i.e., whether and how Ce is compared to La, Pr, and Nd).

From Dr. Rosalie Tostevin (pers. comm. 2024) "there are two common approaches in circulation: linear and geometric. Older papers, but some newer ones too, compare the concentration of Ce to its immediate neighbours, La and Pr [Ce/Ce* = 2Ce/(La+Pr)]. Because seawater has a positive La anomaly, this can result in a false negative Ce anomaly. To correct for this, these papers then cross plot Ce/Ce* against Pr anomalies to distinguish true Ce anomalies [Pr/Pr* = 2Pr/(Ce + Sm)]. Other papers calculate the Ce anomaly using the geometric formula [Ce/Ce* = Ce/(Pr/Nd^2)], which avoids comparison with La. [...] Note: all concentrations referred to in formulas above are PAAS-normalised.

Of 24 studies in SGP with Ce/Ce* values

  • 15 use the geometric formula [Ce/Ce* = Ce/(Pr/Nd^2)]
  • 5 use the linear formula [Ce/Ce* = 2Ce/(La+Pr)]
  • 1 uses the linear formula [Ce/Ce* = 3Ce/(2La+Nd)]
  • 3 are unknown.

Proxy Primer

Dr. Rosalie Tostevin, Cerium anomalies https://www.youtube.com/watch?v=TQ8lkd_w1qI

I/Ca and I/[Ca+Mg]

Commonly cited method papers

Proxy Primer

Dr. Zunli Lu, I/Ca ratios https://www.youtube.com/watch?v=wkHys_KG91A

analyte(s) count_res code translation ana_method(s)
Carbonate isotopes
DELTA_C13_CARB, DELTA_O18_CARB 21369 H3PO4 Phosphoric acid CF-IRMS, CRDS, EA-IRMS, GC-IRMS, IRMS
DELTA_C13_CARB, DELTA_O18_CARB 1401 NULL NULL EA-IRMS, IRMS, MassBal, N/A, SIMS
DELTA_C13_CARB, DELTA_O18_CARB 164 Roast_380deg Roasted at 380degC IRMS
DELTA_O18_CARB 115 LaserFluor Laser fluorination IRMS
Carbonate
Carbonate 5390 HCl(decarb) Decarbonated with HCl ML, VOL
Carbonate 1447 NULL NULL COUL, HAWK, N/A, STOICH
CaCO3 1407 MA4 HNO3/HClO4/HF/HCl ICP:ES
Carbonate 309 Decarb Decarbonated (no details provided) EA-CF-IRMS, ML
CaCO3 59 SeqA Sodium acetate extraction, 48hr, 50degC (Poulton and Canfield 2005) ICP:MS
I/Ca
I/Ca, I/[Ca+Mg] 910 HNO3(3%)_TA HNO3, tertiary amine solution ICP:MS, Q-ICP:MS
I/[Ca+Mg] 47 HNO3(3%) 3% nitric acid ICP:MS
Carbonate-phase Elements
Al-carb, As-carb, Ba-carb, Ca-carb, Cd-carb, Ce-carb, Co-carb, Cr-carb, Cs-carb, Cu-carb, Dy-carb, Er-carb, Eu-carb, Fe-carb, Ga-carb, Gd-carb, Ge-carb, Hf-carb, Ho-carb, La-carb, Li-carb, Lu-carb, Mg-carb, Mn-carb, Mo-carb, Nb-carb, Nd-carb, Ni-carb, P-carb, Pb-carb, Pr-carb, Rb-carb, Re-carb, Sb-carb, Sc-carb, Se-carb, Sm-carb, Sn-carb, Sr-carb, Ta-carb, Tb-carb, Th-carb, Ti-carb, Tl-carb, Tm-carb, U-carb, V-carb, W-carb, Y-carb, Yb-carb, Zn-carb, Zr-carb 15538 AcOH(0.85N) 0.85N acetic acid ICP:MS-HR
Al-carb, Ca-carb, Ce-carb, Dy-carb, Er-carb, Eu-carb, Fe-carb, Gd-carb, Ho-carb, La-carb, Lu-carb, Mg-carb, Mn-carb, Nd-carb, Pr-carb, Sm-carb, Sr-carb, Tb-carb, Tm-carb, Y-carb, Yb-carb 9370 HNO3(2%) 2% nitric acid ICP:ES, ICP:MS, Q-ICP:MS
Al-carb, Ba-carb, Ca-carb, Ce-carb, Co-carb, Dy-carb, Er-carb, Fe-carb, Gd-carb, K-carb, La-carb, Mg-carb, Mn-carb, Mo-carb, Na-carb, Nd-carb, P-carb, Pr-carb, Rb-carb, Sm-carb, Sr-carb, Th-carb, Ti-carb, Tl-carb, U-carb, V-carb, Zn-carb 4219 HCl(1N) 1N hydrochloric acid ICP:ES, ICP:ES/MS, ICP:MS, Q-ICP:MS, QQQ-ICP:MS
Al-carb, Ca-carb, Eu-carb, Fe-carb, K-carb, Mg-carb, Mn-carb, Mo-carb, Na-carb, Nd-carb, P-carb, Rb-carb, Re-carb, Sr-carb, Th-carb, Ti-carb, U-carb, V-carb 3712 HNO3(1M) 1M nitric acid Q-ICP:MS
Al-carb, Ca-carb, Ce-carb, Cr-carb, Dy-carb, Er-carb, Eu-carb, Gd-carb, HREE-carb, Ho-carb, LREE-carb, La-carb, Lu-carb, MREE-carb, Mg-carb, Mn-carb, Nd-carb, Pr-carb, Sc-carb, Sm-carb, Sr-carb, Tb-carb, Th-carb, Tm-carb, U-carb, Y-carb, Yb-carb 1597 HCl(0.5N) 0.5N hydrochloric acid ICP:ES, ICP:MS-HR, Q-ICP:MS
Al-carb, Cu-carb, Mn-carb, Mo-carb, Ni-carb, U-carb, V-carb 973 NaOAc(1M) 1M sodium acetate (AcOH buffered) ICP:MS
Al-carb, Ca-carb, Ce-carb, Dy-carb, Er-carb, Eu-carb, Fe-carb, Gd-carb, Ho-carb, La-carb, Lu-carb, Mg-carb, Mn-carb, Nd-carb, Pb-carb, Pr-carb, Rb-carb, Sm-carb, Sr-carb, Tb-carb, Th-carb, Tm-carb, U-carb, Y-carb, Yb-carb 892 HNO3(0.4M) 0.4M nitric acid Q-ICP:MS
Al-carb, Ce-carb, Dy-carb, Er-carb, Eu-carb, Gd-carb, Ho-carb, La-carb, Lu-carb, Mn-carb, Mo-carb, Nd-carb, Pr-carb, REY-carb, Sm-carb, Sr-carb, Tb-carb, Tm-carb, Y-carb, Yb-carb 880 HCl(2N) 2N hydrochloric acid ICP:MS
Ce-carb, Dy-carb, Er-carb, Eu-carb, Gd-carb, Ho-carb, La-carb, Lu-carb, Nd-carb, Pr-carb, Sm-carb, Tb-carb, Tm-carb, Y-carb, Yb-carb 585 HCl(0.1NSeq) 0.1N HCl in 4hr, 2hr, 10min sequential steps ICP:MS
Al-carb, Ca-carb, Fe-carb, Mg-carb, Mn-carb, Sr-carb, U-carb 488 HNO3(1M/conc) HNO3(1M) and HNO3(conc) Q-ICP:MS
Ce-carb, Dy-carb, Er-carb, Eu-carb, Gd-carb, Ho-carb, La-carb, Lu-carb, Nd-carb, Pr-carb, REE-carb, Sm-carb, Tb-carb, Th-carb, Tm-carb, Y-carb, Yb-carb 271 AcOH Acetic acid ICP:MS
Ce-carb, Dy-carb, Er-carb, Eu-carb, Gd-carb, Ho-carb, La-carb, Lu-carb, Nd-carb, Pr-carb, REY-carb, Sm-carb, Tb-carb, Tm-carb, Y-carb, Yb-carb 256 HNO3(5%) 5% nitric acid Q-ICP:MS
Ca-carb, Mg-carb, Mn-carb, Sr-carb 168 AcOH(1N) 1N acetic acid ICP:ES
Ca-carb, Fe-carb, Mg-carb, Mn-carb, Sr-carb 141 HCl(3N) 3N hydrochloric acid AAS
Al-carb, Ba-carb, Ca-carb, Cr-carb, Fe-carb, K-carb, Mg-carb, Na-carb, Sr-carb 117 HCl(6N) 6N hydrochloric acid ICP:MS
Fe-carb 114 HCl(24h/cold) Cold HCl (1M or 10%) for 24hr (Raiswell et al. 1994) ICP:MS
Ca-carb 79 NH4Ac(1M) 1M ammonium acetate ICP:MS
Pb-carb, Th-carb, U-carb 42 HNO3(5%)_AE(HBr-HCl) 5% HNO3, converted with HBr, anion exchange chromatography Q-ICP:MS

Nitrogen and Phosphorus

Phosphorus

Commonly cited method papers

Notes

See the papers above for detailed discussion and figures illustrating methodological steps for SEDEX ("Sedimentary Extraction").

For total phosphorus see Elements section below.

In SGP we have no code for the first SEDEX step, which is for modern sediments.

SGP codes for the older (Ruttenberg) method are

  • SeqAphos
  • SeqBphos
  • SeqCphos
  • SeqDphos

SGP codes for the newer (Thompson) method are

  • SeqAphos
  • SeqBphos
  • SeqCphos
  • SeqDphos(mod)
  • SeqEphos(mod)
  • SeqFphos(mod)

The first three steps are shared. SeqFphos(mod) is the same procedure as SeqDphos, but in a different place sequentially.

Any sum of components is stored in the proxy table, not presented on the website in Phase2. These include:

  • P-FeT = P-Fe1+P-mag+P-Fe2
  • P-react = P-Fe+P-auth+P-org
  • P-tot = P-Fe1+P-auth+P-mag+P-Fe2+P-det+P-org

There is variability in how analytes are reported in papers, especially P-fe/Fe1 and P-det.

SGP uses P-Fe1 for the analyte measured from the first step (SeqAPhos), whether or not the new or old sequential method is used (i.e. there can be studies where “P-Fe1” was measured but “P-Fe2” was not).

SGP uses P-det for the analyte measured from the third step (SeqCPhos), whether or not the new or old sequential method is used. P-cryst and Px1 are variations in the literature: Thompson et al. 2019 state that “The Pdet step of the original SEDEX procedure has been redefined as Pcryst, and represents crystalline apatite which may include recrystallized CFA as well as detrital apatite of igneous or metamorphic origin”. Creveling et al. 2014 (pre-dating Thompson) use the variation Px1, and their method is described as a “modified version of Ruttenberg”. Bowyer et al. 2020 and 2023 cite the Thompson method but use P-det as the name.

One outlier method “SeqC+Ephos_Guilbaud” was added to account for a modification of Guilbaud et al. 2020. This method code might be changed if other similar data is added - for now this is the only example.

analyte(s) count_res code translation ana_method(s)
P-Fe1(seq) 524 SeqAphos CDB pH 7.6 8h (Ruttenberg 1992, Thompson et al. 2019) ICP:ES
P-auth(seq) 613 SeqBphos Na Acetate pH 4.0 6h (Ruttenberg 1992, Thompson et al. 2019) MolyB
P-det(seq) 538 SeqCphos 1M HCl 16hr (Ruttenberg 1992, Thompson et al. 2019) MolyB
P-org(seq) 225 SeqDphos Ash 550decC, HCl (Ruttenberg 1992). MolyB
P-mag(seq) 362 SeqDphos(mod) Ammonium oxalate 6h (Thompson et al. 2019) ICP:ES
P-Fe2(seq) 364 SeqEphos(mod) CDA ph 4.8 6h (Thompson et al. 2019) ICP:ES
P-org(seq) 364 SeqFphos(mod) Ash 550degC, 1M HCl 6h (Thompson et al. 2019) MolyB
P-inorg 38 HCl(decarb) Decarbonated with HCl UV-Vis
P-det(seq) 74 SeqC+Ephos_Guilbaud SeqC_phos + MA_5 after SeqD_phos MolyB

Nitrogen

The majority of nitrogen isotopes in SGP are run using well-established methods (usually no method paper is cited). See above for carbon, often measured alongside. C:N ratios are atomic. N is usually measured along with the isotopes, and included here but see Element section below for other measurements of total N.

The reference standard for nitrogen isotopes is Air.

Proxy primer

Dr. Eva Stüeken, Nitrogen isotopes https://youtu.be/2cNkWSPqMo4?si=I7rGSO8dHmWNvRcX

analyte(s) count_res code translation ana_method(s)
C:N, DELTA_N15, N 5972 HCl(decarb) Decarbonated with HCl CHNS-EA, EA, EA-CF-IRMS, EA-IRMS, IRMS
DELTA_N15_KER 132 MA2b_ZnBr HCl/HF, heavy liquid separation in ZnBr EA-IRMS
C:N, DELTA_N15, N 126 HCl(decarb)_MA2b Decarbonated with HCl, HCl/HF EA-IRMS
DELTA_N15_KER 111 SOX(DCM)_MA3 Soxhlet dichloromethane-extraction, HF/HCl/HNO3 EA-IRMS
DELTA_N15, DELTA_N15_KER, N 78 Decarb Decarbonated (no details provided) EA-CF-IRMS, IRMS
DELTA_N15_KER 61 HCl(decarb)_HF/BF3 Decarb. with HCl, HF and BF3 for kerogen extraction (see Robl and Davis 1993, Stüecken et al. 2015) EA-CF-IRMS
DELTA_N15_KER 51 SOX(DCM)_MA2b Soxhlet dichloromethane-extraction, HF/HCl EA-CF-IRMS
C:N, DELTA_N15, DELTA_N15_KER, N 3072 NULL NULL EA-CF-IRMS, EA-IRMS, IRMS, N/A

Metal Isotopes

Metal isotope analysis generally includes

  • leach/digestion step
  • a purification step (chromatography)
  • measurement by ICP:MS-MC or TIMS/NTIMS
  • analytical correction (double-spike/standard sample bracketing)

In SGP the experimental code aims to capture the digestion and purification steps in as much relevant detail as possible. Thus far we do not include information in the code itself about analytical correction methods (e.g. mass-bias correction) such as double-spike or standard sample bracketing. For the most part the approach used tends to be standardized within a given isotopic system; in some instances double-spike and bracketing are used in combination.

Given the methodological complexity and the inconsistency in how procedures are reported across the literature, some degree of compromise has been necessary. These codes are a work in progress, and feedback is welcome.

Digestion

SGP uses the same codes for this step as for elemental digests (see below) e.g. CB_MA3. If the digest is partial or light the strength of the acid is included e.g. HCl(0.25N).

Steps between the initial digest and purification are difficult to code in a standardized way. These may include e.g. +/- HClO₄ +/-H₂O₂, secondary acid treatments, and various additional heating steps (e.g., microwave, ashing*). While these intermediate treatments often serve the same purpose (e.g. to prevent issues such as fluoride precipitation or to oxidize organics) they can vary in order, composition, and intensity across labs and publications. In some cases, it is not clear if these steps were included but not explicitly mentioned (authors may link to a citation which is ambiguous, or cite papers several layers deep). Users should be aware, therefore, that these steps are often not included in the code and we recommend consulting the original publications for details.

*Note that if combustion/ashing is part of the initial digest, we do aim to include it in the code - we refer here to steps between initial digest and chromatography

Purification

In addition to the acid digest, the code captures the use of ion exchange (IE) or more specifically anion exchange (AE), cation exchange (CE), or a combination of both.

Where possible, we also attempt to capture the number of purification steps or columns. However, terminology in the literature is inconsistently applied: the term "step" may refer to either multiple elution stages on a single column, or to multiple columns used in sequence. Similarly, "stage" can be ambiguous (e.g., “two-stage” vs. “two-step”), and usage varies across isotope systems, and sometimes within a single isotope system (albeit less common).

As a result, SGP includes a numerical prefix (e.g., "2AE") where publications consistently refer to the number of steps, stages, or columns, and particularly if a distinction is explicitly drawn between methods within one isotope system.

Resins and eluents are generally not included in the purification code, as most isotope systems use standard combinations. However, resins are noted in the full experimental method description. When a non-standard resin is used (e.g., TRU resin instead of UTEVA for uranium), this is included in the code to highlight significant deviations from the norm.

Isotope Dilution

Element concentrations are sometimes/often measured alongside isotopes by isotope dilution methods. We note that, on occasion, it can be difficult to tell in a data table whether an element has been measured with the isotopes, or with other elements by e.g. standard acid-digest and ICP:MS etc.

Calcium and Magnesium Isotopes

Commonly cited method papers

Notes

For calcium and magnesium isotope analysis in carbonates, automated ion chromatography (e.g., Dionex systems) is commonly used. Some studies use traditional gravity-flow columns. SGP experimental codes include a numerical prefix (e.g. 2AE), to reflect “two-stage” and/or “two sets of columns”, when explicitly stated.

The majority of studies in SGP so far use ICP:MS-MC.

BioRad AG MP-50 is the standard resin used (variably reported as e.g. “MP 50”, "AG MP-50" etc.)

The reference standard for calcium isotopes is seawater for studies in SGP so far - but note that other reference standards can be used. The reference standard for magnesium isotopes is DSM3 (from Dead Sea Magnesium Ltd., Israel).

Proxy Primer

Dr. Anne-Sofie Ahm, Calcium Isotopes: https://youtu.be/nQf2ykhpgpk?si=7D6OBwe1mr_tlO4v

analyte(s) count_res code translation ana_method(s)
DELTA_Ca44_Ca40_CARB, DELTA_Mg26_CARB 518 AcOH(dil)_AIC Dilute acetic acid (no strength specified), automated ion chromatography ICP:MS-MC
DELTA_Ca44_Ca40_CARB, DELTA_Mg26_CARB 318 AcOH(0.1N)_AIC 0.1N acetic acid, automated ion chromatography ICP:MS-MC
DELTA_Mg26_CARB 125 HCl(1N)_2CE 1N HCl, two-step cation ion exchange chromatography (AGMP-50 resin) ICP:MS-MC
DELTA_Mg26_CARB 69 HCl(1N)_AIC 1N HCl, automated ion chromatography ICP:MS-MC
DELTA_Mg26_CARB 39 HCl(0.5N)_2CE 0.5N HCl, two-step cation exchange chromatography (AGMP-50 resin) ICP:MS-MC
DELTA_Ca44_Ca40_CARB 34 HCl(0.5N)_CE 0.5N HCl, cation exchange chromatography (AGMP-50 resin) TIMS
DELTA_Mg26_CARB 13 HCl(6N)_CE 6N HCl, cation exchange chromatography (AGMP-50 resin) ICP:MS-MC

Cadmium Isotopes

Commonly cited method papers

Frederiksen et al. 2022 https://doi.org/10.1016/j.scitotenv.2021.150565

Notes

Thus far cadmium isotopes in SGP are from one paper (Fernandes et al. 2025 https://doi.org/10.1016/j.chemgeo.2024.122548) and measured along with chromium isotopes (see below). The resin used is AG-1X8.

The reference standard for cadmium isotopes is NIST SRM 3108.

analyte(s) count_res code translation ana_method(s)
DELTA_Cd114_CARB 13 HNO3(0.5M)_3AE 0.5M HNO3, three step anion exchange chromatography (AG-1X8 resin) TIMS

Chromium Isotopes

Commonly cited method papers

Notes

One approach to purification for chromium isotopes is a “three-step” procedure, although depending on the details, separation goals are slightly different.

Anion exchange with AG1-X8 resin

  • removal of Fe from the samples (Bauer et al. 2021 (Copenhagen))

Anion exchange (sometimes microcolumns are specified) with AG1-X8 resin

  • V and Ti removed (Bauer et al. 2021 (Copenhagen))
  • Traces of Fe removed/remove all remaining Fe (Bauer et al. 2021 (Yale), Mänd et al. 2022 (Yale))

Cation exchange with AG50W-X8 resin

  • Cr separated from major matrix elements such as Ca, Mg, Mn and Al as well as residual Fe (Bauer et al. 2021 (Copenhagen))
  • to ensure complete Ti and Cr separation/to remove Ti (Bauer et al. 2021 (Yale), Mänd et al. 2022 (Yale))

In most cases treatment with ammonium persulfate (NH4)2S2O8 is explicitly mentioned, which is used to oxidise Cr(III) to Cr(VI) for retention on the AG1-X8 resin. In one example (Bauer et al. 2021, samples run at Yale) potassium peroxidisulfate (K2S2O8) is used. This oxidizing step either takes place prior to the first anion exchange step, or prior to the second.

In other papers, a two-step approach is used - anion followed by cation exchange.

The reference standard for chromium isotopes is NIST SRM 979.

analyte(s) count_res code translation ana_method(s)
DELTA_Cr53 46 LMF_2AE/CE Lithium metaborate flux, anion (x2) and cation exchange chromatography ICP:MS-MC
DELTA_Cr53 41 CB_MA3_2AE/CE Combustion/ashing, HNO3/HCl/HF, anion (x2) and cation exchange chromatography ICP:MS-MC
DELTA_Cr53 35 MA2h_AE/CE HF/AR, anion and cation exchange chromatography TIMS
DELTA_Cr53_CARB 44 HCl(2N)_AE/CE 2N HCl, anion and cation exchange chromatography TIMS
DELTA_Cr53_CARB 18 HCl(0.5N)_2AE/CE 0.5N HCl, anion (x2) and cation exchange chromatography ICP:MS-MC
DELTA_Cr53_CARB 14 HNO3(0.5M)_(3AE)_AE/CE 0.5M HNO3, (anion exchange for Cd), anion and cation exchange chromatography TIMS
DELTA_Cr53_AUTH 18 NULL NULL CALC

Copper and Zinc Isotopes

Commonly cited method papers

Notes

Thus far Cu and Zn isotopes in SGP are from one paper (Le Boudec et al. 2014 https://doi.org/10.1002/2013GC005068), measured alongside iron isotopes (see below). Sample-standard bracketing is used.

The reference standards used are NIST SRM 976 for copper and JMC 3-0749 for zinc.

analyte(s) count_res code translation ana_method(s)
DELTA_Cu65, DELTA_Zn66 52 CB_MA4_AE Combustion/ashing, HCl/HF, HClO4/HNO3, anion exchange chromatography (AG MP-1 resin) ICP:MS-MC

Iron Isotopes

Commonly cited method papers

Notes

Standard method includes a total acid digest (usually with HF, usually with combustion/ashing first to remove organics), followed by anion exchange chromatography using AG1X8, AG1X4 or AGMP-1 resin.

An intermediate acid step (e.g. taken up in HCl + heated) to ensure "complete dissolution of fluoride compounds" is sometimes described but not included in the code.

The majority of studies use sample-standard bracketing (+/- in combination with an internal Cu "element spike"), with one exception using double-spike. The most commonly cited method paper is Arnold et al. 2004.

Fe-isotopes in pyrite were measured in two studies (Duan et al. 2010, Ostrander et al. 2022) after a sequential extraction. From Duan et al 2010: "a sequential extraction was carried out to quantify the following three individual Fe pools and in preparation for iron isotope analysis of the pyrite (Raiswell et al., 1988; Canfield 1989; Huerta-Diaz and Morse, 1990; Raiswell et al., 1994 ): (1) Fe HCl : extracted using 12 N boiling HCl for 1 min to target all Fe oxides and some of the Fe in clays, followed by (2) Fe Si : 10 N HF for 16 h to extract all residual alumino-silicate Fe and (3) Fe Py : 16 N HNO 3 for 2h to extract all pyrite Fe".

The reference standard for iron isotopes is IRMM-14.

analyte(s) count_res code translation ana_method(s)
DELTA_Fe56 145 CB_MA3_AR_AE Combustion/ashing, HNO3/HCl/HF, aqua regia, anion exchange (AG1X4 resin), sample-standard bracketing ICP:MS-MC
DELTA_Fe56 125 CB_MA3_AE Combustion/ashing, HNO3/HCl/HF, anion exchange (AG1X8 resin), sample-standard bracketing ICP:MS-MC
DELTA_Fe56 120 MA3b_AR_AE HNO3/HF/HClO4, aqua regia, anion exchange chromatography (AGMP1 resin), sample-standard bracketing ICP:MS-MC
DELTA_Fe56 100 MA3_AE HNO3/HCl/HF, anion exchange chromatography (AG1X8 or AGMP1 resin), sample-standard bracketing ICP:MS-MC
DELTA_Fe56 61 CB_MA2_AE Combustion/ashing, HNO3/HF, anion exchange (AG1X8 or AGMP1 resin), sample-standard bracketing ICP:MS-MC
DELTA_Fe56 30 MA2_AE HF/HNO3, anion exchange chromatography (AG1X8 resin), sample-standard bracketing ICP:MS-MC
DELTA_Fe56 26 CB_MA4_AE Combustion/ashing, HCl/HF, HClO4/HNO3, anion exchange (AGMP1 resin), sample-standard bracketing ICP:MS-MC
DELTA_Fe56 16 CB_MA2_AE(DS) Combustion/ashing, HF/HNO3, anion exchange chromatography Fe double-spike (Swanner et al. 2015) ICP:MS-MC
DELTA_Fe56_AUTH 121 NULL NULL CALC
DELTA_Fe56_PY 19 SeqPy_AE Seq extract of pyrite with HNO3, anion exchange (AGMP1 resin), sample-standard bracketing ICP:MS-MC
DELTA_Fe56_PY 18 CB_SeqPy_AE Combustion/ashing, seq extract py w/ HNO3, anion exchange (AG1X8 resin), sample-standard bracketing ICP:MS-MC

Lithium Isotopes

Commonly cited method papers

Notes

Digestion and pre-treatment for shales is a total acid digest with HF/HNO3/HClO4 followed by HNO3/HCl, in one case perchloric acid is used "as needed".

To target the carbonate fraction, there is some variability in approach including dilute HCl treatment, 1 M sodium acetate buffered to pH 5 with acetic acid, or leach with ammonium acetate followed by a sequential leach in 0.05M HCl. See papers by Pogge von Strandmann et al. for discussion/evaluation of different approaches.

Li et al. 2022 provide a summary of chromatographic methods. Most studies in SGP use a two-column cation exchange procedure, with AG50W-X12 resin, one study follows a three-step procedure.

The reference standard for lithium isotopes is LSVEC.

analyte(s) count_res code translation ana_method(s)
DELTA_Li7 93 MA3b_3CE HF/HNO3/HClO4, HCl/HNO3, three cation exchange chromatography ICP:MS-MC
DELTA_Li7 34 MA3b_2CE HF/HNO3/HClO4, HCl/HNO3, two-step cation exchange chromatography (AG50W-X12 resin) ICP:MS-MC
DELTA_Li7_CARB 78 HCl(0.1N)_2CE 0.1N HCl, two-stage cation exchange chromatography (AG50W-X12 resin) ICP:MS-MC
DELTA_Li7_CARB 58 NH4Ac(1M)_HCl(0.05NSeq)_CE 1M ammonium acetate, 0.05N HCl in 4hr/2hr/10min seq. steps, cation exchange (AG50W-X12 resin) ICP:MS-MC
DELTA_Li7_CARB 48 NaOAc(1M)_2CE 1M sodium acetate (AcOH buffered), two stage cation exchange chromatography (AG50W-X12 resin) ICP:MS-MC
DELTA_Li7_CARB 3 MeOH_2CE Methanol/ultrasonic cleaning, two-stage cation exchange chromatography (AG50W-X12 resin) ICP:MS-MC

Molybdenum Isotopes

Commonly cited method papers

Notes

The majority of the molybdenum isotopes in SGP are from a total acid digest (with or without a combustion/ashing initial step), followed by a two-step chromatographic procedure: anion exchange (with AG1-X8 resin) and cation exchange (with AG50W-X8), referencing e.g. Barling et al. 2001 and Duan et al. 2010.

Scheller et al. 2018 (https://doi.org/10.1016/j.precamres.2017.12.009) use a reverse-aqua regia digest and a single-column approach, referencing Pearce et al. 2009.

Three studies - Luo et al. 2021, Hodgskiss et al. 2021, O'Sullivan et al. 2022 - have molybdenum isotopes from carbonate fractions, after a (relatively) light digest.

Most studies use a double-spike to correct for fractionation during chromatography and to correct for mass-bias. Some studies use sample-standard bracketing, and some compare both double-spike and sample-standard bracketing.

The reference standards used for molybdenum isotopes have been variable through time, with older studies tending to use a variety of in-house standards (e.g. RochMo2, various other Johnson Matthey (JMC) Specpure ICP Mo standard solutions). Most studies now report measurements relative to NIST SRM 3134 "where the standard NIST 3134 = 0.25permil". See Goldberg et al. 2013 and Nägler et al. 2013 for discussion. Five studies older than 2013 in SGP use RochMo2, JMC Specpure lot#702499I and JMC-Mo Sie lot#602332B.

analyte(s) count_res code translation ana_method(s)
DELTA_Mo98 911 CB_MA3_AE/CE Combustion/ashing, HNO3/HCl/HF, anion exchange (most AG1-X8 resin), cation exchange (AG50W-X8 resin) ICP:MS-MC
DELTA_Mo98 180 CB_MA2_AE/CE Combustion/ashing, HNO3/HF, anion exchange (AG1-X8 resin), cation exchange (AG50W-X8 resin) ICP:MS-MC
DELTA_Mo98 161 MA3_AE/CE HNO3/HCl/HF, anion exchange (AG1-X8 resin), cation exchange (AG50W-X8 resin) ICP:MS-MC
DELTA_Mo98 26 CB_HCl(conc/boil)_AE Combustion/ashing, concentrated boiling HCl (3 times), anion exchange chromatography (AG1-X8 resin) ICP:MS-MC
DELTA_Mo98 21 MA2_AE/CE HNO3/HF, anion exchange (AG1-X8 resin), cation exchange (AG50W-X8 resin) ICP:MS-MC
DELTA_Mo98 12 ARrev_AE Reverse aqua regia digest, anion exchange chromatography (AG1-X8) (see Pearce et al. 2009) ICP:MS-MC
DELTA_Mo98_CARB 148 HCl(6N)_AE/CE 6N HCl, anion exchange (AG1-X8 resin), cation exchange (AG50W-X8 resin) ICP:MS-MC
DELTA_Mo98_CARB 49 HCl(6N)_BHPA 6N HCl, BHPA resin chromatography (see Li et al. 2014) ICP:MS-MC
DELTA_Mo98, DELTA_Mo98_AUTH 236 NULL NULL CALC, ICP:MS-MC

Selenium Isotope

Commonly cited method papers

Notes

Most studies in SGP with selenium isotopes are based on the methods of Stüeken et al. 2013 - refer to that paper for detailed description and diagram of steps.

analyte(s) count_res code translation ana_method(s)
DELTA_Se82_Se78 198 MA3b_TCF_AR HF/HClO4/HNO3, TCF filter, Aqua Regia (Method E of Stüeken et al. 2013) ICP:MS-MC
DELTA_Se82_Se78 100 MA3b_TCF HF/HClO4/HNO3, TCF filter (Method D of Stüeken et al. 2013) ICP:MS-MC
DELTA_Se82_Se78 4 MA3b_TCF+/-AR HF/HClO4/HNO3, TCF filter +/- Aqua regia (Average of Method D and Method E of Stüeken et al. 2013) ICP:MS-MC

Uranium Isotopes

Commonly cited method papers

Notes

Uranium isotopes in SGP are relatively evenly divided between total/bulk and carbonate-specific measurements, with rare examples coded as authigenic. Bulk isotopes are determined after a strong acid digest (often with a combustion/ashing step) and carbonate isotopes (and one authigenic) after a light or moderate acid digest.

White et al. 2018, and subsequent related papers, describe a procedure where the "sample powder was digested at room temperature by adding 20 mL of 1M HNO3, followed by the slow addition of 3 mL of concentrated HNO3 to replace the acid neutralized by reaction with CaCO". This is coded simply as HNO3(1M).

Authigenic uranium isotopes in SGP come from two studies so far. Those from Lu et al. 2020 are calculated relative to PAAS. Those from Dang et al. 2022 are measured after an aqua regia leach - see Dang et al. 2022 for discussion of authigenic components generally.

Additional steps not coded As discussed above, many protocols include pre-digest cleaning steps, intermediate treatments, or post-column-chemistry steps, often with similar aims, which are not coded for. For example:

  • a pre-digest cleaning step described in Tostevin et al. 2019, based on Clarkson et al. 2018: "two-step reductive and oxidative cleaning procedure to remove potential Mn-oxides and residual organic matter"
  • an intermediate treatment described in Dang et al. 2022 (after initial acid digest): "Clear solutions were dried at 95degC before samples were redissolved in 4 mL HCl. The solutions were dried again and a second 4 mL of HCl were added. These steps were designed to dissolve any fluoride precipitate. If needed (brown-colored solutions), 0.5 to 2 mL of H2O2 was added in HCl acid media to oxidize any residual organic content"
  • a similar intermediate treatment described in White et al. 2018, and related papers (after initial 1M HNO3 digest): " Spiked samples were subsequently dried down to equilibrate the spike mixture, and the residue was treated with a solution of 0.3 mL 32% H2O2 and 2 mL concentrated HNO3 at ~100°C for one hour to oxidize any residual organic carbon leached from the samples prior to column chemistry."
  • a post-column chemistry step described in Lu et al. 2023: "After column chemistry, samples were treated with both concentrated HNO3 and 30% H2O2 (hydrogen peroxide) twice to break down any residual organic matter from the resin"

Chromatography/Purification

By far the most commonly used resin is Triskem/Eichrom UTEVA. Others use TRU or RE resins, these are specified in the code.

In some cases, it is explicitly stated that two column steps/two column passes were used, and this is included in the code. In some cases, two steps are described with different resins, for example

  • anion exchange with AG1X8 resin, preceding ion exchange with UTEVA in Clarkson et al. 2021
  • ion exchange with DGA resin ("to remove excess Na"), after ion exchange with UTEVA e.g. Cheng et al. 2020, Remirez et al. 2024.

Double-spike (usually IRMM-3636 236U-233U, sometimes in-house) is used to correct for U isotope fractionation during the column chemistry and instrumental mass bias. Sample-standard bracketing is also commonly used.

In SGP the reference standard used so far for uranium isotopes is CRM-145/CRM-112a, and in one instance NIST SRM 950a (Kendall et al. 2013 http://dx.doi.org/10.1016/j.chemgeo.2013.08.010, with the following noted: "We report the U isotope composition of each sample relative to the SRM950a standard as δ238U [‰] = [238/235Usample / 238/235USRM950a − 1] × 1000. We have determined that standard CRM145 (also known as CRM112a; Telus et al., 2012) has a statistically identical U isotope composition compared to SRM950a (δ238U = 0.04 ± 0.06‰; 2SD, n = 38), in agreement with initial results reported by Weyer et al. (2008)."

Proxy Primer

Dr. Kimberly Lau, Uranium Isotopes https://www.youtube.com/watch?v=tg7Zf6hjaMI

analyte(s) count_res code translation ana_method(s)
DELTA_U238 252 CB_MA3_IE Combustion/ashing, HNO3/HCl/HF digest, ion exchange chromatography (UTEVA resin) ICP:MS-MC
DELTA_U238 53 CB_MA3d_IE Combustion/ashing, HNO3/HF, aqua regia, ion exchange chromatography (UTEVA resin) ICP:MS-MC
DELTA_U238 30 MA3b_IE HF/HNO3/HClO4, ion exchange chromatography (UTEVA resin) ICP:MS-MC
DELTA_U238 29 MA4_IE(TRUresin) HF/HCl/HNO3/HClO4, ion exchange separation (TRU resin) ICP:MS-MC
DELTA_U238 27 MA3_IE HF/HNO3/HCl, ion exchange chromatography (UTEVA resin) ICP:MS-MC
DELTA_U238 9 CB_MA3d_2IE Combustion/ashing, HNO3/HF, aqua regia, ion exchange chromatography (x2)(UTEVA resin) ICP:MS-MC
DELTA_U238_CARB 193 HNO3(1M)_IE 1M HNO3, ion exchange chromatography (UTEVA resin) ICP:MS-MC
DELTA_U238_CARB 133 NaOAc(1M)_IE 1M sodium acetate, ion exchange chromatography (UTEVA resin) ICP:MS-MC
DELTA_U238_CARB 127 HCl(1N)_2IE 1N HCl, two-step ion exchange chromatography (UTEVA resin) ICP:MS-MC
DELTA_U238_CARB 112 HCl(0.25N)_2IE 0.25N HCl, two-step ion exchange chromatography (UTEVA resin) ICP:MS-MC
DELTA_U238_CARB 107 HNO3(1M)_2IE 1M HNO3, 2 x ion exchange chromatography (UTEVA) ICP:MS-MC
DELTA_U238_CARB 83 HCl(1N)_IE 1N HCl, ion exchange chromatography (UTEVA resin) ICP:MS-MC
DELTA_U238_CARB 82 HNO3(1M)_IE/AIC 1M HNO3, ion exchange chromatography (UTEVA) + automated ion chromatography (DGA resin) ICP:MS-MC
DELTA_U238_CARB 78 NH4Ac(1M)_2IE(REresin) NH4Ac(1M), ion exchange chromatography (RE resin) ICP:MS-MC
DELTA_U238_CARB 40 HCl(0.1NSeq)_2IE 0.1N HCl in 4hr, 2hr, 10min sequential steps, two-step ion exchange chromatography (UTEVA resin) ICP:MS-MC
DELTA_U238_CARB 17 AcOH(0.5M)_AE/IE 0.5N acetic acid, anion exchange (AG1X8 resin) ion exchange chromatography (UTEVA resin) ICP:MS-MC
DELTA_U238_AUTH 146 AR_IE(TRUresin) Aqua regia, ion exchange chromatography (TRU resin) ICP:MS-MC
DELTA_U238_AUTH 23 NULL NULL CALC

Vanadium Isotopes

Commonly cited method papers

Notes

Thus far SGP contains data from one study, Heard et al. 2023 https://doi.org/10.1016/j.epsl.2023.118127, who used standard protocols from Woods Hole Oceanographic Institute.

The reference standard used is Alfa Aesar (AA) V specpure standard.

analyte(s) count_res code translation ana_method(s)
DELTA_V51_AUTH 18 HNO3(2M)_CE/3AE 2M HNO3, cation (AG50WX12 resin) and 3x anion exchange chromatography (AG1X8 resin). WHOI method. ICP:MS-MC

Samarium-Neodymium Isotopes

Commonly cited method papers

Notes

Preparation for Sm-Nd isotopes generally involves a combustion/ashing step, strong multi-acid digest, usually heated, usually in multiple stages, and chromatography:

  • anion exchange, AG1X8 resin to remove iron (not always mentioned)
  • cation exchange, Eichrom TRU resin or Bio-Rad AG50W, to remove REE
  • cation exchange, Eichrom LN resin, for Sm and Nd.

In one example (Maloney et al. 2024), the strong acid digest is preceded by treatment in acetic acid to remove carbonate. In another example (Mundl et al. 2018), the sample is digested using flux fusion, and only the last chromatography step is mentioned (cation with LN resin for Sm and Nd).

εNd(0) (aka εNd) is the present-day deviation of the sample from CHUR, defined as follows: εNd = [(143Nd/144Nd)sample – (143Nd/144Nd)CHUR] – 1 * 10000

εNd(t). As described in Maloney et al. 2024: "values are commonly presented as a function of age where both the sample and CHUR 143Nd/144Nd ratios are corrected for 143Nd ingrowth since the time the rocks were deposited.". The age used is stored in the database, but not yet available on the website - refer to original publications for details.

εNdi = Initial ɛNd at time of rock formation

analytes count_res code translation ana_methods
Nd, Nd143_Nd144, Sm, Sm147_Nd144, eNd(0) 70 MA2_2CE HF/HNO3, two-step cation exchange chromatography (Sm Nd with LN resin) ID-NTIMS, TIMS
Nd, Nd143_Nd144, Sm, Sm147_Nd144, eNd(t) 30 LTMF_CE Lithium tetraborate/metaborate fusion, cation exchange chromatography (LN resin) ID-NTIMS, TIMS
Nd, Nd143_Nd144, Sm, Sm147_Nd144, eNd(0), eNd(t) 72 CB_AcOH_MA2_AR/HCl_AE/2CE Ash, AcOH decarb, HF/HNO3, aqua regia, HCl, chrom. (anion AG1X8, cation TRU, cation LN) ICP:MS-MC
Nd, Nd143_Nd144, Sm, Sm147_Nd144, eNd(0), eNd(t) 168 CB_MA2_HCl/HNO3_AE/2CE Combustion/ashing, HF/HNO3, HCl/HNO3, 3step chrom (anion AG1X8, cation TRU, cation LN) ICP:MS-MC
Nd, Nd143_Nd144, Sm, Sm147_Nd144, eNdi 250 CB_MA3_AE/2CE Combustion/ashing, HF/HNO3, aqua regia, HCl, 3step chrom. (anion AG1X8, cation TRU, cation LN) TIMS/ICP:MS-MC
Nd, Nd143_Nd144, Sm, Sm147_Nd144, eNd(0), eNd(t) 90 CB_MA2_HCl/HNO3_2CE Combustion/ashing, HF/HNO3, HCl/HNO3, cation ex. chrom x 2 (AG50W for REE, LN resin for Sm Nd) ID-NTIMS, TIMS

Rhenium-Osmium Isotopes

Commonly cited method papers

Notes

Selby and Creaser (2003) is the most commonly cited paper, see for detailed description of methods. The standard protocol involves Carius-tube digestion with 185Re and 190Os spike/tracer in CrVIO3-H2SO4 solution. Osmium is purified by solvent extraction using chloroform then back-extracted into concentrated HBr and then further purified by micro-distillation. Rhenium is purified using anion exchange chromatography. Re and Os are then analysed by NTIMS (Ni filament for Re, Pt filament for Os).

One exception is Chen et al. 2016, measuring Re-Os isotopes alongside PGE. In that case, digestion was "conducted in a mixture of 2.5 mL of triple-distilled, concentrated HCl and 5 mL triple-distilled, concentrated HNO3".

Os187_Os188(I) (on the website as "Osi") = initial 187Os/188Os isotope ratio

Proxy Primer

Dr. Alan Rooney, Re-Os geochronology and Os isotopes https://www.youtube.com/watch?v=pFRMgyohXbo

analytes count_res code translation ana_methods
192Os, Os, Os187_Os188, Re, Re187_Os188 1011 Carius(CrVI-H2S04)_SE/MD/AE Carius tube digest CrVI-H2SO4, solvent extract./microdist./anion ex. chrom. (Selby and Creaser 2003) ICP:MS, ID-NTIMS, NTIMS
Os, Os187_Os188, Re, Re187_Os188 104 Carius(HCl/HNO3)_SE/MD/AE Carius tube digest HCl/HNO3, solvent extract./microdist/anion exchange chromatography ICP:MS, NTIMS
Osi 219 NULL NULL CALC

Strontium Isotopes

Commonly cited method papers

Notes

Many studies do not cite a method paper, so the selection above may be limited. See Chen et al. 2023 https://doi.org/10.1111/ggr.12531 and the Proxy Primer linked below for in-depth discussion of methodology and leaching protocols in particular.

Proxy Primer

Dr. Graham Shields and Dr. Ying Zhou https://youtu.be/kVmntRYaap8?si=ohzDhT7iWXS18MSw

analyte(s) count_res code translation ana_method(s)
Sr87_Sr86 86 HCl(1N)_CE 1N HCl, cation exchange chromatography (AG 50W X12 resin) TIMS
Sr87_Sr86 65 HCl(0.6N)_CE 0.6N HCl, cation exchange chromatography (AG 50W X12 resin) TIMS
Sr87_Sr86 62 MeOH_NH4OAc(0.2M)_AcOH(0.5M)_CE Methanol, 0.2M ammonium acetate, 0.5M acetic acid, cation exchange (Sr Spec resin) TIMS
Sr87_Sr86 44 NH4Ac(0.2M)_AcOH(0.5M)_CE 0.2M ammonium acetate, 0.5M acetic acid, cation exchange (Sr Spec resin) TIMS
Sr87_Sr86 44 HCl(2N)_CE 2N HCl, cation exchange chromatography (Sr Spec resin) TIMS
Sr87_Sr86 14 HNO3(0.5M)_CE 0.5M HNO3, cation exchange chromatography (Sr Spec resin) TIMS
Sr87_Sr86 11 NULL NULL TIMS

Thallium isotopes

Commonly cited method papers

Notes

For all studies in SGP the digestion procedure starts with a standard step: 2M HNO3 for 12hrs at 130deg. This is used to separate authigenic Tl bound to pyrite from detrital Tl. One study subsequently uses a HNO3/HF digest on the residue left from this step, in order to determine authigenic Tl.

The next steps to remove organics (from the supernatant) are variable, involving acids (e.g. HNO3/HCl/AR/reverse-AR in various combinations), ashing and/or microwave, and +/-H2O2. These steps are not included in the code.

In preparation for column chemistry a treatment with 1M HCl +/- brominated H2O is usually applied which is also not coded. This appears to be almost universal, although “brominated H2O” is not always mentioned.

The primary distinction in the purification step is between one or two columns:

  • One-column - newer approach “shown to work well for high Tl and low Pb samples”
  • Two-column - the standard older approach e.g. “thallium purification was accomplished using two separate columns, one large and one micro-column, using AG1X8 anion exchange resin from Biorad.” (Owens et al. 2017).
analyte(s) count_res code translation ana_method(s)
Tl-auth, e205Tl-auth 785 HNO3(2M)_AE 2M HNO3, one-column anion exchange chromatography (AG1X8 resin) ICP:MS-MC
Tl-auth, e205Tl-auth 296 HNO3(2M)_2AE 2M HNO3, two-column anion exchange chromatography (AG1X8 resin) ICP:MS, ICP:MS-MC
e205Tl-det 13 HNO3(2M)_MA2_2AE 2M HNO3, HNO3/HF, two-column anion exchange chromatography (AG1X8 resin) ICP:MS-MC

Elements

Analysis of elemental concentrations by ICP:MS, ICP:ES or XRF make up the majority of data in SGP.

ICP:MS/ICP:ES/Other

Notes

Many of these analyses are run using standard procedures at commercial laboratories, and some of the initial experimental codes were based on those protocols (e.g MA4 for a four-acid digest from Bureau Veritas Labs). The digestion protocol chosen will depend on the rock type, target elements and analytical method.

Combustion/ashing

The code ‘CB’ (previously ‘CBST’) has been used as a catch-all for combustion or ashing at a range of temperatures, and is a common prefix for multi-acid digests, indicating a heating step used to oxidize organics. The most common temperature is around 500/550 degrees C, which should perhaps more accurately be called ashing, especially since it is the ash powder that is used for the next step of the analysis. However, there are also examples of treatment up to 900 degrees C, or acid treatment after “LOI”, and for now all of these are lumped in together. ‘Calcination’ is also sometimes specified, and lumped in with the ‘CB’ code.

Fusion

Flux fusion (usually with lithium borate of some description) is a common digestion method. Note that the base codes for fusion digestion methods are generally the same, whether or not a glass bead is prepared for XRF (see below) or a subsequent acid digestion is used to prepare the sample for ICP:MS. (One exception specifies the HNO3 digest prior to ICP:MS, since the information was available).

Multi-acid digestion

The other common experimental method is multi acid digestion. The specific acids used are listed in the exp_method_translation. The acid-digestion steps described here are generally aiming for total or near-total digestion, and the use of strong acids is assumed - by contrast, see Carbonate Proxies above where the acid strength is an important component of the experimental code.

Note that the experimental codes allow for the distinction between multiple sequentially administered acid digestion steps, separated by an underscore, but these steps may be short-handed elsewhere as e.g. "a standard X-acid digestion". This can lead to a mix of specific and general classifications, depending on how the procedures were described in the original publications. The choice of code/code creation has been a balance between a) distinguishing meaningfully different methods where possible, and b) speed of data entry - sometimes it is easier to code individual steps if they are specified, and lump them in with a "standard" procedure later.

As an example, all of the following methods are currently coded as "CB_MA3", but note the difference in steps, combinations of acids, and specificity. Previously some of these were coded as "CB_MA2_AR_HCl", where MA2 corresponds to HNO3/HF a common two-acid digestion used elsewhere.

  • Approximately 100 mg of powder was ashed overnight at 550°C to oxidize organic matter. Ashed powders were digested at 110°C in 2.5 ml concentrated HNO3 and 0.5 ml concentrated HF for 48 h, followed by digestion in 4 ml aqua regia for 48 h and finally in 2 ml concentrated HCl for 24 h (Kunert and Kendall 2023).
  • Finely powdered samples were first ashed at 550°C overnight to remove volatiles, and the loss on ignition was recorded and used later to correct elemental abundances for the original sample weight. 10-20 mg of ashed sample was then dissolved using a standard multi-acid (HNO3-HCl-HF) digestion (Kendall et al., 2010). The digestion procedure involved progressive acid treatments at ~150°C in Savillex Teflon bombs with HF-NHO3, aqua regia (HNO3-HCl), and finally, HCl. A subset of samples was processed using perchloric acid (HClO4) to digest organic matter, rather than loss on ignition (Guilleaudeau and Kah 2013).
  • Powdered sample splits were ashed for 8-10 h at 550°C and dissolved by HF-HNO3-HCl acid digestion (Sahoo et al. 2016).
  • In short, powdered samples were ashed overnight in a muffled furnace at 550°C to help rid samples of organic material. Then, each sample was transferred to a trace metal clean lab and subjected to multiple rounds of concentrated acid digestion using trace metal grade hydrofluoric, hydrochloric, and nitric acid (Ostrander et al. 2020).
  • Concentrations of total Fe (FeT) and Mo were measured using a standard multi-acid digestion (HNO3-HCl-HF) as follows. Distilled HNO3 and HCl and trace-metal grade HF reagents were used in all cases. An aliquot of powdered sample was weighed into a porcelain crucible, ashed at 850°C for 12 h, and weighed again after cooling. The mass lost on ignition (LOI) was recorded and used later for correction of the elemental abundances. About 100 mg of ashed sample were weighed accurately in a 15 ml Savillex Teflon bomb equipped with a screw cap. The sample was first digested by adding ~0.2 ml water and ~ 1 ml concentrated HNO3 and heated at 200°C for 2 h. The sample was then transferred to a sterile 15 ml centrifuge tube after cooling and spun at 6,000 r.p.m. for 5 min. The supernatant was removed and retained, while the residual undigested sample was returned to the Teflon bomb. The purpose of this step was to remove cations such as Ca2+ (primarily from carbonates) that can form insoluble fluoride precipitates during reaction with HF. This step was repeated for carbonate-rich samples (usually >30pct). The sample residue was further digested by adding ~0.2 ml water and ~ 1 ml HNO3/HF (1:2) and heated at 200°C for at least 24 h. The sample was subsequently dried down in order to evaporate the acids. The last digestion was in ~0.2 ml water and ~1 ml concentrated HCl, which was heated at 200°C for at least 2 h. If the rock powders were not completely digested after this treatment, additional rounds of digestion were performed (Li et al. 2012).
analyte(s) count_res code translation ana_method(s)
Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Hg, Ho, In, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, Pb, Pr, Rb, Re, Sb, Sc, Se, Si, Sm, Sn, Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn, Zr 488707 Tot_digest Total digestion (NGDB method) COLOR, ICP:ES, ICP:MS, N/A
Ag, Al, Al2O3, As, Au, B, Ba, Be, Bi, Ca, CaO, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Hg, Ho, In, K, K2O, LREE, La, Li, Lu, MREE, Mg, MgO, Mn, MnO, Mo, Na, Na2O, Nb, Nd, Ni, Pb, Pr, REY, Rb, Re, Sb, Sc, Se, Si, Sm, Sn, Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn, Zr 473173 MA4 HNO3/HClO4/HF/HCl ICP:ES, ICP:ES/MS, ICP:MS, Q-ICP:MS, QQQ-ICP:MS
Ag, Al, Al2O3, Ba, Be, Ca, CaO, Ce, Co, Cr, Cr2O3, Cs, Cu, Dy, Er, Eu, Ga, Gd, Hf, Ho, K, K2O, La, Lu, Mg, MgO, Mn, MnO, Na, Na2O, Nb, Nd, Ni, Pb, Pr, Rb, Sc, Si, SiO2, Sm, Sn, Sr, Ta, Tb, Th, Ti, TiO2, Tm, U, V, W, Y, Yb, Zn, Zr 125067 LTF Lithium tetraborate (aka lithium borate) fusion ICP, ICP:ES, ICP:MS
Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Hg, Ho, In, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, Pb, Pd, Pr, Pt, Rb, Re, Sb, Sc, Se, Sm, Sn, Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn, Zr 117786 AR Aqua regia (3:1 HCl:HNO3) AAS, ICP:ES/MS, ICP:MS
Ag, Al2O3, As, Ba, Be, CaO, Cd, Ce, Co, Cr, Cr2O3, Cs, Cu, Dy, Er, Eu, Ga, Gd, Hf, Ho, K2O, La, Lu, MgO, MnO, Mo, Na2O, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Sc, SiO2, Sm, Sn, Sr, Ta, Tb, Th, TiO2, Tm, U, V, W, Y, Yb, Zn, Zr 93758 LMF_HNO3(5%) Lithium metaborate fusion, 5% HNO3 (see e.g. Bureau Veritas method 4A-4B) ICP, ICP:ES, ICP:ES/MS, ICP:MS
Ag, Al, Al2O3, As, B, Ba, Be, Bi, Ca, CaO, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Ho, In, K, K2O, La, Li, Lu, Mg, MgO, Mn, MnO, Mo, Na, Na2O, Nb, Nd, Ni, Pb, Pr, REE, Rb, Re, Sb, Sc, Se, Si, SiO2, Sm, Sn, Sr, Ta, Tb, Te, Th, Ti, TiO2, Tl, Tm, U, V, W, Y, Yb, Zn, Zr 61417 Na2O2Fus Sodium peroxide sinter/fusion ICP:ES, ICP:ES/MS, ICP:MS
Ag, Al, Al2O3, As, Au, B, Ba, Be, Bi, Ca, CaO, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Hg, Ho, In, K, K2O, La, Li, Lu, Mg, MgO, Mn, MnO, Mo, Na, Na2O, Nb, Nd, Ni, Pb, Pd, Pr, Pt, Rb, Re, Sb, Sc, Se, Si, SiO2, Sm, Sn, Sr, Ta, Tb, Te, Th, Ti, TiO2, Tl, Tm, U, V, W, Y, Yb, Zn, Zr 34429 Digest Unspecified digestion (CMIBS method) AAS, COUL, DCP-OES, FLOUR, ICP:ES, ICP:MS, ICP:MS-ID, WC
Al, Al2O3, Ba, Be, Ca, CaO, Ce, Co, Cr, Cr2O3, Cs, Cu, Dy, Er, Eu, Ga, Gd, HREE, Hf, Ho, K2O, LREE, La, Lu, MREE, Mg, MgO, Mn, MnO, Mo, Na2O, Nb, Nd, Ni, Pb, Pr, Rb, Re, Sc, Si, SiO2, Sm, Sn, Sr, Ta, Tb, Th, Ti, TiO2, Tl, Tm, U, V, W, Y, Yb, Zn, Zr 33902 LMF Lithium metaborate (LiBO2) fusion DCP-OES, ICP, ICP:ES, ICP:MS, Q-ICP:MS
Ag, Al, Al2O3, As, Ba, Be, Bi, Ca, CaO, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Ho, In, K, K2O, La, Li, Lu, Mg, MgO, Mn, MnO, Mo, Na, Na2O, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Sc, Si, SiO2, Sm, Sn, Sr, Ta, Tb, Te, Th, Ti, TiO2, Tl, Tm, U, V, W, Y, Yb, Zn, Zr 32874 Fusion digestion Fusion digestion (CMIBS method) AAS, COLOR, EM, ICP:MS
Ag, Al2O3, As, Ba, BaO, Be, Bi, CaO, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Ho, In, K2O, La, Lu, MgO, MnO, Mo, Na2O, Nb, Nd, Ni, Pb, Pr, REE, Rb, Sb, Sc, SiO2, Sm, Sn, Sr, Ta, Tb, Th, TiO2, Tl, Tm, U, V, W, Y, Yb, Zn, Zr 26290 LTMF_HNO3(5%) Lithium tetraborate/metaborate fusion, 5% HNO3 ICP:ES, ICP:MS
Al, Al2O3, As, B, Ba, Be, Bi, CaO, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Ho, In, K2O, La, Li, Lu, MgO, Mn, MnO, Mo, Na2O, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Sc, SiO2, Sm, Sn, Sr, Ta, Tb, Th, Ti, TiO2, Tl, Tm, U, V, W, Y, Yb, Zn, Zr 19273 MA2 HNO3/HF ICP:ES, ICP:ES/MS, ICP:MS, ICP:MS-HR, Q-ICP:MS, SN-ICP:MS
Ag, As, Ba, Be, Bi, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Hg, Ho, In, La, Li, Lu, Mo, Nb, Nd, Ni, Pb, Pr, Rb, Re, Sb, Sc, Se, Sm, Sn, Sr, Ta, Tb, Te, Th, Tl, Tm, U, V, W, Y, Yb, Zn, Zr 19176 M_MA4 Microwave + acid digest (Labwest method) ICP:ES/MS
Al, Al2O3, As, Ba, Ca, CaO, Cd, Ce, Co, Cr, Cu, Hf, K, K2O, La, Mg, MgO, Mn, Mo, Na, Na2O, Nb, Nd, Ni, Pb, Rb, Re, Sc, Si, Sr, Th, Ti, TiO2, Tl, U, V, W, Zn, Zr 22995 CB_MA3 Combustion/ashing, HNO3/HCl/HF DS_ID, ICP:ES, ICP:MS, ICP:MS-HR, Q-ICP:MS, QQQ-ICP:MS
Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, K, La, Li, Mg, Mn, Mo, Na, Nb, Ni, Pb, Sb, Sn, Sr, Ti, U, V, W, Y, Zn, Zr 18490 Part_digest Partial digestion (NGDB method) COLOR, ICP:ES, N/A
Ag, Al, As, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Ho, In, K, LREE, La, Li, Lu, MREE, Mg, Mn, Mo, Na, Nb, Nd, Ni, Pb, Pr, REY, Rb, Re, Sb, Sc, Sm, Sn, Sr, Tb, Th, Ti, Tl, Tm, U, V, Y, Yb, Zn, Zr 17937 MA3 HNO3/HCl/HF ICP:ES, ICP:MS, Q-ICP:MS
Al, As, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Hf, Ho, In, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, Pb, Pr, Rb, Re, Sb, Sc, Si, Sm, Sn, Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn, Zr 17162 CB_MA3b Combustion/ashing, HF/HNO3/HClO4 ICP:ES, ICP:MS, Q-ICP:MS
Ag, Al, Al2O3, As, Ba, Be, Bi, CaO, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Hf, Ho, K2O, La, Li, Lu, MgO, Mn, MnO, Mo, Na2O, Nb, Nd, Ni, Pb, Pr, REE, Rb, Sc, Sm, Sn, Sr, Ta, Tb, Th, Ti, TiO2, Tl, Tm, U, V, W, Y, Yb, Zn, Zr 8432 MA3b HF/HNO3/HClO4 AAS, ICP, ICP:ES, ICP:MS, N/A, Q-ICP:MS
Ba, Be, Bi, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Hf, Ho, La, Li, Lu, Mn, Mo, Nb, Nd, Ni, Pb, Pr, Rb, Sc, Sm, Sn, Sr, Ta, Tb, Th, Ti, Tm, U, V, W, Y, Yb, Zn, Zr 7824 CB_MA5 Combustion/ashing, HNO3/HClO4/HF/H3BO3/HCl ICP:MS
As, Ba, Ce, Cr, Cs, Dy, Er, Eu, Gd, Hf, Ho, La, Lu, Nb, Nd, Pb, Pr, Rb, Sc, Sm, Sr, Ta, Tb, Th, Tm, U, Y, Yb, Zr 5394 MA3b_AR HNO3/HF/HClO4, AR ICP:MS
Al, Ba, Ca, Ce, Cr, Cu, Dy, Er, Eu, Gd, Ho, K, La, Lu, Mg, Mn, Mo, Na, Nd, Ni, Pr, Re, Sm, Sr, Tb, Ti, Tm, U, V, Yb, Zn 5130 MA3b_H3BO3 HNO3/HF/HClO4 digest, H3BO3 ICP:ES, ICP:MS
Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, K, Mg, Mn, Mo, Ni, Sr, Th, Ti, Tl, U, V, Zn 4480 NaOAc(1M)_MA3b Sum of extract first with sodium acetate, followed by HF/HNO3/HClO4 digestion Q-ICP:MS
Al, Al2O3, Ca, CaO, Co, Cr, Cu, K, K2O, Mg, MgO, Mn, MnO, Mo, Na2O, Ni, Pb, Si, SiO2, TiO2, Zn 3040 MA_HF Multi-acid digestion with HF (CMIBS method) AAS, COUL
Al, As, B, Ba, Be, Ca, Cd, Ce, Co, Cr, Cu, K, La, Li, Mg, Mn, Mo, Na, Ni, Pb, Sc, Si, Sr, Ti, V, Y, Zn, Zr 2800 HNO3(7N) 7N nitric acid ICP:ES
Ag, Al, As, Au, B, Ba, Bi, Ca, Cd, Co, Cr, Cu, Ga, Hg, K, La, Li, Mg, Mn, Mo, Na, Ni, Pb, Sb, Sc, Se, Sr, Te, Th, Ti, Tl, U, V, W, Zn 2744 AR_part Partial digestion with aqua regia (CMIBS method) AAS, ICP:MS
Ba, Ce, Cs, Dy, Er, Eu, Gd, Hf, Ho, La, Lu, Nb, Nd, Pb, Pr, REE, Rb, Sc, Sm, Sr, Ta, Tb, Th, Tm, U, Y, Yb, Zr 2467 LTF_MA3b Lithium tetraborate fusion, HNO3/HF/HClO4 digest ICP:MS
Al, Mn, Mo, Re, U 2435 CB_MA3b_H3BO3 Combustion/ashing, HNO3/HF/HClO4, H3BO3 ICP:ES, ICP:MS, Q-ICP:MS
Al2O3, CaO, Ce, Co, Cr, Dy, Er, Eu, Gd, Ho, K2O, La, Lu, MgO, MnO, Na2O, Nd, Ni, Pr, Sc, SiO2, Sm, Tb, Th, TiO2, Tm, Y, Yb 2416 LTMF_HNO3(dil) Lithium tetraborate/metaborate fusion, dilute HNO3 ICP:ES/MS, ICP:MS
Al, As, Ba, Ca, Co, Cr, Cu, Hg, K, La, Mg, Mn, Mo, Na, Ni, Sc, Si, Sr, Ti, V, Y, Zn, Zr 2349 MA Multi-acid digestion, details unknown AAS, ICP:MS
Ag, Al2O3, Ba, Be, CaO, Ce, Cu, Dy, Er, Eu, Gd, Ge, Hf, Ho, K2O, La, Lu, MgO, MnO, Na2O, Nb, Nd, Ni, Pr, Rb, SiO2, Sm, Sr, Tb, Th, TiO2, Tl, Tm, U, V, Y, Yb, Zn, Zr 1755 LTMF Lithium tetraborate/metaborate fusion ICP:MS
Ag, Au, Pd, Pt 1663 FA Fire assay chemical separation GRAV, ICP:MS
Al, As, Ca, Cd, Co, Cr, Cu, K, Mg, Mn, Mo, Na, Ni, Re, Ti, U, V, Zn 1586 CB_MA2_AR Combustion/ashing, HNO3/HF, aqua regia ICP:MS
Ba, Be, Bi, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Ho, In, La, Li, Lu, Mn, Mo, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Sc, Sm, Sn, Sr, Ta, Tb, Th, Tl, Tm, U, V, W, Y, Yb, Zr 1571 NH4HF2 Digestion with NH4HF2 ICP:MS-HR
Al2O3, Ba, CaO, Cr2O3, K2O, MgO, MnO, Na2O, SiO2, TiO2 1250 LMF_MA2c Lithium metaborate fusion, HF/HClO4 digest ICP:ES
Ba, Ce, Cu, Eu, Gd, La, Nd, Ni, Sm, Sr, V, Zn, Zr 1141 MA4_IE HF/HCl/HNO3/HClO4 and ion exchange separation. ICP:ES
Ag, Bi, Cd, Pb 1019 KClO3(part) Partial digestion with potassium chlorate (CMIBS method) ICP:ES
Al, Mn, Mo, Ti, Tl, V 904 M_MA3 Microwave digest, HNO3/HCl/HF ICP:MS
Al, Mo, U, V 809 MA5 HNO3/HClO4/HF/H3BO3/HCl ICP:ES, ICP:MS
Al2O3, CaO, K2O, MgO, MnO, Na2O, SiO2, TiO2 792 LTMF_HNO3(2%) Lithium tetraborate/metaborate fusion, 2% HNO3 ICP:ES
Al, Ba, Ca, Co, Cr, Cu, K, Mg, Mn, Mo, Na, Ni, Sc, Sr, Th, U, V, Zn 749 CB_MA3_AR Combustion/ashing, HNO3/HCl/HF, AR ICP:ES, Q-ICP:MS
Ba, Cu, Mo, Ni, Re, U, V, Zn 573 CB_MA4 Combustion/ashing, HCl/HF/HClO4/HNO3 ICP:ES/MS, ICP:MS
Al, Cr, Mo, Ni, U, V, Zr 553 CB_MA2 Combustion/ashing, HNO3/HF ICP:ES, ICP:MS, Q-ICP:MS
Au, Ir, Os, Pd, Pt, Re 532 NiS_FA NiS fire assay chemical separation. (CMIBS method) ICP:MS
Cr, Li, V 455 MA2e HClO4/H3PO4 AAS
Co, Cu, La, Mo, Nd, Sc, U, V 368 CB_MA4seq Combustion/ashing, seq acid digest HF, AR, ARrev, HNO3 (Kunzmann et al. 2015, Maloney et al. 2024) ICP:MS
Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sc, Sm, Tb, Tm, Y, Yb 367 Sinter Sinter, unspecified (CMIBS method) IC
Al2O3, CaO, MgO, SiO2 343 CB_MA2_H3BO3 Combustion/ashing, HF/HNO3, H3BO3 to neutralize ICP:ES
Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Tb, Tm, Y, Yb 330 HNO3(10%)_CB_HNO3(10%) 10% HNO3, combustion/ashing, second leach in 10% HNO3 ICP:MS
Al, Ce, Cu, Dy, Er, Eu, Gd, Ho, La, Lu, Mn, Mo, Nd, Ni, Pr, Sm, Tb, Tm, U, V, Yb, Zn 308 LTF_HNO3 Lithium tetraborate fusion, HNO3 ICP:ES, Q-ICP:MS
Ca, Mg, Mn, Sr 287 NaCl/NaOCl/HCl NaCl and NaOCl(bleach), HCl Q-ICP:MS
Ca, Mg 178 HCl(24h/cold) Cold HCl (1M or 10%) for 24hr (Raiswell et al. 1994) ICP:MS
Al, Mn, Mo, U, V 164 M_MA3_H202 Microwave digest, HNO3/HCl/HF, H2O2 ICP:MS
Al, As, B, Ba, Be, Bi, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Ho, La, Li, Lu, Mn, Mo, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Sc, Sm, Sn, Sr, Ta, Tb, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn, Zr 155 HCl(decarb)_MA2 Decarbonated with HCl, HNO3/HF Q-ICP:MS
Cd, Co, Cu, Li, Mn, Ni, Pb, Rb, V, Zn 142 HF Hydrofluoric acid AAS
Co, Cu, Mo, Ni, Pb, Sc, V, Zn 101 MA3_H2O2 HNO3/HCl/HF, H2O2 ICP:MS
Al2O3, SiO2 78 Pressed pellet Pressed powder pellet SEM-EDS
Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Tb, Tm, Yb 38 RC Radiochemical separation (CMIBS method) INAA
Tl-auth, V-auth 36 HNO3(2M) 2M nitric acid ICP:MS
Hg 14 Acid Acidification/acid treatment, details not provided AAS
Ir, Pd, Pt 13 PbO_FA PbO fire assay chemical separation (CMIBS method) AAS
Ce, Dy, Er, Eu, Gd, Nd, Sm, Yb 8 HNO3(part) HNO3 partial digest (no strength specified) ICP:MS
Ag, Al, Al2O3, As, Au, B, Ba, Be, Bi, Ca, CaO, Cd, Ce, Co, Cr, Cr2O3, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, HREE, Hf, Hg, Ho, In, Ir, K, K2O, LREE, La, Li, Lu, Mg, MgO, Mn, MnO, Mo, Na, Na2O, Nb, Nd, Ni, Os, Pb, Pd, Pr, Pt, REE, REY, Rb, Re, Sb, Sc, Se, Si, SiO2, Sm, Sn, Sr, SrO, Ta, Tb, Te, Th, Ti, TiO2, Tl, Tm, U, V, V2O5, W, Y, Yb, Zn, Zr 1367856 NULL NULL AAS, COLOR, CVAAS, DNAA, DNC, ED-XRF, EDEM, ES, ES_Q, ES_SQ, FA, FLOUR, GR, GR-INAA, HgAna, ICP:ES, ICP:ES/MS, ICP:MS, ICP:MS-ID, ICP:MS-LA, ICP:MS-MC, INAA, LC-INAA, LQS, N/A, NAA, NIR, Q-ICP:MS, SC-INAA, SSMS

XRF

Commonly cited method papers

Notes

Sometimes it is explicitly stated that the sample was ashed prior to making fused beads or LOI was measured separately and adjustments made later. In contrast to the multi-acid methods, however, “CB” (for combustion/ashing) has not been included in the code, even for cases where a combustion/ashing step is clearly stated.

It is not always clear whether “lithium borate” is used in the strict sense (i.e. Li2B4O7), or whether sometimes it is assumed to mean a mix of lithium borate (aka tetraborate) and lithium metaborate. The latter seems likely. A distinction is made in the experimental code where the methods are explicit, but note therefore that “LTF” is likely more of a ‘waste-basket’ code than the more precise LTMF. The generic code 'fused beads' is used for cases with no further detail provided, but it is likely to mean lithium borate/metaborate fusion of some description.

Temperature and time of flux fusion is sometimes explicitly stated, but not considered in these codes.

All pressed pellet methods are lumped together, but note that there are variations within - for example, Ansari et al. 2021: “pressed pellets were prepared from the oven dried powdered samples and boric acid (in 6:4 ratio) following the method described by Takahashi (2015).”

Some samples were analyzed via Handheld XRF (HHXRF), although these represent a minority of analyses analyzed by broader XRF methods. The accuracy of HHXRF measurements can vary widely by instrument and by element (see Rowe et al., 2013 https://doi.org/10.1016/j.chemgeo.2011.12.023 and Dahl et al., 2013 http://dx.doi.org/10.1016/j.chemgeo.2013.10.022).

analyte(s) count_res code translation ana_method(s)
Al, Al2O3, As, Ba, Ca, CaO, Ce, Co, Cr, Cu, Ga, K, K2O, La, Mg, MgO, Mn, MnO, Mo, Na, Na2O, Nb, Ni, Pb, Rb, Sb, Sc, Si, SiO2, Sn, Sr, Th, Ti, TiO2, U, V, Y, Zn, Zr 1517 MA2 HNO3/HF XRF
Al, Al2O3, As, Ba, BaO, Ca, CaO, Ce, Cr, Cr2O3, Cu, Ga, K2O, La, Mg, MgO, Mn, MnO, Mo, Na2O, Nb, Nd, Ni, Pb, Rb, Sc, Si, SiO2, Sr, Th, Ti, TiO2, U, V, Y, Zn, Zr 22842 LTF Lithium tetraborate (aka lithium borate) fusion XRF
Al2O3, CaO, Cr2O3, K2O, MgO, MnO, Na2O, SiO2, TiO2 909 Na2O2Fus Sodium peroxide sinter/fusion XRF
Al, Al2O3, As, Ba, BaO, Ca, CaO, Ce, Co, Cr, Cr2O3, Cs, Cu, Ga, Hf, K2O, La, Mg, MgO, Mn, MnO, Mo, Na, Na2O, Nb, Nd, Ni, Pb, Pr, Rb, Re, Sc, Si, SiO2, Sm, Sr, Ta, Th, Ti, TiO2, U, V, Y, Zn, Zr 4656 Fused beads Fused beads XRF
Al, Al2O3, Ba, Ca, CaO, Ce, Co, Cr, Cu, Ga, K, K2O, Mg, MgO, Mn, MnO, Mo, Na, Na2O, Nb, Ni, Pb, Rb, Sc, Si, SiO2, Sr, Th, Ti, TiO2, V, Y, Zn, Zr 52739 LMF Lithium metaborate (LiBO2) fusion XRF
Al2O3, As, Ba, CaO, Ce, Co, Cr, Cu, Ga, K2O, La, MgO, MnO, Mo, Na2O, Nb, Nd, Ni, Pb, Rb, Sc, SiO2, Sr, Th, Ti, TiO2, U, V, Y, Zn, Zr 11159 Pressed pellet Pressed powder pellet XRF
Al, Al2O3, As, Ba, Ca, CaO, Ce, Co, Co3O4, Cr, Cr2O3, Cu, CuO, K, K2O, La, Mg, MgO, Mn, MnO, Mo, Na, Na2O, Nb, Nd, Ni, NiO, Pb, Rb, Sc, Si, SiO2, Sr, Ti, TiO2, V, V2O5, W, Y, Zn, Zr 8109 LTMF Lithium tetraborate/metaborate fusion XRF
Al, As, Ca, Co, Cr, Cu, K, K2O, Mn, MnO, Mo, Ni, Pb, Rb, Si, Sr, Ti, TiO2, U, V, Y, Zn, Zr 6474 Raw powder Raw powder HHXRF
Al2O3, Ca, CaO, K2O, Mn, Mo, Ni, Rb, SiO2, Sr, TiO2, U, V, Zr 8440 Rock surface Rock surface (cut, sometimes polished) HHXRF
Ag, Al, Al2O3, As, Au, B, Ba, BaO, Be, Bi, Ca, CaO, Cd, Ce, Co, Cr, Cr2O3, Cs, Cu, Dy, Er, Eu, Ga, Gd, Ge, Hf, Hg, Ho, In, K, K2O, La, Li, Lu, Mg, MgO, Mn, MnO, MnO2, Mo, Na, Na2O, Nb, Nd, Ni, Pb, Pd, Pr, Rb, Re, Sb, Sc, Se, Si, SiO2, Sm, Sn, Sr, SrO, Ta, Tb, Te, Th, Ti, TiO2, Tl, Tm, U, V, V2O5, W, Y, Yb, Zn, Zr 345454 NULL NULL ED-XRF, HHXRF, XRF

Mineralogy/Composition

XRD

For the majority of XRD data no method paper is cited. Details of sample preparation are generally not included. See for example https://pubs.usgs.gov/of/2001/of01-041/htmldocs/methods.htm for some details about preparation that could be considered. For the most part we report analytes as presented in data tables.

analyte(s) count_res code translation ana_method(s)
Albite, Anatase, Anhydrite, Ankerite, Apatite, Berthierine, Calcite, Chamosite, Chlorite, Dolomite, Fe/Mg-mica, Glauconite, Gypsum, Halite, Hematite, Illite, K-Feldspar, K/Al-mica, K/Mg-mica, Kaolinite, Magnesite, Magnetite, Mica, Montmorillonite, Plagioclase, Pyrite, Pyrrhotite, Quartz, Rutile, Siderite, Talc 9019 Random mount Random/unoriented mount XRD
Calcite, Chlorite, Feldspar, Illite, Illite_Smectite, Kaolinite, Pyrite, Quartz, Total_Clay 423 Oriented mount Oriented mount XRD
1:1 clays, 2:1 clays, Detritals, Glauconite, K-Feldspar, Pyrite, Quartz, Total_Clay 391 HCl(decarb)_RandomMount Decarbonated with HCl, random mount XRD
Albite, Analcime, Anatase, Anhydrite, Ankerite, Anorthite, Apatite, Aragonite, Barite, Berthierine, Biotite, Calcite, Chamosite, Chlorite, Clinochlore, Cristobalite, Dolomite, Dolomite_Iron_Dolomite, Dolomite_Siderite, Feldspar, Fluorapatite, Gypsum, Halite, Hematite, Hydroxylapatite, Illite, Illite_Mica, Illite_Montmorillonite, Illite_Muscovite, Illite_Smectite, Ilmenite, Jarosite, K-Feldspar, Kaolinite, Magnesite, Magnetite, Marcasite, Microcline, Mixed_Layer_Clays, Montmorillonite, Muscovite, Nontronite, Orthoclase, Plagioclase, Pyrite, Quartz, Quartz_Christobalite, Rhodochrosite, Rutile, Sanidine, Siderite, Smectite, Sphalerite, Sum, Talc, Total_Carbonate, Total_Clay, Total_NonClay 17773 NULL NULL XRD

LOI/Sum/Insol

These are values that tend to be associated with batches of data from other methods e.g. XRF, ICP.

  • Sum = sum of components
  • Insol = acid-insoluble residue
  • LOI = loss on ignition

LOI also has the analytical code "LOI", the experimental code is used to give a temperature, if it is provided e.g. 1000deg, 1050deg.

CIA

CIA is the Chemical Index of Alteration, generally defined as follows (using Li et al. 2021 as example): "CIA is equal to [Al2O3/(Al2O3 + CaO* + Na2O + K2O)] × 100, where all oxide values are molar quantities, and CaO* represents CaO content in silicate minerals only (Nesbitt and Young, 1984), therefore, the CaO contents of carbonate and phosphate must be deducted from total CaO." Note there are differences in how this is accomplished; see original publications for any variations on the method.

Miscellaneous useful references:

Balaram, V., & Subramanyam, K. S. V. (2022). Sample preparation for geochemical analysis: Strategies and significance. Advances in Sample Preparation, 1, 100010. https://doi.org/10.1016/j.sampre.2022.100010