ClumpyCrunch

readme

A web application for processing Δ₄₇ measurements using the D47crunch library. Currently hosted at clumpycrunch.pythonanywhere.com.

Quick start

Raw data

Paste your data into the Raw Data Input text box, using the following format:

The only mandatory columns are Sample, d45, d46, and d47.

UID cells are treated as arbitrary strings and are intended to provide an unique identifier for ech analysis.

Session cells are also treated as arbitrary strings and are intended to provide an unique identifier for each analytical session (defined as a discrete time window during which analytical conditions are presumed to have remained stable). Without a Session column, all analyses will be treated as belonging to the same session.

Without a D17O column, all analyses will be treated as having an ¹⁷O anomaly of zero relative to VSMOW (with a λ value defined in the Oxygen-17 Correction Settings panel).

Optional d13Cwg_VPDB and d18Owg_VSMOW columns may be used to specify explicitly the “bulk” isotopic composition of the working gas. These fields must be filled in for analysis (i.e. each line). If the option Explicitly defined in the raw data is not selected in the Working Gas Composition Settings panel, these fields are ignored.

Optional Nominal_d13C_VPDB and Nominal_d18O_VPDB columns may be used to treat some samples as carbonate standards for δ¹³C and δ¹⁸O normalization (see Carbon-13 Standardization and Oxygen-18 Standardization panels) and/or to compute working gas compositions (see Working Gas Composition Settings).

Empty cells are treated as nan (not a number).

Table cells may be separated by tabs, by commas, or by semicolons (no mixing of delimitors), and spaces surrounding these delimitors are ignored.

WG settings

Two options are available. By default, the bulk composition of the WG in each session is computed based on carbonate standard analyses (i.e. lines with non-empty values for both Nominal_d13C_VPDB and Nominal_d18O_VPDB) within that session.

Alternatively, you may specify the WG bulk composition explicitly in, by including columns d13Cwg_VPDB and d18Owg_VSMOW in the raw data table.

¹³C and ¹⁸O standardization settings

By default, bulk isotopic compositions are standardized using a “two-point” affine transformation (correcting for small offsets and stretching effects) based on carbonate standard analyses (i.e. lines with non-empty values for Nominal_d13C_VPDB and/or Nominal_d18O_VPDB) within each session.

Optionally, you may opt instead for a “single-point” standardization approach not correcting for strecthing effects, for instance if the cabonate standards cover only a small fraction of the full isotopic range of your measurements.

You may also opt to perform no a posteriori standardization of bulk isotopic compositions, which implies that the quality of your final δ¹³C and δ¹⁸O values will depend strongly on the accuracy of your working gas composition and the linearity of your instrument.

Δ₄₇ standardization settings

under construction...