LEPR 3.0 / TraceDs 1.0 / DCO-EPC 1.0

About ExPetDB

The Experimental Petrology DataBase (also known as LEPR/traceDs) comprises three data collections. The Library of Experimental Phase Relations was the original database, and brought together published experimental studies involving liquid-solid phase equilibria relevant to natural magmatic systems. TraceDs is a synthesis of experimental studies of trace element distributions between liquid, solid and fluid phases. DCO-EPC is a subset of the newer phase equilibria data that includes the dataset used for calibration of rhyolite-MELTS with a mixed H2O-CO2 fluid and data compiled for an upcoming calibration of pMELTS+CO2. The default download of ExPetDB data is a combination of LEPR, DCO-EPC and liquid-solid phase equilibria for silicate systems from traceDs.

Although it is not part of ExPetDB proper, this site also hosts the pMELTS calibration dataset (including the original MELTS calibration dataset) that was previously available on the MELTS software site. As the pMELTS calibration data entries have fewer metadata than the ExPetDB schema expects, they will not show up in some search views. You can download the full compilation as an Excel workbook though.

The production server for ExPetDB is hosted by EarthChem. The development version is hosted on the MAGMA@Caltech server. Account administration is currently handled at Caltech. If you have any problems using the web site, please contact the database administrator.

Please be patient while this site is under construction! We are in the process of implementing authentication via GitHub, and LEPR/traceDs accounts that were created before June 2025 will eventually be retired. You are welcome to preview the new site by logging in via GitHub. Please register at https://github.com if you don't already have a GitHub account.

Log in or Sign up for GitHub    Search ExPetDB data collections

How to cite data downloaded from this database?

Most importantly, cite the original experimental data source!

Secondly, cite the appropriate synthesis publication:

  • For LEPR 3.0: Hirshmann M.M., Ghiorso M.S., Davis F.A., Gordon S.M., Mukerjee S., Grove T.L., Krawczynski M, Medard E., Till C.B., 2008, Library of Experimental Phase Relations (LEPR): A database and web portal for experimental magmatic phase equilibria. Geochemistry, Geophysics, Geosystems, 9, Q03011, DOI: 10.1029/2007GC001894.
  • For traceDs: Nielsen R., Ghiorso M.S., Trischman T., 2015, V33C-3119: What We Have Learned About the Existing Trace Element Partitioning data During the Population Phase of traceDs. AGU Fall Meeting abstracts, San Francisco (ADS: 2015AGUFM.V33C3119N; ResearchGate: 283142168)

How to access the data?

You can access the ExPetDB, traceDs and pMELTS data using the "Search ExpetDB data collections" button above, or by clicking "Search databases" in the menu, or by selecting one of the menu items in the dropdown under "Search databases". The first time you try to access the search you should be directed to log in via GitHub. Search results are presented in interactive tables with links to experiment details and with download buttons for Excel output.

There are six ways to select data:

  1. Browse previous compilations and download prepared Excel workbooks
  2. Quick search - browse references or laboratories and select all relevant experiments
  3. Search by Composition or by a Phase that must be present or absent
  4. Search by P, T, and fO2 conditions
  5. Browse current compilations and download prepared Excel workbooks (as of 7th Sept, 2026)
  6. Download pre-compiled and processed files with calculated partition coefficients

Note that clicking the 🔍 icon will perform a keyword search of the website, rather than a database search. If the text search gives an error you can use your browser's back button to return to previous page.

Database help and more information

Database sources and vocabulary can be found here and on the PyLEPR wiki:

More information can be found at EarthChem and DCO websites:

These videos are out of date but may still be useful to show the kind of information data included:

Would you like to contribute data to ExPetDB?

The experimental petrology community welcome your assistance in keeping ExPetDB up to date by helping to expand database content. If you notice that some data are missing from ExPetDB and think that they should be included in the database, perhaps you can help us prepare the data for inclusion in ExPetDB? The process is simple to do and your help would be very much appreciated.

If you would like to be a new ExPetDB contributor please contact Roger Nielsen (traceDs) or Gokce Ustunisik (LEPR) for assistance. They will guide you on how to submit data to the EarthChem Library and review those data for inclusion in ExPetDB.

If you have previously contributed, the upload procedure has changed somewhat since you signed up for access to the LEPR/traceDs data entry functions. If you would like to contribute new data to ExPetDB please contact Paula Antoshechkina by email for assistance.

Thanks in advance for your interest in contributing to ExPetDB!