Traceds: An Experimental Trace Element Partitioning Database

Abstract:

The goal of this project, which is part of the EARTHCHEM initiative, is to compile the existing experimental trace element partitioning data, and to develop a transparent, accessible resource for the community. The primary goal of experimental trace element partitioning studies is to create a database that can be used to develop models of how trace elements behave in natural geochemical systems. The range of approaches as to how this is accomplished and how the data are reported differs dramatically from one system to another and one investigator to another. This provides serious challenges to the creation of a coherent database – and suggests the need for a standard format for data presentation and reporting.

The driving force for this compilation is to provide community access to the complete database for trace element experiments. Our new effort includes all the published analytical results from experimental determinations. In compiling the data, we have set a minimum standard for the data to be included. The threshold criteria include:

• Experimental conditions (temperature, pressure, device, container, time, etc.)
• Major element composition of the phases
• Trace element analyses of the phases

Data sources that did not report these minimum components were not included. The rationale for not including such data is that the degree of equilibration is unknown, and more important, no rigorous approach to modeling the behavior of trace elements is possible without a knowledge of the actual concentrations or the temperature and pressure of formation.

The data are stored using a schema derived from that of the Library of Experimental Phase Relations (LEPR), modified to account for additional metadata, and restructured to permit multiple analytical entries for various element/technique/standard combinations.

Our ultimate goal is to produce a database together with a flexible user interface that will be useful for experimentalists to set up their work and to build calibration datasets, for petrologists to find appropriate partition coefficients, and to help reviewers evaluate models submitted for publication. As an additional benefit, we hope that this investigation will help to set new publication standards for experimental data.

The database will be assessable at the portal lepr.ofm-research.org.