Fission-track and (U-Th)/He database scope and development

Schemas for the AusGeochem fission-track data model (Tables S1-S5) and (U-Th)/He data model (Tables S6-S8) were designed with the aim of accommodating retrospective and prospective datasets alike. Such flexibility requires that the data schema can archive analyses produced across mineral systems and via the breadth of historical fission-track and (U-Th)/He techniques. For the fission-track system, this includes results generated from the outdated population method⁸⁹, conventional external detector method (EDM, e.g., 32), and state-of-the-art in-situ fission track analysis using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS, e.g., 89, 90) or electron probe microanalysis (EPMA), in the case of analysis of relatively U-rich mineral assemblages like zircon⁹². For the (U-Th)/He system, the current version of the (U-Th)/He relational data model is built to accommodate whole-grain and in-situ age determinations. While the current AusGeochem (U-Th)/He relational data model cannot accommodate results generated via the emerging ⁴He/³He or Continuous Ramped Heating methods³¹, its flexible architecture would allow for straightforward integration of bespoke data tables for these analysis types, should they be designed in the future (Fig. 1).

The relational FT database was also designed to handle wildly varying degrees of (meta-)data reporting granularity found across the gamut of published thermochronology studies. So, in addition to archiving whole-rock fission-track results (Table S1), the model can accommodate both detailed single-grain fission-track count (Table S3) and age data (Table S2), when available. Similarly, users are able to upload both comprehensive confined fission-track length data (Table S4) generated using digital microscopy software (e.g., FastTracks, 48), or legacy binned confined track data reported simply as length histograms without the corresponding detailed length parameters (Table S5). While the fission-track model is strictly designed to accommodate fission-track analyses sensu stricto, associated in-situ geochemical analyses obtained via EPMA or LA-ICP-MS trace element analysis can be archived and related to fission-track results on a per-sample, per-grain, and per-spot basis in the linked Major, Minor and Trace Element Geochemistry Data Model (Fig. 1).

The (meta-)data fields and corresponding units of the fission-track and (U-Th)/He data tables were designed after global community-agreed reporting recommendations. The (U-Th)/He data model and corresponding tables (Tables S6-S8) were designed following the data reporting best-practices of Flowers et al.³¹. While the fission-track model (Tables S1-S5) was designed after the recommended data reporting practices currently being prepared for submission to Geological Society of America Bulletin special edition on “Reporting and Interpretation of Fission-Track Chronology Data”, with which co-authors of this article (B.K, S.B., A.G., and M.D.) are involved.