CSIRO Shortwave infrared spectral library – Evaluation and status report 2016

[摘要] The current shortwave infrared (SWIR) spectral reference library (SRL) has been built on spectral libraries from many sources, mostly acquired in the late 1990s and early 2000s. The names of the reference spectra often do not contain enough information to locate the sample that was measured, making it difficult to validate the minerals. A large portion of the spectra were acquired from an unknown source/spectrometer. Thus, these will need to be replaced.It appears that there could have been discrepancies of wavelength features for some of the minerals that were scanned with different spectrometers. The example is two different PIMAs measuring the same sample have different absorption minima for the key features. This highlights the need for proper quality control and calibration of instrumentation, and calls into question the integrity of the rest of measurements in the current SWIR-SRL.This report summarises the current status of the SWIR-SRL, by 1) attempting to clarify the provenance and composition of the minerals used in the SWIR-SRL, 2) assessing the completeness of the current set of samples in the SWIR-SRL, and 3) identifying potential minerals for replacement and addition to the current SWIR-SRL.Recommendations for the SWIR-SRL would be to replace the spectra of immediately available minerals (such as Well Crystalline Kaolinite, Alunite, Jarosite and others) and look into finding suitable samples for the rare minerals. It would also be useful to investigate the inclusion of more minerals into the SRL in TSG, but have the minerals turned off in the default settings. This would allow users a greater number of minerals and would reduce the need to use external reference libraries, such as the USGS Spectral Library, as attached auxiliary files.Any changes to the SWIR-SRL, without doubt, will have some impact on TSG’s “The Spectral Assistant” (TSA) results. To evaluate the impact of changes to the SWIR-SRL on TSA, it is recommended to set up a new test data set, which contains only validated (mineral and other geological) sample materials. The required data could be gathered, for example, from the growing holdings of ad-hoc validation by the NVCL nodes, 2) the rock validation project (part of the spectral library activity of the NVCL FY16/17 project, and/or 3) past and current non-confidential CSIRO projects (e.g. NGSA FTIR dataset, Rocklea Dome (Haest el al. 2012), Mindanao (Sontag et al., 2012), Antamina, etc.). Importantly, any replacements or additions to the SWIR-SRL would be only implemented in TSA after their impact has been evaluated.

[发布日期] 2016-08-30 [发布机构] CSIRO

[学科分类] 地球科学(综合)