The Confocal Laser Scanning Microscopy Working Group of the ICCP: Final report 2021

This report summarizes the activities and results of the Confocal Laser Scanning Microscopy (CLSM) working group (WG) of the International Committee for Coal and Organic Petrology (ICCP), from its inception in September, 2015, to the present day (September, 2021). The purpose of this report is to document the history of the working group and to compile and evaluate its results. The CLSM WG examined an immature, organic-rich sample of Kimmeridge Clay, which was characterized via CLSM imaging and spectroscopy. In addition, mechanically polished and broad ion beam (BIB) milled sample preparations were characterized via atomic force microscopy. Highlights of findings from the CLSM WG include: the interpreted presence of Botryococcus; incomplete blocking of laser light from highly reflective materials; surface roughening and surface flattening induced by differential BIB milling dependent on location and scale of measurement; substitution of uranium for iron in sulfides; red-shift of reflectance and auto-fluorescence from below the sample surface; positive alteration from laser-induced photo-oxidation of the sample surface including fluorescence blue-shift; blueshift associated to higher fluorescence intensity regions in amorphous organic matter; need for fluorescence spectroscopy standardization as applied via CLSM; and the suitability of CLSM to predict solid bitumen reflectance via calibration to an extant data set. Due to the inability of WG members to continue participating in a WG format, the CLSM WG is hereby finalized. This report represents the final product of WG activity, with the aim to summarize the information included herein for a future peer-reviewed manuscript.