Abstract

Hot-cathodoluminescence (CL) microscopy and high-resolution trace-element analyses by Particle Induced X-ray Emission (micro-PIXE) using the proton microprobe have been applied to samples of quartz arenite in order to obtain information about their diagenetic environment and the provenance of quartz detritus. The occurrence of an intensely zoned orange-brown cement generation within quartz overgrowths in quartzitic lenses from the Fontainebleau Sand (Oligocene, Paris Basin) coincides with increased Fe concentrations of up to 192 ppm. In contrast, the Fe content of a nonluminescing generation within the same overgrowths is significantly lower. This finding suggests that the CL is either activated by the Fe itself or caused by defects induced by the incorporation of Fe into the structure. Detrital grains of quartz from sandstone samples of different ages and locations (Wiehengebirgsquarzit, Upper Jurassic, northwestern Germany; Fontainebleau Sand, Oligocene, Paris Basin) yield a good correlation between CL color and Fe and Ti concentrations, with Fe (up to 455 ppm) being more abundant in red-brown-luminescing grains and Ti (up to 298 ppm) confined to grains with blue-violet luminescence. Ti is universally present in quartz from plutonic and extrusive igneous rocks, but rarely observed in quartz from metamorphic rocks. This supports the general contention that the blue-violet-luminescing quartz was formed under higher temperatures than the quartz with brown luminescence, an observation important for studies of sandstone provenance. Concerning the mechanisms of CL activation, these results do not unequivocally prove that the observed colors are activated by the elements sought. Despite the advantages of the microanalytical technique, the observed trace-element contents may still reflect submicroscopic inclusions rather than element incorporation into the structure.

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