Combined visual cathodoluminescence (CL) and spectral analyses of CL reveals periodic enrichments of rare earth elements (REE3+) and manganese (Mn2+) within the laminations of eight calcitic lateglacial to postglacial stalagmites. In the annual layers, the enrichment of trace elements can be correlated with the autumn/winter laminae, which are strongly pigmented and rich in organic carbon. During the Holocene, they occur especially in the Atlantic stage and in subrecent/recent times. The enrichment of REE3+ and Mn + reflects times of more intense weathering, which presumably prevailed during the Atlantic warm and humid climate. In subrecent/recent times, especially the last 100 years, these enrichments may have been at least partially anthropogenically induced.
Authigenic quartz overgrowths and hydrothermal quartz crystals from locations
in Oman and Switzerland have been investigated with SIMS, EPMA, SEM-CL and SEM-CC.
All techniques reveal similar zonation patterns with SEM-CL having the best
resolution followed by SEM-CC, EPMA and finally SIMS. The observed zonations
reflect chemical and/or physical changes during growth in the precipitation
environment or disequilibrium precipitation at the crystal surface (i.e. sectoral
and intrasectoral zonation). Based on the total Al content, two types of
authigenic quartz are distinguishable. When the Al concentration is <500 μg
g–1 the predominant CL emission is at ~630 nm; in such
quartzes, SEM-CL and SEM-CC are directly correlated, and signal intensities drop
as a function of increasing Al concentration. In contrast, authigenic quartz with
Al concentrations between 500 μg g–1 and 1000 μg
g–1 has CL emission maxima at both ~630 nm and ~380—400
nm, at which point the panchromatic SEM-CL and SEM-CC intensities become
decoupled.
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