Activators of luminescence in speleothems as source of major mistakes in interpretation of luminescent paleoclimatic records

Abstract

This work summarizes the main results of the operation of the International Program "Luminescence of Cave Minerals" of the commission on Physical Chemistry and Hydrogeology of Karst of UIS of UNESCO in the field of activators of speleothem luminescence. It discusses Activators of Luminescence in Speleothems as a source of major mistakes in the interpretation of luminescent paleoclimatic records. It demonstrates the existence of 6 types of luminescence of speleothems and cave minerals in dependence of the type of the luminescence center and its incorporation in the mineral. 24 different activators of photoluminescence of speleothem calcite and 11 of aragonite are studied. This paper demonstrates that it is impossible to produce reliable Paleotemperature or Past Precipitation records from luminescence of speleothems without establishing the organic origin of the entire luminescence of the particular sample.

Microbialites in a High-Altitude Andean Lake: Multiple Controls on Carbonate Precipitation and Lamina Accretion

“…Guido et al 2012). Although several inorganic ions can produce fluorescence, cathodoluminescence reveals only dull luminescence (related to low concentrations of Mn 2+ , which is a primary activator, Shopov 2004). Additionally, observed variation in UV fluorescence is at a scale much finer than that observed under cathodoluminescence, suggesting that the main control on fluorescence is organic matter incorporated into the carbonates, rather than variation in carbonate trace element content.…”

20 years of speleothem paleoluminescence records of environmental changes: an overview

“…This increasing is preceding the one suggested by the Orbital theory with about 10 kyrs and is due to the most powerful cycle of the solar luminosity with duration of 11.5 kyrs superposed on the orbital variations curve. Solar luminosity variations appear to be as powerful as orbital variations of the solar insolation and can produce climatic variations with intensity comparable to that of the orbital variations (Shopov et al 2004). So paleoluminescence speleothem records may serve as a reliable tool for studying the mechanisms of formation and precise timing of glaciations.…”

“…In many samples all or a significant part of the luminescence is produced by ions of uranium and Pb. Sometimes they even have annual banding due to variations of acidity of the karst waters (Shopov, 2004), causing variations of the solubility of some pollutants or toxic compounds (Shopov, 1997). Uranium compounds have such migration behavior.…”

“…In dependence of the excitation source there are specific kinds of luminescence: "photoluminescence" (excited by UV and other light sources), "X-ray luminescence" (by x-rays), "Cathodoluminescence" (by electron beam), "Thermoluminescence" (by heat), "Candoluminescence" (by flames) and "triboluminescence" (by crushing). Different types of excitation may excite different luminescent centers-electron defects of the crystal lattice; admixture ions substituting ions in the crystal lattice or incorporated in cavities of that lattice; inclusions of other minerals; or fluid Shopov, 2004, same volume) Aragonite 11 types of luminescence (see Shopov, 2004, Shopov (1989b) continued Comments to table 1: *36-41 Organic origin of luminescence of these minerals is under question, because molecules of absorbed water may cause similar luminescence (Tarashtan, 1978) in aggregates like studied samples (moonmilk).…”

Organic matter of fossil origin in the amberine speleothems from El Soplao Cave (Cantabria, Northern Spain)

“…Fernando Gázquez 1 , José-María Calaforra 1* , Fernando Rull 2 , Paolo Forti 3 , and Antonio García-Casco 4 et al, 1993;Shopov et al, 1994;Baker et al, 1996;White, 1997;van Beynen et al, 2001;Shopov, 2004;Crowell & White, 2012).…”