IDENTIFICATION AND VALUATION OF PARAMAGNETIC RADICALS IN NATURAL DOLOMITES AS AN INDICATOR OF GEOLOGICAL EVENTS

Abstract

Geological sedimentary dolomite samples from the Superior Proterozoic are studied using electron paramagnetic resonance (EPR) spectroscopy. The complex spectra in the g=2.0 region is composed of Mn2+ lines and signals due to crystallization and radiation-induced defects. Measurements in microwave frequencies of 9.5 GHz (X-band) and 35 GHz (Q-band), and thermal and/or radiation treatments allowed identification of seven paramagnetic radicals in the g=2.0 region: (1) isotropic organic radical; (2) axial SO2-; (3) axial PO20 or PO22-; (4) isotropic CO2-; (5) axial CO2-; (6) axial CO33-; (7) isotropic unknown line. The use of these paramagnetic centres as indicators of geological events is discussed.