ABSTRACT

Examination of gamma-ray activated glow curves of several natural dolomites revealed the presence of three groupings based on glow curve shapes. These shapes are expressed numerically as the peak height ratio of the middle temperature (235° C) peak to the low temperature (115° C) peak. If stratigraphic and petrologic evidence is acceptable for inferring the genesis of dolomites, it becomes possible to relate the three groupings to three types of sedimentary dolomites.

One group of glow curves shows an intense low temperature peak relative to other peaks present and has peak height rations ranging form 0.12 to 0.45. Based on field and laboratory data, the samples represented by this group may be primary precipitates. Another group of curves has an intense middle temperature peak relative to other peaks present and has a peak hight ratio range of 1.81 to 3.53. The samples represented by this group are metasomatic dolomites. The third set of curves has low and middle temperature peaks of similar intensities and peak height rations of 0.65 to 1.30. Geologic data allow an assignment of possible penecontemporaneous (early diagenetic) origin to the dolomites of this group.

Anomalies do exist using this technique for determining genesis, but whether the groupings are related to imperfections in the crystal lattice or presence of certain impurities, either of which might be unique to a particular type of dolomite, is unknown. The results are highly suggestive, and with continued research, the technique could prove valuable for supplementing other data used to determine the origin of dolomite.

BRIEF HISTORY OF DOLOMITE THERMOLUMINESCENCE