BROMINE IN SALT DEPOSITS AS A TEMPERATURE INDICATOR OF BRAINS OF PALEOBASINS

Estimation technique has been proposed for temperatures of formation o f potassium-bearing sediments based on the differences in temperature dependence of bromine distribution coefficients for sylvite and halite . It uses bromine contents in paragenetic sylvite (Br(s)) and halite ( Br(h)): T = 1100/(5.587 - ln(Br(s)/Br(h))). For lack of direct evidenc es of sylvite - halite paragenesis the validity of the geothermometer can be estimated by comparison of the predicted and observed bromine c ontents as if these salts were crystallized simultaneously from the ma rine water. For this purpose a technique has been developed allowing t o perform a genetic study of the halite - sylvite association by the p oint position on the diagram Br(s)-Br(h). It has been shown that any p rimary-sedimentary associations (both paragenetic and secondary ones) can be used for temperature evaluation. The proposed technique has bee n applied to estimate the temperatures of formation of Neogene salt-be aring sediments of Upper Rein graben (36 to 61-degrees-C for different parts of a section), upper-Permian sediments of Werra region (average 24-degrees-C), early-Kambrian sediments of Nepskoe potassium deposit (average 48-degrees-C), and that of Kansko-Tassevskaya depression (ave rage 50-degrees-C).