Trace-element distribution across calcite veins: A tool for genetic interpretation

Abstract

Profiles of Sr/Ca, Mg/Ca and Ba/Ca in two sets of calcite veins within chalks of Senonian age in the Judean Desert, Israel, were utilized to identify both the system in which the calcite vein crystallized and the source of the indurating solution. The Mg/Ca, Sr/Ca and Ba/Ca profiles in veins located at the Dead Sea Rift boundary were different from profiles in veins located away from the Rift boundary. Na/Ca distribution, on the other hand, was affected by a post-crystallization source in both localities. It is suggested that during the first stage of vein growth Mg/Ca, Sr/Ca and Ba/Ca profiles in the veins closer to the Rift boundary were affected by the dolomitized country rock. The Sr/Ca and Mg/Ca profiles in the veins are too high to be explained by a congruent dissolution of the country rock during the second stage of their growth. Therefore, it is suggested that the solution which precipitated the veins during their second stage of growth obtained its high trace-element content either from incongruent dissolution of the country rock or, more likely from intrusion of post-dolomitization Rift water. During the second stage of vein growth, the Ba/Ca profile in this type of veins was determined by partial dissolution of barite. In contrast to veins located at the Rift boundary, the Mg/Ca, Sr/Ca and Ba/Ca profiles in veins located away from the Rift boundary were mainly determined by the mode of calcite crystallization (i.e. open vs. closed system). It seems that trace-metal distribution across calcite veins in the Judean Desert can be related to epigenetic processes such as intrusion of Rift waters, as well as regional and local tectonic activities.