ABSTRACT

An integrated study was made of the petrography and strontium content of sixty-two samples of oolitic limestones. The range in strontium content is from 230 parts per million for a sample of Cambrian oolite to 10,080 parts per million for a recent Bahaman oolite. Excepting Quaternary samples, the mean strontium content of the samples is 414 parts per million, a value nearly identical to the mean strontium content known to occur in other types of carbonate rocks. Diagenesis of ancient oolitic sediments could have involved a reduction in the strontium content as large as 10,000 parts per million and possibly more. Maximum loss of strontium occurs during early diagenesis before major cementation, when aragonite allochems change to calcite. Factors of secondary importance in the loss of s rontium may include changes brought about by solid-state recrystallization and decomposition of organic material. The overall loss of strontium is probably related most directly to the expulsion of fluids from individual allochems and thence from the entire sediment mass.

Recrystallization of allochemical constituents in oolites is more common than recrystallization of cement and matrix material. No systematic relationship was detected between the amount of strontium and the degree of recrystallization on a bulk sample basis.

Study of seven samples indicates that the carbonate cementing material contains, on the average, nearly twice as much strontium as the allochems. Diagenetic modifications of allochems probably continue after cementation.