New Mineralogic Observations on Stylolite Seams: ABSTRACT

Stylolites in the Fredonia limestone of southern Illinois fluorspar areas and in other typical limestone districts were sampled systematically and the geometric patterns classified into six types. The following features in these stylolites were investigated in detail: (1) pressure lamellae in carbonates and their mechanical symmetry; (2) oriented quartz prisms along stylolite layers; (3) the diagenetic paragenesis of sphalerite, galena, and pyrite; (4) the residual accumulation of sphalerite along stylolite seams; (5) pyrite along bituminous portions of the seams. The following conclusions are derived: (1) sphalerite formed before, galena and pyrite during, the stylolite formation; (b) the age of the stylolites in most cases falls within Dapples' second and third period of diagenetic compaction and crystallization; and (c) the diagenetic age of the stylolites and their relation to slumping patterns suggest, together with other sedimentation features, that most of the V-structures in the fluorspar district End_Page 515------------------------------ of southern Illinois are submarine eorsion channels, in part triggered by faulting. End_of_Article - Last_Page 516------------