Liesegang rings in pelagic limestones: genetic considerations

Abstract

Liesegang rings have been recognized in Middle Jurassic pelagic marly limestones of the Subbetic, Southern Spain. The rings of these structures consist of iron hydroxide concentrations and/or small textural changes and are three-dimensionally distributed in the limestone and marly limestone beds. These structures have been previously described in siliceous rocks, in volcanic rocks and only rarely in limestones and marls. Liesegang rings are the result of geochemical and textural self-organization processes mainly produced by iron-rich fluids coming possibly from contemporaneous volcanic rocks. Chemical, mineralógica! and textural changes occurred prior to the lithification of the marly limestone beds, as is demonstrated by the presence of synsedimentary faults affecting these structures