Facies, dolomitization and karstification of lagoonal carbonates: Triassic of the Northern Alps

Abstract

Lagoonal carbonates of the Wetterstein Limestone reflect cyclic sedimentation patterns established in near-reef and far-reef environments. The near-reef lagoonal cycles consist of thickly bedded limestones with a predominant gragestone facies intercalated with vadose pisolitic crusts revealing a broad spectrum of various textures of vadose diagenesis. Far-reef cycles are composed of dasycladacean beds or mudstones intercalated with loferites, stromatolites and peritidal breccias. In the upper parts of the far-reef profiles numerous syngenetic karst horizons with a great variety of structural features are included. Karstification appears along with prominent changes of the textures of reef and lagoonal rocks. Superficial and deep burial epigenetic dolomitization are the most important processes with respect to volume in these textural alterations. Distributary pattern of facies, early diagenetic realms, mode and duration of karst periods and intensity of late diagenetic alterations are definitly connected with different rates of spreading of the Wetterstein platform thus reflecting various specific paleogeographic configurations.