Abstract

The most bulk (98%) of the carbonate buildups are developed on Proterozoic crystalline basement blocks. Lagoons with mud banks and patch reefs range in width from several to several tens of kilometres but the reef margin is very narrow, only some tens or few hundreds of metres wide. Thickness of the buildups is generally between 200 and 1000 m. The mean subsidence rates, calculated according to buildup thickness and duration of the buildup accumulation, varied from 20.0 to 86.7 m Myr^-1. The platform margin has a general retreating trend up to the upper Frasnian Palmatolepis gigas Zone, when an advancing trend started. Coral-stromatoporoid benthic communities are present from Eifelian to the lower Famennian Palmatolepis crepida Zone.

Four megacycles occur which display a general succession of dark wackestones, Amphipora-bearing rocks and boundstones. These megacycles culminate in (1) the Eifelian-Givetian boundary interval, (2) the upper part of the middle Givetian, (3) the lower Frasnian, and (4) the uppermost Frasnian. These culminations are characterized by maximum rates of buildup accumulation and also the synchronous deposition of black anoxic sediments (generally in deeper environments — the otomari, Phariceras, Manticoceras and Kellwasser events). The volumes of limestones corresponding to the standard microfacies (in the sense of Flugel 1978) were calculated with following results: Standard microfacies No. 9 (SMF 9) — biomicritic limestones with bioclasts, 39.4%, SMF 7 — biolitic limestones, 23.7%, SMF 8 — biomicritic limestone with biomorphs, 7.4%, etc. The abundant micrite formed in a variety of ways; partly mechanical, partly algal and other biochemical origins. Cementation at various stages completely fills porosity except for dolomitized and fractured horizons. The 129 microfacies which were distinguished during the evaluation of the material are reclassified according to the standard microfacies system (in the Flugel’s sense) as well as according to Devonian microfacies associations and Devonian development stages systems (in the sense of the author, Hladil, 1986). The quantitatively restricted dependence is shown in .