Two hundred million years of karst history, Dachstein Limestone, Hungary

Abstract

Platform carbonates of the Upper Triassic Dachstein Limestone in Naszály Hill have been karstified extensively over the past 200 million years. They provide an excellent example of polyphase karstic diagenesis that is probably typical of many subaerially exposed carbonate sequences. Seven karstic phases are recognized in the area, each of which include polyphase karstic events. The first karst phase was associated with the Löfer cycles. Meteoric waters caused dissolution; enlarged fractures and cavities, were filled by marine and/or vadose silts and cement. The second karst phase was caused by local tectonic movements. Bedding‐plane‐controlled phreatic caves were formed, and filled by silts. The third karst phase lasted from the end of the Triassic to the Eocene. This was a regional, multiphase karstic event related to younger composite unconformities. Bauxitic fill is the most characteristic product of this phase. The karst terrain reached its mature or senile stage with very little porosity. Narrow veins and floating rafts of white calcite marks karst phase 4, which resulted from hydrothermal activity associated with Palaeogene magmatism. The early Rupelian phase of Alpine uplift caused large‐scale rejuvenation of the former karst terrain (karst phase 5). Subsequently Naszály Hill was buried as an area of juvenile karst with significant porosity. A second period of hydrothermal activity in the area (karst phase 6) was induced by Miocene volcanism, which resulted in wide, pale green calcite veins. Finally karst phase 7 was of tectonic origin. Following the most recent, Miocene uplift of the Naszály Hill, the carbonates have again become the site of vadose karst development.

Selective blackening of bioclasts via mixing‐zone aragonite neomorphism in Late Triassic limestone, Zlatibor Mountains, Serbia

“…, 1985). The values are slightly lower than those reported from meteoric crystal silt that filled the solution‐enlarged fissures of a syndepositional palaeokarst phase in the Dachstein Limestone of Hungary (Juhász et al. , 1995).…”

Interpretation of ancient epikarst features in carbonate successions — A note of caution

“…palaeo-karst surfaces. These buried karst landforms range in magnitude from shallow dissolutional features, formed during brief episodes of marine emergence and exposure to subaerial processes (epigenetic karst), to 'mature', rugged karst landscapes with reliefs of tens to hundreds of meters and large cave systems that have taken millions of years to develop (Juhász et al, 1995;Klimchouk, 2009). The oldest known examples of palaeo-karst are found in Archean rocks (N2500 Ma) of the Canadian Shield (Eriksson and Altermann, 1998).…”

Karastic features associated with unconformity surfaces, a case study from the United Arab Emirates

“…Some ancient carbonate build-ups have undergone many phases of karst porosity development during their history. An understanding of these phases is crucial, not only for interpreting the porosity history of a carbonate sequence but also for understanding the general diagenetic history ( Juhasz et al, 1995).…”