CARBON ISOTOPE STRATIGRAPHY OF LOCHKOVIAN TO EIFELIAN LIMESTONES FROM THE DEVONIAN OF CENTRAL AND SOUTHERN EUROPE

Abstract

Lower to Middle Devonian carbonates of the Prague Syncline, the Carnic Alps, the Montagne Noire, and the Cantabrian Mountains were investigated for δ13Ccarb and δ13Corg. These values were measured on bulk rocks, selected components and cements. Many carbonates exhibit primary marine values, but some are altered by diagenesis. A δ13C curve can be presented for the latest Pridolian to Emsian time interval. Several sharp or broad positive excursions are obvious in the woschmidti-postwoschmidti, sulcatus, kitabicus, Late serotinus, and kockelianus conodont zones. The excursion at the Silurian–Devonian boundary is known worldwide and therefore considered global in nature. Some of the others are described for the first time from central and southern Europe, and their global nature has to be verified by further investigations in other regions. Most excursions relate to and/or started during major regressions whereas sea-level highstands correspond to minimal δ13C values. Similar relationships between sea-level changes and δ13C have been observed from other early Palaeozoic intervals. The transgressive Choteč (?) and Kačák events are marked by positive isotope excursions, this type of combination is usually observed in late Palaeozoic to Cenozoic black shale events.