科研之友
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摘要
Rapid and profound changes in Earth surface environments and biota across the Frasnian-Famennian (Fr-Fa) boundary are well known and related to one of the five most severe mass extinction events in Earth history. Here, we present sedimentological, biostratigraphical, petrophysical (gamma-ray spectrometry, magnetic susceptibility) and geochemical (X-ray fluorescence) data from environmentally distinct sections in the Moravian Karst (Czech Republic) and compare them with the Steinbruch Schmidt section in the Kellerwald (Rheinisches Schiefergebirge, Germany). Both areas were located at the southern margin of Laurussia. The studied sections span the interval from the Lower or Upper rhenana to the Palmatolepis minuta minuta or younger conodont zones and the foraminiferal Eonodosaria evlanensis Zone and Eonodosaria evlanensis-Quasiendothyra communis Interzone including high resolution biozonation of the Fr-Fa boundary interval. In the Moravian Karst pure limestone facies of an inclined carbonate ramp reflect the worldwide trend in the widespread occurrence of calcimicrobes during upper Frasnian and lower Famennian. Geochemical and petrophysical data show a decrease in grain size of the siliciclastic supply and carbonate productivity in the Kellwasser Event intervals probably due to a deepening and correlate with maximum flooding surfaces and highstand system tracts in the Steinbruch Schmidt. Certain differences in some geochemical proxies between the Moravian Karst and Steinbruch Schmidt are due to lower carbonate dilution of the latter. Significant Zr, TiO2, Mn or Fe2O3 enrichments may indicate the influence of volcanic sources in the studied Moravian Karst Fr-Fa sections.
- 出版日期2017
