The correlation potential of magnetic susceptibility and outcrop gamma-ray logs at Tournaisian-Viséan boundary sections in western Europe

摘要: We have measured five deep-water carbonate and carbonate-siliciclastic sections at the Tournaisian-Visean (Tn/V) boundary in western Europe, using petrophysical outcrop logging techniques (gamma-ray spectrometry /GRS/ magnetic susceptibility /MS/). The aim was to trace correlatable log patterns across flanks of London-Brabant Massif from eastern Ireland Germany. Both GRS MS proved useful for long-distance (up ~1000 km) correlation. can be interpreted terms sea-level fluctuations. A late Tournaisian regression, a sequence Tn/V boundary, early Visean lowstand systems tract an overlying transgressive regressive succession identified logs. correlated with exposure features karstic surfaces up-dip shallow-water settings between 4 5 Hance et al. (2001, 2002). This indicates that fluctuations around were synchronous traceable on Massif. GRS-based has greater correlation potential than as it applied broad spectrum facies depositional settings. In certain sections, signal shows increasing trend during transgression decreasing which is opposite paradigm platform These trends are assumed result landward/basinward shifts low-productivity ramp system. Lowstand shedding tempestites turbidites results low values while rise backstep, developing retrograding its distal parts, associated upward-increasing values.