Paper No. 257-4
Presentation Time: 2:15 PM
FORAMINIFERAL BIOSTRATIGRAPHY IN THE BASHKIRIAN-MOSCOVIAN BOUNDARY BEDS (TAURIDES, TURKEY): EVIDENCE FOR GLACIO-EUSTATIC SEA-LEVEL CHANGE IN THE EARLY PENNSYLVANIAN
Bashkirian-Moscovian boundary beds, made up of carbonate and mixed siliciclastic-carbonate lithologies, are widely exposed along the Tauride Belt in southern Turkey. Three overlapping sections have been measured and collected on a bed-by-bed basis.The Bashkirian portion of the sections has been divided into five zones: namely Pseudostaffella praegorskyi-Profusulinella staffellaeformis Zone (Askynbashky); Pseudostaffella gorskyi-Eoschubertella obscura Zone (lower Tashastinsky); Ozawainella pararhomboidalis Zone (upper Tashastinsky); Pseudostaffella subquadrata-Profusulinella tashliensis Zone (Asatausky); and Profusulinella praeprisca Zone (Asatausky). The lower Moscovian (Solontsovsky) is characterized by the Profusulinella prisca-Aljutovella aljutovica Zone. Stacking patterns of upward-shoaling meter-scale cycles in the measured sections indicate the presence of two third-order sequences. A prominent quartz arenitic sandstone intercalated within the Upper Bashkirian carbonate succession has been interpreted as a falling stage systems tract corresponding to stratal offlap during the culmination phase of the second glacial interval in the Carboniferous. Following the sea-level fall in the earliest Asatausky, a new carbonate regime was installed in the Asatausky-Solontsovsky interval by a glacio-eustatic sea-level rise. The Bashkirian-Moscovian boundary seems to be located within the transgressive systems tract of this new carbonate regime.Timing of a glacio-eustatic sea-level data derived from the sequential development of the Bashkirian-Moscovian boundary beds supports the previously introduced scenario arguing that the diachronous appearances of the genus Profusulinella and related fusulinid taxa in the Midcontinent-Andean Province are migratory appearances from the Eurasian-Arctic Province. According to this scenario, the dispersal of the fusulinid taxa in the Midcontinent-Andean Province could have been accomplished via westward migration from the Donbass-Urals-Russian Platform areas through the Franklinian Corridor. These migrations were probably facilitated by a glacio-eaustatic sea-level rise starting from the latest Bashkirian (Asatausky) as evidenced from this study.