Ostracods and lithofacies of the Devonian-Carboniferous boundary beds in the Avesnois, North of France

摘要: Seven major carbonate microfacies are defined in the Devonian-Carboniferous (D-C) transitional strata (90 m) of Bocahut quarry (Avesnes "basin"), and ten levels ranging through Epinette, Etrocungt, Avesnelles Hastiere formations recognized. The "bathymetric" sequences range from open marine spiculite, below storm wave base to semi-restricted lagoon. A standard sequence records a shallowing-upward trend, environments strongly eroded supratidal pre-evaporitic environments. Faunal components (echinoderms, brachiopods...) point an domain for first six microfacies. Except "black" mudstones containing rare algae, environment is located within dysphotic-euphotic zone. Ostracods abundant diversified throughout studied section. Sixty-six species identified belong assemblage Eifelian ecotype indicating oxygenated shallow generally between fair-weather bases. absence some platycopid ostracods at Formation could be related hiatus observed formations. That probably corresponds Hangenberg Event; however, its effect on distribution was very reduced. sedimentology show that displays most complete succession presently known D-C transition Northern France "basin") Southern Belgium (Dinant basin) although it far being continuous. Two new described: Saccelatia? advena nov. sp. Healdianella dorsosulcata