The Albian Stage in its type area, the Aube (France): a synthesis in a global sedimentary context

Abstract

The Albian Stage in its type area, the Aube (France): a synthesis in a global sedi- mentary context.- The Aube department is the type locality of the Albian stage created by d'ORBIGNY (1842). Two formations are recognised in the clay facies (the Gault auct.) of the stratotype, the Argi- les tegulines de Courcelles (82 m), which is overlain by the Marnes de Brienne (43 m). The boundary between the two formations is defined at the top of an indurated bed (hardground L'Etape) that is rea- dily identifiable, both in the field, and from boreholes. The type area of the Albian stage is of great interest because of the size of the clay facies (more than 120 m) unique in the Anglo-Paris basin. To- day, 82 % of the lithological succession is documented accurately from 16 outcrops. In two intervals of respectively 33 m and 28.50 m thick, composite sections are made of overlapping sections which are correlated in the field with the help of lithological marker beds. Six successive facies are described: in the Argiles tegulines de Courcelles and from bottom to top: 1 - phosphatic nodules bed; 2 - silty clays; 3 - clays and limestone beds; in the Marnes de Brienne: 4 - clay marls; 5 - gaize; 6 - clay marls. On a smaller scale, a decimetre to metre-scale rhythmicity can be identified in the sedimentation. This is re- flected in the Argiles tegulines de Courcelles by pluri-decimetric cycles that start with a silty level and