Aptian-Cenomanian stratigraphy and sedimentary evolution of the BortziriCinco Villas Paleozoic Massif margins (mid-Cretaceous, western Pyrenees)

Résumé

In this work we present the correlation among the Aptian-Cenomanian lithostratigraphic units defined in the N, NW and S margins of the Bortziri Massif. Their stratigraphical and sedimentological affinities indicate that geological settings, processes and sediments were similar around the massif margins. The Aptian-Cenomanian stratigraphic record is presented in time intervals bound by main discontinuities (D1-D5). The Upper Aptian, bound between the D1 and D2, is only recorded in the NW margin as shallow-marine mixed-platform deposits. Upper Aptian to Lower Albian deposits crop out in the NW and S margins and are suggestive of sedimentation in a shallow-marine carbonate platform. Their top is represented by D3, which indicates an important erosive event during the Middle Albian. Upper Albian to Lower Cenomanian sediments were deposited in shallow- and deep-water marine environments, and recorded a tectonic pulse represented by D4 (Late Albian, dispar Zone-Early Cenomanian). Hemipelagic calcareous sedimentation characterizes the latest Early Cenomanian above D5 in the NW and S margins, and in stratigraphic continuity in the N margin. The sedimentary evolution of the margins shows the tectonic control of the depositional systems as well as the influence of a regional transgression.