Proposed magnetostratigraphy susceptibility magnetostratotype for the Eifelian-Givetian GSSP (Anti-Atlas, Morocco)

The magnetosusceptibility event and cyclostratigraphy (MSEC) record for the Eifelian-Givetian Global Boundary Stratotype Section and Point (GSSP) loca ted in the western Sahara of southeastern Morocco is used to establish a se quence of magnetostratigraphic susceptibility units organized into magnetos tratigraphic susceptibility zones (MSZ) and magnetostratigraphic susceptibi lity subzones (MSSZ). Magnetic susceptibility data are summarized into two complete MSZs (Atrous and Mech Irdane) and two partial MSZs (Gheris and Ris sani). The Atrous (Upper Eifelian) is comprised of 3 MSSZs and the Mech Ird ane (uppermost Eifelian and lowermost Givetian) of 11 MSSZs. The Eifelian-G ivetian boundary falls within Mech Irdane MSSZ 2 making the magnetosubzone an important boundary marker unit. Large-scale transgressive and regressive patterns in the MSEC data establish that the Eifelian-Givetian boundary in the GSSP sequence occurs immediately after the first regressive pulse foll owing the transgressive conditions established during the Atrous MSZ. The L ower Kacal/otomari Event occurs in Atrous MSSZ 3 and Kacak/otomari Event oc curs in Mech Irdane MSSZ 1. The magnetic properties of the MSZs and MSSZs a re tested by comparison with a coeval magnetostratigraphic susceptibility s equence in the Montagne Noire region of southern France.