S. Doring et M. Kazmierczak, Stratigraphy, geometry, and facies of a Middle Devonian ramp-to-basin transect (eastern Anti-Atlas, SE Morocco), FACIES, 44, 2001, pp. 137-150
In the eastern Anti-Atlas (SE Morocco), a small sedimentary basin (Mader Ba
sin) evolved during the late Palaeozoic. The Middle Devonian deposits consi
st of shales and limestones with a thickness up to 700 m in the depocentre.
Sedimentary structures and sole marks of Middle Devonian limestones indica
te transport from the northwest and the south towards the basin centre, loc
ated in the central Mader area. Lithostratigraphic, biostratigraphic, and d
ynamic stratigraphic approaches were applied to correlate stratigraphic sec
tions. Five correlatable large-scale base-level hemicycles were recognized
in the Middle Devonian succession. Thickness trends of Middle Devonian depo
sits, regional correlations, and facies-trends reveal the geometry of a car
bonate ramp. The carbonate ramp was slightly inclined (< 1 degrees) to the
NE. A sedimentary wedge, consisting of limestones and limestone/marl altern
ations, was deposited during the Eifelian and marks the transition from the
ramp to the adjacent basin. Middle Devonian water depths are estimated as
close to and within the storm wave-base at the southern area of the ramp an
d far below storm wave-base in the northeastern part of the ramp. Shallowes
t conditions (inner-ramp environment), close or within the fairweather wave
-base, existed during the early Givetian as documented by the abundance of
reefal fauna (stromatoporoids, corals) and calcimicrobes (lumps, micritic e
nvelopes) in the eastern and southeastern area of the ramp.