Numidian Flysch of the Constantine Mountains (Tell Orientale, Algeria)

E. Moretti, R. Coccioni, F. Guerrera, J. C. Lahondere, F. Loiacono, D. Puglisi

In the geotectonic evolution of the Maghrebidian orogeny, the Numidian Flysch represents one of the main structural-stratigraphic units during the Oligocene-Miocene. The interdisciplinary approach used in this study has made it possible to better define the Numidian Flysch outcropping in the south Kabylian location.

From the geostructural analysis carried out on the Constantine Mountains, we found that the Numidian Flysch rests with mechanical contact mainly on the "Nappes Telliennes." Its stratigraphic substrate consists of Tubotomaculum varicolored clays.

Facies analyses of two sections revealed arenaceous and conglomeratic facies generated by debris flows or high-density turbidity currents. Sedimentological features indicate deposition on a submarine slope. During strong erosional activity (lowstand stage), thick beds of coarse-grained sediments were probably deposited; during periods of less-intense erosion (highstand stage), slope movements due to seismic and tectonic activity were probably responsible for remobilization and deformation of slope sediments.

The arenaceous mode of the analyzed samples can be referred to the quartzarenite groups. The sandstones are, in fact, characterized only by noncarbonate extrabasinal framework grains, mainly consisting of detrital quartz. These are products of very mature composition which, from the point of view of texture, are often characterized by poor or moderate granulometric sorting and sometimes by the presence of an abundant matrix.

The planktonic foraminiferal assemblages, although rare and poorly preserved, allow us to attribute some samples to the latest Chattian. Nevertheless, this association must be considered reworked, and more biostratigraphic analyses are needed.

Comparison with the Maghreb scale facilitates a better comprehension of this important subject.

AAPG Search and Discovery Article #91032©1988 Mediterranean Basins Conference and Exhibition, Nice, France, 25-28 September 1988.