Miocene sediment mineralogy of the lower Chelif basin (NW Algeria): implications for weathering and provenance

Abstract

Mineralogical investigations of clay and nonclay minerals were conducted on the Miocene sediments from three sections of the lower Chelif basin, northern Algeria. Bulk rock analyses of Miocene sediments show that these clastic sediments are dominated by variable mineralogical compositions and concentrations. Quartz is the dominant mineral through the three stratigraphic intervals and calcite (except in the upper layers) and dolomite are lacking in the Messinian deposits. The clay mineralogy is dominated by smectite (24%) and mixed-layer illite-smectite (I-S) (22%) during the Burdigalian-Langhian, illite (36%) and kaolinite (28%) in the Tortonian, and illite (49%) and IS (20%) in the Messinian stratigraphic range. The smectite-(kaolinite+chlorite)-illite ternary diagram shows that, in general, Miocene sediments originated from a mixed mafic and felsic source and were influenced by physical erosion and chemical weathering processes.