acknowledgement
contents
introduction
prevision work
scope of the present work
gross lithologic variation
previous lithostratigraphic classifications
the duwi formation
granulometric analysis
procedure
size parameters
modal analysis and classification
modal analysis
classification of abu tartur phosphorites
geochemistry of phosphorites
major elements in liffiya,liffita-maghrabi and maghrabi sectors
geochemistry of phosphorites
trace elements in the liffiya-maghrabi sector
zinc
geochemistry of black shales of the duwi formation
calcium
barium
effect of weathering on the chemical composition of phosphorites and intercalating shale
method of study
effect of weathering on the x-ray differaction pattern of the phosphate mineral
conclusion
summary and conclusion
references
الملخص العربى