MORPHOGENESIS AND PETROGENESIS OF HYDROTH ERMAL TRAVERTINES IN SKOURA(SOUTHERN MOROCCO)

This study addresses the genesis of travertines of Skoura in southern Morocco. These are enigmatic deposits because of their isolated geogra phic position within the Quarzazate depression, their morphology and t heir distinct facies. The research methods (geomorphological survey an d petrographic analysis) used to evaluate their origin provide converg ent results. These suggest that the genetic processes responsible for the travertine development are hydrothermal in nature. Other secondary factors such as surficial hydrology, biogenetic and physico-chemical factors were also influencal but to a lesser extent. A chronological s equence of three different travertine generations is present and inclu ses: 1) a first generation of early Quaternary age located at highest altitude (about 1250 m), 2) a second generation of middle Quaternary a ge located just below the first one (about 1230 m), and a third more r ecent generation, located at the bottom of incised dell (1230 m) emban ked into previous generation of travertine. U/Th datation confirms tha t the first travertine generation is older than 300 000 years BP.