Author/Authors :
amakrane, jemaa university mohammed premier - faculty of sciences - department of geology, applied geosciences laboratory (lga), Morocco , amakrane, jemaa university of liège - department of geology, argiles, géochimie et environments sédimentaires (ages), Belgium , azdimousa, ali university mohammed premier - faculty of sciences - department of geology, applied geosciences laboratory (lga), Morocco , rezqi, halima university mohammed premier - faculty of science - department of geology, applied geosciences laboratory (lga), Morocco , el hammouti, kamal university mohammed premier - faculty of sciences - department of geology, applied geosciences laboratory (lga), Morocco , el ouahabi, meriam university of liège - department of geology, argiles, géochimie et environments sédimentaires (ages), Belgium , fagel, nathalie university of liège - department of geology, argiles, géochimie et environments sédimentaires (ages), Belgium
Abstract :
Micropaleontology and sedimentological analyses of sediments in the Guercif basin (Northeastern, Morocco) allowed biostratigraphic, paleoenvironmental and sequential reconstructions. The samples were taken from a geological section located at the southwestern part of the basin. The section can be divided in three lithological units, dated from the Tortonian to the Messinian. The transition and lithostratigraphical continuity between the late Tortonian and the Messinian are defined by the characteristics of planktonic foraminifera in the sediments horizons of (eg., Globorotalia menardii group, right coiling) for the upper Tortonian, (eg., Globorotalia miotumida group, left coiling) for the Messinian. Benthic foraminifera associations evidence an evolution of the sedimentary environments over the studied section. The Tortonian calcarenitic units were deposited in the shallow neritic (infralittoral) environment, especially marked by the species Ammonia beccarii accompanied by Nonion commune and Textularia sagittula. The environment gradually evolves to a deep epibathyal environment, evidenced by the presence of an association of Uvigerinids at the base of the marls-sandstones levels. The intermediate upper Tortonian unit is marked by an association of Lenticulinids and by an alteration of gypsiferous marls and sandstones suggesting rather a circalittoral environment. Finally the Messinian gypsiferous marls were first deposited in circalittoral identified by an association of Lenticulinids. The co-occurrence of Ammonia beccarii and Cibicides lobatulus rather suggest an infralittoral environment. The sequential analysis attests for the presence of a complete sedimentary cycle consisting of different staking sedimentary environments which are related to local eustatic variations.
NaturalLanguageKeyword :
Biostratigraphy , Foraminifera , Sequence stratigraphy , Paleoenvironment , Late Miocene , Guercif basin , Morocco
