X- Ray Diffraction Studies of Patti Claystone Member of the Campano-Maastrichtian Patti Formation, Southern Bida Basin, North Central Nigeria

Abstract

X-ray diffraction and field studies were carried out on the Patti Clay Member of the Patti Formation in the southern Bida Basin. The studies involved field collection of samples and XRD laboratory analysis of clay samples in order to determine the dominant clay type, subordinate associated minerals, geologic processes and paleoenvironment of deposition. Field study involved standard litho-description by noting textural properties, facies type, fossil presence, structure and diagenetic effect. Laboratory XRD analysis procedure included sample grinding, XRD recording condition, selection and measurement of reference minerals, quantification of clay minerals using XRD processing software, XPert-Highscore Plus to generate results indicating clay mineral type and other minerals peaks. Lithostratigraphic section is dominated by the alternation of sandstone and claystone layers. The sedimentary structures are planar parallel and cross bedding in nature. The sandstone at Ahoko and along Lokoja-Abuja highway is characterized by liesegang ring and bioturbation structures. XRD results indicated that the Patti Clay Members are dominated by kaolinite with subordinate illite, montmorillonite and zincite in rare cases. The clay members were suggested to be deposited by moderate to low energy of transportation, moderate to low rate of deposition through prograding mechanism in a marginal marine setting. The kaolinite clay was formed by meteoric water reaction with the shallow-seated clay members through leaching of K+, Na+ and silica ions with resultant kaolinite stable at adequate pH that was not acidic.