Geochemistry and paleocurrent studies of sandstone facies of the Albian Bima Formation in Kaltungo Inlier, Gongola Sub-Basin, Nigeria: implications for provenance, tectonic setting and paleoweathering condition

ABSTRACT

This research article presents the resulting appraisal of the paleocurrent analysis and geochemical aspects of the Bima Group aimed at puzzling out the provenance of the sediment, paleotectonic, prevailing paleoclimatic, and paleoweathering conditions that existed during the Albian time in the less studied Kaltungo Inlier section of the Gongola Sub-Basin, Nigeria. A total of twenty-two (22) samples of the sandstone were analyzed for major elements using XRF geochemical method, which shows the Bima Group samples to be generally highly siliceous with SiO₂ values ranging from (77.01-91.89) wt. % with an average of 85.726 in the samples. We observed a high chemical index of weathering value above 90%, a chemical index of alteration above 73%, and a predominantly low index of compositional variability values less than 1% which denote compositional maturity of the sediments resulting from sediment recycling unloaded in moderate chemical weathering under humid stifling paleoclimate and tectonically active setting. Geochemical data show that these sandstones are subarkose to sublitharenite, litharenite, and Fe-sand. Provenance studies point to derivation chiefly from pre-existing sedimentary rocks with lesser influence from igneous (felsic) rocks, while the tectonic discrimination parameters indicate continental drift of the passive margin paleotectonic regime. The palaeocurrent analysis suggests a southwestern direction, which means that the sediment was sourced from the northeastern direction. From the results of the palaeocurrent direction, paleoweathering, paleoclimate, and provenance studies of the Bima Group, it can be gathered that nearly all of the sediments are from pre-existing Cretaceous sedimentary rocks of the Gongola Sub-Basin and have not experience-prolonged transportation, which is in agreement with the regional geology and distribution of the pre-Santonian sediments in the Gongola Basin.