Mineralogy and Geochemistry of Mud Rock Units of the Late Cretaceous Kanawa and Gulani Formations, Eastern Gongola Basin, North-Eastern Nigeria: Implications for Provenance Studies

Abstract

The clay mineralolgy and geochemistry of the mud rock units of the Late Cretaceous Kanawa and Gulani formations in the eastern Gongola Basin were investigated with the sole aim of unravelling the provenance. The distinctive clay minerals and other accessories minerals identified from XRD analysis included; dioctahedral smectite, partially ordered and well ordered kaolinites, illite, and glauconite, palygorskite, sepiolite (found only in the glauconitic horizon) etc, and quartz, microcline, anatase, muscovite, phosphate, hematite etc, respectively. The elemental composition within the same mud rocks unit analysed using XRF revealed the presence of the following major elements: Al₂O₃, Fe₂O₃, SiO₂, K₂O, CaO and TiO₂ in virtually all samples and P₂O₅ in only two samples. Additionally, trace elements identified from some of the samples are; V₂O₅, Cr₂O₃, BaO, MoO₃ etc.  The major elements are consistent with the chemical composition of the clay minerals and other non-clay minerals present. The presence of Illite or/and smectite, and well ordered kaolinite suggest intense climatic fluctuations between warm and dry, to hot and humid tropical condition.  From the geochemical evaluation of the mudrock units within the Late Cretaceous Kanawa and Gulani formations shows that they were probably derived from mafic (basaltic) rocks.

Keywords: Late Cretaceous; Kanawa and Gulani formations; north-east Nigeria, intense climatic fluctuation between warm and dry- hot and humid; sourced from mafic (basaltic) rocks.