Geochemistry and Genesis of the Paleocene–Eocene Kolosh Formation Northeast of Iraq

Abstract

Geochemical investigation on mudstones from clastic sediments was conducted to deduce the origin and successive post-depositional changes in the Kolosh Formation north of Iraq during the Paleocene–Eocene period. The analysis of the major oxides exposes a relatively constant descent for the mudstones. The geochemical examination indicates that these mudstones are carbonate-rich (calcareous to dolomitic mudstones) by predilection pattern terrigenous shales, and CaO + MgO dominance, elucidating a carbonate mud mode, denoting the limited terrestrial clay inputs and control of carbonate deposition. These signatures suggested accessible carbonate rock, probable inclusive of limestone and dolostone genesis origin. Furthermore, the low content of siliciclastic rocks proposed a shallow marine environment with low energy. Established on the elemental rates, these mudstones are categorized as graywacke and lithic arenite, which are derived from mixing igneous source rocks. The mudstone in the descent recognition diagrams locus in the oceanic island arc, continental island arc, and active continental margin maintains the signature of a recycled source. The Chemical Index of Alteration, Chemical Index of Weathering, and Index of Chemical Variability propose recycling processes, and that the provenance area has endured a moderate grade of chemical weathering and immature sediments. The geochemical individuality ratios display immature texture. It is obvious, that such chemical weathering for the source materials is mightily influenced by arid and dry climate status allowing moderate weathering and the arid environment directing to simple ratio of maturation.