Abstract
This study presents a comprehensive geochemical analysis of siliciclastic sediments from the Shendam area
in the Middle Benue Trough, Northcentral Nigeria, to elucidate their origin, tectonic setting, and
depositional environment. The sediments, primarily derived from intermediate to felsic igneous rocks,
exhibit significant chemical weathering, indicative of prolonged exposure to warm, humid climatic
conditions. Geochemical indices, including the Chemical Index of Alteration (CIA), Plagioclase Index of
Alteration (PIA), and Chemical Index of Weathering (CIW), reveal intense weathering of the source rocks,
with CIA values ranging from 3.64 to 99.41 (avg. 73.20). Provenance analysis, supported by Al₂O₃/TiO₂
ratios and bivariate plots, indicates a mixed source of intermediate and felsic igneous rocks, consistent with
the Younger Granites of the region. The tectonic setting, inferred from major and trace element
geochemistry, aligns with a passive continental margin, reflecting the broader tectonic evolution of the
Benue Trough during the breakup of Gondwana. Paleo-redox conditions, assessed using trace element
ratios (e.g., V/Cr, V/Ni, Sr/Ba), suggest deposition in anoxic to dysoxic environments, predominantly in
freshwater settings with occasional brackish influence. This study underscores the interplay between source
rock composition, weathering intensity, and tectonic activity in shaping the sedimentary record of the
Middle Benue Trough, providing valuable insights into the region’s geological history and depositional
processes.