Biogenic and Abiogenic Origins of Authigenic Pyrite of Gombe Inlier, Gongola Arm, Upper Benue Trough N.E Nigeria.

Abstract

This study constrains the origin of pyrite of the Gombe In-lier to either biogenic or
abiogenic using the analytical techniques Scanning Electron Microscopy and Energy
Dispersive X-ray Spectroscopy and stable sulfur isotopes studies. The stable isotope
compositions are useful indicators of the pathways of both biogenic and abiogenic
pyrite formation. Textural and compositional information preserved in sedimentary
pyrite from sediment-hosted ore deposits has contributed to elucidate their
environment of formation. Backscattered SEM images of pyrite samples of this
study were compared with that of the Huitrin Formation, Neuquén Basin in
Argentina which is Aptian in age together with that of the offshore core samples of
the Captain sands of Western Moray Frith Basin, United Kingdom with an Aptian
age, the Valanginian (Lower Cretaceous) Wealden group of the Wessex Basin in
Dorset, United Kingdom, the Turonian Afowo Formation in the Dahomey Basin of
Nigeria. Result showed that in all SEM images, micrographs indicate either euhedral
or framboids pyrites. Their respective isotopes results (mean) were also compared.
The isotope result places the samples of the Gombe inlier with strong evidence that
they could either have an origin that is biogenic or abiogenic, with a positive δ34S
values signifying a closed system sulfate reduction during the pyrite mineralization
of the area and of low temperature mineralization.