Foraminifera Microfauna from Pindiga Formation and their Paleoecological Interpretations, Gongola Basin, Northern Benue Trough, Nigeria

Abstract

Nineteen (19) shale samples were taken from the Pindiga formation for
foraminiferal analysis. About fourteen species of mostly arenaceous foraminifera
belonging to seven genera were recovered. Bathysipon foliformis, Bathysipon sp,
Haplophragmoides pindigensis and Ammobaculites pindigensis are the most
abundant species recovered occurring in most of the sampled shale while
Bathysipon argentus, Haplophragmoides sp, Ammobaculites gombensis,
Ammobaculites bauchensis, Heterohelix globulosa, Heterohelix reussi, Milliamina
pindigensis occur sparsely within the formation. The distribution, abundance and
diversity of these foraminifera species is used to interpret the paleoecological and
paleoenvironmental conditions that prevailed during the deposition of these shale.
Recovery of predominantly deep dwelling Bathysipon species amounting to about
81% of the total recovered foraminifera within the formation indicates it was
deposited in a shallow to deep marine environment under saline water conditions
allowing for the crystallization of gypsum within the shale. Heterohelix species
recovered were used alongside previous work done on ostracods and other fossils
to establish the age of the Pindiga Formation to be Turonian-Coniacian. It was
discovered that the Pindiga shale was deposited under anoxic conditions making it
rich in organic matter and also a potential source rock for hydrocarbon generation.