Soft Sediment Deformation Structures in the Maastrichtian Patti Formation, Southern Bida Basin Nigeria: Implications for the Assessment of Endogenic Triggers in the Maastrichtian Sedimentary Record ()
ABSTRACT
Detailed fieldwork
carried out in the southern part of Bida Basin, Nigeria, allowed the documentation
of soft sediment deformation structures (SSDS) in the Maastrichtian Patti
Formation. The aim of this study is to examine the sedimentary successions,
describe and analyse these deformation features, discuss their deformation
mechanisms and potential triggers. The Maastrichtian Patti Formation is
composed of lithofacies interpreted to have been deposited in tidal and fluvial
sedimentary environments. Soft sediment deformation structures recognised in
the tidal sediments were clastic dykes, load cast, isolated sand balls,
dish-and-pillar structures, convolute lamination, diapiric structures and recumbent
folds. Severely deformed cross beds, ring structures, associated sand balls,
normal folds and recumbent folds were identified in the fluvial sediments. SSDS
recognised were interpreted to have been caused by effects of liquefaction and
fluidization. Field observations, facies analysis and morphology of the SSDS
indicate that there are relationship between the depositional environments and
SSDS. Endogenic processes are considered as the trigger agents and they are
represented by rapid sedimentation and overloading, impact of breaking waves,
pressure fluctuations caused by turbulent water flow, cyclic stress and current
generated by storm waves and changes in water table. The present study did not
identify exogenic processes as trigger agent. The occurrence of SSDS in
southern Bida Basin strongly favoured a non-tectonic origin but a clear
relationship high energy processes in tidal and fluvial depositional environments.