Palynology: A useful tool in understanding palaeoclimatic changes through the Pliocene-Pleistocene from the deep offshore Niger Delta,Nigeria

Recent global ecological problems have necessitated more research into past environments so that accurate comparisons between past and present climatic conditions can be established and projections made for the future. In order to achieve this, palynological data from Well-C from the deep offshore (> 200 m) Niger Delta region were employed in an attempt to reconstruct the Late Pliocene-Pleistocene palaeoclimate. Four informal palynofloral assemblage zones (PAZ) I–IV are defined and correlated with four major cycles of alternating dry and wet climatic conditions. Within the major cycles, savanna and montane pollen assemblages became dominant in the late-Pliocene and mid-Pleistocene, while mangroves, brackishwater swamp, freshwater swamp and lowland rainforest prevailed during the early- and late-Pleistocene. The palaeoclimate of the late Pliocene and mid-Pleistocene was relatively colder and drier, with alternating relatively warmer and wetter conditions in the early and late Pleistocene, respectively. The pollen data from Well-C showed periods of climatic change during Late Pliocene-Pleistocene times, while the periods of climatic change revealed by pollen data from Lake Tilla, NE Nigeria, during Holocene times ranged from ～2.0 to ～3.8 Ka. Therefore, the cyclicity of climate change during Upper Pliocene-Pleistocene time is far greater than that of Holocene times. Our palaeo-climatic reconstruction conflicts with those that indicate predominantly dry climatic conditions in the Niger Delta region during the Pliocene-Pleistocene. The reconstructed palaeoclimate in this study can help to compare the past climatic conditions to that of the present and perhaps serve as a basis for studies of future climatic change.