synthesis of late cretaceous geological development of nigeria...synthesis of late cretaceous...

Synthesis of Late Cretaceous geological development of Nigeria

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Edegbai, A.J*1, 2, Schwark, L2 and Oboh-Ikuenobe, F.E3

1.Department of Geology, University of Benin, Benin City, Nigeria2. Institute of Geoscience, Kiel University, Kiel, Germany

3. Department of Geosciences and Geological and Petroleum Engineering, Missouri University of Science and Technology, Rolla MO, USA

* Corresponding author: [email protected]; +23465743132

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Introduction

2Ye et al., 2018

Edegbai et al., 2019 (and references therein) 3

Tectonostratigraphy

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• The opening and evolution of the Atlantic is co-genetic with WARS evolution

Seismic line showing Cretaceous - Tertiary megasequences

Pre- mid Albian

• WARS initiation characterized by deposition of coeval non marine syn-rift sandstones and mudstones

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Aptian to early Albian paleogeography of parts of Africa (Ye et al., 2018)

• Flooding of the Benue trough following the opening of the Equatorial Atlantic.

• Coeval deposits of sandstones and mudstones

Conceptual late Albian paleogeography of Nigeria (Edegbai et al., 2019)

Mid-Albian – Cenomanian

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• Total flooding of the following the establishment of the Trans-Saharan seaway

• Deposition of coeval limestones, mudstones and sandstones

Conceptual early Turonian paleogeography of Nigeria (Edegbai et al., 2019)

Cenomanian - Coniacian

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Change in stress regime in the Santonian led to inversion characterized by folding, faulting, uplift and magmatism due to:• Differential spreading rates of the Central Atlantic (slower) and

South Atlantic (faster)• Africa and Europe plate interactions (collision)

Santonian CompressionSantonianPre- Santonian

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• Renewed sedimentation following thermal induced subsidence

• Deposition of coeval, mudstones, ironstones, sandstones and coal

Conceptual late Albian paleogeography of Nigeria (Edegbai et al., 2019). 9

Campanian-Maastrichtian

10Latest Cenomanian to Paleocene stratigraphic chart of Nigeria (Edegbai et al., 2019)

My research• Investigate the upper Cretaceous flooding

episodes. – Controls on rates sedimentation – Decipher the prevailing paleo-oceanographic

conditions– Sedimentary provenance– Sedimentary and organic facies distribution

• Findings are targeted at hydrocarbon and mineral resource exploration

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Campanian -Maastrichtian(Outcrop)

Turonian -ConiacianCampanian-Maastrichtian

Graphic Logs of outcrops

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L1L3

L2 & L3

L1 & L2

L3L1 & L2L3L1

L4

L5 & L6L6

Bay-Barrier/ Beach

Bay

Fluvial – Tidal channel

L5 & L6

L1 & L2

L6

L6L5L1 & L2L6

Fluvial – Tidal channel

Central basin

Marsh -Fluvial – Tidal

channel

Central basinFluvial – Tidal

channel

OkpekpeImiegba

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Paleoclimate, Provenance and Paleotectonics

Humid Maastrichtian paleoclimate (Chumakov et al. in Hay and Floegel, 2012) confirmed by Dominance of

Kaolinite, high CIA and low ICV

Note: CIA and ICV are different for pre-Santonian units

Dominance of HFSTE = felsic provenance

• Dominance of phytoclasts suggest oxic bottom waters

• Pyritization reveals the existence of anoxic zone below the sediment-water interface

Organic facies and paleoredox determination

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Upper CretaceousResource Potential

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Hydrocarbon potentialPre-Santonian strata

Basin location Parameters

Sokoto Basin

Chad Basin

Northern Benue Trough

Central Benue Trough

Southern Benue Trough

Anambra Basin

Bida Basin

Benin Basin

Organic richness

No data

Fair to excellent (coal)

Fair to excellent (coaly unit)

No data

Fair to good

Source quality

No data Marine source (Type III-IV)

Lower marine source unit (Type III/IV); and subordinate upper coaly source unit (Type III/II)

No data Type II/III (marine source)

Thermal maturity

No data Immature to late mature

Mature to post-mature No data Early mature

Comments Predominantly of higher thermal maturity (due in part to volcanism) marine rocks. We note here that the heavy oil within oil seeps and tar sand deposits (Eze-Aku and Awgu groups, and Bima and Afowo formations) is sourced these dominantly marine source units

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Hydrocarbon potentialPost-Santonian strata


Sokoto Basin

Chad Basin

Northern Benue Trough (Gongola sub-basin)



Anambra Basin

Bida Basin

Benin Basin

Organic richness

No data Fair to excellent (coal)

No source potential



Good to excellent

Source quality

No data (Type III-IV) Type III/II

Type III Type II (marine source)

Thermal maturity

No data Immature to early mature

Immature to early mature

Immature Early mature

Comments Predominantly low thermal maturity marginal marine sediments predorminantly with gas prone hydrocarbon potential

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Mineral resource Pre-Santonian strata


Sokoto Basin

Chad Basin




Anambra Basin

Bida Basin

Benin Basin

Limestone

Economically viable limestone units across the Benue Trough. The Nkalagu, Yandev and Ashaka

limestone deposits are good examples

Ironstone Pockets of sub-economic deposits

Coal Pockets of coal deposits Groundwater Mostly aquicludes, except in a few areas where

permeable sand units occur. Good sand

aquifer Comments Higher sea level favored the formation of huge Limestone reserves and widespread

aquicludes.

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Mineral resource Post-Santonian strata


Sokoto Basin

Chad Basin




Anambra Basin

Bida Basin

Benin Basin

Limestone Sub-economic deposits

Sub-economic deposits


Ironstone Sub-economic deposits



Huge reserves

Coal Sub-economic deposits

Sub-economic deposits Huge reserves



Groundwater Good aquifers. Good sand aquifers. aquicludeComments Lower sea level favored the deposition of widespread coal, ironstone deposits and good

sand aquifers.

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Thank You

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