scholarly journals Late Miocene–Early Pliocene planktic foraminiferal biostratigraphy of deep offshore southwestern Niger Delta

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Bamidele Adeniyi Adebambo ◽  
Suyi Lawrence Fadiya
Keyword(s):  
Late Miocene ◽  
Niger Delta ◽  
Early Pliocene ◽  
Foraminiferal Species ◽  
Processing Techniques ◽  
Foraminiferal Biostratigraphy

AbstractThe planktic foraminiferal biostratigraphy of the deep offshore southwestern Niger Delta has been studied from three wells (DPW-1, DPW-2 and DPW-3). A total of 418 ditch cutting samples (104 samples from DPW-1, 165 from DPW-2 and 149 from DPW-3) taken at 18-m intervals were subjected to standard micropaleontological processing techniques. In total, 42, 52 and 40 planktic foraminiferal species were identified from DPW-1, DPW-2 and DPW-3, respectively. The identified planktic species allow the delineation of the studied section into four biozones—Globorotalia acostaensis (N16), Globigerinoides obliquus extremus/Globorotalia merotumida (N17), Globorotalia margaritae primitiva (N18) and Globorotalia margaritae evoluta/Globigerina nepenthes (N19) zones, based on the first appearance datums (FADs), last appearance datums (LADs) of the nominate taxa and associated assemblages. The well sections dated Late Miocene to Early Pliocene based on the occurrence of certain diagnostic planktic foraminiferal datums such as FADs Globorotalia acostaensis, Globigerinoides obliquus extremus, Globorotalia merotumida/plesiotumida, Globorotalia margaritae primitiva and the LADs Globigerina nepenthes, Globorotalia margaritae primitiva and Globorotalia margaritae evoluta. The Miocene/Pliocene boundary was placed at the FAD Globorotalia margaritae primitiva. In the Niger Delta, this boundary is commonly placed at the FADs Globorotalia margaritae margaritae and Globorotalia crassaformis probably due to nonrecovery of Globorotalia margaritae primitiva. However, in this studied section of the deep offshore southwestern Niger Delta, FAD Globorotalia margaritae primitiva occurs consistently in the three study wells and is therefore considered an appropriate datum for the placement of the Miocene/Pliocene boundary.

scholarly journals High-Resolution Biostratigraphic Studies of Step-1 Well, Offshore, Western Niger Delta

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
M. E. Nton ◽  
S. O. Famori
Keyword(s):  
High Resolution ◽  
Late Miocene ◽  
Niger Delta ◽  
Calcareous Nannofossils ◽  
Early Pliocene ◽  
Sequence Stratigraphic ◽  
Foraminiferal Species ◽  
Stratigraphic Model ◽  
Niger Delta Basin ◽  
Preparation Techniques

Abstract A high-resolution biostratigraphic study of the STEP-1 well, offshore Western Niger Delta Basin, Nigeria, was carried out using foraminifera, calcareous nannofossils and palynomorphs. The study was aimed at identifying the biostratigraphic zones, age deductions as well as palaeoenvironmental and palaeoclimatic reconstructions. From the studied well section of 609 m (1,829–2,438 m), 50 ditch cuttings were used for foraminifera and calcareous nannofossils, while 25 samples were used for palynological studies at 12 m and 24 m intervals, respectively. Standard laboratory preparation techniques were employed for the three microfossil groups. Due to the occurrence of some forms such as Globigerina praebulloides, Haplophragmoides spp, Bolivina scalprata miocenica, Valvulina flexilis and Cyclammina cf. minima, two planktonic and one benthonic foraminifera zones were identified as follows: Lower N18, Upper N17 zone (early Pliocene, late Pliocene) and Cyclammina minima zone (late Miocene), respectively. Two biozones were recognized for the nannofossils and include NN12 (Ceratolithus cristatus zone) and NN11 (Discoaster berggrenii zone). These zones were assigned to early Pliocene and late Miocene, respectively. Other forms include Discoaster pentaradiatus, Sphenolithus abies and Ceratolithus armatus. Echitricolporites spinosus/P800zone has been assigned for the Palynomorph assemblages and was dated late Miocene due to the quantitative occurrence of Cyperaceaepollis spp. Four identified major condensed sections include intervals at 1,926, 1,987, 2,097 and 2,316 m, which have been dated 5.0, 5.8, 6.3 and 7.0 Ma, respectively. Based on the benthonic foraminiferal species and Palynological Marine Index, a shallow marine environment is deduced for the studied interval which was interpreted to be deposited under both wet and dry palaeoclimatic conditions. The findings, no doubt could serve as a template for a sequence stratigraphic model, generally beyond the resolution of seismic stratigraphy.

scholarly journals Foraminifera biostratigraphy and paleoenvironmental studies of well-x, eastern Niger delta

2021 ◽  
Vol 9 (1) ◽  
pp. 28
Author(s):  
Samuel Ibukunoluwa Adeola ◽  
John Adewole Adeola ◽  
Victoria Abiola Dairo
Keyword(s):  
Marine Environment ◽  
Late Miocene ◽  
Niger Delta ◽  
Middle Miocene ◽  
Shallow Marine ◽  
Shallow Marine Environment ◽  
Foraminiferal Species ◽  
Neogloboquadrina Dutertrei

Ditch cutting samples from Well-X drilled in the Eastern part of the Niger delta were subjected to biostratigraphy and paleoenvironmental studies using micropaleontological analysis to identify the foraminifera present in the sections penetrated by the well.A total of 50 (fifty) foraminifera species made up of benthonic and planktic spp were recovered from the sections. The marker species identified are Globorotalia acostaensis, Globorotalia mernadii cultrate, Neogloboquadrina dutertrei, Globorotalia plesiotumida, Globorotalia obesa, Globorotalia nepenthes, Sphaeroidinella subdehiscens, Neogloboquadrina dutertrei, Globigerinoides sudquadratus.The four (4) biozones identified are N16 (Late Miocene 9.5Ma - 10.9Ma), N15-N14, N13-N12 and N12-N11 (Middle Miocene with corresponding ages 10.9Ma -11.8Ma, 11.8Ma-12.2Ma and 12.2Ma respectively).Using the encountered benthonic foraminiferal species, the paleoecology was determined; and it was revealed that the paleoenvironment of the section ranges from Inner Neritic to Outer Neritic Environment. Also, the lithological analysis revealed an intercalation of Shale, Mudstone and Sand which indicates various paleoecological episodes that led to their deposition.The age of the well was inferred from the bioevents of the marker species to be Middle Miocene to Late Miocene with the sparse occurrence of the Calcareous Benthic and the Plankonic species suggesting a shallow marine environment.   

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