Palynozones and Palaeoenvironments of Gongila Formation, Bornu Basin , Northeastern Nigeria
Palynozones and Palaeoenvironments of Gongila Formation, Bornu Basin , Northeastern Nigeria.
OGUNYEMI, O. Oluyemi* Department of Geology, University of Ibadan , Ibadan - Nigeria.
Palynological and sedimentological analysis have been carried out on ditch cutting samples from T-1 well located along the NE-SW transect of the Bornu Basin. Palynological analysis of twenty composite samples representing intervals 2285 – 2890m resulted in the identification of 66 pollens, spores, dinoflagellate cyst and algae. The stratigraphic distribution of these palynomorphs was used to establish three palynozones which are Hexaporotricolpites emelianovi zone, Triorites africaensis zone and Cretacaeiporites scrabratus acme zone. Hexaporotricolpites emelianovi zone ranges from Upper Cenomanian to Lowermost Turonian and corresponds to depth 2465 – 2890m. Triorites africaensis zone dated Lowermost Turonian marks the intervals 2375 – 2465m while Cretacaeiporites scrabratus acme zone of Turonian age is within the depth of 2285 – 2375m.
Four hundred and ninety-five samples from intervals 50 – 3620m were subjected to sedimentological analysis. The samples constitute mudrock, sandstone, shale, shaly sand, sandy shale and carbonate. The intervals 355 – 720m is composed of mudrock with intercalated sandstone. Interbeds of carbonaceous shale and sandy shale were recorded at depth 720 – 1465m. Shaly sand and mudrock characterize depth 2950 – 3620m while 50 – 295m, 295 – 355m and 2005 – 2950m are predominantly mudrock, sandstone and shale respectively. Colour varies from light to dark brown (mudrock), milky to pinkish brown (sandstone), light to dark grey (shale) and whitish to light grey (carbonate) respectively.
The stratigraphic evolution and distribution of these palynomorphs within the established lithofacies were used to reconstruct the palaeoenvironments of Gongila Formation as fluvial – estuarine ( Hexaporotricolpites emelianovi zone), estuarine (Triorites africaensis zone) and estuarine – fluvial ( Cretacaeiporites scrabratus acme zone).
OGUNYEMI OLUYEMI
Dept. Of Geology,
University of Ibadan
Box 19311,
Ibadan,
Oyo State,
Nigeria.
234-8056259633
ogunyemi@gmail.com
OGUNYEMI, O. Oluyemi* Department of Geology, University of Ibadan , Ibadan - Nigeria.
Palynological and sedimentological analysis have been carried out on ditch cutting samples from T-1 well located along the NE-SW transect of the Bornu Basin. Palynological analysis of twenty composite samples representing intervals 2285 – 2890m resulted in the identification of 66 pollens, spores, dinoflagellate cyst and algae. The stratigraphic distribution of these palynomorphs was used to establish three palynozones which are Hexaporotricolpites emelianovi zone, Triorites africaensis zone and Cretacaeiporites scrabratus acme zone. Hexaporotricolpites emelianovi zone ranges from Upper Cenomanian to Lowermost Turonian and corresponds to depth 2465 – 2890m. Triorites africaensis zone dated Lowermost Turonian marks the intervals 2375 – 2465m while Cretacaeiporites scrabratus acme zone of Turonian age is within the depth of 2285 – 2375m.
Four hundred and ninety-five samples from intervals 50 – 3620m were subjected to sedimentological analysis. The samples constitute mudrock, sandstone, shale, shaly sand, sandy shale and carbonate. The intervals 355 – 720m is composed of mudrock with intercalated sandstone. Interbeds of carbonaceous shale and sandy shale were recorded at depth 720 – 1465m. Shaly sand and mudrock characterize depth 2950 – 3620m while 50 – 295m, 295 – 355m and 2005 – 2950m are predominantly mudrock, sandstone and shale respectively. Colour varies from light to dark brown (mudrock), milky to pinkish brown (sandstone), light to dark grey (shale) and whitish to light grey (carbonate) respectively.
The stratigraphic evolution and distribution of these palynomorphs within the established lithofacies were used to reconstruct the palaeoenvironments of Gongila Formation as fluvial – estuarine ( Hexaporotricolpites emelianovi zone), estuarine (Triorites africaensis zone) and estuarine – fluvial ( Cretacaeiporites scrabratus acme zone).
OGUNYEMI OLUYEMI
Dept. Of Geology,
University of Ibadan
Box 19311,
Ibadan,
Oyo State,
Nigeria.
234-8056259633
ogunyemi@gmail.com
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