Geochemical evidence for a Cretaceous oil sand (Bima oil sand) in the Chad Basin, Nigeria

Bata, Timothy; Parnell, John; Samaila, Nuhu K.; Abubakar, M.; Maigari, Abubakar Sadiq

doi:10.1016/j.jafrearsci.2015.07.026

Cited by 22 publications

(5 citation statements)

References 38 publications

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“…Closely associated with Pangea's breakup and the subsequent disintegration of continents are a series of volcanic activities that emitted large volumes of CO 2 into the atmosphere (Larson, 1991). It is estimated that during the Cretaceous, the global atmospheric level of CO 2 was significantly higher than that at present (Berner and Kothavala, 2001;Bice and Norris, 2002;Bice et al, 2003;Bata et al, 2015). As the Earth's surface temperature is significantly affected by greenhouse gases (mainly CO 2 ), the enhanced tectonic activity during the Cretaceous, which emitted large quantities of CO 2 into the atmosphere, resulted in a corresponding rise in global temperatures, leading to a greenhouse climatic condition in the Cretaceous (Huber et al, 2002;Jenkyns et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

Evidences of Widespread Cretaceous Deep Weathering and Its Consequences: A Review

Bata¹

2016

ESR

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This study highlights the effect of the Cretaceous greenhouse climate on weathering processes. Atmospheric CO2 level was relatively higher in the Cretaceous than it was in both the Jurassic and the Cenozoic. Consequently, temperature and humidity were higher in the Cretaceous than in the Jurassic and the Cenozoic. The interaction among the high levels of atmospheric CO2, extreme global warmth, and humidity in the Cretaceous resulted in widespread deep weathering. Cretaceous palaeo-weathering profiles are observed to occur at higher palaeolatitudes relative to the Jurassic and Cenozoic palaeo-weathering profiles. This implies the upward warming of the Cretaceous palaeolatitude, consistent with palaeotemperature estimates for the Cretaceous. The present thickness of weathering profiles in some selected tropical zones is approximately 200 m. During the greenhouse climatic condition in the Cretaceous, the thickness of weathering profiles at those areas could have been up to 4–5 times the present value. This suggests that many sediments were produced from the Cretaceous weathering events.

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Section: Discussionmentioning

confidence: 99%

Evidences of Widespread Cretaceous Deep Weathering and Its Consequences: A Review

Bata¹

2016

ESR

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“…The TICs show the presence of unresolved complex mixture (UCM) humps. This is a common characteristic of oils that have undergone biodegradation [31][32][33]7,19,2]. TIC fragmentograms of oils extracted from the studied oil sands showing progressive depletion of chromatographically resolved hydrocarbons (e.g.…”

Section: Oil Geochemistry (Evidence Of Biodegradation)mentioning

confidence: 96%

“…The heavy oils associated with these Cretaceous oil sands were generated as conventional light oils which later degraded into heavy oils by means of biodegradation and water washing [19,2,20]. An important geological factor controlling the widespread occurrence of these Cretaceous oil sands is the prevalence of Cretaceous reservoir sands with good reservoir capabilities.…”

Section: Introductionmentioning

confidence: 99%

Common Occurrences of Authigenic Pyrite Crystals in Cretaceous Oil Sands as Consequence of Biodegradation Processes

Bata¹,

Samaila²,

Maigari³

et al. 2017

Geol. behav.

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Ten (10) Cretaceous oil sands from different localities around the world were studied with the aim of reporting the common occurrence of authigenic pyrite crystals in them. The observed pyrite crystals (both framboid and euhedral) are restricted to the pore spaces of the studied oil sands, in close association with biodegraded oils and other authigenic minerals. Diagenetic processes in one of the studied samples triggered the transformation of framboidal pyrite crystals to octahedral pyrite crystals. This study demonstrates that geological conditions/ processes that lead to the formation of authigenic pyrite crystals in sandstones are those that favour biodegradation. Potentially, these conditions include occurrence at shallow depths (< 2000 m), moderate reservoir temperatures that can support microbial life (temperature < 80° C), availability of micro-organisms that are capable of degrading oils in the reservoir, nutrient availability (e.g., iron, nitrogen, potassium, and phosphorus), and oil volume in the reservoir. Studied framboidal pyrite crystals were observed to occur within confined spaces. The oils (organic matter) associated with the studied samples are believed to have played an important role of providing the source of spherule moulds for framboid pseudomorphs and aided the stabilization of the gel in which the framboid crystals were protected. TIC fragmentograms of the saturate fractions of the oils extracted from the studied oil sands show progressive depletion of chromatographically resolved hydrocarbons (e.g. n-alkanes, acyclic isoprenoid alkanes; alkyl benzenes, naphthalenes and phenanthrenes) relative to the unresolved hydrocarbon mixture, forming unresolved complex mixture (UCM) humps, consistent with oils that have undergone biodegradation.

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“…Late Jurassic silcretes have been reported in Australia, South Africa, France, Canada and Brazil (Al-Ramadan et al, 2005;Du Toit and Reed 1954;Krausse and Mello, 2010;Laity, 2009;Pierini et al, 2010;Twidale and Campbell, 1995;Wopfner, 1978). The Earth continued to warm during the Cretaceous, with average global surface temperature peaking at ~28°C in the mid-Cretaceous (Scotese, 2001;Skelton, 2003;Veizer et al, 2000;Wang et al, 2014;Bata et al, 2015). This resulted in a dramatic increase (of ~100%) in quartz solubility (from ~6 ppm in the Early Jurassic to ~12 ppm by the mid-Cretaceous).…”

Section: Jurassic To Cenozoic Silcrete Depositsmentioning

confidence: 99%

Widespread Development of Silcrete in the Cretaceous and Evolution of the Poaceae Family of Grass Plants

Bata¹

2016

ESR

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The Cretaceous period, which is considered one of the most remarkable periods in Earth's history, saw episodes of abrupt greenhouse warming and cooling. The Cretaceous was also exceptional in that it was associated with the widespread occurrence of silcrete. To demonstrate this, the present study collated records of silcrete occurrences from the Jurassic to the present and compared them with records of variation in palaeotemperature and atmospheric CO 2 levels. Quartz solubility, which is one of the key factors that controls the rate of silcrete development, was also calculated over the same period. The results demonstrate that a marked increase (approximately 100%) in quartz solubility occurred during the Cretaceous. This was found to be a direct consequence of the extreme global warmth witnessed at that time. Furthermore, this study shows that silcrete occurrences are consistent with records of palaeotemperature and that silcretes have formed mostly in regions that have experienced warm climatic conditions, with no instances found in polar regions. The Poaceae family of grass plants are known to have evolved and diversified during the Cretaceous, which coincide with the period when silica was readily available. X-ray spectra and backscattered images from SEM examination of the internal structure of a modern wild grass (which belongs to the Poaceae family of grass plants) reveals that silica is an important constituent of the grass. This suggest a possible link between evolution of the Poaceae family in the Cretaceous and the high availability of silica during the Cretaceous.

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Geochemical evidence for a Cretaceous oil sand (Bima oil sand) in the Chad Basin, Nigeria

Cited by 22 publications

References 38 publications

Evidences of Widespread Cretaceous Deep Weathering and Its Consequences: A Review

Evidences of Widespread Cretaceous Deep Weathering and Its Consequences: A Review

Common Occurrences of Authigenic Pyrite Crystals in Cretaceous Oil Sands as Consequence of Biodegradation Processes

Widespread Development of Silcrete in the Cretaceous and Evolution of the Poaceae Family of Grass Plants

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