Diagenesis and Mass Transfer Between Permo-Triassic Sandstones and Interbedded Mudstones, Ulster Basin

Ahmed, Wolela

doi:10.4314/bcse.v16i1.20946

Cited by 8 publications

(12 citation statements)

References 16 publications

(36 reference statements)

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“…Mechanically compacted mudstone and siltstone of the Mercia mudstone group expelled large volume of mineralised pore water, which migrated into the Permo-Triassic sandstones. The free movement of the formation water along the bedding planes helped to expel mineralised water from the silty, muddy and shaly facies into the sandstone-rich section of the basin [31,32]. In hot arid and semi-arid climates where evaporation is greater than precipitation, high pH, high retention of Mg 2+ , Ca 2+ and Na + and high Si:Al ratio favour the authignesis of smectite [38,39].…”

Section: Discussionmentioning

confidence: 99%

“…Considering a geothermal gradient of 30 °C/km [34], the sediment reached a temperature of nearly 90 °C, which initiated the conversion of smectite and mixed-layer illite-smectite into illite. Smectite and illite-smectite become unstable between 60 and 100 °C, when they will be transformed into illite [32].…”

Section: Discussionmentioning

confidence: 99%

“…The presence of chlorite in the Cultra samples is related to the Tertiary diabasic sills and dikes that intruded the Permo-Triassic sandstones. The magnesium and iron for the authignesis of chlorite possibly derived from volcanic intrusions and hydrothermal fluids [32].…”

Section: Discussionmentioning

confidence: 99%

“…Core samples confirmed the presence of chlorite cements in deep burial. The dissolution of carbonate cements and unstable grains, volcanic and hydrothermal activities might have instigated precipitation of chlorite during the late diagenetic environment [4,32].…”

Section: Diagenesis Of the Permo-triassic Sandstonesmentioning

confidence: 99%

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Contrast in clay mineralogy and their effect on reservoir properties in sandstone formations

Ahmed¹

2008

Bull. Chem. Soc. Eth.

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ABSTRACT. Adigrat sandstone formation in the Blue Nile Basin is dominated by quartz arenite and subarkosic arenite, and cemented by carbonate, clay minerals and quartz overgrowths. Clay minerals in the Adigrat sandstone formation are dominated by kaolinite, illite and chlorite. Illite is the common grain-coating clay mineral. The common pore-filling minerals are kaolinite, illite and chlorite. The formation reaches a depth of 3 km, which facilitated the change of kaolinite to illite. Clay minerals are the major reducer of porosity and permeability in the Adigrat sandstone formation.The Permo-Triassic sandstones in the Ulster Basin were deposited in NE-SW trending fault-bounded asymmetrical graben. The Permo-Triassic sandstones reaches a burial depth of 1/2 km in the marginal areas and 4.5 km in the basin center. The basin underwent multiple episodes of uplift and erosion in the Upper Jurassic, and Mid-Cretaceous, and uplift and inversion in the Upper Tertiary. The difference of the clay mineralogy in the Permo-Triassic in the Ulster Basin depends upon the depositional environments, source area geology and burial history of the basin. Illite-smectite is grain coating, whereas smectite, illite-smectite, smectite-chlorite, chlorite, illite and kaolinite are the common pore-filling clay minerals in the Permo-Triassic sandstones in the Ulster Basin. Clay minerals reduced the porosity and permeability of the Permo-Triassic sandstones.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Diagenesis Of the Permo-triassic Sandstonesmentioning

confidence: 99%

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Contrast in clay mineralogy and their effect on reservoir properties in sandstone formations

Ahmed¹

2008

Bull. Chem. Soc. Eth.

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“…The type of mineralized pore water released from the fine-grained sediments has a significant influence on the trends of sandstone diagenesis. Mechanically compacted mudstones, siltstones and shales expelled large volume of mineralized pore water, which might migrated into the sandstone-rich section [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Comparison of authigenic minerals in sandstones and interbedded mudstones, siltstones and shales, East Berlin formation, Hartford Basin, USA

Ahmed

2007

Bull. Chem. Soc. Eth.

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The East Berlin formation consists mainly of alternating sequences of fluviatile, lacustrine and playa sediments. Diagenetic sequences reconstruction revealed the same range of authigenic minerals in the studied sandstones and the interbedded fine-grained sediments (mudstones and siltstones). This indicates that the diagenetic processes that took place in the sandy facies also took place in fine-grained sediments. Mechanically infiltrated clays, graincoating clay/hematite, quartz and feldspar overgrowths, carbonate cements and pore-filling and pore-lining clay minerals that precipitated in the sandy facies also precipitated in the fine-grained sediments. The abundance of authigenic minerals in decreasing order include: sandstone > siltstone > mudstone > shale. Except minor amounts of authigenic illite-smectite and illite, the shaly facies dominated by detrital clay, carbonate, quartz and feldspars framework grains. Authigenic minerals such as quartz, albite and K-feldspar are absent in the shaly facies, possibly related to early destruction of porosity. The lacustrine sandstones, siltstones and mudstones followed marine diagenetic trend, whereas playa and fluviatile sandstones, siltstones and mudstones followed red bed diagenetic trend. Mechanically compacted mudstones, siltstones and shales expelled large volume of mineralized pore water, which might migrated into the sandstonerich section. Part of the ions for the precipitation of quartz overgrowths and carbonate cements in the sandy facies possibly contributed from the interbedded siltstones, mudstones and shales facies.

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Diagenetic contrast of sandstones in hydrocarbon prospective Mesozoic rift basins (Ethiopia, UK, USA)

Wolela

2014

Journal of African Earth Sciences

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Diagenesis and Mass Transfer Between Permo-Triassic Sandstones and Interbedded Mudstones, Ulster Basin

Cited by 8 publications

References 16 publications

<b>Contrast in clay mineralogy and their effect on reservoir properties in sandstone formations</b>

<b>Contrast in clay mineralogy and their effect on reservoir properties in sandstone formations</b>

<b>Comparison of authigenic minerals in sandstones and interbedded mudstones, siltstones and shales, East Berlin formation, Hartford Basin, USA</b>

Diagenetic contrast of sandstones in hydrocarbon prospective Mesozoic rift basins (Ethiopia, UK, USA)

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