Skip to main content Accessibility help
×
Home

Petrography, mineralogy and diagenesis of overpressured Tertiary and Late Cretaceous mudrocks from the East Shetland Basin

  • J. M. Huggett (a1)

Abstract

The petrography, mineralogy and diagenesis of an overpressured Tertiary and Late Cretaceous mudrock sequence from a single well in the East Shetland Basin (North Sea) are described. The clay fraction is believed to be dominated by volcanic glass above 1400 m depth and by smectite below 1400 m. The smectite content increases with depth due to an increase in detrital smectite and to in situ alteration of volcanic glass and grains; this commenced almost immediately after deposition and is still not complete at burial depths >2300 m. There is little evidence of alteration of the smectite to illite despite a local available supply of K+ in the form of K-feldspar and the presence of K in the more deeply buried smectite. Very little leaching or precipitation of quartz has occurred. Microfossil tests filled with authigenic clays such as have been reported in other Tertiary mudrocks in the North Sea were not observed, though a few fossil cavities are filled with carbonate cements, and very rarely with microquartz. The suprisingly limited reactivity of this mudrock sequence may be due to the early development of overpressure, resulting in a “closed” system, and to the absence of interbedded higher permeability layers or open faults through which fluids could be exchanged.

Copyright

References

Hide All
Berggren, W.A. (1972) A Cenozoic time-scale—some implications for regional geology and palaeobiogeography. Lethia, 5, 195–215.
Boles, J.R. & Franks, S.G. (1979) Clay diagenesis in Wilcox sandstonesof southwest Texas. 7. Sed. Pet., 49, 55–;70.
Bruce, C.H. (1984) Smectite dehydration—its relation to structural development and hydrocarbon accumulation in the Northern Gulf of Mexico Basin. Bull Am. Assoc. Petrol. Geol., 68, 673–683.
Chamley, H. (1989) Clay Sedimentology. Spring-Verlag, Berlin.
Curtis, C.D. (1983) Link between aluminium mobility and destruction of secondary porosity. Bull. Am. Assoc. Petrol. Geol., 67, 380–393.
Curtis, C.D. (1985) Geochemistry of porosity enhancement and reduction in clastic sediments. Bull. Trans. R. Soc. A 315, 113–;125.
Curtis, C.D. (1987) Mineralogical consequence of organic matter degradation in sediments: inorganic/organic diagenesis. Pp. 108–;123 in: Marine Clastic Sedimentology (Leggett, J.K. & Zuffa, G.G, editors). Graham & Trotman, London.
Deyu, Z. (1987) Clay mineralogy of the Upper Palaeocene clay sediments in Denmark. Bull. Geol. Soc. Denmark,, 36, 249–258.
Freed, R.L. (1981) Shale mineralogy and burial diagenesis of the Frio and Vicksburg Formations in two geopressured wells, McAllen Ranch area, Hidalgo County, Texas. Trans. Gulf Coast Assoc. Geol. Soc., 31, 189–293.
Hopkinson, J.P. & Nysaether, E. (1974) North Sea petroleum geology. Offshore North Sea Technology Conf., Stravanger,, 1-33.
Huggett, J.M. & Shaw, H.F. (1992) Diagenesis of Jurassic mudrocks of the North Sea. Mineralogical Society, Spec. Publ.(in press).
Huggett, J.M. (1992) Diagenesis of Tertiary and Late Cretaceous overpressured mudrocks for the East Shetland Basin. Clay Minerals Soc. Spec. Vol.(in press).
Jacque, M. & Thouvennin, J. (1975) Lower Tertiary tuffs and volcanic activity on the North Sea. Pp. 455-465 in: Petroleum and the Continental Shelf of North-West Europe. Geology, 1 (Woodland, A.W., editor). Applied Science Publishers, London.
Jezek, P.A.& Noble, D.C. (1978) Natural and ion exchange of obsidian: an electron microprobe study. Am. Miner., 63, 266–273.
Karlsson, W., Vollset, J., Bj0rlykke, K. & J0rgensen, P.(1979) Changes in mineralogical composition of Tertiary sediments from North Sea wells. Proc. Int. Clay Conf., Oxford,, 281-289.
King, C. (1981) Stratigraphy of the London Clay and Associated Deposits. Backhuys, Rotterdam.
Knox, R.W. O'B. & Ellison, R.A. (1979) A lower Eocene glass sequence in SE England. Proc. Geol. Soc. Lond., 136, 251–253.
Knox, R.W. O'B. & Morton, A.C. (1983) Stratigraphical distribution of early Palaeogene pyrodastics in the North Sea basin. Proc. Yorks. Geol. Soc., 25, 355–363.
Knox, R.W.O'B. & Morton, A.C. (1988) The record of early Tertiary N Atlantic volcanism in sediments of the North Sea Basin. Pp. 407^419 in: Early Tertiary Volcanism and the Opening of the NE Atlantic(Morton, A.C. & Parson, L.M., editors). Blackwell, Oxford.
Malm, O.A., Bruun Christensen, O., Furnes, H., Løvlie, R. & Rueslatten, H. (1984) The Tertiary Balder Formation: and organogenetic and tuffaceous deposit in the North Sea region. Pp. 149–;170 in: Petroleum Geology of the North European Margin(Spencer, A.M., editor). Graham & Trotman, London.
Murata, K.J. & Larson, R.R. (1975) Diagenesis of Miocene Siliceous shales, Temblor Range, California. U.S. Geol. Surv. J. Res., 3, 553–566.
Nielsen, O.B. (1974) Sedimentation and diagenesis of lower Eocene sediments at Olst, Denmark. Sed. Geol., 12, 25–44.
Nielsen, O.B. & Heilmann-Clausen, C. (1988) Palaeogene volcanism: the sedimentary record in Denmark. Pp. 395–;405 in: Early Tertiary Volcanism and the Opening of the NE Atlantic(Morton, A.C. & Parson, L.M., editors). Blackwell, Oxford.
Pearson, M.J. (1990) Clay mineral distribution and provenance in Mesozoic and Tertiary mudrocks of the Moray Firth and Northern North Sea. Clay Miner., 25, 519–542.
Primmer, T.J. & Shaw, H.F. (1987) Diagenesis in shales: evidence from back-scattered electron microscopy and electron microprobe analyses. Proc. Int. Clay Conf, Denver,, 135–;143.
Pollastro, R.M. (1990) The illite/smectite geothermometer—concepts, methodology and application to basin history and hydrocarbon generation. Pp. 1–;18 in: Applications of Thermal Maturity Studies to Energy Exploration(Nuccio, V.F. & Barker, C.E., editors). Rocky Mountain Section, SEPM, Denver.
Shaw, H.F. (1972) The preparation of orientated clay mineral specimens for X-ray diffraction analysis by a suction- onto-ceramic-tile method. Clay Miner., 9, 349–350.
Schultz, L.G. (1964) Quantitative interpretation of mineralogical composition from X-ray and chemical data for the Pierre Shale. U.S. Geol. Surv. Prof. Paper 371-Cy, 31pp.
Środoń, J. (1980) Precise identification of illite/smectite interstratifications by X-ray powder diffraction. Clays Clav, 28, 401–;411
Tardy, T. & Touret, O. (1987) Hydration energies of smectites: a model for glauconite, illite and corrensite formation. Proc. Int. Clay Conf. Denver,, 46–;52.
Velde, B. (1977) Clays and Clay Minerals in Natural and Synthetic Systems. Elsevier, Amsterdam.
Velde, B. (1985) Clay Minerals: a Physico-Chemical Explanation of their Occurrence. Elsevier, Amsterdam.
Velde, B., Suzuki, T. & Nicot, E. (1986) Pressure-temperature-composition of illite/smectite mixed layer minerals— Niger Delta mudstones and other examples. Clays Clay Miner., 34, 435–441.
Wensaas, L., Shaw, H.F., Gibbons, K., Agaard, P. & Dypvik, H. (1989) Clay mineral diagenesis in overpressured sequence of mudrocks for the Gullfaks Field, Northern North Sea. Abstract Int. Clay Conf. Strasbourg.
Yau Y-C., Peacor, D.R. & McDowell, S.D. (1987) Smectite-to-illite reactions in Salton Sea shales: a transmission and analytical electron microscopy study. J.Sed. Pet. 51-,, 335-342.
Ziegler, W.H. (1975) Outline of the geological history of the North Sea. In: Petroleum and the Continental Shelf of North-West Europe(Woodland, A.W., editor). Applied Science Pubishers, London.

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed