Hostname: page-component-76fb5796d-r6qrq Total loading time: 0 Render date: 2024-04-26T23:28:40.880Z Has data issue: false hasContentIssue false
  • English
  • Français

Stable isotopes in illite: the case for meteoric water flushing within the Upper Jurassic Fulmar Formation sandstones, UK North Sea

Published online by Cambridge University Press:  09 July 2018

M. Wilkinson ,
A. E. Fallick ,
G. M. J. Keaney ,
R. S. Haszeldine  and
W. J. McHardy
M. Wilkinson
Affiliation:
Department of Geology and Applied Geology, Glasgow University, Glasgow G12 8QQ, UK
A. E. Fallick
Affiliation:
Isotope Geology Unit, Scottish Universities Research and Reactor Centre, East Kilbride G75 0QU, UK
G. M. J. Keaney
Affiliation:
Department of Geology and Applied Geology, Glasgow University, Glasgow G12 8QQ, UK
R. S. Haszeldine
Affiliation:
Department of Geology and Applied Geology, Glasgow University, Glasgow G12 8QQ, UK
W. J. McHardy
Affiliation:
Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen AB9 2QJ, UK
Get access Rights & Permissions [Opens in a new window]

Abstract

The extent to which the diagenesis of sedimentary sequences within the UK North Sea is influenced by the passage of meteoric water is subject of current debate. Petrographic (SEM, TEM, thinsection) observation and stable isotope ratios from authigenic illite separates are used to deduce the pore-fluid evolution of the Fulmar Formation within well 29/10-2 from the Central Graben, with emphasis on the past importance of meteoric water flushing.

Petrographic observation shows the illite to have two modes of occurrence (pore-filling and as pseudomorphs after feldspar). These can be equated with two authigenic crystal morphologies (plates and laths) observed by TEM within illite separates prepared for isotopic analysis. The laths are equated with late stage ‘hairy’ pore-filling illite, the plates with illite pseudomorphs after feldspar which are difficult to date petrographically.

The δD (−55 to −87‰ SMOW) and δ18O (12.4–14.6‰ SMOW) analyses can be interpreted in terms of a conventional hydrogen-oxygen cross-plot to indicate illite precipitation from pore-waters of meteoric origin at 50–60°C. However, these predicted precipitation temperatures are irreconcilable with the observed petrographic sequence. The hydrogen isotope compositions may have undergone resetting during burial. Consequently, only the δ18O data may be confidently interpreted in terms of the conditions of illite precipitation. This implies illite growth at temperatures above 80°C from waters with δ18O between −2.5 and +6‰ SMOW, leaving the case for meteoric water flushing of the sandstones unproven.

Type
Research Article
Information
Clay Minerals , Volume 29 , Issue 4 , October 1994 , pp. 567 - 574
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1994

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Aplin, A.C., Warren, E.A. & Grant, S.M. (1994) Mechanism of quartz cementation in North Sea reservoir sands: constraints from fluid compositions. Bull. A.A.P.G. (submitted)Google Scholar
Bjørlykke, K., Aagaaro, P., Dypvik, H., Hastings, D.S. & Harper, A.S. (1986) Diagenesis and reservoir properties of Jurassic sandstones from the Haltenbanken area, offshore Mid-Norway. Pp. 275-386 in: Habit of Hydrocarbons on the Norwegian Continental Shelf (Spencer, A.M., editor). Norwegian Petroleum Society, Graham & Trotman, London.Google Scholar
Bjørkum, P.A. & Gjelsvik, N. (1988) An isochemical model for formation of authigenic kaolinite, K-feldspar, and illite in sediments. J. Sed. Pet. 58, 506–511.Google Scholar
Burlev, S.D. & Macquaker, J.H.S. (1992) Authigenic clays, diagenetic sequences and conceptual diagenetic models in contrasting basin-margin and basin-centre North Sea Jurassic sandstones and mudstones. Pp. 81- 110 in: Origin, Diagenesis and Petrophysics of Clay Minerals in Sandstones (Houseknecht, D.W. & Pittman, E.D., editors). SEPM Spec. PuN. 47, Tulsa, USA.Google Scholar
Burley, S.D., Mullis, J. & Matter, A. (1989) Timing diagenesis in the Tartan Reservoir (North Sea): constraints from combined cathodoluminescence microscopy and fluid inclusion studies. Mar. Petrol. Geol., 6, 98–120.CrossRefGoogle Scholar
Clelland, W.D., Kantorowicz, J.D. & Fens, T.W. (1993) Quantitative analysis of pore structure and its effects on reservoir behaviour: Upper Jurassic Ribble Member sandstones, Fulmar Field, UK North Sea. Pp. 57-79 in: Advances in Reservoir Geology. (Ashton, M., editor). Geol. Soc. Spec. Pun. 69, London.Google Scholar
Ehrenberg, S.N. & Naoeau, P.H. (1989) Formation of diagenetic illite in sandstones of the Garn Formation, Haltenbanken Area, mid-Norwegian Continental Shelf. Clay Miner. 24, 233–253.Google Scholar
Fallick, A.E., Haszeldine, R.S. & Pearson, M.J. (1993a) Overview of clay mineral stable isotope (6180, r systematics in the Northern North Sea. Abstract: Diagenesis, Overpressure and Reservoir Quality, Mineralogical Society (Clay Minerals Group) Meeting, Cambridge, 1993, p. 26.Google Scholar
Fallick, A.E., Macaulay, C.I. & Haszeldine, R.S. (1993b) Implications of linearly correlated oxygen and hydrogen isotopic compositions for kaolinite and illite in the Magnus Sandstone, North Sea. Clays Clay Miner. 41, 184–190.Google Scholar
Glasmann, J.R., Lundegard, P.D., Clark, R.A., Penny, B.K. & Collins, I.D. (1989) Geochemical evidence for the history of diagenesis and fluid migration: Brent Sandstone, Heather Field, North Sea. Clay Miner. 24, 255–284.Google Scholar
Hamilton, P.J., Fallick, A.E., Macintvre, R.M., & Elliot, S. (1987) Isotopic tracing of the provenance and diagenesis of Lower Brent Group Sandstones, North Sea. Pp. 939-949 in: Petroleum Geology of North West Europe (Brooks, J. & Glennie, K., editors). Graham & Trotman, London.Google Scholar
Hamilton, P.J., Kelly, S. & Fallick, A.E. (1989) K-Ar dating of illite in hydrocarbon reservoirs. Clay Miner. 24, 215–232.CrossRefGoogle Scholar
Haszeldine, R.S., Brint, J.F., Fallick, A.E., Hamilton, P.J. & Brown, S. (1992) Open and restricted hydrologies in Brent Group diagenesis: North Sea. Pp. 401-419 in: Geology of the Brent Group (Morton, A.C., Haszeldine, R.S., Giles, M.R. & S. Brown, editors). Geological Society Special Publication 61, London.Google Scholar
Knauth, L.P. & Epstein, S. (1976) Hydrogen and oxygen isotope ratios in nodular and bedded cherts. Geochim. Cosmochim. Acta, 40, 1095–1108.CrossRefGoogle Scholar
Longsraffe, F.J. & Ayalon, A. (1990) Hydrogen-isotope geochemistry of diagenetic clay minerals from Cretaceous sandstones, Alberta: evidence for exchange. Appl. Geochem. 5, 657–688.Google Scholar
Macaulay, C.I., Haszeldine, R.S. & Fallick, A.E. (1992) Diagenetic porewaters stratified for at least 35 million years: Magnus Oil Field, North Sea. Am. Assoc. Petrol. Geol. 76, 1625–1634.Google Scholar
Marshall, J.D. & Ashton, M. (1980) Isotopic and trace element evidence for submarine lithification of hardgrounds in the Jurassic of eastern England. Sedimentology, 27, 271–289.CrossRefGoogle Scholar
Savln, S.M. & Lee, M. (1988) Isotopic studies of phyllosilicates. Pp. 189-224 in: Hydrous Phyllosilicates (Exclusive of Micas) (Bailey, S.W., editor) Reviews in Mineralogy 19, Mineralogical Society of America, Washington, DC.Google Scholar
Small, J.S., Hamilton, D.L. & Habesh, S. (1992) Experi- mental simulation of clay precipitation within reservoir sandstones 2: mechanisms of illite formation and controls on morphology. J. Sed. Pet. 62, 520–529.CrossRefGoogle Scholar
Stewart, D.J. (1986) Diagenesis of the shallow marine Fulmar Formation in the Central North Sea. Clay Miner 21, 537–564.Google Scholar
Yeh, H.-W. (1980) D/H ratios and late stage dehydration of shales during burial. Geochim. Cosmochim. Acta, 44, 341–352.Google Scholar