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K-Ar geochronology and the timing of detrital I/S clay illitization and authigenic illite precipitation in the Piper and Tartan Fields, Outer Moray Firth, UK North Sea

Published online by Cambridge University Press:  09 July 2018

S. D. Burley  and
M. Flisch
S. D. Burley
Affiliation:
Geologisches Institute, Universität Bern, Baltzerstrasse 1, CH-3012 Bern
M. Flisch
Affiliation:
Geologisches Institute, Universität Bern, Baltzerstrasse 1, CH-3012 Bern
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Abstract

Piper and Tartan Fields are Upper Jurassic reservoirs located in fault blocks on either side of the Witch Ground Graben. The reservoirs are divided into a series of structural units, each successively downthrown towards the graben, covering a total depth interval of 8500–15 000 ft. Mudrocks interbedded with and overlying the reservoir sequence show a progressive increase in illite content with depth from ordered I/S clays with around 40% smectite to almost pure illites with low expandibility. K-Ar analyses on 13 <0·5 µm illite separates from mudrocks covering this depth interval give ages that range from 153 to 68 Ma. Shallowest samples give the oldest ages which are considered to reflect clay neoformation in Jurassic weathering profiles. In the 40Ar/K Harper diagram this data set falls on a mixing line which reflects the amount of smectite present. Deepest samples give the youngest ages and show a major reduction of 40Ar* with increasing K content indicating formation of new illite. These data are considered to document that ‘illitization’ proceeds via a two-step reaction: initial destruction of smectite followed by neoformation of illite. According to decompacted burial curves, ‘illitization’ took place 60–50 Ma ago. Reservoir sandstones have undergone a complex diagenetic history, involving multiple illite authigenesis. K-Ar analyses of 21 <0·5 µm illite separates selected across the oil-water contact in each of the main structural units show progressively younger ages in the water zone and with increasing depth of burial. Oldest ages in the oil zone (144–120 Ma) reflect eogenetic illite authigenesis whilst progressively younger ages in the water zone result from successive mesogenetic illite generations. The youngest age of 29 Ma was obtained from an illite-rich zone at the present oil-water contact in the Tartan downthrown block. Assuming illite authigenesis in the Tartan downthrown block took place shortly after oil accumulation, ∼29–35 Ma can be considered as a maximum age for the present oil accumulation. A minimum age for oil accumulation is calculated as 22 Ma on the basis of contamination of the 29-Ma sample with up to 10% of 93-Ma authigenic illite.

Type
Research Article
Information
Clay Minerals , Volume 24 , Issue 2 , June 1989 , pp. 285 - 315
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1989

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References

Aronson, J.L. & Douthitt, C.B. (1986) K/Ar systematics of acid-treated illite/smectite: implications for evaluating age and crystal structure. Clays Clay Miner. 34, 473–482.Google Scholar
Aronson, J.L. & Hower, J. (1976) Mechanism of burial metamorphism of argillaceous sediment: 2. Radiogenic argon evidence. Geol. Soc. Am. Bull. 87, 738–744.Google Scholar
Aronson, J.L. & Lee, M. (1986) K/Ar systematics of bentonite and shale in a contact metamorphic zone, Cerrillos, New Mexico. Clays Clay Miner. 34, 483–487.Google Scholar
Bissada, K.K. (1983) Petroleum generation in Mesozoic sediments of the Moray Firth Basin, British North Sea area. Advances in Organic Geochem. 1981, 7–15.Google Scholar
Boote, D.R.D. & Gustav, S.H. (1987) Evolving depositional systems within an active rift, Witch Ground Graben, North Sea. Pp. 819–833 in: Petroleum Geology of North West Europe(Brooks, J. and K., Glennie, editors). Graham and Trotman, London.Google Scholar
Burley, S.D. (1986) The development and destruction of porosity within Upper Jurassic reservoir sandstones of the Piper and Tartan oilfields, Outer Moray Firth, North Sea. Clay Miner. 21, 649–694.Google Scholar
Burley, S.D., Mullis, J. & Matter, A. (1989) Timing of diagenesis in the Tartan reservoir (UK, North Sea): constraints from combined cathodoluminescence microscopy and fluid inclusions studies. J. Mar. Pet. GeoL 6, 98–120.Google Scholar
Flisch, M. (1982). Potassium-argon analysis. Pp. 151–158 in: Numerical Dating in Statigraphy (Odin, G.S., editor). John Wiley, Chichester.Google Scholar
Flisch, M. (1986) K-Ar dating of Quaternary samples. Pp. 299–323 in: Dating Young Sediments(Hurford, A.J., Jager, E. and J.A.M. Ten Cate, editors) Proc. CCOP Workshop Technical Publication 16, Bangkok, Thailand.Google Scholar
Harker, S.D., Gustav, S.H. & Riley, L.A. (1987) Triassic to Cenomanian Stratigraphy of the Witch Ground Graben. Pp. 809–818 in : Petroleum Geology of NW Europe (Brooks, J. and K. Glennie, editors). Graham & Trotman, London.Google Scholar
Harper, C.T. (1970) Graphical solutions to the problems of radiogenic 40Ar loss from metamorphic minerals. Eclogae Geologica Helveticae 63, 119–140.Google Scholar
Hurley, P.M., Brookins, D.G., Pinson, W.H., Hart, S.R. & Fairbairn, H.W. (1961) K-Ar age studies of Mississippi and other river sediments. Bull. GeoL Soc. Am. 72, 1807–1816.Google Scholar
Hurley, P.M., Hunt, J.M., Pinson, W.H. & Fairbairn, H.W. (1963) K-Ar age values in the clay fractions in dated shales. Geochim. Cosmochim. Acta 27, 279–284.Google Scholar
Jourdan, A., Thomas, M., Brevart, O., Robson, P., Sommer, F. & Sullivan, M. (1987) Diagenesis as the control of Brent sandstone reservoir properties in the Greater Alwyn Area, East Shetland Basin. Pp. 951–961 in: Petroleum Geology of NW Europe (Brooks, J. and Glennie, K., editors). Graham and Trotman, London.Google Scholar
Lee, M., Aronson, J.L. & Savin, S.M. (1965) K-Ar dating of time of gas emplacement in Rotligended Sandstones, Netherlands. Am. Assoc. Pet. GeoL Bull. 69, 1381–1385.Google Scholar
Lee M., , Aronson, J.L. & Savin, S.M. (1989) Timing and conditions of Permian Rotliegende sandstone diagenesis, southern North Sea: K/Ar and oxygen isotope data. Am. Assoc. Petrol. GeoL Bull. 73, 195-215.Google Scholar
Liewig, N., Clauer, N. & Sommbr, F. (1987) Rb-Sr and K-Ar dating of clay diagenesis in Jurassic sandstone oil reservoir, North Sea. Am. Assoc. Pet. GeoL Bull, 71, 1467–1474.Google Scholar
Maher, C.E. (1980) The Piper Oilfield. Pp. 131–172 in: Giant Oil and Gas Fields of the Decade 1968-1978 (Halbouty, M.T., editor). Am. Assoc. Petrol. Geol. Mem. 30.Google Scholar
Pearson, M.J. & Small, J.S. (1988) Illite-smectite diagenesis and palaeotemperatures in northern North Sea Quaternary to Mesozoic shale sequences. Clay Miner. 23, 109–132.Google Scholar
Perry, E.A. (1974) Diagenesis and the K-Ar dating of shales and clay minerals. Geol. Soc. Am. Bull. 85, 827–830.Google Scholar
Peters, T.J. & Hofmann, B. (1984) Hydrothermal day mineral formation in a biotite-granite in northern Switzerland. Clay Miner. 19, 579–590.Google Scholar
Schumacher|E. (1975) Herstellung von >99°9997 per cent 38Ar fur die 40K/40Ar Geochronologie. Chimia 29, 441–442.99°9997+per+cent+38Ar+fur+die+40K/40Ar+Geochronologie.+Chimia+29,+441–442.>Google Scholar
Schmidt, V., & McDonald, D.A., (1979) The role of secondary porosity in the course of sandstone diagenesis. Pp. 175–208 in: Aspects of Diagenesis (Schoiie, P.A. and Schluger, P.R., editors). SEPM Spec. Publ. 26.Google Scholar
Sommer, F. (1975) Historic diagenetique d'une serie gresense de Mer du Nord: Datation de Tintroduction des hydrocarbons. Revue Inst. fr. Petrole 30, 729–741.Google Scholar
Steiger, R.H. & Jager, E. (1977) Subcommission on geochronology: convention on the use of decay constants in geo- and cosmochronology. Earth Planet. Sci. Lett. 36, 359–362.Google Scholar
Srodon J.& Eberl, D.D. (1984) Illite. Pp. 495–544 in: Micas(Bailey, S.W., editor). Min. Soc. Am. Reviews in Mineralogy 13.Google Scholar
Thomas, M. (1986) Diagenetic sequences and K/Ar dating in Jurassic sandstones, central Viking Graben: effects on reservoir properties. Clay Miner. 21, 695–710.CrossRefGoogle Scholar
Turner, C.C., Richards, P.C., Shallow, J.L. & Grimshaw, S.P. (1984) Upper Jurassic stratigraphy and sedimentary facies in the central Outer Moray Firth Basin, North Sea. J. Mar. Pet. Geol 1, 105–117.Google Scholar
Weaver, C.E. & Wampler, J.M. (1970) K, Ar, illite burial. Geol. Soc. Am. Bull. 81, 3423–3430.CrossRefGoogle Scholar
Weir, A.H., Omerod, E.C. & E.L. Mansey I.M.I. (1975). Clay mineralogy of sediments of the Western Nile Delta. Clay Miner. 10, 269–386.Google Scholar
Wilson, M.D. & Pittman, E.D. (1977) Authigenic clays in sandstones recognition and influence on reservoir properties and palaeo-environmental analysis. J. Sedim. Petrol. 47, 3–31.Google Scholar
Yoder, H.S. & Eugster, H.P. (1955) Synthetic and natural muscovites. Geochim. Cosmochim. Acta 8,225-280.Google Scholar