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

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Authors:Burley, S. D.; Flisch, M.
Author Affiliations:Primary:
Univ. Bern, Geol. Inst., Bern, Switzerland
Volume Title:Clay Minerals
Source:Clay Minerals, 24(2), p.285-315. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0009-8558
Publication Date:1989
Note:In English. 25 refs.; illus. incl. 6 tables, sketch map
Summary:Mudrocks interbedded with and overlying the reservoir sequence show a progressive increase in illite content with depth. K/Ar analyses give ages of 153-68 m.y. Shallowest samples give the oldest ages, probably reflecting clay neoformation in Jurassic weathering profiles. It is considered that illitization proceeds via a two-step reaction: initial destruction of smectite followed by neoformation of illite. This is considered to have happened 60- 50 m.y. ago. Reservoir sandstones have undergone a complex diagenetic history, involving multiple illite authigenesis. The youngest K/Ar determination of 29 m.y. at the present Tartan downthrown block is a maximum age for illite authigenesis in the water zone. If this authigenesis took place shortly after oil accumulation the maximum age of oil accumulation is constratined to 29-35 m.y., while a minimum age of oil accumulation is calculated as 22 m.y. on the basis of contamination of the 29 m.y. sample with <10% of 93 m.y. authigenic illite. [R.E.S.]
Subjects:Authigenic minerals; Clay mineralogy; Clay minerals; Diagenesis; Geochronology; Illite; Illitization; Jurassic; K/Ar; Mesozoic; Mineral data; Oil and gas fields; Precipitation; Processes; Reservoir rocks; Sediments; Sheet silicates; Silicates; Smectite; TEM data; Upper Jurassic; Atlantic Ocean; Europe; Great Britain; Moray Firth; North Atlantic; North Sea; Scotland; United Kingdom; Western Europe; Piper Field; Tartan Field
Abstract Numbers:90M/2653
Record ID:1989080955
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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