Diagenetic illite-chlorite assemblages in arenites; I, Chemical evolution

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Authors:Jahren, J. S.; Aagaard, P.
Author Affiliations:Primary:
University of Oslo, Department of Geology, Oslo, Norway
Volume Title:Clays and Clay Minerals
Source:Clays and Clay Minerals, 40(5), p.540-546. Publisher: Clay Minerals Society, Clarkson, NY, United States. ISSN: 0009-8604
Publication Date:1992
Note:In English. 25 refs.; illus. incl. 2 tables, sketch map
Summary:Authigenic chlorites and illites coexisting in clastic reservoir sandstones have been studied by energy dispersive X-ray spectroscopy (EDS) in the transmission electron microscope (TEM). All 16 samples studied are drill or sidewall cores from sandstones of relatively uniform age situated offshore Norway with burial depths ranging between 2400 m and 5000 m and representing temperatures between 90°C and 180°C. Chlorites and illites with authigenic equilibrium type texture and morphology were analyzed by EDS. Tetrahedral Al and octahedral Fe+Mg in chlorite increases with burial at the expense of Si and vacant octahedral positions in the chlorite structure. Illites show a clear increase in K. These factors indicate that a continuous chemical modification of these minerals takes place in the diagenetic interval studied through continuous dissolution and precipitation reactions.
Subjects:Arenite; Authigenic minerals; Chemical properties; Chlorite group; Clastic rocks; Diagenesis; Illite; Mineral composition; Offshore; Petroleum; Porosity; Reservoir rocks; Sandstone; Sedimentary rocks; Sheet silicates; Silicates; TEM data; X-ray data; Arctic Ocean; Atlantic Ocean; Europe; Haltenbanken; North Atlantic; North Sea; Norway; Norwegian Sea; Scandinavia; Western Europe; European Atlantic
Abstract Numbers:93M/3927
Record ID:1993033924
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland
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