Formation and transformation of mixed-layer minerals by Tertiary intrusives in Cretaceous mudstones, West Greenland
Drits, Victor A. (Russian Academy of Sciences. Geological Institute)
Lindgreen, Holger (Geological Survey of Denmark and Greenland)
Sakharov, Boris A. (Russian Academy of Sciences. Geological Institute)
Jakobsen, Hans Jorgen (University of Aarhus. Instrument Centre for Solid-State NMR Spectroscopy. Department of Chemistry)
Fallick, Anthony E. (Scottish Universities Environmental Research Centre)
Salyn, Alfred L. (Russian Academy of Sciences. Geological Institute)
Dainyak, Lidia G. (Russian Academy of Sciences. Geological Institute)
Zviagina, Bella B. (Russian Academy of Sciences. Geological Institute)
Barfod, Dan N. (Scottish Universities Environmental Research Centre)

Date:	2007
Abstract:	In the Nuussuaq Basin, West Greenland, a thick succession of Tertiary dolerites has penetrated Upper Cretaceous mudstone. The mixed-layer minerals of mudstone core samples have been analyzed by X-ray diffraction, solid-state Si and Al magic-angle spinning nuclear magnetic resonance, Mössbauer and infrared spectroscopies, thermal analysis, chemical analysis, stable isotopes (O/O), and K/Ar dating. The mixed-layer minerals include for each sample two mixed-layer phases consisting of pyrophyllite, margarite, paragonite, tobelite, illite, smectite and vermiculite layers. The main, 80 m thick intrusion resulted in the formation of pyrophyllite, margarite, paragonite and tobelite layers. However, the tobelite layers are absent in samples <21 m from this intrusion. Furthermore, chlorite was formed and kaolinite destroyed in samples adjacent to minor intrusions and at distances <60 m from the large intrusion. For the first time, the detailed, complex mixed-layer structures formed during contact metamorphism of kaolinitic, oil-forming mudstones have been investigated accurately. The formation of tobelite layers reveals that oil formation has taken place during contact metamorphism. Furthermore, K/Ar dating of mixed-layer minerals from shale indicates that the intrusives are of early Eocene age. The 80 m thick intrusive is responsible for the main mixed-layer transformations, whereas two thin (3 m and 0. 5 m thick) intrusions contribute little. Thus, the detailed mixed-layer investigation has contributed significantly to the understanding of the regional geology and the contact metamorphic processes.
Rights:	Tots els drets reservats.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Burial Diagenesis ; Greenland ; Illite-smectite ; Oil-source Rocks ; Tobelite
Published in:	Clays and Clay Minerals, Vol. 55, Núm. 3 (2007) , p. 260-283, ISSN 1552-8367

DOI: 10.1346/CCMN.2007.0550304

24 p, 1.7 MB  UAB restricted access

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