Investigation of the clay fraction (<2 µm) of the Clay Minerals Society reference clays

• Published in: Clays and clay minerals Vol. 50; no. 3; pp. 388 - 400
• Main Authors: Vogt, Christoph, Lauterjung, Jörn, Fischer, Reinhard X
• Format: Journal Article
• Language: English
• Published: Boulder, CO Clay Minerals Society 01-06-2002; The Clay Minerals Society
• Subjects: Arctic Ocean; beidellite; Central Europe; chlorite; chlorite group; clay minerals; Clay Minerals Society; Clay Minerals Society Cms; computer programs; data bases; data management; data processing; Earth sciences; Earth, ocean, space; Europe; Exact sciences and technology; Germany; information management; kaolinite; KTB; Laptev Sea; Marine Geology; Mineralogy; montmorillonite; quantitative analysis; Quantitative Phase Analysis; QUAX; Reference Clays; sed rocks, sediments; Sedimentary petrology; sheet silicates; Silicates; Source Clays Repository; spectra; X-ray diffraction data; X-ray fluorescence spectra; XRD; Xrf; Russian Federation; Laptev Sea; West Pacific; Japan Sea; Siberia; software; Eurasia; impurities; X-ray diffraction; feldspar; clay; mineral assemblages; marine geology; sheet silicates; silicates; framework silicates; data bases; marine sediments; clastic rocks; quality; sedimentary rocks; grain size; new data; X-ray fluorescence; Arctic Ocean; clay minerals; Pacific Ocean; powder diagrams; methodology; sediments
• ISSN: 0009-8604; 1552-8367
• DOI: 10.1346/000986002760833765

We studied a set of 15 reference clays from The Clay Minerals Society (CMS) Source Clays repository. Our aim was to use them as reference materials in our version of the QUAX mineral database. The QUAX software (Quantitative Phase-Analysis with X-ray Powder Diffraction) has been used successfully at the KTB site (German Continental Deep Drilling) to determine mineral assemblages quickly, in an automatic fashion, on a large number of samples (∼40,000). It was also applied to Quaternary marine sediments of the Japan Sea. Our current research focuses on marine and lacrustrine sediments from the Arctic Ocean and Siberia. QUAX is a full-pattern method using a reference materials database. The quality of a particular quantification depends on the availability of the relevant mineral phases in the database. Our aim is to extend and improve the database continuously with new data from our current projects, particularly from clay and feldspar minerals. A reference material in the QUAX software must be monomineralic. Before X-ray diffraction (XRD) patterns of CMS clays could be added to the database, quantification of any impurities was necessary. After measuring the bulk material by XRD, the <2 µm fraction was separated because we assumed it would contain the smallest amount of impurities. Here we present grain-size data, XRD data and X-ray fluorescence (XRF) data for this clay-sized fraction. The results of chemical and mineralogical preparation techniques and (elemental) analysis methods were combined. For XRD, random and oriented clay-aggregate samples as well as pressed pellets for QUAX analysis were prepared. Semi-quantitative clay mineral determinations were run for comparison.