Analcime in lake and lake-margin sediments of the Carboniferous Rocky Brook Formation, Western Newfoundland, Canada

Authors

  • Q. GALL,

    1. Mineral Resources Division, Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada
    Search for more papers by this author
    • 1

      Correspondence: Department of Earth Sciences, Carleton University, Ottawa, Ontario, K15 5B6, Canada.

  • R. HYDE

    1. Department of Earth Sciences, Memorial University, St. Johns, Newfoundland A1N 2M9, Canada
    Search for more papers by this author

ABSTRACT

In the Deer Lake Basin of western Newfoundland, Canada, analcime has been found within fine-grained, siliciclastic and carbonate, lake and lake-margin sediments of the Carboniferous Rocky Brook Formation. Analcime is the only zeolite observed in these unmetamorphosed and non-volcanogenic rocks. Microscopic analcime occurs as vug-filling, limpid, isotropic to anisotropic crystals. Microprobe analyses show this type of analcime to be lower in silica than most analcime in sedimentary rocks. A second textural type of finer-grained submicroscopic analcime can be detected from X-ray diffraction spectra of Rocky Brook Formation mudstones, where it is associated with phyllosilicates (illite, interstratified chlorite/smectite, smectite, chlorite), other silicates (quartz, feldspar) and carbonates (dolomite, calcite). Results of this study suggest that the analcime in the Rocky Brook Formation formed either by direct lakewater/porewater precipitation or by reaction of these waters with one or more clay mineral types or plagioclase.

Ancillary