Keratophyre

Keratophyre is a volcanic rock of intermediate composition. Although similar to trachyte, keratophyre's plagioclase component is richer in sodium than the plagioclase found in trachyte.[1] Keratophyre forms lava flows and subvolcanic intrusions (dykes and sills). Keratophyre occurs, for example, at Hüttenrode in the Harz Mountains of Germany and in the Berwyn Hills of Wales.[2] Keratophyre tuff of Early Devonian age occurs in Sauerland (Germany).[3]

The term quartz keratophyre has traditionally been used in the Nordic countries to describe a metamorphosed, felsic extrusive rock, corresponding to rhyolite, dacite, or rhyodacite according to IUGS terminology.[4]

References

  1. ↑ Schermerhorn, L.J.G. (1973). "What is keratophyre?". Lithos 6: 1–11. doi:10.1016/0024-4937(73)90076-5.
  2. ↑ Jevons, H. Stanley (1904). "Note on the Keratophyres of the Breidden and Berwyn Hills". Geological Magazine 1: 13–16. doi:10.1017/S0016756800119223.
  3. ↑ Wolf, K. H. (editor) (1981). Handbook of Strata-bound and Stratiform Ore Deposits (Part III volume 9): Regional Studies and Specific Deposits. Amsterdam: Elsevier. p. 539. ISBN 0-444-41824-5.
  4. ↑ Slagstad, T.: Geochemistry of trondhjemites and mafic rocks in the Bymarka ophiolite fragment, Trondheim, Norway: Petrogenesis and tectonic implications. Norwegian Journal of Geology, vol. 83, pp. 167-185. Trondheim 2003, ISSN 0029-196X
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