Beitrag
Chromites from the Bergen Arcs Ultramafics
Takla, Maher A.
Neues Jahrbuch für Mineralogie - Abhandlungen Band 144 Heft 1 (1982), p. 56 - 72
35 Literaturangaben
veröffentlicht: Jun 1, 1982
ArtNo. ESP154014401003, Preis: 29.00 €
Abstract
Mineralogy, mineral chemistry and mode of occurrence of the chromites from some ultramafic masses of the Bergen Arc System, Norway, are given. The chromites occur as disseminated grains in dunite, massive and “schistose” serpentinites and as cumulus lenses and layers. The alteration of chromite is attributed to serpentinization and regional metamorphism of the ultramafic masses. The transformation of chromite into ferrichromite and chromian magnetite involved remarkable chemical variability which is exhibited by microscopically visible zoning as well as invisible gradation in each zone. Primary structures such as rhythmic layering, lateral interfingering, mineral- and size-grading are still preserved in the rather fresh ultramafic bodies.
Schlagworte
Chromite • dissemination • alteration • zoning • texture • chemical composition • ultramafic rock; Southern Norway (Bergen Arc System)