The Formation of a Flecky Gneiss and Similar Phenomena in Relation to the Migmatite and Vein Gneiss Problem

Replacement veins in gneiss from the Precambrian of south-eastern Sweden

“…Green biotite associated with andalusite was also reported by Loberg (1963) in mineral assemblages very similar to those described in the present paper.…”

“…Characteristic for the fleck gneiss is the development in micaceous meta-arenites of welldefined flecks, containing a dark core surrounded by an aplite-like zone or mantle. The "fleck gneiss" has been described and discussed by Loberg (1963). With respect to mineral and chemical composition, the various rock elements are very similar to those in the present example.…”

“…which deals with the shape of the sillimanite nodules and their relation to the structural elements of the metamomhic host rock. The nostatements of Loberg (1963)in his discussions of the relations between steep linear structures in his "m.atrix" and the development of flecks.…”

Metamorphic differentiation at Einasleigh, Northern Queensland

“…Recent intensive studies of mineral concentrates, such as those by King (1948), Mehnert (1951), Ramberg (1956Ramberg ( , 1960, Reitan (1956Reitan ( , 1959, Ljunggren (1957), Loberg (1963), andSmith (1964) have shown that the vein-forming process is more varied and more complex than was initially anticipated. Complexity and diversity in the vein-forming process is also indicated by the present study.…”

“…The conclusion invariably drawn from the study of extraction zones is that some or all of the vein-forming matter was obtained from the immediately surrounding rock. Thus certain detailed investigations of the bulk composition of veins plus extraction zones as compared to unaltered rock have shown that nothing was lost or added during the segregation process (Mehnert, 1951), while other studies have made it possible to specify the elements which have been added to or subtracted from the site of mineral segregation and the magnitude of these additions or subtractions (Ljunggren, 1957;Loberg, 1963).…”