GENESIS OF THE ALKALINE ROCKS 105 
Almunge, Sweden.—Among the most noteworthy publications 
of late years is Quensel’s paper on the alkaline rocks of Almunge.* 
Consisting of dominant umptekite with an aplitic marginal zone and 
with huge inclusions of canadite (albite-nephelite syenite), these 
rocks form a stocklike body measuring 4.5 by 3.5 km. It cuts 
granite of two types. Quensel’s memoir is full of valuable informa- 
tion, but two chief points are of present importance. One is the 
abundance of the two lime minerals, vesuvianite and primary 
cancrinite, in the canadite. The other is Quensel’s suggestion as 
to the genesis of this rock. His statement may be quoted (p. 106): 
Vesuvianite has always been considered a typical mineral of the contact 
metamorphism of calcareous rocks. It seems difficult to explain its presence 
in the Almunge canadites in any other way than that it represents the remains 
of otherwise fully assimilated calcareous sediments. Its occurrence would then 
be comparable with the primary calcite of Alné or Bancroft, formed through 
assimilation of limestones by the igneous magma under such circumstances that 
the CO, could not abscond. The very essential amount of cancrinite in all 
these rocks would then probably be a manifestation of the same geological 
features. The presence of a hydrated mineral in an igneous rock is hardly 
more remarkable than CO, partaking in the constitution of other magmatic 
minerals under similar circumstances. 
Though nothing can be said with certainty about the origin of the alkaline 
rocks, several features seem, however, to point to the possibility of the origin 
of nepheline-syenites in some way having been connected with the assimilation 
of calcareous sediments. As previously mentioned, paragneisses with inter- 
bedded limestone are found at no very great distance south of the area and may 
possibly be present at deeper levels within the Almunge district itself. 
The writer is free to admit that future field work at a number of 
other localities is not likely to yield results positively favorable to 
the sediment-syntectic hypothesis for the alkaline rocks. Yet the 
™P. D. Quensel, Bull. Geol. Inst. Upsala, XXII (1914), 129. While the proofs of 
the present paper were being read, Thorolf Vogt’s account of the rocks of Hortavaer, 
Norway, reached America [Videnskapsselskapets Skrifter, I Mat.-naturv. Klasse, 
Christiania (1915), No. 8]. Vogt describes the peripheral solution of large limestone 
masses in intrusive subalkaline magma, with the resulting generation of alkaline 
pyroxenes which chiefly compose “‘hortite,’’ a new plutonic type. He concludes that 
the injection temperatures were in the neighborhood of 1300°C. for the intrusives 
at Hortavaer and at Alnd, Sweden! Still other features of Vogt’s paper are signifi- 
cant in connection with the sediment-syntectic hypothesis, which he regards as 
sound at least in part, but space fails for a fuller discussion of this careful petrological 
study. 
