I92I. No. 8. ox THE ECLOGITES OF NORWAY. -g 



pendent facias, closest related to the eclogite faciès. The appearance of 

 such amphibole probably depends upon a fall of the temperature, and a 

 reduction ot pressure is perhaps not at all ni'cessarv. 



Eclogitc-honihh'iidrgahbro. 



Of quite another character is the development of the minerals of the 

 hornblende-gabbro faciès at the last phase of the consolidation of eclogites. 

 As an example of it, we have given a quantitative investigation of the 

 eclogite-hornblende-gabbro of Romsdalshorn (p. 43 1 and here will be men- 

 tioned a few other examples of this very common phenomenon. 



As the transition into the new faciès usually takes place when much 

 garnet has already crystallized out, the rest-magma is then enriched in lime, 

 and diopside separates out along with hornblende and plagioclase. A 

 characteristic example was a specimen from Vaagse, Nordfjord, where 

 the eclogite-pyroxene had altered into the diopside-plagioclase-symplectite, 

 and a granular mass of brown hornblende and plagioclase fills up the 

 interstices of the older minerals. 



A specimen from Rofjeldets Hammere, Nordmøre, on the other 

 hand, represents a case where the residual magma had excessive magnesia 

 and a bulk composition somewhat various from that of the ordinary eclo- 

 gites. Here the diopside-plagioclase-symplectite is present as elongated 

 grains, and between them are vein-shaped strings of oligoclase, green 

 hornblende and biotite. 



A specimen from Brandsaeter, Kornstad fjord. Nord m ©re, 

 shows well developed eclogite minerals and between them a granular ag- 

 gregate of brown hornblende and plagioclase (fig. 13, pi. III). 



The change of facies also may result in a rock quite devoid of py- 

 roxene. An example of this is a specimen from \'ik, Gursko, Sondmere, 

 containing garnet, greenish brown hornblende and bytownite. 



A specimen from H als n es. Tus te ren. Nord me re, is similar with 

 the Romsdalshorn rock. This contains large rounded crystals of- garnet 

 and clinop3'roxene, the latter in part altered into diopside-plagioclase-sym- 

 plectite, both embedded in still larger indivixuals of plagioclase in which 

 also are smaller grains of brown hornblende and biotite, in part filling up 

 the interstices between the older minerals. 



In this connection I shall still give a note of some rocks from Han e- 

 dalstind, of which Professor V. M. Goldschmidt kindly lent me four thin 

 sections. Their crystallization has begun in the eclogite facies, and one 

 of them is composed of garnet and diopside-plagioclase-s3'mplectite, whose 

 interstices are filled up with green hornblende. Another thin section shows 

 the same symplectite as large grains in a ground-mass of brown horn- 

 blende, biotite and plagioclase, and, instead of garnet, large groups of 

 green hornblende and magnetite. The plagioclase (andesinel is too abun- 

 dant for an earlier eclosrite. 



