1 92 1. No. 8. 



ON THE ECLOGITES OF NORWAY, 



59 



This very conspicuous alteration into amphibolite (the altered rock 

 consists of hornblende and plagioclase) which is a constant feature of the 

 eclogites in the gneiss, will be discussed in a special chapter. 



I had myself good opportunity to study the inclusions near Bryggen 

 in Nordfjord. The main rock is a stretched-out veined gneiss, in which 

 frequent lenses of eclogite or amphibolite are enclosed. Fig. 8 shows such 

 lenses, the larger of which, in their central parts, consist of almost non- 

 foliated fine-grained eclogite rich in pyroxene surrounded by thick zones 

 altered into amphibolite. Smaller lenses are entirely composed of amphi- 

 bolite and, as may seem probable from the analogy, it is wholl}- evident 

 from the relict features, that these have been primarily lenses of eclogite, 

 now perfectl}^ altered into amphibolite. 



Fig. -J. Eclogite as a larger mass in gneiss, with zones of amphibolite at the boundaries and 

 on joints. Silden, Selje. After H. H. Reusch. 



Other lenses have no amphibolitic border-zones; these contain only 

 amphibole besides the garnet which is almandite, and the rock is thus an 

 almandite-amphibolite, stable in the amphibolite facies. 



At two places near Bryggen were observed larger masses of fine- 

 grained amphibolite which contains a few portions of eclogite enclosed. It 

 appears here that all the amphibolite once was eclogite. That it has here 

 been amphibolitized throughout such large masses ma}' be understood in con- 

 nection with the fact that thin lenses or veins of quartz have been injected 

 into the amphibolite. This amphibolite is a pavement-like mixture of green 

 hornblende and plagioclase with quartz and biotite and zoisite and, oc- 

 casionally, margarite. Crystals of garnet may occur. 



Near one of these places, about 300 meters west of Bryggen, the 

 rock has developed into a veritable eclogite-adergneiss. The veins for the 

 most part consist of quartz-garnet-rock or pure quartz, though true aplitic 

 veins also occur. 



