348 R. A. DALY THE OKANAGAN COMPOSITE BATHOLITH 



tite, but bearing no hornblende. These zones were regarded in the field as 

 located along planes of maximum shearing. They accord very faithfully in 

 attitude with a strike of north 2 to 25 degrees west and a dip nearly verti- 

 cal, but sometimes 75 degrees or more to the east-northeast — structural 

 elements induced by regional orogenic movements in the Cordillera. It is 

 improbable that the banding represents peripheral schistosity about the 

 Cathedral batholith. The chief reason for excluding this view is that 

 peripheral schistosity is lacking in the great Similkameen batholith, which 

 is also cut by the Cathedral granite. It appears, on the other hand, that 

 the Eemmel batholith was already crushed and its banding produced be- 

 fore either the Similkameen or Cathedral granite was intruded. 



Six-sevenths of the total area mapped in the Eemmel batholith is under- 

 laid by hornblende-bearing rock much more nearly identical with the 

 original granodiorite. In fact the description of the granodiorite has 

 been based on specimens taken from the more massive rock facies occur- 

 ring in the larger area. The rocks of this "Western phase" are crushed 

 and sheared, but distinctly less so affected than the mass forming the 

 Eastern phase. Where strong shear zones occur in the Western phase 

 they are occupied by dark greenish-gray, fine grained, fissile hornblende 

 gneiss very rich in hornblende and similar to the secondary filling of 

 shear zones in the Osoyoos granodiorite. Between these narrow shear 

 zones the more normal rock usually shows mechanical granulation and 

 fracture rather than extensive recrystallization. 



Interpretations of the Eastern and Western phase. — Three interpreta- 

 tions of the two phases are conceivable. They may be supposed to be dis- 

 tinct intrusions of two different magmas ; or, secondly, original local dif- 

 ferentiation products in the one batholith; or, thirdly, distinguished in 

 their present compositions because of the unequal dynamic metamorphism 

 of a once homogeneous magma. Against the first view is the fact that the 

 two phases, where in contact, seem everywhere to pass insensibly into each 

 other. In favor of the third view are several facts which do not square 

 with the second hypothesis, and the writer has tentatively come to the con- 

 clusion that the third hypothesis is the correct one. Among those facts 

 are the following : 



1. The Eastern phase covers that part of the Eemmel body which has 

 suffered the greatest amount of dynamic stresses exhibited either in the 

 Eemmel or in any other of the larger components of the Okanagan Com- 

 posite batholith. It has been seen that the less intense though still nota- 

 ble dynamic metamorphism of the Osoyoos granodiorite led to the special 

 excretion of most or all of the hornblende, apatite, magnetite, and titanite 

 from that rock and the secretion of those leached-out compounds in the 



