358 R. A. DALY — THE OKANAGAN COMPOSITE BATHOLITH 



contacts are insufficiently shown to warrant any decision in the case. The 

 A.shnola gabbro may similarly be the residual part of an injected body. 

 That it was a comparatively small body is suggested by an apparent flow 

 structure still preserved even in the medium grained facies of the gabbro. 

 In a batholithic rock of that texture, fluidal arrangement of the minerals 

 is very rare. The infinitely diverse composition and structure of the 

 Basic complex much more clearly points to a non-batholithic origin. One 

 imagines rather that the lithological and structural complication are in 

 this case such as might appear at the deep-seated focus of an ancient vol- 

 canic area. The geological record has, however, been too largely obscured 

 or destroyed that any of these hypotheses concerning the basic intrusives 

 can be verified. 



One fact is certain, that all of the bodies are older than the granites by 

 which they are surrounded. Their contacts with the granites are the 

 sharpest possible; gabbro or peridotite is pierced by many typical 

 apophyses of granite or granodiorite which has often shattered the basic 

 rocks and isolated blocks which now lie within the basic body. Here 

 there is no question of the gabbros being differentiation products from 

 their respective granitic magmas, as so often described in the granodiorite 

 batholiths of California.* There remains, secondly, the conclusion that 

 these basic intrusives were probably not of batholithic size. They show 

 that some time before the real development of the Okanagan Composite 

 batholith began, a basic, subcrustal magma was erupted on a limited 

 scale — possibly in the form of stocks, possibly in the form of chonoliths. 



Undoubted batholithic intrusion began with the irruption of the grano- 

 diorites. The familiar phenomena of such intrusion are exhibited along 

 the contacts of the Osoyoos batholith. For several hundred yards from 

 the igneous body the phyllites have been converted into typical, often gar- 

 netiferous, mica schists. This collar of thermal or hydrothermal meta- 

 morphism would doubtless be yet more conspicuous if at the time of 

 intrusion the Paleozoic series had not already been partly recrystallized 

 in the earlier dynamic metamorphism of the region. 



The Remmel batholith is, as we have seen, composed of granodiorite 

 similar in original composition to the rock of the Osoyoos batholith. 

 Possiliferous Lower Cretaceous arkose sandstones, grits, and conglom- 

 erates overlie the Remmel unconformably. The materials for these rocks 

 were in part derived from the secular weathering of the Remmel grano- 

 diorite, the weathering being accompanied by rapid deposition of the 

 debris in a local sea of transgression. Arkose sandstones, which alone 

 measure more than 10,000 feet in thickness, were thus deposited in a 



*See many of the California!! folios issued by the U. S. Geological Survey. 



