THE PROBLEM OF THE ANORTHOSITES 97 



3. The lack of effusive equivalents of the anorthosites and other 

 monomineral igneous rocks is quite a natural consequence of 

 their great viscosity and their consequent inability to reach the 

 earth's surface in the liquid state. I have previously pointed to 

 that conclusion. Bowen refutes these considerations but without 

 any arguments. 



4. The minerahzers, and those minerals which are to be referred 

 to their action, are in general very rare in basic rocks. In many 

 gabbros they are quite absent. Meantime we may remember 

 that the zoisite mentioned above in certain anorthosites from the 

 Oural, and the primary serpentinization of the dunites are to be 

 referred to the action of mineralizers. 



5. The stratigraphical relations of the anorthosites argue for 

 their igneous and not for their sedimentary or metamorphic origin. 

 Their igneous origin is demonstrated by their intimate connection 

 with the rocks of the gabbro group and through these with syenites 

 by the anorthositic (and pyroxenitic) facies of the banded gabbros, 

 by several features illustrating their intrusion into the neighboring 

 rocks, and by contact metamorphic actions, as for instance, around 

 the big Canadian anorthosite bodies. But it is not enough to state 

 their intrusive origin in such general terms, for there are in the 

 geological literature two different interpretations of the anorthosites, 

 both, as already stated, relying on the theory of intrusion. It is 

 necessary, therefore, to analyze more closely the stratigraphical 

 relations in order to see whether they support the views of most 

 writers or those of Bowen. 



Adams'' states with reference to the Morin laccolith; "Fassen wir 

 noch einmal zusammen, so haben wir in diesem Gebiet eine grosse 

 intrusive Masse von Anorthosit, welche die Grenville Stufe durch- 

 bricht, grosse Gneissblocke einschliesst, Apophysen in die umge- 

 benden Gesteine entsendet und an vielen Stellen, wie es scheint, 

 von einem eigenartigen Contactproduct begleitet wird." Espe- 

 cially important seem to me the contact phenomena and the small 

 intrusive sheets of anorthosite in the gneiss. Daly (p. 331) agrees 

 with Adams, and says, in reference to the Morin laccoHth and several 

 intrusive bodies of gabbro and anorthosite in the HaUburton- 



' F. Adams, op. cit., p. 433. 



