[Proc. Rot. Soc. Victoria, 26 (N.S.), Pt. II., 1914]. 



Ak'I'. XIX. -On the Origin and Relation f>]iip of some 

 Victorian Igneous Rocks. 



By H. S. summers, D.Sc. 

 (Lecturer and Deinon.strator in Greology, Univei'sity of Melbonrne). 



[Read 9th October. 1913 J. 



Contents. 



I. Introduction. 

 II. Victorian Igneous Series. 



(a) Macedon Dacite-Granodiorite Series. 



(b) Victorian Upper Palaeozoic Series. 



(c) Lilydale Devonian Series. 



(d) Macedon Kaiuozoic Series 

 III. Differentiation of Victorian Series. 



(a) Macedon Dacite-Granodiorite Series. 



(b) Victorian Upper Palaeozoic Series. 



(c) Macedon Kainozoic Series. 



(d) Lilydale Devonian Series. 



IV. Relation of Igneous Rocks to Earth-Movements in Victoria. 



(a) Heathcotian iSeries. 



(b) Upper Palaeozoic Series. 



(c) Kainozoic Alkaline and Calcic Series. 

 V. Petrographic Regions. 



\ I. The Origin of Victorian Magmas. 

 VII. Summary. 

 VIII. References. 



I. Introduction. 



During the past several years I have been engaged in conjunction 

 with Professor Skeats in making a careful study of the igneous rocks 

 of the Macedon District. An account of our work in this area has 

 recently been published as a Bulletin of the Geological Survey of 

 Victoria (19), but since that paper went to the press I have continued 

 to work on the question of relationship and differentiation of the 

 two igneous series which are so well developed in the neighbourhood 

 of Macedon and Woodend. This has led on to the study of the 

 relationship of the Macedon dacites and granodiorites to rocks of 

 other areas in Victoria, and the evidence that has been collected 

 seems to have considerable hearing on certain aspects of modern 

 petrology. 



The most important point to be raised is the relationship of the 

 so-called alkaline and sul)-alkaline or calcic groups of rocks to one 

 another. Hai-ker (4) !)elieves that these two branches of igneous 

 rocks are (juite distinct from one another, and that the former 



