294 



PETKOLOGICAL NOTES. No. i. IGNEOUS ROCKS AND 

 TUFF FROM THE CARBONIFEROUS OF NEW 

 SOUTH WALES. 



By M. Aurousseau, B.Sc , Deas-Thomson Mineralogy Scholar, 

 University of Sydney; Assistant Lecturer in Geology, 

 University of W^estekn Australia. 



(Plate xl.) 



Introduction. — The study of tlie genetic and tectonic relation- 

 ships of the Carl)oniferous igneous rocks of New South Wales is 

 a work of pressing importance in Australian petrolog}^, and one 

 which I had planned to take up, but my removal to Western 

 Australia has caused its abandonment, at any rate for some 

 years. 



The following notes represent a small amount of preliminary 

 collecting and study. The field-relations of the rocks dealt with 

 have not yet been worked out, but are indicated to some extent 

 on Professor David's maps (David, 1907). 



The igneous rocks are interbedded with littoral sedimentaries 

 and tuffs belonging to the upper part of the Lower Carboniferous 

 (Benson, 1913, Pt. i.), but, owing to the absence of persistent 

 horizons in the sedimentaries (Jaquet, 1901), correlation will 

 depend largely on the igneous rocks. For this reason, and as 

 the rocks described will have to be identified in the field as 

 mapping proceeds, the descriptions have been made fairly 

 detailed. 



The rocks to be described are from Martin's Creek, near 

 Paterson; and Eelah, Hudson's Peak and Knockfin, near Gos- 

 forth, in the Hunter River Valley, N.S.W. 



Martin's Creek, Paterson. 

 {0)^) Py7'oxene-am,phibole-mica andesite.- A handsome green- 

 ish to brownish-grey rock with occasional red patches; porphy- 



