METAMORPHIC ROCKS OF S.B. QUEENSLAND. 



263 



The problems connected with these schists of uncertain age and 

 uncertain composition I have not gone into yet, and their discussion 

 must be left over until more work has been done upon them, but I 

 propose in this paper to deal more critically with the Mount Mee 

 metamorphic rocks which I have studied more closely. 



In a previous paper to the Linnean Society of New South Wales 

 (loc. cit.J I have given petrological descriptions of many of the Mount 

 Mee rocks, which it will be unnecessary to recapitulate. The following 

 table is constinacted to assign these rocks to their right positions under 

 Grubenmann's classification. 



Name under which Rock 

 was Described. 



1. Cyanite-rutile-granu- Coarse, uneven, 

 lite (Delaney's Creek) lepidoblastic 



layer structure 



2. Granulitic Mica-schist j Medium grained 



(Mount Delaney) lepidoblastic 



(Uomooblastic) 



3. Muscovite - granulite 

 (Mount Delaney) 



4. Greenstone (Fife's 

 Range) . (Epidiorite r) 



5. Hornblende - schist 

 (Mount Mee) 



6. Epidote - actinolite - 

 topaz-schist (Leacy's 

 Creek) 



7. Epidote - cordierite - 

 chlorite - schist 

 (Leacy's Creek) 



8. Albite-chlorite-schist 

 (Leacy's Creek) 



9. Glaucophane rocks 

 (several localities) 



Heteroblastie and 

 lepidoblastic in 

 in layers 



Honiooblastic 

 and grano- 



blastic 



Nematoblastic ... 



Xetnatoblastic 



Nematoblastic 



Mainly nemato- 

 blastic var. 

 diablastic 



Nematoblastic ... 



Chief Minerals. 



New Name in 



Grubenmann's 



System . 



Quartz, orthoelase, 

 topaz, muscovite, 

 cyanite, rutile 



Orthoelase, musco- 

 vite, sericitc, 

 chlorite 



Orthoelase. musco- 

 vite, cjuartz, seri- 

 cite, chlorite, 

 topaz, biotite, 

 zoisite, rutile 



Orthoelase, actino- 

 lite, titaniferous 

 magnetite, epi- 

 dote, chlontoid 



Anthophyllite. acti- 

 nolite, chlorite, 

 treraolite, uralite, 

 sillimanite 



Epidote, felspar, 

 actinolite, topaz, 

 (juartz, sericite, 

 siUimanite 



Orthoelase, albite, 

 calcite, silli- 



manite, epidote, 

 chlorite 



Glaucophane and 

 epidote 



Lowest or Kata ") Alkali - fel - 

 middle Meso j spar-gneiss 

 (probably sedi- 

 mentogene) 



Meso (or kata) alu- 

 minous silicate 

 gneiss (probably 

 sedinientogeue) 



Kata (or meso) alu- 

 minous silicate 

 gneiss (sedimen- 

 logene) 



Lowest or 

 middle 



Lowest or 

 middle 



Upper 



Lowest or 

 middle 



Middle or 

 lowest 



Middle or 

 lowest 



Middle 



Middle or 

 upper 



Epi-orthoclase am- 

 phibolite, igneous 



Chlorite - meso- 

 amphibolite, 

 igneous 



Epidote - meso - am- 

 phibolite, igneous 



Epidote 



schist 



chlorite- 



Meso-albite-chlorite- 

 sillimanite-schist 



Glaucophane-schist 

 (meso or epi) 



The here presented arrangement of Mount Mee and other 

 rnetamoi-phic rocks under Grubenmann's system is only tentative, inas- 

 much as when I did my field work several years ago this system was 

 unknown to me, and I neglected to make many obsei-vations which I 

 would have made if the system had then been known to me. Never- 

 theless the utility of the classification shows clearly. By its means we 

 are able to approximate much more closely to the age of the Mount 

 Mee schists and granulites than we ever could before. We see clearly 

 that they are older than Gympie, for even many igneous rocks have 

 been completely metamorphosed in the middle and deepest zones, not 

 merely metasomatfsed by circulating waters in the upper zone, as is 

 the case with the Gympie rocks. We realise that some of the meta- 

 morphosed dykes like the greenstones (No. 4 in the list) were intruded 

 during re-emergence from the zone of flowage as they show only the 

 metamorphosis characteristic of the lower levels of the upper zone; 

 wliile dykes of igneous gneisses ecxist which were intriided before the 

 depression of the region into the zone of flowage. 



