PRE-CAMBRIAN LITERATURE OF NORTH AMERICA 645 



Cobalt series — Nearly flat-lying conglomerate with bowlders of granite and 

 syenite 

 Unconformity 

 Post Timiskaming intrusives — Granite, syenite, feldspar, porphyry, lampro- 



phyre 

 Intrusive contact 



Timiskaming series — Quartzite, graywacke, conglomerate with schistose 

 derivatives. The conglomerates contain a variety of 

 pebbles derived from the Keewatin 



Keewatin — Greenstone (basalt andesite) diabase, quartz porphyry, feldspar 

 porphyry, iron formation, dolomite 



Burrows' maps the Matachewan Gold area on Montreal River 

 in latitude 48. Below is the table of formations: 



Animikean-Cobalt series— Conglomerate, quartzite, graywacke, slate 



Unconformity 

 Algoman — Granite, syenite, and thin acid intrusives 



Intrusive contact 

 Laurentian — Granite and gneiss 

 Keewatin — Greenstones, iron formation, some quartzite, conglomerate, etc. 



Burrows^ classifies the pre-Cambrian rocks of the Porcupine 

 Gold area of Ontario as follows : 



Keweenawan — Quartz diabase, oUvine diabase 



Intrusive contact 

 Algoman — Granite porphyry, feldspar porphyry 



Intrusive contact 

 Pre-Algoman — Lamprophyre, serpentine quartz porphyry 



Intrusive contact 

 Timiskaming series — ^A series of schistose conglomerates, interbanded slate 

 and grayTvacke, quartzite "carbonate" rock 



Unconformity 



Keewatin — ^A couple of largely schistose basic to acid volcanics, agglomerates, 

 ash rocks, iron formation, rusty weathering, "carbonate," 

 diabase, serpentine, etc. 



The gold occurs in quartz veins cutting the Keewatin and 

 Timiskaming series and the pre-Keweenawan intrusives. They are 

 believed to be related genetically to the Algoman intrusives. 



' A. G. Burrows, "The Matachewan Gold Area," Ontario Bur. Mines, Ann. Kept., 

 Vol. XXVII (igi8), Part I, pp. 215-40, maps and illustrations. 



^ A. G. Burrows and P. E. Hopkms, "The Porcupine Gold Area" (Third Report), 

 Ontario Bur. Mines, Ann. Kept., Vol. XXIV, Part III (191 5), pp. 1-57, 44 figs, inclusive, 

 maps; see also ihid. (Second Report), Ontario Bur. Mines 21st Ami. Kept., Vol. XXI 

 (1912), pp. 205-49, 37 figs. 



