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Contact: FOR FURTHER PLEASE CONTACT: BY TELEPHONE: BY E-MAIL: INFORMATION ON The Reproduction of MNDMF Publication Local: (705) 670-5691 the EIP or Content Services Toll Free: 1-888-415-9845, ext. 5691 [email protected] (inside Canada, United States) The Purchase of MNDMF Publication Local: (705) 670-5691 MNDMF Publications Sales Toll Free: 1-888-415-9845, ext. 5691 [email protected] (inside Canada, United States) Crown Copyright Queen’s Printer Local: (416) 326-2678 Toll Free: 1-800-668-9938 [email protected] (inside Canada, United States) Ontario Department of Mines Geological Branch Open File Report 5001 Geology of the Black River Area 1967 ONTARIO DEPARTMENT OF MINES GEOLOGICAL BRANCH OPEN FILE REPORT No 5001 GEOLOGY OF THE BLACK RIVER AREA MARCH 1, 1©67 by V. G. Milne v6', GEOLOGICAL BRANCH ONTARIO PARLIAMENT BUILDINGS DEPARTMENT OF MINES TORONTO 2, ONTARIO Open-file Reports Open-file reports are made available to the public subject to certain conditions. Anyone using them shall be deemed to have agreed to these conditions which are as follows: This report is unedited. Discrepancies may occur for which the Department does not assume liability. Open-file copies may be read at the following places: The Library (Room 1433, Whitney Block), Department of Mines, Parliament Buildings, Toronto. The office of the Resident Geologist in whose district the area covered by this report is located. A report cannot be taken out of these offices. Handwritten notes and sketches may be made from it. This particular report is on file in the Resident Geologist's office located at: 179 South Algoma St. , Port Arthur pen-file reports cannot be handed out for office reading until a card, giving the name and address of the applicant, is filed with the Resident Geologist or Librarian. A copy of this report is available for inter- library loan. The Department cannot supply photocopies. Arrangements may be made for photocopying by an outside firm at the user's expense. The Librarian or Resident Geologist will supply information about these arrangements. The right to reproduce this report is reserved by the Ontario Department of Mines. Permis­ sion for other reproduction must be obtained in writing from the Director, Geological Branch. J. E. Thomson, Director, Geological Branch. ONTARIO DEPARTMENT OF MINES GEOLOGY OF THE BLACK RIVER AREA DISTRICT OF THUNDER BAY by V. G. Milne Geological Report No. 5001 Project 64-7 Table of Contents Abstract Introduction Prospecting and Mining Activity- Present Geological Survey Acknowledgments Previous Geological Work Topography Natural Resources General Geology Table of Formations Archean Mafic to Intermediate Metavolcanic Rocks Silicic to Intermediate Metavolcanic, Pyro and Metasedimentary Rocks Metasedimentary Rocks Mafic and Ultramafic Intrusive Rocks Metagabbro Serpentinized Peridotite Anorthositic Gneiss Mineralization Early Silicic Plutonic Rocks Late Silicic Plutonic Rocks Fourbay Lake Pluton Gowan Lake Pluton Bullring Lake Pluton Musher Lake Pluton Dotted Lake Batholith Silicic Dikes -// - Proterozoic Diabase Dikes 84 Pleistocene and Recent 88 Structural Geology 93 Folding 93 Faulting 100 Major Faults 101 Bullring Lake Fault 101 Phil Lake Fault 102 Pinegrove Lake Fault 102 Jenny Creek Fault 103 White Lake Fault 104 Other Faults 104 Economic Geology 107 Introduction 107 Stratigraphic Considerations in Mineral Exploration 108 Descriptions of Mineral Showings 111 Fairservice Occurrence(1) 111 Kusins Occurrence(2) 113 von Klein Occurrences(3) 115 Occurrence No. 1 116 Occurrence No. 2 116 Occurrence No. 3 117 Occurrence No. 4 118 Other Mineral Occurrences 120 Considerations in Future Exploration 122 Selected ZefccHCts /IS -///- FIGURES No. 1 - A hypothetical structural cross-section on a north- south line through the Black River and bordering areas to the north and south, (page 99) No. 2 - Plan of the pit locations and geological sketch map of the Kusins lead-zinc showing, (page 113) No. 3 - Surface geology and location of drill holes and electro­ magnetic anomalies on the von Klein property based on assessment work filed in 1962 by Mclntyre Porcupine Mines Ltd., O.D.M. File No. 63-1210. (page 116) No. 4 - Geological plan in the location of electromagnetic anomalous zone B (see Figure No. 3) with assay results of trench samples. Based on assessment work filed in 1962 by Mclntyre Porcupine Mines Ltd., O.D.M. File No. 63-1210. (page 118) No. 5 - Geological plan in the location of electromagnetic anomalous zone C (see Figure No. 3) with assay results of trench samples. Based on assessment work filed in 1962 by Mclntyre Porcupine Mines Ltd., O.D.M. File No. 1210. (page 118) "^ Illustrations are located at the rear of this report ABSTRACT The map-area covers approximately 600 square miles bounded on the east by the Pic River Area (Ontario Department of Mines, 196 ), on the north by the Manitouwadge Area (Ontario Department of Mines, 1957) and extending as far east as White Lake. The report describes the geology, structure and mineral showings and briefly discusses regional structure on the basis of information from this area and from the adjoining areas noted above. The consolidated rocks are all of Precambrian age but much of the area is blanketed by thick deposits of glaciolacustrine and glaciofluvial gravel, sand and clay of Pleistocene age. Within the map-area a mafic metavolcanic formation, which includes pillowed units, has been interpreted as the oldest formation. The mafic metavolcanic rocks appear to form the lowermost horizon of a gradational sequence, younging throughAa thin formation of s'l/iti't mixed a-oi-4 to intermediate metavolcanic rocks, pyroclastic rocks and minor metasediments,.into a thick succession of metasediments consisting essentially of conglomerate and greywacke. These rocks have been intruded by metagabbro, serpentinite and granodiorite gneiss and folded about east-northeast and north-northwest trending axes. The extrusive and sedimentary rocks have been regionally metamorphosed to amphibolite facies and metamorphism and folding are believed to have developed at catazonal level cogenetically with the intrusion of the granodiorite gneiss which forms a domical mass of batholithic dimensions. Subsequently these rocks were intruded by large plutons, some of batholithic size, composed of hornblende-biotite and biotite granodiorite and - Vttt - quartz monzonite. Finally all these formations were intruded by swarms of diabase dikes. Small showings of zinc and lead-zinc are present in the mafic metavolcanic rocks but of greater economic interest are 51 lie i e copper-nickel showings in the pyroclastic-acid- metavolcanic formation adjacent to the mafic metavolcanic unit.