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Ministry of Northern Development and Mines Ontario

Ontario Geological Survey Open File Report 5761

Regional Sedimentology and Paleoplacer Gold Potential of the Lorrain Formation, Huronian Supergroup, in the Cobalt Plain

1991

ONTARIO GEOLOGICAL SURVEY

Open File Report 5761

Regional Sedimentology and Paleoplacer Gold Potential of the Lorrain Formation, Huronian Supergroup, in the Cobalt Plain

by R. J. Rice

1991

Parts of this publication may be quoted if credit is given. It is recommended that reference to this publication be made in the following form: R.J. Rice 1991. Regional sedimentology and paleoplacer gold potential of the Lorrain Formation, Huronian Supergroup, in the Cobalt Plain; Ontario Geological Survey, Open File Report 5761, 118p.

CANADA Tnis project is part of the five-year Canada-Ontario 1985 Minerai Develop- ONTARIO ment Agreement (COMDA), a subsidiary agreement to the Economic and Mineral )evSmment Regional Development Agreement (ERDA) signed by the governments of Canada and Ontario.

)ueen©s Printer for Ontario, 199

Ontario Geological Survey

OPEN FILE REPORT

Open File Reports are made available to the public subject to the following conditions:

This report is unedited. Discrepancies may occur for which the Ontario Geological Survey does not assume liability. Recommendations and statements of opinions expressed are those of the author or authors and are not to be construed as statements of government policy. This Open File Report is available for viewing at the following locations: (1) Mines Library Ministry of Northern Development and Mines 8th floor, 77 Grenville Street Toronto, Ontario M7A 1W4 (2) The office of the Regional or Resident Geologist in whose district the area covered by this report is located. Copies of this report may be obtained at the user©s expense from a commercial printing house. For the address and instructions to order/ contact the appropriate Regional or Resident Geologist©s office(s) or the Mines Library. Microfiche copies (42x reduction) of this report are available for $2.00 each plus provincial sales tax at the Mines Library or the Public Information Centre, Ministry of Natural Resources, W-1640, 99 Wellesley Street West, Toronto. Handwritten notes and sketches may be made from this report. Check with the Mines Library or Regional/Resident Geologist©s office whether there is a copy of this report that may be borrowed. A copy of this report is available for Inter-Library loan. This report is available for viewing at the following Regional or Resident Geologist©s offices: Algonquin District, Box 190, Dorset POA 1EO Southwestern District, Box 5463, 659 Exeter Road, London N6A 4L6 Sudbury District, 200 Brady St., 6th Floor, Sudbury P3A 5W2 Cobalt District, Box 230, Presley Street, Cobalt POJ ICO Porcupine District, 60 Wilson Ave., Timmins P4N 2S7 The right to reproduce this report is reserved by the Ontario Ministry of Northern Development and Mines. Permission for other reproductions must be obtained in writing from the Director, Ontario Geological Survey.

V.G. Milne, Director Ontario Geological Survey

iii

V

CONTENTS

Abstract...... xix Introduction...... l Physiography...... 2 Access...... 3 Historical Background...... 4 Previous Provincial and Federal Geological Survey Investigations...... 5 Present Investigation...... 7 Acknowledgements...... 10 Regional Geological Setting...... 11 Stratigraphic Setting...... 11 Structural Setting...... 12 Large Scale Tectonic Setting...... 13 Sedimentology of the Lorrain Formation...... 16 Lithologic Analysis...... 16 Basal Member...... 16 Facies Description...... 16 Middle Member...... 21 Facies Description...... 21 Upper Member...... 24 Facies Description...... 24 Environment of Deposition...... 27 Basal Member...... 30 Middle and Upper Member...... 43 Paleocurrent Analysis...... 46 Evaluation of Paleoplacer Gold Potential...... 47 Recommendations for Future Study...... 52 References...... 54 Appendix A...... 68 Appendix B...... 91 Conversion Table...... 118 Figures Figure l Location Map...... xxiv Figure 2a Origin of Finer Grained Arenite Association in a Siliciclastic Shelf Environment...... 107 Figure 2b Origin of Finer Grained Arenite Association in a Siliciclastic Shelf Environment...... 108 Figure 2c Origin of Finer Grained Arenite Associations in a Siliciclastic Shelf Environment...... 109 Figure 2d Origin of Finer Grained Arenite Association in a Siliciclastic Shelf Environment...... 110 Figure 3 Schematic Representation of Episodic Transgression During Basal, and Possibly Middle and Upper, Lorrain Formation Time...... 111

Vll Figure 4 Detrital vs Diagenetic Modes, Lorrain FM. 112 Figure 5 Station Locations in the Basal, Middle and Upper Members of the Lorrain Formation in the Cobalt Plain .back pocket Figure 6 Paleocurrent Data Recovered From the Lorrain Formation in the Cobalt Plain back pocket Photos Photo l Characteristic lithofacies sequence in the basal member of the Lorrain Formation in southwestern Auld Township...... 113 Photo 2 Characteristic lithofacies sequence of the middle member arenite in the Lorrain Formation as displayed in outcrop on Chiniguchi Lake, Mcconnell Township...... 114 Photo 3 The lithofacies sequence characteristic of the upper member of the Lorrain Formation as displayed in outcrop on southern Makobe Lake, McGiffin Township...... 115 Clay drapes (arrows) accentuating trough-shaped foresets in the middle member arenite of the Lorrain Formation exposed on the western shore of central Lorrain Lake in South Lorrain Township...... 116 Photo 5 Photomicrograph of a sample (46/2) from the coarser-grained arenite association in the middle member of the Lorrain Formation in northwestern Willet Township showing a partially silicified plagioclase feldspar grain (Fp) surrounded by monocrystalline quartz grains (Qm) of approximately equal size...... 117

IX

List of Figures Figure 1. Location map of the study area in the Cobalt Plain of the Southern Province. The regions investigated during each of the three field seasons (1986, 1987, 1988) are distinguished. Figures 2a d. A four-stage block diagram representation of the formation and preservation of lenses of the finer-grained arenite association in a siliciclastic shelf setting. Figure 3. Schematic representation of an episodic transgression suggested to be the principal control over sedimentation during basal member time of the Lorrain Formation. Frequent stillstands alternating with marine innundations are suggested to account for the deposition of hundreds of meters of immature detritus in a shallow siliciclastic shelf setting. Preliminary petrologic studies suggest that this transgressive environment was maintained during the deposition of the sediments of the middle and upper members of the Lorrain Formation. Figure 4. QFL ternary diagram presenting preliminary petrographic data on the Lorrain Formation in the Cobalt Plain. Differing detrital (triangles) and diagenetic (squares) modes for the same samples suggests that the upward increase in compositional maturity displayed by the formation may only be apparent and attributable to burial diagenesis. Samples 4, 5, 7, 8, 10 are from the basal

XI member arenite; l, 2, 3, 9 are from the middle member arenite, and sample 6 represents the upper member arenite. Figure 5. (pocket) Station location map for the study area within the Cobalt Plain of east-central Ontario. Station locations in the basal (squares), middle (triangles), and upper (diamonds) members of the Lorrain Formation are annotated with selected lithologic information. Figure 6. (pocket) Paleocurrent data from the Lorrain Formation in the Cobalt Plain. Number besides arrows indicates number of measurements from which mean value was obtained. (No number: one measurement only).

List of Tables Table l; Ontario Geological Survey publications (1891-1988) dealing with the Lorrain Formation in the Cobalt Plain. Table 2. Descriptive attributes of lithofacies defined in the basal member of the Lorrain Formation in the Cobalt Plain. Table 3. Descriptive attributes of lithofacies defined in the middle member of the Lorrain Formation in the Cobalt Plain. Table 4. Descriptive attributes of lithofacies defined in the upper member of the Lorrain Formation in the Cobalt Plain. Table 5. (Appendix B) Major element analyses from the basal member arenite of the Lorrain Formation in the Cobalt Plain (1986 and 1987 data only). Table 6. (Appendix B)

Kill

Major element analyses from the basal member arenite of the Lorrain Formation in the Cobalt Plain (1986 and 1987 data only). Table 6. (Appendix B) Trace element analyses from the basal member arenite of the Lorrain Formation in the Cobalt Plain (1986 and 1987 data only). Table 7. (Appendix B) Major element analyses from the middle member arenite of the Lorrain Formation in the Cobalt Plain (1986 and 1987 data only) Table 8. (Appendix B) Trace element analyses from the middle member arenite of the Lorrain Formation in the Cobalt Plain (1986 and 1987 data only). Table 9. (Appendix B) Major element analyses from the upper member arenite of the Lorrain Formation in the Cobalt Plain (1986 and 1987 data only). Table 10. (Appendix B) Trace element analyses from the upper member arenite of the Lorrain Formation in the Cobalt Plain (1986 and 1987 data only).

List of Photographs

Photo 1. The characteristic lithofacies sequence in the basal member of the Lorrain Formation in southwestern Auld Township. Finer- grained arenite lenses (fga) gradationally cap crudely tabular coarser-grained arenite bodies (cga) and are erosively succeeded by similar coarser-grained arenite units. A similar lithofacies sequence exists in the middle and upper members of the formation (see Photos 2 and 3). Large symmetrical waveforms (sw) occur

XV along the upper contact of the finer-grained arenite lenses suggesting wave reworking of these surfaces. Nine centimeter scale. Photo 2. The characteristic lithofacies sequence of the middle member arenite in the Lorrain Formation as displayed in outcrop on Chiniguchi Lake, Mcconnell Township. The darker colored, recessive weathering units (arrows) are finer-grained arenite lenses separating lighter weathering, coarser-grained arenite bodies. This lithofacies sequence is also found in the basal and upper members of the formation (see Photos l and 3). The top recessive horizon is ea. 45 cm thick. Photo 3. The lithofacies sequence characteristic of the upper member of the Lorrain Formation as displayed in outcrop on southern Makobe Lake, McGiffin Township. Tabular, coarser-grained arenite bodies (cga) are separated by recessive horizons of finer-grained arenite (fga). This sequence also characterizes the basal and middle members of the formation (see Photos l and 2). Photo 4. Clay drapes (arrows) accentuating trough-shaped foresets in the middle member arenite of the Lorrain Formation exposed on the western shore of central Lorrain Lake in South Lorrain Township. Nine centimeter scale with arrow pointing in the upstream direction. Photo 5.

XV11

Photomicrograph of a coarser-grained arenite from the middle member of the Lorrain Formation in northwestern Willet Township showing a partially silicified plagioclase grain (Fp) surrounded by monocrystalline quartz grains (Qm) of approximately equal size. The near equivalence in size of feldspar and quartz suggests recylcling of quartz. Crossed polarizers, length of photograph is 1.1 mm.

XIX

Abstract The Early Proterozoic Lorrain Formation in the Cobalt Plain of east-central Ontario consists overwhelmingly of arenite. Except in Lorrain Township, on the eastern margin of the Cobalt Plain, conglomerate exists only as relatively common, thin (cm - 10©s cm), quartz-granule/pebble-rich lenses in the coarser- grained arenites. In Lorrain Township, a basal Lorrain conglomerate, approximately up to 150 m thick, lies transitionally between granitic basement and overlying basal member arenites. The basal conglomerate is interpreted to represent debris flow and stream flow deposition in a proximal to intermediate position on a basin marginal alluvial fan(s). Lorrain Formation arenites display an upward increasing compositional maturity from feldspar-rich basal member arenites to quartz-rich upper member arenites. Preliminary petrographic data indicate that the increasing compositional maturity is attributable to burial diagenetic purging of the more labile feldspar grains. Finer-grained (minor) and coarser-grained (dominant) arenite facies associations are identified. These facies associations present a consistent lithofacies sequence throughout the Cobalt Plain regardless of stratigraphic position. The finer-grained arenite association is the key to the understanding of the depositional environment as the coarser-grained association contains non-diagnostic sedimentary features. The interpretation of the finer-grained arenite association is equivocal. Regional stratigraphic and tectonic constraints, however, combined with

XXI some sedimentological features found in the association allow some degree of paleoenvironmental interpretation. The author favours a marine (siliciclastic shelf) rather than a fluvial (sandy braid-plain) paleoenvironment for the Lorrain Formation. A marine transgressive regime with several stillstands is proposed as a mechanism to account for the compositional immaturity of the detritus. Assuming that gold placers were present in the coastal braid-plain, the critical aspect of the episodic transgression hypothesis, with respect to the possible preservation of such placers during periods of reworking by shelf currents, is the depth of erosion relative to the amount of aggradation that occurred during preceding braid-plain progradation. Even a best case scenario of partial preservation of a braid-plain fabric might not result in reasoned expiration for paleoplacer mineralization as abraid-plain lithofacies sequence is not necessarily distinctive from that formed on a siliclastic shelf. Geochemical analyses for gold (Au) (1986, 1987), predominantly of arenites, not conglomerates, returned low values ranging from 2-13 parts per billion (ppb).

REGIONAL SEDIMENTOLOGY AND PALEOPLACER GOLD POTENTIAL OF THE LORRAIN FORMATION, HURONIAN SUPERGROUP, IN THE COBALT PLAIN

BY

R. J. RICE1

1991

Geologist, Precambrian Geology Section, Ontario Geological Survey.

Approved for publication by B.O. Dressler, Acting Chief Geologist, Precambrian Geology Section, Ontario Geological Survey, May, 1990. This report is published with the permission of V.G. Milne, Director, Ontario Geological Survey.

XXIV

Figure 1. Locadon map of the study area in the Cobalt Plain of east-central Ontario. Regions investigated during the 1986,1987, and 1988 field seasons are distinguished.

Introduction This report presents the results of an investigation of the depositional environments and the paleoplacer gold potential of the Early Proterozoic Lorrain Formation in the Cobalt Plain of east-central Ontario (Figure 1). The Cobalt Plain is the easternmost tectonic subdivision of the Southern Province, a structural division of the southern Canadian Shield (Card et al. , 1972). The Southern Province consists of Proterozoic sedimentary and volcanic rocks/ their Archean basement, and younger Proterozoic felsic and mafic intrusions (Card et al., 1972). It is bounded by the Superior Province to the north and the Grenville Province to the south. The supracrustal rocks of the Southern Province extend ea. 1300 km between Minnesota, U.S.A. and the Cobalt-Noranda region of Ontario and Quebec (Card et al., 1972). The Early Proterozoic Lorrain Formation of the upper (Cobalt Group) Huronian Supergroup is found throughout that part of the Southern Province lying in Ontario and Quebec, and has correlative units in the Chocolay Group of the Marquette Range in Michigan (Young, 1983). In the Sault Ste Marie-Blind River region, the westernmost portion of the Penokean Foldbelt (another tectonic subdivision of the Southern Province (Card et al., 1972)) in Ontario, the formation is up to ea. 2500 m thick (Hadley, 1968) and has not been regionally metamorphosed beyond lower greenschist grade (Card et al., 1972). In the Sudbury- Espanola region, the easternmost portion of the Penokean Foldbelt, the formation ranges between 1500-2400 m in thickness (Card et al., 1977) and, in places, has been regionally metamorphosed to amphibolite grade (Card et al., 1972). In the Cobalt Plain the formation reaches a maximum thickness of ea. 2500 m and ranges between low to middle greenschist metamorphic grade in the southwest, to sub-greenschist grade throughout the remainder of this area (Meyn, 1973, Sims et al., 1981). In May, 1986, a three year project was started by the Ontario Geological Survey to evaluate the paleoplacer gold potential of the Lorrain Formation throughout the Cobalt Plain. The study was prompted by anomalous gold values (up to 1.2 parts per million) found in hematitic sandstone and quartz pebble conglomerate lithofacies in the northwest portion of the Cobalt Plain (Colvine 1981, 1983). To facilitate this evaluation, a regional sedimentologic study of the formation was undertaken by the author to determine the depositional environments in which Lorrain detritus accumulated. Physiography Topography throughout the Cobalt Plain is low to moderate. The study area lies within a region that is crudely delineated by a number of the larger lakes: to the north, Elk Lake, at an elevation of ea. 283 m, and Gowganda Lake (at Gowganda) at ea. 343 m; to the west, Welcome Lake at ea. 396 m; to the south, Wanapitei Lake at ea. 267 m; to the southeast and east, Lake Temagami (near Temagami) at ea. 293 m, and Lake Timiskaming (at New Liskeard) at ea. 175 m, respectively. Relief increases in the west-central portion of the region in the area of Ishpatina Ridge, in Corley and Ellis Townships. Ishpatina Ridge is one of the highest points in Ontario, at an approximate elevation of 700 m. A maximum relief of ea. 525 m occurs between Ishpatina Ridge and Lake Timiskaming. Three major rivers occur in the study area. The largest is the Montreal River, flowing northwest-southeast through the eastern portion of the study area. The Lady Evelyn and Wanapitei rivers are smaller, the former flowing northwest-southeast in the central region of the study area, emptying into Lady Evelyn Lake, and the latter flowing northwest-southeast along the western boundary of the study area, emptying into Wanapitei Lake. Additional large lakes in the study area are Longpoint Lake in the north, Chiniguchi Lake in the south, Rabbit Lake in th©e southeast, Anima Nipissing Lake in the east, Lady Evelyn Lake in the east-central region, and Smoothwater, Makobe, and Florence lakes in the central region. Outcrop density in the bush is poor to moderate throughout the study area; the best outcrops occur along fault scarps. In general, outcrop density is poorest in the western region of the study area where there is thick and extensive glacial deposits. Good outcrops occur along the margins of the larger lakes, in particular, Welcome, Makobe, Chiniguchi, Florence, Lady Evelyn, Rabbit, Rib, Blueberry, Sunrise, and Lorrain lakes. Highway 560, running across the northern margin of the study area, provides excellent exposures of the basal Lorrain Formation, as well as several exposures of the contact with the underlying Gowganda Formation.

Access There is moderate access throughout the study area owing to a combination of paved highways, forest access roads, past and current logging roads, power-line roads, and the larger lakes and rivers. Access is worst in the south-central region involving Selkirk, Dundee, and Acadia townships. Floatplanes for easy access to southern and eastern parts of the study area can be rented at Longpoint Lake and in Temagami. Historical Background And Previous Provincial And Federal Geological Survey Investigations In The Cobalt Plain Involving The Lorrain Formation Historical Background What is now the Lorrain Formation, in the Sault Ste. Marie- Blind River area, appears to have been first described by Bigsby (1821, cited in Frarey, 1977). In the Cobalt Plain, near Lake Timiskaming, the formation was initially inspected by W.E. Logan (1847, cited in Frarey, in prep.). The formation was named by W.G. Miller (Miller and Knight, 1906, cited in Frarey, in prep.), the original locality being in Lorrain Township, on the west shore of Lake Timiskaming, south of the Town of Cobalt. The stratigraphy of the Lorrain Formation was first delineated in the Bruce Mines region of Ontario by Murray (1859, cited in Frarey, in prep.) who divided the formation into three units, each of formation rank. Collins (1925, cited in Frarey, 1977) rejected the formation status assigned to these units, considering them to be informal members in a single formation. Two type sections have been defined for the Lorrain Formation, one near Bruce Mines (Frarey, 1977) and the second near Whitefish Falls (Card, 1976) southwest of Sudbury. At both type sections the formation was partitioned into six (6) informal lithostratigraphic members, although they differed between these two locations. Previous Provincial and Federal Geological Survey Investigations This literature search deals principally with prior geological work by the Ontario Geological Survey. While federal (GSC), large scale / mapping projects have been included, an extensive search of publications of the Geological Survey of Canada has not been conducted. Similarly, journal publications and thesis were not included in the search; the volume of this type of literature is expected to be very small, as the author is unaware of any journal papers dealing exclusively with the Lorrain Formation. The interested reader should refer to Junnila (1987) for this literature. Previous geological survey investigations in the Cobalt Plain, involving the Lorrain Formation, can be separated into large scale regional mapping projects and smaller scale projects. A large provincial survey literature exists wherein the Lorrain Formation was examined as part of a fairly small exercise, often a mapping project involving only several townships. Large Scale Mapping Projects Two large scale mapping projects involving the Lorrain Formation in the Cobalt Plain have occurred: 1) Collins (1917) spent three seasons (1908-1910 or 1909- 1911; this is unclear from his report) mapping the Onaping Map- Area, which overlaps approximately the western half of the present study area. Collins© description (p. 71-72) of the Lorrain Formation is brief. The basal part of the formation is described as being highly feldspathic, consisting of quartz, feldspar (mainly alkali feldspar), and occasional mica. Collins (p. 71) felt that it had been subjected to vigorous mechanical breakdown and brief transportation. The middle portion of the formation is described as a less feldspathic quartzite with thin beds of conglomerate. The amount of conglomerate relative to the quartzite was small, ea. 5!?), and conglomerate lenses did not exceed three feet in thickness. The upper portion of the formation lacked conglomerate, and is described as a light grey, compositionally more mature (feldspar impoverished) quartzite. 2) The most recent large scale mapping project in the Cobalt Plain, involving the Lorrain Formation, was that conducted by Card et al. (1973; Operation Maple Mountain). The area covered by this mapping project overlapped the eastern half of Collins© Onaping Map-Area and represents roughly 70 ife of the study area of this report. The Lorrain Formation, in this region, was reported as transitionally overlying the Gowganda Formation. It was divided into seven lithostratigraphic members which, overall, indicated an upward increase in maturity. The basal Lorrain Formation was suggested to represent fluvial deposition, while the upper, more mature members, were considered to have been reworked in a shallow epicontinental sea. Smaller Scale Projects Table l contains prior publications of the Ontario Geological Survey in which the Lorrain Formation in the Cobalt Plain is involved. The depth of investigation has been classified as either a mention brief discussion, or discussion. This table covers the period 1891-1988. Present Investigation The investigation reported on herein deals with the depositional environments and paleoplacer gold potential of the Lorrain Formation of the Huronian Supergroup in the Cobalt Plain of east-central Ontario (Figure 1). A similar study of the Lorrain Formation has recently been completed in the Sault Ste. Marie - Elliot Lake region of the Penokean Foldbelt (Lowey, 1985). Interest in the formation as a host for paleoplacer gold mineralization in the Cobalt Plain stems from the report of gold values, up to 1.2 ppm, in a hematitic quartz pebble conglomerate lithofacies in the northwestern portion of the Cobalt Plain (Colvine, 1981, 1983). In the context of the greenstone belt gold camps lying north of the Cobalt Plain, and the southerly preferred orientation of Lorrain Formation paleocurrent data in the Cobalt Plain, these anomalous gold values were considered to warrant further investigation. Although a paleoplacer interpretation of the gold bearing reefs of the South African Witwatersrand gold field remains controversial, the possibility was considered that the Lorrain Formation might contain similar "reefs".

The objective of this study was to locate anomalous gold occurrences in the Lorrain Formation in the Cobalt Plain and to relate these to one, or an assemblage, of sedimentary attributes which might then be utilized as an exploration tool. 8

The depositional setting and the paleoenvironmental interpretation of the Lorrain Formation have been, and continue to be, controversial, with the argument centering on a fluvial versus a marine interpretation. This distinction is critical with respect to the likelihood of encountering economic accumulations of a heavy mineral such as gold. In-channel fluvial depositional settings are highly suited to the concentration of heavy minerals. Channels have a restricted areal extent and variable strength, unidirectional currents which tend to concentrate the largest and/or densest detritus as a lag along the channel talweg. A beach is also favorable for the concentration of heavy minerals due to the constant reworking of the sediment by swash and breaking waves. An open shelf setting, however, is not as conducive to the concentration of economic accumulations of heavy minerals due to the dispersive effect of a number of interacting current regimes such as, intruding ocean currents, tidal currents, meterological currents and density currents (Johnson and Baldwin, 1986). However, heavy mineral accumulations can form in open marine environments as a result of storm reworking of the seabed (Aitchison, 1988); in such settings hummocky cross-stratified strata and associated gravel lags would be the preferred exploration targets. Heavy mineral accumulations can also form in more restricted marine settings, also a result of storm reworking (Emory-Moore et al., 1988, Hein and Syvitski, 1988). The importance of determining the depositional environment(s) led to the project being conducted as a regional sedimentologic evaluation of the Lorrain Formation, as opposed to simply locating and sampling conglomerate horizons or sites of heavy mineral accumulation. During the course of this three-year study (1986, 1987, 1988) the Lorrain Formation was examined in sixty-eight townships of the Cobalt Plain (Figure 1). As a result, during a field season usually only two to three days per township could be allotted to the examination of the formation^ Examination of the best and/or the most accessible exposures was given priority. These locations were determined through the examination of aerial photographs at the beginning of each field season. Detailed sedimentologic data could not be obtained at many exposures due to time constraints. In the course of conducting this regional study the best exposures have been located in the basal, middle and upper members of the formation. The logical next step in the determination of depositional conditions would be very detailed work at these and other key localities in the Cobalt Plain. The assessment of the likelihood of the Lorrain Formation to host economic paleoplacer gold mineralization is based on the regional sedimentologic work reported on herein. A two-man crew spent the months of June, July, and August in the field for each of 1986, 1987, and 1988. The northern portion of the Cobalt Plain was investigated during the 1986 field season, the central portion during the 1987 field season, and the southeastern and southern outliers of the formation during the 1988 field season. During this project outcrop examination combined mapping and section measuring, the choice depending on outcrop type, quality, time, and available equipment. 160 10

localities, including 19 stratigraphic sections were examined during the course of this project. Section thickness ranged from 8.3 to 71 m. Sections were measured in all three members of the Lorrain Formation wherever suitable, and safely workable, exposures were encountered. The best stratigraphic sections in the Cobalt Plain are commonly fault scarps. However, many of these are often unsafe for free climbing resulting in either poor data or no data. Climbing ropes were used during the 1988 season which resulted in all sections of fifty meters or less being safely workable. Geochemical analyses in this report represent the work of the Geoscience Laboratories, Ontario Geological Survey. Acknowledgements Leo Burns (1986), Derrick Watson (1987), and John Burton (1988) were the very capable and enthusiastic field assistants for this project. The project was conceived by Sandy Colvine, Chief Geologist, Precambrian Geology Section, Ontario Geological Survey. Leo Owsiacki, resident geologist, Cobalt, Wilf Meyer, resident geologist, Sudbury, and John Wood, regional director, northwestern region, Kenora, are thanked for their continued interest and advice over the duration of this study. Don Phipps (geologist, INCO Limited) is thanked for his co-operation in allowing the examination of drill core. Darrel Long, Laurentian University, Rob Rainbird, University of Western Ontario, and Brian Rust, Geoff Burbidge, and Mike Hitch, University of Ottawa are thanked for their stimulating discussions at different stages of the project. Peter Born and Andy Fyon, (geologists, Ontario 11

Geological Survey), also provided interesting discussions on the Lorrain Formation at various stages of the work. Regional Geological Setting Stratigraphic Setting Huronian stratigraphy in the Cobalt Plain has been reviewed by Card et al. (1972) from which some of the following summary has been taken. The Huronian Supergroup of the Southern Province contains twelve formations and has been formally partitioned into four groups - Elliot Lake, Hough Lake, Quirke Lake, and Cobalt (Robertson et al., 1969). The contacts between the groups are conformable to disconformable/unconformable (Card et al., 1972). The Cobalt Group is the most areally extensive of the four. The group is 3300 - 3900 m thick in the Cobalt Plain. In ascending stratigraphic order, the constituent formations of the Cobalt Group are: Gowganda Formation, Lorrain Formation, Gordon Lake Formation, Bar River Formation. The basal unit throughout the Cobalt Plain is commonly the Gowganda Formation, however, locally it is missing and the Lorrain Formation can be found nonconformably overlying basement. In the southern Cobalt Plain formations of the Hough Lake and Quirke Lake groups also occur. The contacts amongst the formations of the Cobalt Group are conformable and transitional to sharp. Locally, the Gowganda- Lorrain contact displays evidence of erosion. The Gowganda Formation in the Cobalt Plain consists of two members, a lower, glacigenic, Coleman Member, and an upper, non-glacial, Firstbrook Member (Rainbird, 1985). The Lorrain Formation commonly 12 transitionally overlies the Firstbrook Member, however, this member is not always present/ and where absent the Lorrain Formation sharply overlies the Coleman Member. The Lorrain Formation in the Cobalt Plain reaches a maximum thickness of ea. 2500 m (Meyn, 1973). Two major mapping projects partially cover the study area of this report. Collins© (1917) Onaping map area includes nearly all of the western portion of the Cobalt Plain, and as such overlaps with the western region of the study area of this project. Collins recognized three, principally compositional, subdivisions of the formation: a basal feldspathic arenite, a middle less feldspathic arenite and conglomerate, and an upper, feldspar impoverished, arenite to quartz arenite. As a result of mapping in the central region of the Cobalt Plain, Card et al., (1973), found the formation to be divisible into seven lithostratigraphic members of variable thickness ranging from several hundred to several thousand feet. For the purpose of this regional study the members defined by Card et al. (1973) were found to be very difficult to objectively discriminate in the field. For this reason, the simpler, three-fold, informal division of the formation used by Collins (1917) was adopted. Structural Setting The structural geology of the Cobalt Plain has been summarized by Card et al. (1972) from which most of the following has been taken. A significant disparity exists between the western and eastern portions of the Cobalt Plain with respect to the severity 13 of diastrophism. In the east, substantial deformation exists only adjacent to major faults, whereas the western and southern regions exhibit a more complex structural style possibly attributable to block faulting and, in places, folding. Two compressional events are indicated in the west by major north-south trending fold axes intersected by east-west fold axes. The result is doubly-plunging antiforms and synforms. Two major fault systems have affected the Cobalt Plain. In the west, the north-northwest trending Onaping Fault System formed prior to deposition of the Huronian, as normal faults. Movement continued on these faults after Huronian deposition but was of a reverse nature. In the east, the Cobalt Plain is affected by the northwest trending Timiskaming Fault System. Although some authors (Kumarapeli and Saull, 1966) have suggested that the Timiskaming Faults are Phanerozoic, being associated with the St. Lawrence Valley rift structure, the presence of alluvial fan lithofacies adjacent to the faults in Lorrain Township (reported herein) indicates that they are at least Early Proterozoic in age, and could only have been reactivated in the Phanerozoic. Smaller north, northeast, and east-west trending faults are also present in addition to the two major fault systems. Large Scale Tectonic Setting Plate tectonic models for Early Proterozoic sedimentary rocks of the Southern Province commonly tend to partition the sediments into two geographic regions: 1) the Lake Superior region, which includes the Animikie Group at the west end of Lake 14

Superior in USA and Canada , and the Marquette Range Supergroup, south of Lake Superior / in Wisconsin and Michigan and 2) the Lake Huron region which includes the Huronian Supergroup exposed roughly between Sault Ste. Marie in the west and the Sudbury- Espanola area in the east. Although the Cobalt Plain is commonly incorporated in figures accompanying these interpretations/ it is apparent that the plate tectonic models are intended only for the Penokean Foldbelt of the Lake Superior region and the Huronian Supergroup along the north shore of Lake Huron. The models discussed subsequently do not address their applicability to the Cobalt Plain, whose roughly orthogonal orientation to the strike of the Huronian belt between Sault Ste. Marie and Sudbury would suggest that it should be treated as a distinct tectonic entity. No consensus exists regarding the plate tectonic setting of the Huronian Supergroup and the Penokean Foldbelt. The Penokean Foldbelt is commonly/ and also here/ considered to include the Huronian Supergroup in Ontario. Four plate tectonic models exist in the literature: 1) aulacogen 2) passive margin setting following a continent-continent collision 3) active margin setting with an arc-continent collision and either a north or south dipping subduction zone 4) intracratonic. The Huronian was initially suggested by Dietz and Holden (1966) to represent a miogeoclinal sequence. Van Schmus (1976), basing his interpretation on the Lake Superior region/ was the first of several authors to suggest that the Penokean Foldbelt constituted an arc-continent orogen; his subduction zone was dipping to the north. Cambray (1978) and Larue and Sloss (1980) also proposed 15 an arc-continent collision for the Penokean Foldbelt of the Lake Superior region. Sims et al. (1980, 1981) defined the Great Lakes Tectonic Zone (GLTZ) as a major, long-lived, crustal fracture. Upon finding no evidence of oceanic crust during any extensional event along the GLTZ, they concluded that the Early Proterozoic of the Lake Superior and Lake Huron regions represented wholly intracratonic deposition and orogenesis. Larue and Ueng (1982) and Larue (1983) suggested that the Lake Superior region of the Penokean Foldbelt exemplified an arc- continent collision with a southward dipping subduction zone. They interpreted the Penokean of Wisconsin and Michigan to constitute a collage of tectono-stratigraphic terranes as a result of post-collisional transcurrent faulting of miogeoclinal and magmatic arc sequences. Young (L983) relied heavily on paleocurrent data in proposing that the Penokean Foldbelt of the Lake Huron and Lake Superior regions represented an aulacogen, and in so doing, drew a strong analogy with the Athapuscow aulacogen of Hoffman (1980). In this model, the bulk of the Huronian marine deposition is suggested to have occurred in an area now occupied by the northwestern Grenville Province. Zolnai et al. (1984) have proposed the only passive margin, continent- continent collisional model for the Penokean Foldbelt. They based their model on structural cross-sections in the Sault Ste. Marie-Sudbury region and tentatively suggested that, based on chronologic, stratigraphic, and structural grounds, the Lake Superior and Lake Huron regions of the foldbelt may constitute 16 two crustal blocks that experienced similar, but not equivalent, depositional histories. Sedimentology of the Lorrain Formation Lithologic Analysis Basal Member Exposures of the basal member of the Lorrain Formation are most plentiful in the northern portion of the Cobalt Plain, the best occurring along Highway 560 between the towns of Elk Lake and Gowganda. The following lithologic analysis derives principally from observations made in this region supplemented with a smaller number of observations made in the central and eastern regions of the Cobalt Plain. Stratigraphic sections (1) measured in the basal member of the Lorrain Formation are presented in Appendix A. Facies Description The basal member of the Lorrain Formation is composed of two main lithofacies, arenite and conglomerate. While the former is found wherever basal member exposures occur, the latter was observed only in Lorrain Township, in the eastern region of the Cobalt Plain. Facies l - Conglomerate A conglomerate facies was described from the basal member of the Lorrain Formation in Lorrain Township by Lovell and de Grijs (1976). This facies was observed by the author at the granitic basement - Lorrain contact at widely spaced localities and thus appears to have considerable areal extent in Lorrain Township. 17

The conglomerate is predominantly clast supported, but displays local matrix support. The percentage of matrix varies considerably, averaging ea. lS-20%. Matrix in the conglomerate is a pale green weathering/ commonly poorly sorted, fine- to very coarse-grained feldspathic arenite. Clasts are nearly always sub-round to well-rounded, ranging in size from pebbles to boulders. Clast shape is predominantly sub-equant. The conglomerate is polymictic. Four lithic clast types were recognized near Paradis Bay in the northern region of the township; in descending order of abundance they are: 1. Pink weathering granitic clasts ranging from pebble to boulder size; these are round to well-rounded, commonly have diffuse boundaries with the adjacent matrix, occasionally display weathering rinds, and are much more abundant than all other clast types combined. 2. Pale tan to greenish weathering, fine-to medium-grained feldspathic arenite clasts; these are commonly in the pebble to cobble size range and are usually sub-round to round. 3. Maroon weathering, sub-angular to well-rounded siltstone clasts commonly in the pebble size range (siltstone of the Firstbrook Member of the Gowganda Formation ?). 4. Black, locally greenish weathering, sub-round to round ultramafic volcanic clasts commonly in the pebble size range. While the diversity of clast types is not as obvious at other localities, granitic lithics remain dominant. Very little organization is displayed by the conglomerate. Clast grading and imbrication are absent. Occasional lenses 18

(10©s cm long and ea. 5-20 cm thick), and thicker horizons (several tens of centimetres thick) of matrix were observed, rarely displaying heavy mineral accentuated laminae and rippling. Near Paradis Bay, the contact between the conglomerate and overlying arenites is inferred to be gradational and conformable based on the presence of a transitional arenite containing lenses and horizons of pebble size granitic lithics. The conglomerate is transitional downward into a zone of weathered granitic basement. Only a non-stratified conglomerate facies (la) is recognized (Table 2). Facies 2 - Arenite Basal member arenites in the Lorrain Formation are characteristically pink- to grey-weathering, occasionally pale green-weathering. Sorting is usually only moderate, but ranges from poorly- to well-sorted. Estimated average grain size is also variable and is a function of whether the Lorrain is overlying the Firstbrook Member of the Gowganda Formation, the Coleman Member of the Gowganda Formation, or the basal conglomerate of the Lorrain Formation. It is characteristically fine-grained when overlying the Firstbrook, coarse- to very coarse-grained when above the Coleman, and a pebbly arenite when transitional from an underlying conglomerate lithofacies. However, regardless of the characteristic grain size, basal member arenites throughout the Cobalt Plain also contain common thin lenses or horizons of pale green-weathering, very fine grained, slightly micaceous arenite. These lenses or horizons of 19 very fine-grained arenite are found separating coarser-grained units (Photo 1). Their basal contact with the underlying coarser-grained unit is characteristically transitional while their upper contact with the overlying unit is characteristically erosional, however, both contacts can be either transitional or erosional. Commonly, the very fine-grained arenite units are missing through the erosional amalgamation of the overlying and underlying coarser-grained units. Lenses of very fine-grained arenite are several meters to several tens of meters in length and several centimeters to several tens of centimeters in thickness. Coarser-grained units characteristically range from several tens of centimeters to several meters in thickness. Coarser-grained bodies are commonly crudely tabular in geometry. The coarser-grained basal member arenites in the Lorrain Formation always contain significant amounts of predominantly alkali feldspar. In this respect they are compositionally distinct from middle and upper member arenites which invariably show progressively less feldspar content. While all exposures of the basal member arenite contain sedimentary structures, significant portions of numerous outcrop are non-stratified. No representative vertical sequence of sedimentary structures is apparent in the coarser-grained basal member arenite units. The more common sedimentary features in these units are laminae and ripple cross-laminae (asymmetrical and symmetrical) often accentuated by heavy minerals; granule to pebble lags as isolated clasts or accumulations in pockets, lenses, and horizons commonly several centimeters or less thick 20

(quartz, feldspar, occasionally granite, jaspilite, arenite or siltstone lithics, pyrite clasts); variably well-defined normally graded units usually 5 - 20 cm thick, occasionally occurring stacked in intervals ea. 50 cm thick; large scale planar tabular and trough cross-stratification (laminae and bedding) usually 10©s cm thick but occasionally reaching 1-2 m in thickness; and rare occurrences of convolute lamination accentuated by heavy minerals. Cross-stratification in the coarser-grained bodies commonly displays perpendicular-normal foreset grading and rarely, clay drapes (single and multiple). Several instances of possible chevron sets were recorded, but as measurement was impossible confirmation could not be obtained. Occasional exposures appeared to represent compound bedforms. These outcrop display several scales of cross-stratification eaclj suggesting differing paleoflow directions. Scour surfaces representing the migration of small scale bedforms are plentiful, and commonly display lags, however, larger scours, ie. scours on the order of meters, are rare in the basal member arenite. Very fine-grained arenite units in the basal member of the Lorrain Formation are characteristically non-stratified. However, the following sedimentary features do occasionally occur: small scale trough cross-laminae (ripples) and parallel laminae accentuated by heavy minerals, large scale (to ea. 20 cm thick), planar tabular cross-stratification, and isolated, or rare lenses, of quartz, feldspar and very rare arenite granules. Rarely, larger scale (amplitude - 10-20 cm, wavelength - 15-50 cm) symmetrical waveforms are preserved along the upper contact 21 of the very fine-grained arenite with the overlying coarser- grained unit. Irrespective of grain size, ten sub-facies can be distinguished in the basal member arenites of the Lorrain Formation (Table 2). Of these, non-stratified arenite (2a), arenite with normally graded units (2b), small scale trough cross-laminated arenite (2h), and large scale planar tabular cross-stratified arenite (2f) are most common. Middle Member Most exposures of the middle member of the Lorrain Formation examined during this study are located in the southeastern and southern outcrop area of the formation in the Cobalt Plain. In the southeast, the best exposures of the middle member were found sporadically along the western shoreline of Lake Timiskaming, as well as on Sunrise, Blueberry, Obashkong, southern Rabbit, Rib, and Lorrain lakes. At various locations on Chiniguchi Lake excellent exposures of the middle member occur . Seven stratigraphic sections measured in the middle member of the Lorrain Formation are presented in Appendix A. Facies Description The middle member of the Lorrain Formation contains two main lithofacies, arenite and conglomerate. Contrasting with the large exposures of conglomerate found in the basal member of the formation, occurrences of this lithofacies in the middle member are restricted to thin lenses found within the arenites. Facies l - Conglomerate 22

Lenses of conglomerate, up to several tens of centimeters thick and several meters in length, occur quite commonly within arenite units throughout the middle member of the formation, usually near the middle or base of the unit. They are framework supported, lack significant amounts of finer-grained interstitial matrix, and contain rounded to well-rounded clasts usually in the low to mid-pebble grain size range. The lenses are commonly oligomictic (quartz); occasionally smaller, rounded, jaspilite clasts also occur. The conglomerates of the middle member do not display any stratification (Table 3). Facies 2 - Arenite Middle member arenites in the Lorrain Formation most commonly weather green-white or green-grey, but occasionally will display a pink-white or pink-grey color. Middle member arenites are compositionally more mature than basal member arenites with the reduction in feldspar content being reflected by the differing weathering colors. They generally do not exhibit as large a grain size range. Sorting usually ranges from poor to well sorted and grain size commonly ranges between medium to coarse grained. The lithofacies sequence described previously for the basal member arenites (coarser-grained arenite unit followed gradationally by a thin lens of finer-grained arenite in turn erosionally overlain by another coarser-grained unit) is also present in the middle member arenites throughout the Cobalt Plain (Photo 2). The geometry, scale, and contact relationships of both the finer-grained arenite lenses and the coarser-grained 23 arenite bodies are similar in the middle member arenites to what has been described above for the basal member arenites. As reported for the coarser-grained basal member arenites, the coarser-grained arenite bodies of the middle member do not contain any representative vertical sequence of sedimentary structures. The most common sedimentary features encountered are: isolated, granule to pebble size, quartz and feldspar clasts; lenses or horizons of granule to lower pebble size quartz and feldspar lag occasionally containing slightly smaller jaspilite or granitic clasts; variably well defined normally graded units, commonly 5-20 cm thick; ripple cross-lamination; and heavy mineral lamination. Less commonly encountered sedimentary features are planar tabular and trough cross-bedding, perpendicular-normal foreset grading, and siltstone lithics. Pyrite is a rare constituent in coarser-grained arenite bodies of the middle member. A fairly common feature of the coarser- grained arenite bodies of the middle member, which only rarely occurs in the basal member, are drapes of yellow to brown weathering clay sized detritus (Photo 4). Either single or multiple clay drapes can occur as both low-angle lamination and on cross-stratification. This feature was encountered at various locations in the southeastern outlier, as well as in outcrop surrounding Chiniguchi Lake in the southern Cobalt Plain (Rice, 1988). The finer-grained arenite lenses in the middle member tend to be darker green in color and to display more sedimentary features than their counterparts in the basal member. These 24 features are isolated , subangular to subround, quartz and feldspar granules, millimeter thick lenses of coarser-grained sand size detritus, heavy mineral laminae, ripple cross- lamination, asymmetrical waveforms along their top contact with the overlying coarser-grained arenite unit, normally graded units several centimeters thick, and rare, small scale, planar tabular cross-lamination. Perpendicular-normal foreset grading and clay drapes are also fairly common, while the latter was not observed in the finer-grained units of the basal member. The middle member arenites of the Lorrain Formation, irrespective of grain size, display nine sub-facies (Table 3). The most common sub-facies in the middle member arenites are non- stratified arenite (2a), arenite displaying normally graded units (2b), large scale planar tabular cross-stratified arenite (2f), and small scale trough cross-laminated arenite (2h). Upper Member The upper member of the Lorrain Formation was examined extensively during the 1987 field season which concentrated on the central region of the Cobalt Plain (Rice, 1987). The best exposures of the upper member in this region occur principally on the margins of the larger lakes, such as Welcome, Diamond, Makobe, and Florence lakes. Excellent exposures were also examined on Ishpatina Ridge in Corley Township, and on a large fault scarp in east-central Acadia Township. Eleven stratigraphic sections measured in the upper member of the Lorrain Formation are presented in Appendix A. Facies Description 25

Two main lithofacies, arenite and conglomerate, constitute the upper member of the formation. As was reported above for the middle member, the conglomerate lithofacies is very minor, occurring only as small lenses within arenite units. Facies l - Conglomerate Lenses of non-stratified conglomerate (Table 4), up to ea. 60 cm thick and 2 - 3 m in length, occasionally occur within arenite bodies in the upper member of the formation. These conglomerates are very similar, in both geometry and composition, to those occurring in the middle member of the formation. They characteristically are framework supported with little interstitial matrix and consist of well-sorted, rounded to well- rounded, quartz clasts of low to intermediate pebble grade. Occasionally, smaller, sub-round to round jasper clasts will also occur in the conglomerate lenses. Facies 2 - Arenite Upper member arenites in the Lorrain Formation characteristically weather white, occasionally with a pale greenish tinge. Sorting is moderate overall, but ranges from poor to well-sorted. Upper member arenites are characteristically medium to coarse grained, but considerable variation from fine to very coarse grained does occur. The most diagnostic feature of the upper member arenites is their compositional maturity. The rocks consist almost entirely of quartz. Only rarely can small amounts of feldspar be detected with the hand lens. 26

The lithofacies sequence described previously from the basal and middle members of the formation is also present in the upper member throughout the Cobalt Plain (Photo 3). The geometry, scale, and contact relationships of this sequence are similar to those described from the basal and middle members. The finer- grained arenite lenses in the upper member differ slightly from their counterparts in the basal and middle members with respect to weathering color, grain size, and composition. In the upper member finer-grained arenite units weather a pale grey or brown, rather than green as in the basal and middle members; they are also somewhat finer-grained (very fine sand, possibly coarse silt), and are less micaceous. Many units appear to contain no micaceous minerals, however, in those exposures that show evidence of structural deformation the presence of a small amount is indicated by the fact that only the finer-grained units display any cleavage. The coarser-grained arenite units in the upper member fail to display any representative vertical sequence of sedimentary features, as do coarser-grained units in the basal and middle members of the formation. Although sedimentary features are common, significant portions of many exposures are non- stratified. Sedimentary features include common large scale (up to several meters) planar tabular and trough cross- stratification, common small scale trough cross-lamination, occasional parallel lamination, occasional convolute lamination, and common normally graded units usually 5 - 20 cm thick. Perpendicular-normal foreset grading is also present in many of 27 the cross-stratified coarser-grained units. Rare features are apparent chevron cross-sets noted only at Welcome Lake, and clay drapes found on cross-laminae in normally graded units only at the southern and northern end of Florence Lake. Occasional exposures of the coarser-grained arenite units in the upper member displayed several scales of cross-stratification separated by bounding surfaces suggestive of compound bedforms. Finer-grained arenite units in the upper member are largely non-stratified. Occasional sedimentary features include small scale trough cross-lamination, convolute lamination, parallel lamination, and in the thicker units, rare large scale, planar tabular cross-stratification. Ten sub-facies can be distinguished in the upper member arenites irrespective of grain size (Table 4). The most common are non-stratified arenite (2a), large scale planar tabular cross-stratified arenite (2f), normally graded arenite (2b), and small scale trough cross-laminated arenite (2h). Environment of Deposition Regional considerations, such as the stratigraphic and tectonic context, are always important constraints when deciding upon a depositional scenario for a formation. However, in the case of the Lorrain Formation in the Cobalt Plain, they assume a particularly significant role due to the fact that Lorrain Formation arenites, which dominate lithologically, contain an effectively non-diagnostic assemblage of primary sedimentary features. It is for this reason that the formation has previously received various interpretations by different authors. 28

A number of tectonic interpretations have been proposed for the Huronian Supergroup of the Southern Province in Ontario. An overview of these interpretations was presented previously in this report. The Huronian Supergroup comprises a Proterozoic succession of predominantly siliciclastic detritus with only volumetrically minor volcanic rocks. The Huronian is considered to represent a wedge of detritus that thickens southward, away from the Superior craton, to a thickness of ea. 10 km (Card et al., 1972). The author favours the tectonic hypotheses of Sims et al., (1980) and Young (1985), who propose that Huronian detritus was deposited on a passive, Atlantic-type plate margin. However, regardless of which tectonic model is favoured, all support a southward to southeastward opening ocean basin with more northerly regions, including the Cobalt Plain, representing an inner shelf area. The drift phase of a Wilson Cycle of ocean basin evolution is proposed to have been established by early Cobalt Group (Gowganda Formation) time as a result of foundering of the continental margin due to thermal relaxation following earlier rifting (Young, 1983). No depositional record of subsequent uplift and erosion associated with ocean basin closure (molasse sequence) is found in the Cobalt Group. The depositional interpretation proposed for the Gowganda Formation is compatible with this tectonic scenario. The basal member of the formation (Coleman Member) has been interpreted to represent deposition in front of a tidewater glacier (lower basal Coleman) and under, and in front of, an ice shelf (upper basal Coleman) (Mustard and Donaldson, 1987), while the upper member of the 29 formation (Firstbrook Member) is interpreted to constitute a non- glacial, marine deltaic sequence (Rainbird and Donaldson, 1988). Therefore, as the Lorrain Formation lies conformably and characteristically transitionally above the Gowganda Formation (locally, above either the Coleman or the Firstbrook member), the constraints imposed on the depositional framework for the Lorrain Formation by the tectonic and stratigraphic setting of the Cobalt Group are: 1. Lorrain Formation deposition occurred on a subsiding, passive continental margin; no tectonic uplift is proposed during Cobalt Group time. 2. The Lorrain Formation inherited a shallow, siliciclastic shelf depositional setting from the Gowganda Formation.

The viability of any environmental interpretation proposed for the Lorrain Formation must be judged by the degree of compatibility with these regional tectonic and stratigraphic constraints. In this report the depositional environments in the Lorrain Formation are interpreted through the study of facies associations. While individual facies carry no genetic significance, sequences of facies used in defining facies associations represent frequently associated depositional conditions, which considered cumulatively, serve to delineate a depositional setting. The following criteria, considered in aggregate, are used to distinguish facies associations in the basal, middle, and upper 30 member arenites of the Lorrain Formation: 1) characteristic grain size 2) mica content 3) type and abundance of primary sedimentary features 4) characteristic nature of basal contacts 5) position in lithofacies sequence and 6) characteristic thickness.

Basal Member Three facies associations can be distinguished in the basal member of the Lorrain Formation, a single conglomerate association and two arenite associations. Conglomerate Association The conglomerate association is restricted to Lorrain Township on the northeastern margin of the Cobalt Plain. This association is compositionally simple relative to the arenite associations discussed subsequently; it consists almost entirely of a single sub-facies, non-stratified conglomerate (la). Non- stratified arenite (2a), parallel-laminated arenite (2c), and small scale trough cross-laminated arenite (2h) occur only occasionally in relatively uncommon, poorly sorted, arenite lenses and horizons found in the conglomerate. Lovell and de Grijs (1976) tentatively suggested that the entire basal conglomerate unit in Lorrain Township represents a regolith. It is herein suggested that the basal conglomerate unit in Lorrain Township largely represents a proximal to upper intermediate alluvial fan setting developed in association with Early Proterozoic fault activity related to the Timiskaming and Cross Lake faults. A sub-aerial environment is suggested by the 31 occasional weathering rinds found on the granitic boulders. Both debris flow and stream flow processes are interpreted to have been operative during fan deposition, the former dominating. The scarcity of sorting/ and almost no organization are complimentary in suggesting a debris flow mechanism. The occasional lens or horizon of poorly sorted arenite in the conglomerate is interpreted to represent stream flow reworking of debris flow surfaces. Proof of reworking lies in the occasional presence of exotic clasts such as ultramafic volcanics, arenites, and siltstones, as well as in indicators of bed-material load transport such as heavy mineral laminae and ripple lamination. Matrix content decreases, exotic clasts become less abundant and, what little organization there is, is lost as proximity to the granitic basement increases. This is interpreted to represent a regolith between the granitic basement and the overlying alluvial fan debris- and stream-flow deposits. While no paleocurrent observations were recorded from the arenite lenses in the conglomerate, the NNW-SSE orientation of the fault systems, along with the location of the conglomerate exposures on the eastern margin of the Cobalt Plain, would suggest that the alluvial fan(s) had a west to southwestward direction of progradation.

Arenite Associations The lithofacies sequence (i.e. coarser-grained arenite body - very fine-grained arenite lens - coarser-grained arenite body) described above for the basal member arenites of the Lorrain Formation does not serve to distinguish this member from the 32 remainder of the formation. As discussed above/ it is also present in the middle and upper member arenites throughout the Cobalt Plain. The basal member coarser-grained arenites are distinctive only by their greater compositional immaturity compard with the middle and upper members. An environmental interpretation of this member must therefore satisfactorily account for both the observed lithofacies sequence as well as the immaturity of the detritus. It must also explain the presence of the same lithofacies sequence in the middle and upper member arenites. Two facies associations are distinguished for the basal member arenites, a coarser-grained and a finer-grained association. Coarser-Grained Arenite Association The coarser-grained arenites that constitute this facies association have been previously described in this report. The intent of this section is to discuss the problems associated with attempting an environmental interpretation of the Lorrain Formation based only on this facies association. All ten arenite sub-facies presented in Table 2 can occur in units of this association/ however/ not all will be found at one location or outcrop. This association (considering the coarser- grained arenites in the middle and upper members as well) effectively is the Lorrain Formation. Both the conglomerate and the finer-grained arenite are very minor lithological components. Descriptions of basal member coarser-grained arenites provided previously in this report provide criteria for the distinction of 33 the coarser-grained arenite association: 1) a coarser grain size than that of the finer-grained arenite association 2) a negligible mica content, less than that normally found in the finer-grained arenite association 3) a greater diversity and abundance of sedimentary features than displayed by the finer- grained arenite association 4) a characteristically erosional basal contact 5) invariably, a basal position in a couplet composed of a coarser-grained unit overlain by a finer-grained unit and 6) a unit thickness which characteristically exceeds that of finer-grained arenite units. Considered in isolation, the coarser-grained arenite association of the basal, middle, or upper members of the formation is herein interpreted to contain a non-diagnostic assemblage of sedimentary features. The controversy concerning the depositional environment of the Lorrain Formation essentially revolves around a marine versus a fluvial interpretation and is suggested to be directly attributable to this characteristic of the coarser-grained arenite association.. Of the variety of sedimentary features displayed by the coarser-grained arenite of the association basal member several are worthy of mention as suggestive, but non-diagnostic, environmental indicators: 1) Clay laminae rarely occur as foreset drapes in cross- stratified sets in the coarser-grained arenite. These usually occur in isolation, but multiple drapes do exist. While such drapes are relatively common in shelf environments where they are attributable to periodically varying energy levels associated with tidal currents, they are also capable of forming in fluvial 34 regimes where they are attributed to a variable stage associated with changing discharge. 2) Rarely / exposures of the basal member coarser-grained arenite association appear to represent large compound bedforms displaying varying scales of cross-stratification (set thicknesses up to ea. 1m have been observed) and an accompanying variation in paleoflow direction. A reliable indication of the size of the compound bedform is not obtainable due to lack of large exposures. The compound bedforms are at least on the order of several meters high and several meters in length. Compound bedforms displaying this scale of cross-stratification are known from either siliciclastic shelf or fluvial environments. 3) Sets of apparent chevron cross-stratification are rare. While chevron cross-strata seldom occur in fluvial strata, they are relatively common in marine deposits where they are attributed to flood- and ebb-tidal currents. Confirmation of the opposed nature of the sets was not obtainable, however, and the number of occurrences is small to be of great environmental significance. 4) Large scale cross-stratification commonly displays perpendicular-normal foreset grading (Allen, 1984, volume 2, p. 154). This feature results from avalanching of cohesionless detritus down the lee slope of bedforms of various sizes and has been recorded from both fluvial and shelf deposits. 5) Rare large scours, several meters in width and several tens of centimeters in depth, occur in the coarser-grained arenites of the basal member. Scours of this scale are easily 35 attributed to bar or channel migration in a fluvial environment or topographically confined unidirectional flow in a shelf environment. Finer-Grained Arenite Association Descriptions of the basal member finer-grained arenites composing this facies association can be found in earlier portions of this report. This facies association is very minor relative to the coarser-grained arenite association. As described above, units of this facies association are found as thin lenses (cm - 10©s cm) between units of the coarser-grained arenites, characteristically displaying a gradational to sharp basal contact and an erosional upper contact. Only sub-facies 2a (non-stratified arenite), 2c (parallel laminated arenite), 2f (large scale planar tabular cross-stratified arenite), and 2h (small scale trough cross-laminated arenite) occur in this association (Table 2); all will not be found in any one unit. The finer-grained arenite association is distinct from the coarser-grained arenite association by virtue of its reduced unit thickness, its greater, but still minimal, mica content, its reduced assemblage of sedimentary features, its finer grain size (estimated as very fine-grained with hand lens), its usually non- erosional basal contact, and its position as a capping-unit to the underlying coarser-grained arenite. The finer-grained arenite association is the key to the interpretation of the depositional setting of the Lorrain Formation in the Cobalt Plain. To the best of the author©s knowledge, this association was not described, nor its 36

significance realized/ prior to 1986. Both the author/ and P. Born/ also of the Ontario Geological Survey but assigned to a different project/ noted these units in the Lorrain Formation during the 1986 field season. The interpretation of the finer- grained arenite association is not unequivocal/ as most sedimentary features are non-diagnostic of environment. However/ it is herein considered to contain a sedimentary feature that hints at the true nature of the depositional setting of the Lorrain Formation. Where erosional/ i.e. nearly all places, the upper contact of finer-grained arenite lenses with the overlying coarser-grained arenite always displays some degree of undulosity. The configuration of the convex upward portions of this surface is nearly always asymmetrical with varying amplitudes and wavelengths. In several instances/ however/ the contact displayed symmetrical convex upward portions with amplitudes of ea. 8 - 15 cm and wavelengths from ea. 40 - 110 cm (Photo 1). These symmetrical/ convex upward undulations are interpreted to indicate that the erosional upper contacts of the finer-grained arenite lenses were created by storm waves reworking the sediment surface in a siliciclastic shelf setting (Figure 2a-d). Although a perfectly symmetrical configuration might be expected to be rare and/or rarely preserved in an open- shelf setting due to the interaction of a variety of currents characteristic of this setting/ the paucity of these features nevertheless casts an equivocal light on the siliciclastic shelf interpretation. In the context of such an interpretation/ however/ possible supporting evidence might exist in the presence 37 of sub-facies 2b (normally-graded arenite) in the coarser-grained arenite association. This sub-facies is very common in coarser- grained units and consists of either a single normally-graded unit ea. 2-20 cm thick, or a sequence of stacked normally graded units cumulatively reaching ea. 50 cm in thickness. While storm- sands commonly display wave- to wave-current-rippled upper portions (Allen, 1984), deposition below fair-weather wave base might explain the absence of this feature from sub-facies 2b. Normally-graded units of this range in thickness, without evidence of combined-flow sediment transport, have been interpreted as storm-sands in stratigraphic records elsewhere (Allen, 1984, volume 2, chapter 12, p. 504). In a sandy, braided fluvial scenario lenses of the finer- grained arenite association would have to represent falling-stage deposition of fines in a topographically protected overbank setting or low-stage, in-channel, deposition. Except the larger scale symmetrical waveforms along the upper contact of the finer- grained units, the sedimentary features found in this facies association could have formed in such a setting. As discussed previously, the sedimentary features of the coarser-grained arenite association are non-diagnostic, they too might have formed in a fluvial setting representing in-channel deposition of coarser-grained detritus. However, a sandy braided fluvial interpretation is herein considered to be the less likely of the two environmental hypotheses for the following two reasons: 1) The frequency with which finer-grained sediment is likely to be preserved in a sandy braided fluvial regime should be low 38 as a result of the combined effects of channel abandonment and migration. In many exposures containing the finer-grained arenite association the lenses are numerous and closely spaced, suggesting frequent deposition and common preservation of finer- grained sediment. Deposition below fair-weather wave base in a siliciclastic shelf setting (Figure 2a-d) is considered to provide a depositional setting much more conducive to the accumulation and preservation of finer-grained sediment. 2) Although symmetrical waveforms are rare along the upper contact of finer-grained units, a depositional hypothesis must explain all observations. Smaller symmetrical ripples are capable of forming during low-stage modification of high-stage deposits in a sandy braided fluvial setting, however, the larger scale of the waveforms noted in the finer-grained arenite association of the basal member is suggested to eliminate this depositional mechanism. While a siliciclastic shelf interpretation can readily account for both asymmetrical and symmetrical bedforms of varying scales, a sandy braided fluvial scenario cannot incorporate larger-scale symmetrical bedforms. This is considered to favor a shelf interpretation for the basal member. Discussion A leading criticism of a siliciclastic shelf interpretation for the basal member arenites of the Lorrain Formation is the compositional immaturity of the detritus. As described above, the basal member arenites are invariably highly feldspathic and characteristically only moderately sorted. These characteristics 39 would seem to mitigate against a marine interpretation since shelf sediments are commonly found to be better sorted and of greater compositional maturity than fluvial sediments. However, consideration of the tectonic and stratigraphic setting is suggested to provide a tenable hypothesis for the presence of immature sediment in a shelf environment. As stated previously, the tectonic setting of the Lorrain Formation in the Cobalt Plain is considered to be an inner shelf on a foundering, divergent, continental margin; a transgressive regime is therefore required. The Lorrain Formation lies stratigraphically above either the shallow glacio-marine Coleman Member (Mustard and Donaldson, 1987) of the Gowganda Formation, or the non-glacial, marine deltaic Firstbrook Member (Rainbird and Donaldson, 1988). This variable stratigraphic position is important in that it necessitates that the basal member of the formation be extremely diachronous. The basal member, where lying directly above the Coleman Member of the Gowganda Formation, must therefore be at least partially time correlative with the Firstbrook Member of the Gowganda Formation of other regions of the Cobalt Plain. Evidence in support of this lateral facies equivalence has been reported from Anima-Nipissing Lake where lithologies typical of the basal member of the Lorrain Formation are interlayered with rocks normally found in the Firstbrook Member of the Gowganda Formation. This interstratification occurs on the scale of hundreds of meters (Born and Burbidge, 1987). The shallow, non-glacial shelf that directly followed Coleman Member time must have been immediately transitional 40 sourceward, i.e. north, toward the Superior Craton into a coastal plain setting. Given the cratonic source region and the absence of vegetation in Early Proterozoic time, it is reasonable to presume that the fluvial regime of this coastal plain was braided. Where the Lorrain Formation immediately overlies the Coleman Member, it would therefore seem valid to suggest that its basal member represent a sandy braid-plain environment. This could explain why the basal member of the formation is coarsest- grained only in these regions. It is also tempting to extrapolate this interpretation to the remainder of the Lorrain Formation. This is the reason why some previous authors (Rainbird and Donaldson, 1988) have felt it necessary that the Lorrain Formation be a sandy braided fluvial environment. However, this seemingly sensible interpretation of the formation, in particular its basal member, is too simplistic and errs in ignoring the tectonic constraint to suggest that up to 2.5 km of braided fluvial detritus is deposited under a transgressive regime. Such an interpretation also errs in failing to recognize that individual sedimentary features, as well as the characteristic lithofacies sequence, in the basal member of the Lorrain Formation can readily be interpreted as indicative of a siliciclastic shelf. It is herein suggested that the basal member of the Lorrain Formation, where it overlies the Coleman Member of the Gowganda Formation, represents braid-plain detritus that has been reworked in a shallow marine environment as a result of transgression associated with a foundering passive continental margin. By 41 analogy with the Atlantic shelf of North America, which was transgressed during the Holocene rise in sea-level, the transgressed basal Lorrain braid-plain would consist of a complex of palimpsest (fluvial deposited - shelf reworked) and moribund (fluvial deposited but not subsequently reworked by local shelf currents) detritus. Conceptually therefore / the basal member could contain an inextractable mixture of fluvial and marine attributes. This hypothesis explains the difficulty in interpreting the coarse-fine-coarse lithofacies sequence characteristic of the basal member, since this sequence could result from autocyclic mechanisms in either a braid-plain or siliciclastic shelf setting. Similarly, where the Lorrain Formation overlies the non- glacial, marine-deltaic Firstbrook Member of the Gowganda Formation the basal member is interpreted to represent transgressively reworked deltaic top-set sediment. The finer- grained character of the basal member in these areas may be a consequence of a finer average grain size in this environment relative to that of a braid-plain setting. As the Firstbrook Member can approach 800 m in thickness in the Cobalt Plain (Rainbird and Donaldson, 1988), the deposition of the basal member in these areas would be considerably later in the transgressive cycle. Where overlying the Firstbrook Member, the basal member of the Lorrain Formation would likely be roughly correlative to the middle member of the formation in areas where the Firstbrook Member is absent. 42

While transgressive reworking of braid-plain and deltaic top-set sediment can explain how shelf detritus could be so immature / a mechanism is required to account for the accumulation of hundreds of meters of such basal Lorrain sediment under a transgressive regime. It is herein suggested that basal Lorrain time was characterized by a transgression which was highly punctuated with stillstands that permitted geologically short- term development of coastal braid-plain conditions (Figure 3). Locally (Lorrain Township region), in early basal member time, braid-plain development appears to have incorporated a basin- marginal alluvial fan complex. The alternation of such stillstands with intervening periods of marine innundations provided a long-lived source of fluvial deposited - shelf reworked detritus and could account for the thickness of the basal member arenite. The concept of an episodic transgression characterized by stillstand interruptions is well established in the literature (Van Wagoner et al., 1988). The basal member arenites of the Lorrain Formation might be expected to display both fluvial and marine signatures under such an interpretation. It is considered that a fluvial signature is manifest in their compositional immaturity and that a later marine signature lies in their characteristic lithofacies sequence. Considering the thickness of the basal member of the Lorrain Formation, as well as that of the Firstbrook Member of the Gowganda Formation, it is unlikely that isostatic rebound associated with the deglaciation that followed Coleman Member time would have been of sufficient duration to provide a long- 43 lived source of detritus from the Superior Craton. It is more probable that isostatic rebound augmented frequent stillstands in earliest basal member time as a means of supplying immature detritus to a shelf environment. There is no evidence that would allow speculation as to what would cause such an episodic transgression during basal Lorrain Formation time. The answer must lie in the realm of basin tectonics, or eustacy, or some complex interplay of both. Application of modern basin analysis techniques to the Early Proterozoic Huronian Basin has never been attempted. Until the by-products of a proper basin analysis are available, such as subsidence curves, the data which might explain a phenomena such as a highly episodic transgression will be missing. Middle and Upper Member The middle and upper members of the Lorrain Formation consist of the same facies as the basal members associations and thus can be interpreted similarly. Both display a coarser- grained and finer-grained arenite association and each lacks the conglomerate association distinguished in the basal member of the formation. As described previously, the vertical arrangement of the coarser- and finer-grained arenites in the middle and upper members is identical to that which characterizes the basal member. This lithofacies sequence is thus characteristic of all arenites in the Lorrain Formation in the Cobalt Plain. The coarser-grained arenite association in the middle member can display all sub-facies found in Table 3 except 2e (very thin- bedded arenite), while units of the finer-grained arenite 44 association in this member are composed only of sub-facies 2a (non-stratified), 2b (normally graded), 2e (very thin-bedded), 2f (large scale planar tabular cross-stratified), 2g (large scale trough cross-stratified), and 2h (small scale trough cross- laminated) . All ten sub-facies contained in Table 4 can occur in units of the coarser-grained arenite association of the upper member, but units of the finer-grained arenite association in this member display only sub-facies 2a, 2c (parallel laminated), 2e, 2f, 2h, 2i (convolute-laminated), and 2j (symmetrical rippled). Any particular unit of either the coarser- or finer- grained association in both members will not contain all possible sub-facies, but rather consists of some sub-set. The middle and upper members of the formation are similar to the basal member in other respects as well. Of the five suggestive, but non-diagnostic, features discussed above from the coarser-grained arenites of the basal member, three (clay drapes, perpendicular-normal foreset grading, and apparent chevron cross- sets) are present in places in the middle member and four (three as above, plus occasional exposures suggestive of compound bedforms) occur in the upper member. Therefore, the coarser- grained arenite association of the middle and upper members of the Lorrain Formation is also interpreted as being non-diagnostic of depositional environment. Similarily the finer-grained arenite association is highly comparable throughout the Lorrain Formation. The major differences between finer-grained units of the three members lie not in position in the lithofacies sequence or contact 45 relationships with the coarser-grained units/ but only in weathering colors and mica content. While large / absolutely symmetrical waveforms were not encountered along the upper contact of finer-grained units in the middle and upper members, this contact was again invariably undulose, as it was in the basal member. This is not significant, since, as discussed previously in this report, asymmetry, not symmetry, would be the expected configuration of a surface that had been reworked under what was, in all probability, a combined-flow regime. The finer- grained arenite association of the middle and upper members is therefore assigned the same interpretation that it was in the basal member. The increased compositional maturity of the middle and upper members compared to the basal member makes it tempting to suggest that the nature of the transgression during middle and upper member time was continual, uninterrupted by stillstands. This would seem to readily account for the accumulation of the compositionally more mature sediment that characterizes the middle and upper members. However, preliminary petrographic data (Figure 4) suggests that the progressive upward increase in compositional maturity displayed in the middle and upper members is attributable to burial diagenetic purging of framework feldspar grains, as originally suggested by Chandler (1986). The estimated detrital modal compositions presented in Figure 4 indicate that the middle and upper members of the Lorrain Formation were, to some degree, also feldspathic at the time of deposition. Therefore, on the basis of preliminary petrographic 46 results which indicate that the quartz arenites in the Lorrain Formation are in fact diagenetic quartz arenites, the application of the episodic transgression theory to the middle and upper members of the formation is felt to be justified.

Paleocurrent Analysis Directional data recovered from the Lorrain Formation in the Cobalt Plain is summarized in Figure 6. This figure presents vectors at each station from which directional data was obtained. For some stations the arrow represents only a single paleocurrent reading. All paleocurrent data was corrected for structural tilt. The overall paucity of data for the Lorrain Formation is in part real; it also reflects the time constraints imposed by the regional scope of the project. More detailed work would produce additional directional data at some stations, however, at many locations cross stratification is present but not measurable. The results presented in Figure 6 display a preferred southward orientation, however, the preference is not strongly developed as a good deal of variation is also apparent in this figure. This type of regional paleocurrent pattern, characterized by a weak preferred orientation, is not unique to a particular depositional environment. In a siliciclastic shelf scenario the preferred orientation could be attributed to tidal asymmetry, while in a fluvial scenario the amount of variability displayed might be attributed to an irregular paleo-topography resulting in locally varying paleo-slopes. However, the fact 47 that the paleocurrent pattern contains elements of both a current regime with a preferred flow direction as well as one with considerable local variation in flow direction lends support to the genetic hypothesis put forth earlier in this report. This hypothesis suggested that the Lorrain Formation contains signatures of both fluvial and marine depositional environments characterized by fluvial deposited - shelf reworked detritus as a result of episodic transgression during Lorrain Formation time. In such a depositional framework as this an ambiguous regional paleocurrent pattern, such as that displayed by the Lorrain Formation in the Cobalt Plain, might be anticipated.

Evaluation of Paleoplacer Gold Potential The objective of this study has been the evaluation of the paleoplacer gold potential of the Early Proterozoic Lorrain Formation in the Cobalt Plain of east-central Ontario. The perspective adopted for this project has been that the only methodology that will ensure a reasoned approach to such an evaluation is a proper sedimentologic investigation of the depositional environment(s) represented in the formation. The justification for the adoption of this methodology is that depositional setting ultimately determines the presence or absence of heavy mineral placers, assuming a source region supply and no significant post-depositional leaching. For this study, the important distinction has been between a continental, ie. sandy braid-plain, and a marine, ie. shallow siliciclastic shelf, environment of deposition. Historically, the Lorrain Formation 48 has been interpreted to contain elements of both environments (eg. Card et al., 1973). This distinction is critical for the Lorrain Formation as a braid-plain environment has a much greater potential to contain economic accumulations of heavy minerals/ such as gold placers, than does a shallow shelf setting where a variety of interacting currents would tend to disperse heavy minerals into non-economic concentrations. However/ storms have been reported to form placers in both restricted and open marine environments (Aitchison, 1988/ Emory-Moore et al./ 1988, and Hein and Syvitski/ 1988). The major and trace element geochemistry of the basal/ middle, and upper members of the Lorrain Formation is presented in Tables 5-10, Appendix B. Results from the basal, middle, and upper members (Tables 6, 8, and 10 , respectively) are not encouraging. The gold (Au) values reported in these tables are predominantly under the detection limit (2 ppb) , or if greater, are not sufficiently large to constitute any encouragement to companies or individuals considering exploration work. The episodic transgression hypothesis put forth in this report (Figure 3) suggests that the basal member, and likely the middle and upper members as well, of the Lorrain Formation contain both braid-plain (compositional immaturity) and shelf (lithofacies sequence) signatures. This is suggested to result from the alternation of stillstands, when braid-plain progradation could occur, with transgressive marine innundations, during which time at least partial reworking of the braid-plain deposits would occur. The critical aspect of this hypothesis, 49 with respect to the potential to contain economic concentrations of paleoplacer gold, is the extent to which the braid-plain deposits get reworked during each marine innundation. If reworking is only partial then relict braid-plain deposits (moribund shelf detritus), including any contained placer mineralization, survive, however, if reworking of braid-plain deposits is complete (palimpsest shelf detritus) dispersal of any contained placer mineralization to sub-economic grade occurs. The depth of marine reworking relative to preceding braid-plain aggradation will determine which scenario takes place. Ultimately, this should be decided by such variables as braid- plain slope and rapidity of innundation as it affects the potential degree of reworking. Conceptually, the outcome could vary from one stillstand-innundation sequence to the next in the overall transgressive sequence that characterizes Lorrain Formation time. In the author©s opinion, minimal slopes would exist in a coastal plain setting which should result in only partial reworking of the braid-plain deposits. However, it could be difficult to distinguish between relict braid-plain sediment and shelf deposits which consist of reworked braid-plain detritus since the lithofacies sequence produced in a shallow shelf environment could be highly similar to one resulting from coastal braid-plain aggradation. In net then, even if relict braid-plain deposits can be considered to be present in the Lorrain Formation, it is unlikely that they could be confidently recognized in outcrop. 50

The following conclusions are reached with respect to the paleoplacer gold potential of the Lorrain Formation: 1. The results of the geochemical analyses do not encourage future exploration.

2. The data obtained during this study is not sufficient to categorically rule out the possibility that the formation contains economic concentrations of paleoplacer gold for the following reasons:

a) The regional scope of this project meant that there are many exposures within the study area that could not be examined or sampled.

b) Nearly all samples analysed were arenites, not conglomerates/ which is the lithology with which placer gold would be associated; this reflects both an actual paucity of thick conglomerate units and the difficulty of sampling the conglomerate lenses that were found.

3. The interpretation given the Lorrain Formation in this study suggests that even if a best case scenario (partial preservation of braid-plain deposits and potentially, contained gold placers) is assumed, the likelihood of being able to distinguish the desirable deposits is questionable.

4. It is speculated that the anomalously high gold values reported from the Lorrain Formation by Colvine (1981) may be the result of hydrothermal enrichment, perhaps controlled by deep seated faulting, as opposed to being paleoplacer in origin. 51

Based on the results of this study the paleoplacer gold potential of the Lorrain Formation is low. This, however, does not rule out that economic gold deposits are possibly present in other formations of the Huronian Supergroup in the Cobalt Plain. This assessment is supported by the results of up to 0.026 oz. gold per ton from deep diamond drilling by the Canico-Eldorado- Noranda-Texasgulf joint venture (see Dressler, 1986). These promising results were obtained from rock units at the base of the Huronian Supergroup in the Chiniguchi Lake area. 52

Recommendations for Future Study The Lorrain Formation is sedimentologically problematic as it contains very little which may be considered indicative of sedimentary environment. The interpretation offered in this report is new and / unlike previous interpretations, is compatible with both regional scale constraints as well as outcrop scale observations. However, the project was regional in nature and as a consequence many exposures either could not be examined in sufficient detail or could not be examined at all. An evaluation of the formation©s potential as a host for paleoplacer gold (Au) mineralization is entirely reliant on the interpretation of the depositional sedimentary environment. The only way to improve upon the interpretation, and therefore the evaluation, is to do considerably more detailed work at the best exposures. It is pos.sible that more detailed observations could add interpretive significance to an assemblage of sedimentary features which on the regional scale of this report were non-diagnostic. In addition to more detailed facies work at the best exposures, future research should: 1) Concentrate on determining the presence or absence of the thick basal conglomerate unit elsewhere in the Cobalt Plain where the Lorrain Formation directly overlies basement. 2) Concentrate on the Gowganda-Lorrain and Lorrain-Gordon Lake contacts as these relationships help to refine the regional stratigraphic constraints which are imposed on the interpretation of the formation. This could also lead to improved 53 lithostratigraphic correlation within the formation, as well as within the Cobalt Group. 3) Concentrate on the petrology of the formation. Preliminary results from this study suggest that it not only has direct bearing on intraformational lithostratigraphic correlation, but also has implications with respect to the depositional history of the formation and the late stage evolution of the Huronian Basin. 4) Concentrate on geochemical lines of investigation. Such work might yield evidence that would help to establish the salinity of the depositional environment and therefore, better define marine or fluviatile paleoenvironments for the formation. 54

References Aitchison, J.C. 1988. An Eocene storm-generated littoral placer, northeast Otago; New Zealand Journal of Geology and Geophysics, volume 31, p. 381-383. Allen, J.R.L. 1984. Sedimentary structures, their character and physical basis; Developments in Sedimentology, volume 30, Elsevier, New York, 1256 p. Bigsby, J.J. 1821. Geological and mineralogical observations on the northwestern portion of Lake Huron; American Journal of Science, first series, volume 3, p. 254-272. Born, P. 1988. Geology of Cassels and Riddell Townships, District of Nippissing, Ontario; Ontario Geological Survey, Open File Report 5663, 147 p. Accompanied by maps P-3073 and P-3074. Born, P. and Burbidge, G.H. 1987. Geology of Brigstocke and Kittson Townships, District of Timiskaming; p. 198-204 in Summary of Field Work and Other Activities 1987, by the Ontario Geological Survey, edited by R.B. Barlow, M.E. Cherry, A.C. Colvine, B.O. Dressler, and O.L. White, Ontario Geological Survey, Miscellaneous Paper 137, 429 p. Burrows, A.G. 1909. The Gowganda and Miller Lakes silver area, Ontario; Ontario Bureau of Mines, Annual Report, 1909, volume 18, part 2, p. 1-20. Accompanied by map 18E. Burrows, A.G. 1922. Gowganda and other silver areas, 1. Gowganda silver area (4th report), District of Timiskaming, Ontario; Ontario Department of Mines, Annual Report, 1921, volume 30, part 3, p. 1-46. Accompanied by map 30B. 55

Cambray, F.W. 1978. Plate tectonics as a model for the environment of deposition and deformation of the Early Proterozoic of northern Michigan; Geological Society of America, Abstracts with Programs, volume 10 (7), p. 376. Card, K. D. 1976. Geology of the Espanola-Whitefish Falls area, Districts of Sudbury and Manitoulin, Ontario; Ontario Division of Mines, Geological Report No. 131, 70 p. Accompanied by Maps 2311 and 2312; scale l inch to 1/2 mile. Card, K.D., Innes, D.G. and Debicki, R.L. 1977. Stratigraphy, sedimentology, and petrology of the Huronian Supergroup in the Sudbury-Espanola area; Ontario Division of Mines, Geoscience Study 16, 99 p. Card, K.D., Mcilwaine, W.H., and Meyn, H.D. 1973. Geology of the Maple Mountain Area, Operation Maple Mountain, Districts of Timiskaming, Nipissing, and Sudbury; Ontario Division of Mines, Geological Report 106, 160 p. Accompanied by Maps 2256, 2257, 2258, 2259; scale l inch to l mile, and Map 2260, scale l inch to 1/2 mile. Card, K.D., Church, W.R., Franklin, J.M., Frarey, M.J., Robertson, J.A., West, G.F., and Young, G.M. 1972. The Southern Province; in R.A. Price and R.J.W. Douglas, editors, Variations in Tectonic Styles in Canada, Geological Association of Canada, Special Paper 11, p. 335-380. Chandler, F.W. 1986. Sedimentology and paleoclimatology of the Huronian (Early Aphebian) Lorrain and Gordon Lake Formations and their bearing on models for sedimentary copper 56

mineralization; in Current Research, Part A, Geological Survey of Canada, Paper 86-1A, p. 121-132. Collins, W.H. 1913. Geology of the Gowganda Mining Division; Geological Survey of Canada, Memoir 33, 121 p. Collins, W.H. 1917. Onaping Map area; Geological Survey of Canada, Memoir 95, 157 p. Accompanied by two maps. Collins, W.H. 1925: North shore of Lake Huron; Geological Survey of Canada, Memoir 143, 160 p. Colvine, A.C. 1981. Reconnaissance of the Lorrain Formation, Northern Cobalt Embayment; p. 187-189 in Summary of Field Work, 1981, by the Ontario Geological Survey, edited by John Wood, O.L. White, R.B. Barlow, and A.C. Colvine, Ontario Geological Survey, Miscellaneous Paper 100, 255p. Colvine, A.C. 1983. Mineral Deposit Studies in the Huronian Supergroup; p. 235-255 in Summary of Field Work, 1983, by the Ontario Geological Survey, edited by John Wood, Owen L. White, R.B. Barlow, and A.C. Colvine, Ontario Geological Survey, Miscellaneous Paper 116, 313p. Debicki, R. 1987. Stratigraphy, paleoenvironment, and economic potential of the Huronian Supergroup in the southern Cobalt Embayment; Ontario Geological Survey, Open File Report 5665, 251 p. Accompanied by two maps. Dietz, R.S., and Holden, J.C. 1966. Miogeoclines in space and time; Journal of Geology, volume 74, p. 566-583. Dressler, B.O. 1979. Demorest, Mcconnell, and Telfer Townships,

District of Sudbury; p. 76-78, in Milne, V.G., White, O.L., Barlow, R.B., and Kustra, C.R., editors, Summary of Field 57

Work, 1979, by the Ontario Geological Survey; Ontario Geological Survey, Miscellaneous Paper 90, 245p. Dressler, B.O. 1980. Geology of the Wanapitei Lake area, NTS 41 I/10N+15S, District of Sudbury, Ontario; Ontario Geological Survey, Open File Report 5287, 150 p. Dressler, B.O. 1981. Geology of the Chiniguchi Lake area, Demorest, Mcconnell, and Telfer Townships, NTS 41 I/15N, 41 P/2SE, District of Sudbury, Ontario; Ontario Geological Survey, Open File Report 5347, 34 p. Dressler, B.O. 1982. Geology of the Wanapitei Lake area, NTS 41 I/10N+15, District of Sudbury, Ontario; Ontario Geological Survey, Report 213, 131 p. Accompanied by maps 2450, 2451. Dressler, B.O. 1986. Geology of the Chiniguchi Lake area, NTS 41 I/15N and 41 P/2SE, District of Sudbury, Ontario; Ontario Geological Survey, Report 242, 19 p. Accompanied by map 2468. Emory-Moore, M., Barrie, J.V., and Solomon, S. 1988. Modelling of two heavy mineral placer deposits on the Canadian continental shelf; Geological Association of Canada, Mineralogical Association of Canada, Canadian Society of Petroleum Geologists, Joint Annual Meeting, 1988, Program with Abstracts, volume 13, p. A37. Frarey, M.J. 1977. Geology of the Huronian Belt between Sault Ste. Marie and Blind River, Ontario; Geological Survey of Canada, Memoir 383, 87 p. Frarey, M.J. in preparation. Lexicon of stratigraphic names in the Southern Province (approximate title). 58 a

Hadley , D.G. 1968. Sedimentology of the Huronian Lorrain Formation, Ontario and Quebec, Canada; unpublished Ph.D. thesis, Johns Hopkins University, Baltimore, Maryland, 301 P- Hein, F.J., and Syvitski, J.P.M. 1988. Evolution of Sept. Iles delta complexes and shallow marine placer, north shore of Gulf of St. Lawrence, Quebec; Geological Association of Canada, Mineralogical Association of Canada, Canadian Society of Petroleum Geologists, Joint Annual Meeting, 1988, Program with Abstracts, volume 13, p. A54. Hoffman, P.F. 1980. Wopmay orogen: a Wilson cycle of Early Proterozoic age in the northwest of the Canadian Shield; in Strangway, D.W., editor, The Continental Crust and its Mineral Deposits, Geological Association of Canada, Special - Paper 20, p. 523-549. Johns, G.W. 1980. Geology of the Firstbrook Lake area, NTS 31 M/5NW, District of Timiskaming, Ontario; Ontario Geological Survey, Open File Report 5303, 79 p. Johns, G.W. 1983. Geology of the Hill Lake area, NTS 41 P/9N+16S, 31 M/12NW+13SW, District of Timiskaming, Ontario; Ontario Geological Survey, Open File Report 5478, 222 p. Johns, G.W. 1985. Geology of the Firstbrook and parts of surrounding townships area, NTS 31 M/5NW, District of Timiskaming, Ontario; Ontario Geological Survey, Report 237, 58 p. Accompanied by map 2474. Johns, G.W. 1986. Geology of the Hill Lake area, NTS 31 M/12NW, 31 M/13SW, 41 P/9NE and 41 P/16SE, District of Timiskaming, 59

Ontario; Ontario Geological Survey, Report 250, 100 p. Accompanied by map 2501. Johnson, H.D., and Baldwin, C.T. 1986. Shallow siliciclastic seas; in Reading, H.G., editor, Sedimentary Environments and Facies, second edition, p. 229-282, Blackwell, Oxford. Junnila, R.M. 1987. A bibliography of the Huronian Supergroup: 1821-1987; Ontario Geological Survey, Open File Report 5651, 71 p. Kumarapeli, P.S., and Saull, V.A. 1966. The St. Lawrence valley system: A North American equivalent of the East African rift valley system; Canadian Journal of Earth Sciences, volume 3, p. 639-658. Larue, O.K. 1983. Early Proterozoic tectonics of the Lake Superior region: tectono-stratigraphic terranes near the purported collision zone; in Medaris, L.G., editor, Early Proterozoic geology of the Great Lakes region, Geological Society of America, Memoir 160, p.33-48. Larue, O.K., and Sloss, L.L. 1980. Early Proterozoic sedimentary basins of the Lake Superior region; Geological Society of America Bulletin, volume 91, part 2, p. 1836-1874. Larue, O.K., and Ueng, W.L. 1982. Early Proterozoic arc- continent collision orogen, Lake Superior region: tectono- stratigraphic terranes; Geological Society of America,

Abstract with Programs, volume 14, p. 542. Lawton, K.D. 1952. Geology of Delhi Township, District of Sudbury, Ontario; Ontario Department of Mines, Preliminary Report 1952-1, 4 p. 60

Lawton, K.D. 1955. Geology of Delhi Township, District of Sudbury, Ontario; Ontario Department of Mines, Annual Report, 1954, volume 63, part 4. Accompanied by map 1954-1. Logan, W.E. 1847. Geological Survey of Canada, Report of progress for 1846-1847, p. 32-34. Lovell, H.L., and De Grijs, J.W. 1976. Lorrain Township, southern part, concessions l to 6, NTS 31 M/SW, District of Timiskaming, Ontario; Ontario Division of Mines, Miscellaneous Paper 51, 16 p. Lowey, G.W. 1985. Stratigraphy and sedimentology of the Lorrain Formation, Huronian Supergroup (Aphebian), between Sault Ste. Marie and Elliot Lake, Ontario, and implications for stratiform gold mineralization; Geological Survey of Canada, Open File Report 1154, 60 p. MaoKean, B.E. 1967. Geology of the Elk Lake Area, District of Timiskaming, Ontario; Ontario Department of Mines, Open File Report 5006, 146 p. Accompanied by Map P-159. MacKean, B.E. 1968. Geology of the Elk Lake area, District of Timiskaming, Ontario; Ontario Department of Mines, Geological Report 62, 62 p. Accompanied by maps 2150-2152. McBride, E.F. 1963. A classification of common sandstones; Journal of Sedimentary Petrology, volume 33, p. 664-669. Mcilwaine, W.H. 1969. Geology of Leith, Charters, and Corkill Townships, District of Timiskaming, Ontario; Ontario Department of Mines, Open File Report 5035, 70 p. Accompanied by Maps P-502, P-503, P-504. 61

Mcilwaine/ W.H. 1970. Geology of South Lorrain Township, District of Timiskaming, Ontario; Ontario Department of Mines and Northern Affairs, Geological Report 83, 95 p. Accompanied by map 2194. Mcilwaine, W.H. 1971. Geology of Leith, Charters, and Corkill Townships, District of Timiskaming, Ontario; Ontario Department of Mines and Northern Affairs, Geological Report 89, 53 p. Accompanied by map 2208. Mcilwaine, W.H. 1975. Geology of the Gowganda Lake-Miller Lake silver area, NTS 41 P/10, District of Timiskaming, Ontario; Ontario Division of Mines, Open File Report 5113, 257p. Mcilwaine, W.H. 1978. Geology of the Gowganda Lake-Miller Lake .silver area, NTS 41 P/10, District of Timiskaming, Ontario; Ontario Geological Survey, Report 175, 161 p. Accompanied by - maps 2348, 2349. Meyn, H. D. 1968. Geology of Hutton and Parkin Townships, District of Sudbury, Ontario; Ontario Department of Mines, Open File Report 5015, 76 p. Accompanied by Maps P-399 and P-400. Meyn, H.D. 1969. Geology of Roberts, Creelman, and Fraleck Townships, District of Sudbury, Ontario; Ontario Department of Mines, Open File Report 5033, 57 p. Accompanied by Maps P-424, P-449, P-450. Meyn, H.D. 1970. Geology of Grigg and Stobie Townships, District of Sudbury, Ontario; Ontario Department of Mines, Open File Report 5047, 46 p. Accompanied by Maps P-514, P-515. 62

Meyn, H. D. 1970. Geology of Hutton and Parkin Townships, District of Sudbury, Ontario; Ontario Department of Mines, Geological Report 80, 78 p. Accompanied by map 2180. Meyn, H.D. 1971. Geology of Roberts, Creelman, and Fraleck Townships, District of Sudbury, Ontario; Ontario Department of Mines and Northern Affairs, Geological Report 91, 48 p. Accompanied by map 2212. Meyn, H.D. 1972. Geology of Grigg and Stobie Townships, District of Sudbury, Ontario; Ontario Department of Mines and Northern Affairs, Geological Report 100, 39 p. Accompanied by map 2238. Meyn, H.D. 1973. The Proterozoic sedimentary rocks north and northeast of Sudbury, Ontario; in G.M. Young, editor, Huronian Stratigraphy and Sedimentation, Geological Association of Canada, Special Paper 12, p. 129-145. Miller, W.G. 1906. The cobalt-nickel arsenides and silver deposits of Temiskaming, Ontario; Ontario Bureau of Mines, Annual Report, 1905, volume 14, part 2, 62 p. Accompanied by maps 14B and 14C. Miller, W.G. 1913. Cobalt-nickel arsenides and silver (Cobalt and adjacent areas), Ontario Bureau of Mines, Annual Report, 1910, volume 19, part 2, chapter l, p. 1-133. Accompanied by maps 19E, 19F, 19G. Miller, W.G. and Knight, C.W. 1906. Map of the cobalt-nickel- arsenic-silver area near Lake Timiskaming, Ontario, second edition; in Cobalt-nickel arsenides and silver deposits of 63

Timiskaming, Ontario, Ontario Bureau of Mines, 14 th Annual Report, part 2, p. 1-51. Moore, E.S. 1956. Geology of the Miller Lake portion of the Gowganda silver area, District of Timiskaming, Ontario; Ontario Department of Mines, Annual Report, 1955, volume 64, part 5. Accompanied by map 1955-3. Moorhouse, W.W. 1944. Geology of the Bryce-Robillard area, District of Timiskaming, Ontario; Ontario Department of Mines, Annual Report, 1941, volume 50, part 4. Accompanied by map 50J. Murray, A. 1859. On the country between the Thessalon River and Lake Huron, and between the Thessalon and the Mississagi; Geological Survey of Canada, Report of Progress, 1858, p. 67-100. Mustard, P.S. and Donaldson, J.A. 1987. Early Proterozoic ice- proximal glaciomarine deposition: The lower Gowganda Formation at Cobalt, Ontario, Canada; Geological Society of America Bulletin, volume 98, p. 373-387. Nemec, W. 1988. The shape of the rose; Sedimentary Geology, volume 59, p. 149-152. Rainbird, R.H. 1985. Sedimentology and geochemistry of the Firstbrook Member of the Gowganda Formation in the eastern Cobalt Basin, Ontario; unpublished M.Se. thesis, Carleton University, Ottawa, 157 p. Rainbird, R.H. and Donaldson, J.A. 1988. Nonglaciogenic deltaic deposits in the early Proterozoic Gowganda Formation, Cobalt 64

Basin, Ontario; Canadian Journal of Earth Sciences, volume 25, p. 710-724. Rice, R. J. 1986. Regional sedimentology of the Lorrain Formation (Aphebian), Northern Cobalt Embayment; p. 297-303 in Summary of Field Work and Other Activities, 1986, by the Ontario Geological Survey, edited by P.C. Thurston, Owen L. White, R.B. Barlow, M.E. Cherry, and A.C. Colvine, Ontario Geological Survey, Miscellaneous Paper 132, 435p. Rice, R. J. 1987. Regional Sedimentology of the Lorrain Formation (Aphebian), Central Cobalt Embayment; p. 210-216 in Summary of Field Work and Other Activities, 1987, by the Ontario Geological Survey, edited by R.B. Barlow, M.E. Cherry, A.C. Colvine, Burkhard O. Dressler, and Owen L. White, Ontario Geological Survey, Miscellaneous Paper 137, 429p. Rice, R.J. 1988. Regional geology and sedimentology of the Lorrain Formation, Cobalt Plain: Southeastern and Southern outliers; p. 288-296 in Summary of Field Work and Other Activities, 1988, by the Ontario Geological Survey, edited by A.C. Colvine, M.E. Cherry, Burkhard O. Dressler, P.C. Thurston, C.L. Baker, R.B. Barlow, and C. Riddle, Ontario Geological Survey, Miscellaneous Paper 141, 507p. Robertson, J.A., Frarey, M.J. and Card, K.D. 1969. The Federal- Provincial Committee on Huronian Stratigraphy: Progress Report; Canadian Journal of Earth Sciences, volume 6, p. 335-336. 65

Simony, P.S. 1964. Geology of northwestern Timagami area, District of Nipissing, Ontario; Ontario Department of Mines, Geological Report 28, 30 p. Accompanied by map 2057. Sims, P.K., Card, K.D. and Lumbers, S. B. 1981. Evolution of Early Proterozoic basins of the Great Lakes region; in F.H.A. Campbell, editor, Proterozoic Basins of Canada, Geological Survey of Canada, Paper 81-10, p. 379-397. Sims, P.K., Card, K.D., Morey, G.B., and Peterman, Z.E. 1980. The Great Lakes Tectonic Zone: a major crustal structure in central North America; Geological Society of America Bulletin, volume 91, p. 690-698. Thomson, R. 1960. Geology of the north part of Lorrain Township, concessions 7 to 12, District of Timiskaming, Ontario; Ontario Department of Mines, Preliminary Report 1960-1, 60 . P- Thomson, R. 1960. Parts of Coleman Township and Gillies Limit to south and southwest of Cobalt, District of Timiskaming, Ontario; Ontario Department of Mines, Preliminary Report 1960-3, 54 p. Thomson, R. 1961. Part of Coleman Township, concession 5, lots l to 6, District of Timiskaming, Ontario; Ontario Department of Mines, Preliminary Report 1961-4, 118 p. Thomson, R. 1961. Part of Coleman Township, concession 6, lots l to 6, District of Timiskaming, Ontario; Ontario Department of Mines, Preliminary Report 1961-3, 173 p. Thomson, R. 1961. Parts of Coleman Township, concession 3, lots l to 5, and Gillies Limit, blocks l and 2, claims A48-58 and 66

A88-100, District of Timiskaming, Ontario: Ontario Department of Mines, Preliminary Report 1961-7, 108 p. Thomson, R. 1961. Parts of Coleman Township, concession 4, lots l to 5, and Gillies Limit, the eastern A claims, District of Timiskaming, Ontario; Ontario Department of Mines, Preliminary Report 1961-6, 105 p. Thomson, R. 1961. Parts of Coleman Township and Gillies Limit, near New Lake, southeast of Cobalt, District of Timiskaming, Ontario; Ontario Department of Mines, Preliminary Report 1961-2, 68 p. Thomson, R. 1966. Geology of Henwood Township, District of Timiskaming, Ontario; Ontario Department of Mines Miscellaneous Paper 5, 48 p. Accompanied by map 2126. Thomson, R. 1968. Proterozoic rocks intersected by a 7000-foot drillhole in Henwood Township, District of Timiskaming, Ontario; Ontario Department of Mines, Open File Report 5019, 16 p. Accompanied by Map 2126. Todd, E.W. 1926. Anima-Nipissing Lake area, Districts of Timiskaming and Nipissing, Ontario Department of Mines, Annual Report, 1926, volume 35, part 3, p. 79-104. Accompanied by map 35C. Van Schmus, W.R. 1976. Early and middle Proterozoic history of the Great Lakes area, North America; Philosophical Transactions of the Royal Society of London, Series A, 280, p. 605-628. Van Wagoner, J.C., Posamentier, H.W., Mitchum, R.M., Jr., Vail, P.R., Sarg, J.F., Loutit, T.S. and Hardenbol, J. 1988. An 67

overview of the fundamentals of sequence stratigraphy and key definitions; p. 39-46, in Wilgus, C.K., Hastings, B.S., Kendall, C.G. St. C., Posamentier, H.W., Ross, C.A., and Van Wagoner, J.C., editors, Sea-level changes: an integrated approach, Society of Economic Paleontologists and Mineralogists, Special Publication 42. Wood, J. 1979. Regional geology of the Cobalt Embayment, Districts of Sudbury, Nipissing, and Timiskaming; p.79-81, in Milne, V.G., White, O.L., Barlow, R.B., and Kustra, C.R., editors, Summary of Field Work, 1979, by the Ontario Geological Survey; Ontario Geological Survey, Miscellaneous Paper 90, 245 p. Young, G.M. 1983. Tectono-sedimentary history of the early Proterozoic rocks of the northern Great Lakes region; in L.G. Medaris, Jr., editor, Early Proterozoic Geology of the Great Lakes Region, Geological Society of America, Memoir 160, p. 15-32. Young, G.M. 1985. The Lower Gowganda Formation in the southern part of the Huronian outcrop belt: Part l - Stratigraphy and depositional environments; Precambrian Research, volume 29, p. 265-305. Zolnai, A.I., Price, R.A., and Helmstaedt, H. 1984. Regional cross-section of the Southern Province adjacent to Lake Huron, Ontario: implications for the tectonic significance of the Murray Fault Zone; Canadian Journal of Earth Sciences, volume 21, p. 447-456. 68

Appendix A

Stratigraphic Sections Measured. In The Lorrain Formation Throughout The Cobalt Plain (refer to Figure 5, in pocket/ for station locations) Measured Sections In The Basal Member

Section Station Township Position in Township 87-12 126 Leo Obisaga Narrows/ Lady Evelyn Lake

Measured Sections In The Middle Member

Section Station Township Position in Township 88-1 127 Lorrain Lake Timiskaming shoreline/ ea. l.5 km south of Mission Point 88-2 130 Lorrain Lake Timiskaming shoreline/ directly west of Isle du College

88-3 131 in Quebec cliffs just south of Ville Marie/ and east of Lac Laperriere

88-4 135 S. Lorrain north end of Lorrain Lake 88-5 136 S. Lorrain middle Lorrain Lake 88-6 134 S. Lorrain south end of Lorrain Lake 88-7 138 Best cliff off central west side 69

of Friday Lake Measured Sections In The Upper Member

Section Station Township Position in Township 87-1 76 Valin fault scarp in north- central portion of township 87-2 82 Valin Welcome Lake 87-3 84 Valin Welcome Lake 87-4 106 Corley Ishpatina Ridge 87-5 107 Selkirk ea. l km west of northern Maggie Lake 87-6 109 Dundee southwestern Florence Lake 87-7 110 Parker northeastern Florence Lake 87-8 111 McGif f in north arm of Lady Evelyn River 87-9 112 Gamble fault scarp in western portion of township 87-10 114 Acadia Little Nasmith Creek 87-11 125 Medina northernmost Diamond Lake 70

Appendix A

Stratigraphic Sections Measured In The Lorrain

Formation Throughout The Cobalt Plain

(refer to Figure 5, in pocket, for station locations)

Measured Sections In The Basal Member

Section Station Township Position in Township

87-12 126 Leo Obisaga Narrows, Lady

Evelyn Lake

Measured Sections In The Middle Member

Section Station Township Position in Township

88-1 127 Lorrain Lake Timiskaming

shoreline, ea. 1.5 km

south of Mission Point

88-2 130 Lorrain Lake Timiskaming ^ f shoreline, directly west of

Isle du College

88-3 131 in Quebec cliffs just south of Ville

Marie, and east of Lac

Laperriere

88-4 135 S. Lorrain north end of Lorrain Lake

88-5 136 S. Lorrain middle Lorrain Lake

88-6 134 S. Lorrain south end of Lorrain Lake

88-7 138 Best cliff off central west side 71

of Friday Lake

Measured Sections In The Upper Member

Section Station Township Position in Township

87-1 76 Valin fault scarp in north-

central portion of

township

87-2 82 Valin Welcome Lake

87-3 84 Valin Welcome Lake

87-4 106 Corley Ishpatina Ridge

87-5 107 Selkirk ea. l km west of northern

Maggie Lake

87-6 109 Dundee southwestern Florence Lake

87-7 110 Parker northeastern Florence Lake

87-8 111 McGiffin north arm of Lady Evelyn

River

87-9 112 Gamble fault scarp in western

*- portion of township

87-10 114 Acadia little Nasmith Creek

87-11 125 Medina northernmost Diamond Lake 72

Note: Very fine —grained arenite lenses (cm thick) are not drawn to scale

Unit 7 detinition very subjective

18.8 m

O m

LEGEND ———— Lens of micaceous, very fine-grained arenite (cm — 10's cm) i i Coarser-grained arenite with/without granules/pebbles e , g , s Erosional, gradational, sharp contact l ngu l gpl Normally-graded units (cm - 10's cm) f granule to pebble lag 0.3 m "^— Cross-stratification/ripple cross—lamination/heavy mineral lamination

Section 87—1 (station 76), Upper Member Arenite, Lorrain Formation, Valin Township 73 Hole: Very fine-grained arenite ensas (cm thick) are not drawn to scale

34.2

O m

i—GEND ^—^——- Lens of micaceous, very fine—grained arenite (cm - 10's cm) i ~i Coarser-groined arenite with/without granules/pebbles e . g . s Erosional, gradational, sharp contact l ngu 7 gpl Normally—graded units (cm - 10's cm) f granule to pabbla lag 0.3 m —-^"^ ~^s ——— Cross—stratification f Ripple Cross—lamination /' parallel lamination

Section 87-2 (station 82), Upper Member Aremite, Lorrain Formation Note: finer-grained arenite lenses are absent 74 at this location due to erosional removal during emplacement of overlying coarser—grained arenite body — several instances of apparent chevron sets

— cross —stratification approachs unit thickness in several instances

12.2 m

O m

LEGEND Lens of micaceous, very fine-grained arenite (cm — 10's cm) Coarser-grained arenite with/without granules/pebbles Q , g , s Erosional, gradational, sharp contact l ngu X gpl Normally-graded units (cm - 10's cm) l granule to pebble lag 0.3 m Cross—stratification f ripple cross-lamination f parallel lamination

Section 87-3 (station 84), Upper Member Arenite, Lorrain Formation 75

O m

^——— Lens of micaceous, very fine—grained arenite (cm — 10's cm) i i Coarser-grained arenite with/without granules/pebbles e , g . s Erosional, gradational, sharp contact l ngu / gpl Normally—graded units (cm — 10's cm) / granule to pebble lag 0.3 m xvy" ——— Cross-stratiflcation/ripple cross-laminotlon/heavy mineral lamination

Section 87-4 (station 106), Upper Member Arenite, Lorrain Formation 76

49.8 m

!

poorly ixpostd

O m ————- Ltns of micaceous. v*ry tine-grained O'enite (cm - 10'j cm) t ^ Coors*r-groln*d orsnhe wilh/wilhoul graautes/pebbl**

l ngu X gpl Normolly-graa*O umll (cm - 10'j cm) f gronul* lo pvbbl* la

Section 87-5 (station 107), Upper Member Arenite, Lorrain Formation 77

Note: Very fine-groined arenite lenses ' (cm thick) ore nol drown lo sea e 1 poor ngu 1 i unit | 1 def n poor ' 1t ; i ngu unit i i •def 'n \ l| l e t i _ ,.

i j , \ l i \ 1 i j 1 i i i poor 1 ! i i unit ' ' e def n 66.4 m 1 e i i i \ , l, poor 1 \ \ unit l \ ~^- def n i 1 i i i ngu j i 1 i ! poor j j i ! '' ' — — unit i e e def 'n e i i 1 1 i ngu i ti e ngu l _ - _ — e -^~j-- e 5 - i i (B T) " \ , ——— ' 1 C poor 1 ngu unit O def n o —— poor CL \ un t 8 "o0) def n ^ - i i u 1 (fi poor o \ i ,^, unit i e i i Mo i i 1 def 'n C l 1 i e ngu ngu i ngu E ^f^- j en 1 1 j i l 1 -^- | JL e O m LEGEND -—^^— Lens of micaceous, very fine—grained arenite (cm — 10's cm) i ~i Coarser-grained oranite with/without granules/pebbles e . g . s Erosional, gradational, sharp contact l ngu / gpl Normally-graded units (cm — 10's cm) / granule to pebble lag 0.3 m ^^-^ ^s —=— Cross-stratification / ripple cross-lamination / faint stratification

Section 87-6 (station 109), Upper Member Arenite, Lorrain Formation 73

Nore: Very fi-e-groined arenite lenses (cm thick) aie not d r own to sco.e

O m ————. Lens of micaceous, very fine-grained arenite (cm - 10's cm) i ~i Coarser—grained arenite with/without granules/pebbles e , g , s Erosional, grodational, sharp contact l ngu 7 gpl Normally-graded units (cm — 10's cm) f granule to pebble lag 0.3 m --w ——— Cross-stratification f ripple cross-lamination f faint laminae or bedding

Section 87 — 7 (station 110), Upper Member Arenite, Lorrain Fm. 79

Not*: V*ry 'i-n-gro rao arenite lenses (cm thick) are not drown to scole

— nnany units contain ciosely spaced (mm) finer—grained horizons

O m

LEGEND -^———. Lens of micaceous, very fine-grained arenite (cm - 10's cm) i i Coarser-grained arenite with/without granules/pebbles l e , g , s Erosional, gradationol, sharp contact ngu f gpl Normally-graded units (cm - 10's cm) X granule to pebble lag ^-o^ "^s —^— Cross-stratification f ripple cross-lamination f faint laminae or bedding

Section 87-8 (station 111), Upper Member Arenite, Lorrain Fm 80

ile: Very fine —groined arenite lenses (cm thick) are not drawn to scale poor f, 29.9/y. m unit ! 1 -- - section is cumu alive; unit def nition def'n i locally poor L i e \

1 poor | un t i def n i l -1. "l e l —— — 1 'i 1 i poor i poor 1 un t 1 unit def'n def'n poor 1 l unit i 1j i def'n i i 1 1 i l i 1 \ i i i \ l \ \ l \ \ \ e i i 1 c o 'c \

i "oi \ poor ' n un t i 'n —— ±: \i def c ————— i D i poor \ O ur it o i Q. poor def'n ^ unit- i 0) def 'n o |: o l/) 1 \ - o "o \ \ C ~^ E — ^~ ^ -

i poor 2 *

unit 1 def'n 1 1 -^ e 1 i poor 1 li unit poor l def '"1 poor unit j ~~- \ unit def n 1 def'n 1 e e e O m LEGEND ——— Lens of micaceous, very fine-grained arenite (cm — 10's cm) i i Coarser-grained arenite with/without granules/pebbles e , g , s Erosional, gradational, sharp contact ngu / gpl Normally—graded units (cm — 10's cm) / granule to pebble lag 0.3l m •~^s —=— Cross-stratification / ripple cross-lamination / faint laminae or bedding

Section 87 — 9 (station 112), Upper Member Arenite, Lorrain Formation 81

Note: Very fine-grained arenite lenses (cm thick) are not drawn to scale

71 m

O m

LEGEND ———— Lens of micaceous, very fine—grained arenite (cm — 10's cm) i ~i Coarser-grained arenite with/without granules/pebbles e , g . s Erosional, gradational, sharp contact l ngu f gpl Normally—graded units (cm - 10's cm) f granule to pebble lag 0.3 m ••"w" ——— Cross —stratification / ripple cross—lamination / faint laminae or bedding Section 87-10 (station 114), Upper Member Arenite Lorrain Formation Note: Very fine-grained arenite lenses (cm thick) are not drawn to scale 82

52.2 m

—O "O^ 11

O m

LEGEND —^—— Lens of micaceous, very fine-grained arenite (cm - 10's cm) i ~i Coarser-grained arenite with/without granules/pebbles l e , g , s Erosional, gradational, sharp contact O.J m ngu / gpl Normally-graded units (cm — 10's cm) / granule to pebble lag 'r^s —zz — Cross— stratification f ripple cross — lamination f faint laminae or bedding

Section 87—11 (station 125), Upper Member Arenite, Lorrain Fm Note: finer-grained lenses unusually thick at this location

O m

LEGEND ,,.i Lens of micaceous, very fine-grained arenite (cm — 10's cm) i ; ~) Coarser-grained arenite with/without granules/pebbles e , g , s Erosional, gradafional, sharp contact l ngu f gpl Normally—graded units (cm — 10's cm) f granule to pebble lag 0.3 m '-^ -~^s —=— Cross-stratification / ripple cross-lamination / laminae or bedding H5Z Heavy mineral lamination Section 87-12 (station 126), Basal Member Arenite, Lorrain Formation

gpl 85

; ngu :J , ———^ __

;'! P ! :' nnl ! : ! ngu 1 i ngu 1 l; 1 1 ,^'^-^ \\ 9P' i \ s j e \ ng u 1 l ng u ; gpi

\ i 1 'l 1 i 1. 1 l i i i. i r" i i ngu 1 i-o^- 1 i i e gpi i ; ngu \ i 18 m i gpi ' i e —— — i i gpi : 1 \ ' A ' , , ngu | ; i i i — l——— *\ ^^ e 1 i

ngu gpl \ , gpl 1 i ngu 'i •^s ngu ' 1 j 1 e \ g e | gpi j e 1 gpl i f - ngu gpi l ngu 1 i i ngu e 1 e gpi i ^^^ *" ^* i ngu ngu 'j ngu gpi ngu i gpi i l e e e \ e O m

Note: very fine-grained arenite lenses (cm thick) are not drawn to scale

LEGEND ——— Lens of micaceous, very fine-grained arenite (cm - 10's cm) i ~i Coarser—grained arenite with/without granules/pebbles e , g , s Erosional, gradational, sharp contact l ngu / gpl Normally-graded units (cm - 10's cm) / granule to pebble lag 0.3 m -^^ ^-S ——— Cross-stratification/ripple cross-lamination/heavy mineral lamination Section 88-2 (station 130), Middle Member Arenite, Lorrain Formation, Lorrain Township 86

ypi Note: Very fine —groined arenite lenses e — —— (cm thick) ore not drawn to scale

gpl

gpi gp"

1 6.8 m

gpi

O m LEGEND """"^^~ Lens of micaceous, very fine —grained arenite (cm — 10's cm) i —i Coarser—grained arenite with/without granules/pebbles e . g , s Erosional, gradationol. sharp contact ngu 7 gpl Normally-graded units (cm - 10's cm) f granule to pebble lag l --^-"' *^s —^— Cross-stratification/ripple cross-lamination/heavy mineral lamination 0.3 m Section 88-3 (station 131), Middle Member Arenite, Lorrain Formation, near Ville Marie, Quebec 87

Mole: Very fine-grained arenite lenses (cm thick) are not drawn to scale ____ e

Note: Unit definition very poor in uppermost unit ngu

15.25 m ngu

ngu

ngu

ngu t

ngu

ngu

ngu

ngu

O m

LEGEND ~""~"""'"" Lens of micaceous, very fine—grained arenite (cm — 10's cm) i i Coarser-grained arenite with/without granules/pebbles e , g , s Erosional, gradational, sharp contact l ngu l gpl Normally-graded units (cm - 10's cm) f granule to pebble lag 0.3 m ""^ ——— Cross-stratii'ication/ripple cross-lamination/heavy mineral lamination

Section 88 — 4 (station 135), Middle Member Arenite, Lorrain Formation, South Lorrain Township Note: Very fine-grained arenite lenses ngu (cm thick) are not arawn to scale

s

8.3 m

s

g e gpi e/s j

s gpi

ngu

s

s/g

s/g

s ^ ngu O m

LEGEND ^BMV Lens of micaceous, very fine—grained arenite (cm — 10's cm) i ~i Coarser—grained arenite with/without granules/pebbles e , g , s Erosional, gradational, sharp contact l ngu 7 gpl Normally-graded unils (cm — 10's cm) f granule to pebble lag 0.3 m —-^"^ "^-s ——— Cross-stratification/ripple cross-lamination/heavy mineral lamination

Section 88 — 5 (station 136), Middle Member Arenite, Lorrain Formation, South Lorrain Township 89 Note: Very fine-grained arenite enses (cm thick) are not drawn to scale

12.7 m 1 \ \ \ ngu \

\ \

s/e \ ^ \ \ \ \

ngu l gpl \ g ^^ gpl

ngu

s/e gpi s/e ^-^

s/e 9PI ngu n9U g?© s/e gpi

O m s/e

LEGEND ^^—-— Lens of micaceous, very fine-grained arenite (cm — 10's cm) i ~i Coarser—grained arenite with/without granules/pebbles e , g , s Erosional, gradational, sharp contact l ngu f gpl Normally-graded units (cm — 10's cm) f granule to pebble lag 0.3 m s^^" "^-^ —— Cross-stratification/ripple cross-lamination/heavy mineral lan.,nation

Section 88-6 (station 134), Middle Member Arenite, Lorrain Formation, South Lorrain Township 90 Note: Very fine —grained arenite lenses (cm thick) are not drawn to scale

5/6 \

e \

O m

LEGEND ——^^^ Lens of micaceous, very fine-grained arenite (cm - 10's cm) r l Coarser-grained arenite with/without granules/pebbles e , g , s Erosional, gradational, sharp contact ngu / gpl Normally-graded units (cm - 10's cm) / granule to pebble lag 0.3l m -^^ -^s —=— Cross-stratification/ripple cross-lamination/heavy mineral lamination

Section 88-7 (station 138), Middle Member Arenite, Lorrain Formation, Best Township 91

Appendix B:

Major Element and Trace Element Geochemistry for the Lorrain Formation in the Cobalt Plain 92 ©b

Appendix C:

M^jor Element and Trace Element Geochemistry for the Lorrain Formation in the Cobalt

Plain 93

TABLE 5 Major Element Analyses, Basal Member Arenite, Lorrain Formation, Cobalt Plain (1986 4 1987 data; 1988 data unavailable) li Fe203 MgQ CaO Na20 K20 T i O? P205 MnO C02

1/3 80. 6 10. 1 1. 31 0. 14 0. 13 2. 51 2.94 0. 14 0. 01 0 01 0. 15 0. 02 2/4 83. 3 9 52 1. 15 0. 09 0.07 0. 56 3.67 0 11 0.02 0. 01 0. 08 0 01 3/4 85.6 8. 11 0. 52 0. 14 0. 09 1.84 2. 82 0 08 0 0. 01 0 07 0 01 4/3 77.6 12. 1 1.61 0. 3 0. 14 2.04 4 24 0. 11 0.02 0. 01 0 16 0. 01 5/1 74 5 12. 3 3.03 1. 3 0. 14 5 38 0 21 0 36 0. 01 0. 02 0 17 0. 01

7/1 71. 3 13. 1 5 24 2.29 0.26 4. 37 0 68 0. 4 0. 03 0. 05 0. 14 0. 01 9/3 84. 3 7 86 2. 17 0.02 0. 06 0 26 3 43 0. 12 0. 01 0 01 0 09 0 01 11/2 80. 2 11. 8 1.43 0.09 0.06 0. 35 4. 35 0 13 0 01 0, 01 0. 1 0 01 12/1 77 10 9 5. 57 0. 1 0.07 0 3. 98 0 2 0 02 0 01 0. 15 0. 02 13/1 80. 8 10 5 2. 71 0. 1 0.05 0 41 3 85 0 15 0, 01 0 01 0. 1 0 01

14/1 83 4 9 46 1 51 0. 07 0 05 0. 28 3 66 0 14 0 0 0 12 0 01 15/3 83 8 9 28 1,65 0. 02 0. 04 0.25 3 67 0 11 0 01 0. 01 0. 08 0 01 27/2 87 7 3 1.62 0.05 0.05 0. 19 3.26 0. 1 0 01 0. 01 0 12 0 01 45/3 82. 1 10 1. 7 0. 08 0.05 02 3. 95 0. 09 0. 01 0 01 0 14 0 02 47/2 85 8. 08 0. 9 0.2 0.07 1.03 3 14 0. 08 0. 01 0 01 0. 09 0 01

48/2 82. 1 9.96 1. 31 0. 1 0. 17 0 3 4. 08 0.07 0. 01 0 01 0 22 0 01 49/2 85. 5 8 44 1. 48 0.01 0.05 0. 11 3.07 0 11 0 01 0 01 0 05 0 01 50/1 82 9. 34 1.68 0. 16 0. 16 2. 89 1 73 0 16 0. 01 0. 01 0. 38 0 01 59/1 86. 2 9 33 0.2 0 0.05 0.26 2. 34 0 14 0 0 01 0. 12 0. 01 60/3 91. 3 5.91 0 04 0.01 0.05 0 18 1 43 0 02 0. 01 0. 01 0. 1 0. 01

61/2 © 92. 2 5. 09 0.07 0.01 0.04 0. 32 1. 26 0.07 0 0.01 0. 14 0 01 63/1 86. 7 7. 49 1.09 0.05 0.05 0 2. 1 0 04 0 01 0. 01 0. 13 0. 01 98/1 73.4 12.2 3. 33 0 1.84 6. 43 0. 56 0 42 0 08 0. 05 1 76 0. 01 100/1 84. 7 8. 54 0. 72 0. 06 0.07 1 38 3 3 0 13 0 01 0 01 0. 1 0 100/5 85. 1 8.64 0. 19 0.02 0. 13 4.62 0. 32 0 13 0 0! 0 01 0 13 0 02

108/2 73. 7 12. 7 3. 6 1.35 0.2 6.21 0. 06 0. 47 0 01 0. 03 0, l 0 01 108/6 84.2 8. 72 0.9 0. 56 0. 16 3.28 1. 33 0 11 0 0. 01 0 05 0, 01 115/1 65 1 16 5 5.22 2. 18 0. 53 3 3. 35 0 57 0 09 0, 04 0. 56 0 115/5 64 17.5 5. 34 2.25 0.29 2.65 4. 07 0.67 0 06 0 03 0. 35 0 116/1 82. 5 9. 79 0. 79 0.03 0. 16 2. 97 2. 82 0. 08 0. 01 0. 01 0. 21 0 01

117/1 71 9 13 3 4 24 2 03 0 25 4 51 1, 3 0 47 0 02 0 03 0. 11 0 118/2 71 13 6 5 03 2. 21 0 18 4 01 1 42 0 42 0 01 0 02 0 2 0 120/2 77 11 2 3 26 0 92 0 13 4 05 1 79 0 3 0 02 0 02 ©0. 34 0 122/1 71. 1 13 9 4 53 1. 7S 0.27 5 12 1 2 0. 39 0. 04 0. 05 0 11 0 123/1 77. 5 12 1 66 0. 64 0. 13 2.28 4 04 0 12 0 01 0 01 0 1 0

124/1 72 7 14.8 2.21 0.64 0. 12 1.65 5.65 0. 13 0. 01 0. 01 0 12 0 126/1 81.9 10. 1 1.02 0.22 0. 14 2.08 3 11 0 09 0. 02 0. 01 0 22 0 01 126/2 71. 7 15.8 2. 27 0.6 0.08 1 49 5 4 0 37 0 01 0 0 08 0 0! Av 79. 7 10. 66 2. 17 0. 55 0. 17 2. 09 2 73 0, 21 0. 02 0. 02 0 20 0 01 Note:

1. St - work station and sample number; eg. 45/3 = station 45, sample 3 2. All values are percentages 3. All samples are ar en i t es 94

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rO CD *f CM Ul en ro CM on r^ 0 CM oo CO CM to LO O LO OO CO CM 0 o T en o CO —t m ~ u LO m ro •n ro -X) co en -* to CO en ro en OD o. 1 CM CO ro en T en CO ^OT^^Ln^rOrnCMHlcSooSilOfOOCTiCOfO^cOtO^T LO LO ro LO r** en ^r CD CO en -*r i--. in c. ID en 10 LO to to LO -^^oio^^-.^^^io^'-^^^.oTI'^S^ ' 'O CO ro CO CO l CO ? 1 1 10 CO

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, 6 . , , -5 96 73 71 -10 2,8 C 33 0 55 0.12 G. 53 0,1 0,35 -53 C 39 0 . 06 .t ©4 J © 2/4 -5 114 30 75 -10 3 1.7 0.33 1.1 3.14 0 86 p,;© 0.46 0.05 0.52 0.06 -2 16 10 i ; 3/4 -5 79 52 55 -10 1.9 1.1 0,27 O.S8 0.07 0.31 0,05 0.17 -50 0 22 -50 -2 c,5 ie 3,5 1 1 3 4/3 -5 141 64 70 -1C 25 1.5 0,33 0.65 0.11 C. 61 0,11 0.36 -50 0 44 C. BS -2 1.2 26 .3 i 1 5". 6 -5 23 153 -10 1.4 1,1 0,28 0.92 0.14 0.95 0.2 0.59 D. 09 0,7! 0.11 2 1 2 15 5,9 55 7/1 5 25 133 199 11 3.1 1.9 0.4 1.5 0.23 1.4 o.:g C. 88 0.12 1 0.15 0,002 2,1 31 15 12 7,6 9/3 -5 112 2- 96 -10 3.6 1,9 C. 3 7 1.1 0.15 0.81 0,14 0.42 0.06 0,5 0.07 -2 1.2 36 IS 13 1 1 © 3 -5 133 li :: -10 3.5 1.8 C 42 1 0.13 0.79 0,16 0.46 0.06 0.49 0.07 -2 1.4 3.- .7 13 3 9 12/1 7 139 34 U4 -10 2.3 1.4 0.2 1 0.16 1 0.19 0.59 0.08 0.68 0.1 -2 1 S c3 12 6,4 4 a 13/1 -5 122 27 6C -10 3.3 2 0.36 1.2 0.16 0.86 0.15 0.48 0.06 0.49 0.07 -2 1.5 33 IS 12 ©.4/1 -5 119 26 65 -10 2.6 1.5 0.28 0.91 0.12 0.55 0.12 0.34 -50 0.37 -50 -2 1.2 27 14 3,7 33 15/3 -S !25 26 71 12 2.2 1.3 2. 26 0.79 0.11 0.58 0.1 0.33 -50 0.37 -50 -2 1 22 11 7,8 27,7 5 se :s .-e -10 3 7 i. t ;,35 1 0.13 3.63 0.11 0 33 -50 0,37 C. 05 -2 2 35 13 13 3 45/3* -5 124 43 61 !2 3.5 0 41 1 2 0.17 0,55 3.13 0.5 O.C8 0 53 0.09 -2 1,4 4 17 13 47/2 -5 96 40 59 -1C 3.1 1.8 0.42 0.9 0.12 0.57 0.1 0.26 -50 0.29 -50 -2 0.6 31 15 11 2 5 48/2 -5 131 42 56 -10 2,8 !.6 a. 35 0.91 0.13 0.66 O.©.I 0.3! -50 0.33 -50 -2 0.9 7 4 P.? 2.6 45/2 -5 103 22 91 -10 28 ©,©l j, 32 0.97 0.13 0,77 0.42 0 06 Q 44 0,07 -2 0 56 U 12 3 i -5 59 56 67 1 0.14 0.74 0.14 0.36 0 06 0 39 s - 59/1 6 5* 44 122 -10 3.6 2.2 0,36 1.1 0.15 0,79 3.14 0.37 0.06 0 42 O.C7 1 5 37 18 li 60/3 ^5 33 92 64 -10 3 3 3.3 0.41 1.6 0.16 0 69 0.1! 0.24 -50 0 23 -? 09 30 13 ©.e 61/2 -5 3! 24 65 -10 1.5 0,59 0,17 0.47 O.C7 0,39 0.07 C. 2 -50 0.22 -50© -2 0,7 i j ©.7 53 55/1 -5 73 1: 55 il 1,4 0 65 C 19 :.52 o.os 0.43 0,09 0,26 -50 0 27 :.ri5 ^2 ©if, 13 f, b -- S SE.1 ! 10 16 13 1S5 -10 ^3.1 3,6 3,76 3.4 O.S5 4.4 0.99 3,2 C. c9 34 0.54 2 3,5 27 11 i 4 100/1 -5 94 45 47 -10 ©o. 62 0.44 0.1! 0.34 0.05 0.29 0.06 3.24 -50 0.28 -50 -2 0,7 5.6 2,9 2.3 1.9 130/5 -5 -5 18 58 -10 0.4 0.46 0.18 0.62 0.16 1.1 0.21 0.61 0.09 0.56 0.08 -2 5 3 26 1.3 1,7 5 2 108/2 6 -5 49 321 12 9 5.6 0.88 3.8 0.56 3.2 0.65 1.9 0.26 1.9 0 28 -2 3.6 J4 IS 34 16 106/6 -5 4! 35 55 -10 3.4 2 0.46 1.3 0.17 0.94 C. If 0.52 0.08 0.45 0.07 -2 1.3 33 17 13 5 115/1 6 136 81 155 12 5.3 3 9 0.94 j 0.46 2.6 r. 52 15 C. 23 1,4 0.21 0,006 3 3 50 26 :: 14 115/5 3 153 75 203 12 5.5 3.7 0.61 3 0.46 2,8 3.57 1.6 0.24 1.6 0.24 -I 1.3 5i 26 21 15 116/1 -5 87 76 52 -10 2.8 1.4 0.32 0.62 0.08 0.44 0.08 0.23 -50 0.32 -50 -2 0.6 26 13 10 2 117/1 6 47 79 252 -10 1.7 1.5 0.41 1.3 0.24 1.5 0.32 1 0.17 1.2 0.19 -2 3.1 16 7.6 6.4 8,6 ne/2 C 33 43 169 10 1.8 1 J 0.35 1.2 0.19 1,2 :.26 C 65. 0.14 0.©:©© 0.14 -2 : . r i? "5 7 j 12C72 -5 54 59 137 -10 13 C, 94 l 23 3.77 0.13 0.85 O.IS 0.58 0.08 0,66 C. 11 -2 i.: 11 5.0 4,6 i 7 122/1 6 40 113 123 -10 3 2.3 0.48 1.3 0.26 1.5 0.31 0.98 0.15 0,99 0.15 -2 2 3 3J 13 11 5.3 123/1 -5 139 74 60 -10 3.1 2 0.45 0.94 0.1 0.48 0.09 e 27 -50 0.3 -50 -2 07 30 17 11 2.4 124/1 -5 194 77 100 -10 0.96 0.74 0.21 0.66 0.12 0.58 O.iS 0.48 0.09 0.61 0.1 -2 i. 2 76 3,9 3.5 3.7 126/1 -S 94 37 54 -10 2 1.1 0.28 o.ee 0.1 0,54 0.11 0.33 C. 05 0.39 0.05 0.002 0.7 20 11 75 2.8 i, ; 126/2 5 179 33 192 -10 3.9 2.4 0.53 1.4 0.19 1 C. 21 0.64 0,1 0.7 0.12 0.004 1 6 37 ; a 14 Ay 6.4 95,2 48.5 108 11.4 2.9 !.9 0.39 1.22 O.iS 1.04 0.21 0.62 0.12 0.67 0,12 0.003 1 7 2 C .5 13 7 1C 6 e 4 lot e: 1. Units - parts per million (ppn) 2. Hegat we values - De low detection 3. Blank values * no analysis 4. St - station and saiip le number; tg. 120/2 - station 120. sotnole 2 96

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Major Element Analyses, Upper Member Arenite, Lorrain Formation. Cobalt Plain (1986 4 1987 data; 1988 data unavailable)

S i 02_____AI203 Fe2 03 .. MgO_____CaO_____Na20_____K20_____T i 02_____P205_____MnO_____C02______S

28/1 87 8 7 87 0 16 0 02 0. 05 0 22 2 05 0 02 0 02 0. 01 0. 12 0, 01 29/2 88. 6 7. 34 0 09 0. 02 0 04 0 02 1.98 0 05 0. 01 0 01 0, 11 0, 01 32/2 93 3 4 32 0, 06 0 01 0 04 0 2! 1 07 0 0. 01 0, 01 0. 15 0 01 33/1 92 4.94 0, 06 0 01 0. 05 0.27 1 23 0. 03 0 01 0 0 1 0 01 34/1 87 4 8. 24 0 04 0 01 0 04 0 18 2 12 0 1 0. 01 0, 01 0 19 0 01

35/1 89 3 6. 71 0. 03 0 0 04 0 17 1 56 0, 07 0. 01 0 0. 11 0, 01 36/1 91. 6 5 05 0, 07 0 0, 06 0 11 1 19 0. 05 0 01 0 01 0. 16 0 01 37/2 88 8. 09 0, 12 0 01 0 06 0 18 1 93 0 1 0 01 0 0. 08 0 01 38/1 91 4 5. 07 0 24 0 0 05 0 27 I 42 0 09 0. 01 0 01 0 14 0 01 39/1 97 1. 74 0 04 0 01 0 05 0. 06 0 34 0. 02 0, 01 0. 01 0. 11 0. 01

40/2 92 447 0 39 0 0. 05 0 32 1 29 0 05 0 01 0 01 0. 07 0 01 41/2 92 9© 4 21 0 08 0 0 09 0 OS 1 12 0, 03 0 01 0. 01 0 08 0 01 43/2 93 5 3. 99 0 12 0, 01 0 06 0 1! 1 02 0 07 0 01 0, 01 0 09 0 01 43/3 90 6 1 0, 13 0.01 0 04 0 23 1 63 0 08 0 0 0 08 0 01 44/2 94, 3 3.87 0 06 0. 01 0. 04 0. 15 0 95 0 01 0. 01 0 01 0 07 0 01

54/1 86 3 7.93 1. 71 0 02 0 06 0 15 2 83 0. 13 0. 01 0. 01 0. 18 0 01 58/1 85 3 8 59 1 16 0 03 0 05 0.2 3, 12 0. 1 0 01 - 0 01 0, 23 0 01 62/1 89. 1 6. 19 0. 45 0. 06 0 04 0. 36 1. 73 0. OS 0 0 01 0. 1 0. 02 64/1 87. 9 7. 1 0. 31 0. 04 0 04 0. 23 2. 65 0. 03 0 02 0. 01 0. 1 0 01 66/1 85 4 7 27 0. 94 0 01 0 07 1 96 2 28 0. 02 0 01 0 0. 07 0 03

76/1 " 92 8 4. 85 0 15 0 03 0 05 0 03 1 29 0. 09 0 0 0 15 0 01 77/2 81. 3 8. 1 5 7 0 02 0 05 0 18 2. 38 0.68 0 0. 01 0 12 0 01 78/1 93 9 3. 73 0 41 0 0.05 0 17 0 87 0. 09 0. 01 0. 01 0 1 0. 04 79/1 91 6, 11 0 07 0 03 0 05 0 16 1 6 0 09 0 0 0 1 0 01 80/1 98 1 1 32 0. 24 0 02 0 05 0 02 0 16 0, 05 0 0. 01 0 08 0, 01

80/2 95 5 2 97 0, 14 0 03 0 09 0 11 0 6 0. 09 0 01 0 01 0. 07 0 01 84/1 98 5 1. 48 0, 03 0. 02 0 04 0 1 0 2 0. 07 0 01 0.01 0 24 0 01 86/2 82 8 10. 6 0 99 0 0 03 0 12 3 0. 2 0 01 0 0. 12 0 01 86/5 82 1 11. 3 0. 87 0 01 0. 03 0. 04 3 15 0 2 0 01 0 0 14 0 01 86/7 89 7 5 76 I 54 0 0 04 0 07 1 42 0, 18 0 0 0 18 0 01

87/1 98 5 0. 96 0 02 0 01 0 04 0 1 0 1 0. 09 0 0 0 05 0 02 87/4 66 1 18. 2 3 25 0.68 0. 05 0 7 46 0. 59 0, 01 0 01 0 11 0 87/6 94, 6 2, 21 1, 75 0 01 0 06 0 07 0 74 0 05 0 01 0. 01 0 2 0 01 91/3 94, 4 2. 62 1.25 0. 01 0 05 0 1 0 8 0 03 0. 01 0. 01 0 08 0 05 96/1 85 9 9, 59 0 15 0 02 0 05 0 16 2 17 0. 2 0 02 0 0 17 0 01

96/2 88 8 7. 64 0 0 01 0, 04 0. 06 1 6 0. 22 0. 01 0 01 0. 24 0 02 97/1 95 4 3 15 0 0.02 0.05 0 2 0, 7 0 04 0 01 0 0 08 0 01 104/1 91, 1 6,22 0. 07 0 0 04 0 1 5 0.06 0 0.01 0. 11 0. 01 106/4 86 7 9. 52 0 0 0 05 0 22 2 0. 12 0 01 0 01 0 09 0 02 106/8 84 9 9 98 0 86 0 03 0 15 0 22 1 66 0. 19 0 02 0. 02 0 15 0 01

107/2 95 3. 11 0. 32 0 03 0. 05 0. 15 0 65 0 03 0. 01 0.01 0 12 Q 01 109/4 93 6 4 5 0 05 0 0 05 0, 29 0, 61 0 06 0. 03 0 01 0. 05 0, 02 110/3 92. 7 4.96 0. 07 0 01 0 04 0. 17 1, 2 0.03 0. 01 0 0. 08 0 02 110/8 93 4. 39 0 07 0 0 05 0 22 0 9 0 04 0 01 0 0. 06 0 01 111/1 87 6. 86 0 57 0 13 0 16 0 72 2, 99 0 09 0. 09 0.01 0. 11 0, 01 99

TABLE 9 (continued)

St S i 02____AI203 Fe203 MgO CaO_____Na20 K20_____TI02____P20S MnO_____C02

111/3 93. 3 5. 29 0. 02 0. 01 0. 04 0. 12 0.27 0. 03 0 0 0.25 0. 01 112/3 89. 6 6. 86 0 06 0. 01 0. 04 0 33 1. 68 0. 07 0 01 0 0. 1 0. 01 113/3 90 7. 19 0.03 0. 01 0. 04 0. 04 1. 34 0. 1 0.01 0. 01 0. 14 0. 01 113/8 90 8 6. 23 0. 06 0 0.05 0.24 1. 42 0. 05 0 0 0. 11 0. 01 114/1 86. 8 8. 71 0 11 0 0. 05 0. 57 2. 3 0. 03 0. 01 0 01 0. 11 0. 01

114/7 87 9. 08 0 24 0 0. 04 0 35 2 32 0 03 0. 01 0 01 0. 17 0. 01 125/1 81 5 9 55 1. 97 0. 86 0 12 2. 82 1 91 0. 17 0 0 02 0. 1 0 01 125/2 89. 5 7. 23 0 26 0 0, 04 0 2 1 91 0 06 0 01 0 0 14 0 01 Av. 89 9 6 21 0, 52 0 04 0 05 0 26 1. 63 0. 10 0 01 0. 01 0 12 0 01 Not e: 1 St - work station and sample number, eg. 80/2 ^ station 80, sample 2 2 All values are percentages 3 Conglomerate samples are© 43/2. 43/3, 80/1. 86/2, 86/7, 96/2, 97/1 100

.1 - 101

s s

—* ao 102 Table l Ontario Geological Survey Publications (1891-1988) involving the Lorrain Formation in the Cobalt Plain. Chronological arrangement Author Year Publication Type Context Miller, W. G. 1906 AR, v.14, pt. 2 brief discussion Burrows, A. G. 1909 AR, v.18, pt. 2 brief discussion Miller, W. G. 1913 AR, v.19, pt. 2 brief discussion Burrows, A. G. 1922 AR, v.30, pt. 3 brief discussion Todd, E. W. 1926 AR, v.35, pt. 3 brief discussion Moorhouse, W. W. 1944 AR, v.50, pt. 4 brief discussion Lawton, K. D. 1952 PR, 1952-1 mention Lawton, K. D. 1955 AR, v.63, pt. 4 brief discussion Moore, E. S. 1956 AR, v.64, pt. 5 brief discussion Thomson, R. 1960 PR, 1960-1 brief discussion Thomson, R. 1960 PR, 1960-3 mention Thomson, R. 1961 PR, 1961-2 mention Thomson, R. 1961 PR, 1961-3 mention Thomson, R. 1961 PR, 1961-4 mention Thomson, R. 1961 PR, 1961-6 mention Thomson, R. 1961 PR, 1961-7 mention Simony, P. S. 1964 R, 28 discussion Thomson, R. 1966 MP, 5 discussion MacKean, B. E. 1967 OFR, 5006 brief discussion MacKean, B. E. 1968 R, 62 discussion Meyn, H. D. 1968 OFR, 5015 discussion Thomson, R. 1968 OFR, 5019 brief discussion Mcilwaine, W. H. 1969 OFR, 5035 brief discussion Meyn, H. D. 1969 OFR, 5033 brief discussion Mcilwaine, W. H. 1970 R, 83 discussion Meyn, H. D. 1970 OFR, 5047 brief discussion Meyn, H. D. 1970 R, 80 discussion Mcilwaine, W. H. 1971 R, 89 discussion Meyn, H. D. 1971 R, 91 discussion Meyn, H. D. 1972 R, 100 discussion Mcilwaine, W. H. 1975 OFR, 5113 brief discussion Lovell, H. L. 1976 MP, 51 discussion Mcilwaine, W. H. 1978 R, 175 discussion Wood, J. 1979 MP, 90 mention Dressler, B.O. 1980 OFR, 5287 discussion Johns, G. W. 1980 OFR, 5303 discussion Dressler, B.O. 1981 OFR, 5347 brief discussion Dressler, B.O. 1982 R, 213 discussion Johns, G. W. 1983 OFR, 5478 discussion Johns, G. W. 1985 R, 237 discussion Dressler, B.O. 1986 R, 242 discussion Johns, G. W. 1986 R, 250 discussion Debicki, R. 1987 OFR, 5665 discussion Born, P. 1988 OFR, 5663 discussion Note: P. Born has two reports in progress that involve the Lorrain Formation in the Cobalt-Temagami area of the Cobalt Plain. AR - Annual Report R - Geological or Geoscience Report OFR - Open File Report PR - Preliminary Report MP - Miscellaneous Paper 103 TABLE 2 Descriptive Attributes of Lithofacies Defined in the Basal Member of the Lorrain Formation in the the Cobalt Plain Sf RA Thk. Additional Features Conglomerate la 100 granitic, volcanic, siltstone, and arenite lithics; lenses of rippled and/or laminated arenite; rare weathering rinds; heavy minerals /Ire/?/1 e 2a 40 cm - 10©s cm siltstone, arenite, granite, jaspilite lithics; rare siltstone lenses; pockets/ lenses of quartz and feldspar granules; small scours 2b 14 2 - 50 cm quartz and feldspar basal granule lags; jaspilite, granite, siltstone lithics; ripple cross-lamination; pyrite grains 2c 4 5 - 15 cm commonly accentuated by heavy minerals 2d l 10©s cm rare arenite, siltstone, granite lithics; common quartz granules/ pebbles 2e 5 cm - 10©s cm quartz and feldspar granules; rare arenite lithics; heavy minerals 2f 12 5 cm - 1.5 m foreset grading; heavy minerals 2g 6 5 cm - l m foreset grading 2h 13 5 - 20 cm rare clay drapes; heavy minerals 2i 5 cm - 10©s cm heavy minerals 2j l l - 5 cm rare clay drapes Note: Sf - sub-facies RA - relative abundance by number) Thk - estimated range in thickness 104

TABLE 2 (continued) 2a - non-stratified arenite 2b - normally-graded arenite 2c - parallel-laminated arenite 2d - thin-bedded arenite 2e - very thin-bedded arenite 2f - large scale planar tabular cross-stratified arenite 2g - large scale trough cross-stratified arenite 2h - small scale trough cross-laminated arenite 2i - convolute-laminated arenite 2j - symmetrical-rippled arenite 105 TABLE 3 Descriptive Attributes of Lithofacies Defined in the Middle Member of the Lorrain Formation in the Cobalt Plain Sf RA Thk. Additional Features Conglomerate la 100 cm - 10©s cm Occasional jaspilite lithics Arenite 2a 33 cm - 10©s cm small scours; occasional heavy minerals; occasional quartz and feldspar lags; rare jaspilite, arenite, siltstone, and granitic lithics 2b 20 cm - 10©s cm basal, and rarely top, quartz and feldspar granule lags; occasional jaspilite, arenite, siltstone, and granitic lithics 2c l 2 - 5 cm occasional heavy mineral laminae 2e 2 cm - 10©s cm occasional clay drapes 2f 21 cm - l m occasional clay drapes; occasional perpendicular-normal foreset grading 2g 7 cm - l m occasional perpendicular-normal foreset grading; occasional clay drapes 2h 14 cm - 10©s cm occasional heavy minerals; occasional clay drapes 2i l 2 - 10 cm occasional heavy minerals 2j l l - 5 cm Note: Sf - sub-facies RA - relative abundance by number) Thk - estimated range in thickness 2a - non-stratified arenite 2b - normally-graded arenite 2c - parallel -laminated arenite 2e - very thin-bedded arenite 2f - large scale planar tabular cross-stratified arenite 2g - large scale trough cross-stratified arenite 2h - small scale trough cross-laminated arenite 2i - convolute-laminated arenite 2j - symmetrical -rippled arenite 106 TABLE 4 Descriptive Attributes of Lithofacies Defined in the Upper Member of the Lorrain Formation in the Cobalt Plain Sf RA Thk. Additional Features Conglomerate la 100 cm - 10©s cm mainly quartz granules and pebbles; occasional smaller jasper clasts Arenite 2a 46 cm - 60 cm small scours; quartz and jasper/ jaspilite (rare) granule lags; rare feldspar grains; occasional granitic lithics 2b 11 2 - 30 cm basal quartz granule lags; rare clay drapes; normally graded units are occasionally stacked 2c 5 2 - 90 cm rare heavy minerals 2d 1 10©s cm 2e 3 10©s cm rare heavy minerals 2f 19 8 cm - 3 m occasional perpendicular-normal foreset grading; rare, apparent chevron sets 2g 4 5 - 54 cm occasional perpendicular-normal foreset grading 2h 8 2 - 20 cm rare heavy mineral laminae 2i l to 15 cm rare heavy mineral laminae 2j 3 l - 5 cm Note: Sf - sub-facies RA - relative abundance (c/* by number) Thk - estimated range in thickness 2a - non-stratified arenite 2b - normally-graded arenite 2c - parallel-laminated arenite 2d - thin-bedded arenite 2e - very thin-bedded arenite 2f - large scale planar tabular cross-stratified arenite 2g - large scale trough cross-stratified arenite 2h - small scale trough cross-laminated arenite 2i - convolute-laminated arenite 2j - symmetrical-rippled arenite O) e n O) CO m 0) > CD o O D ^. (7) o 0; CO

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Landward Episodic Transgression Permits Accumulation of Hundreds of Meters of Immature Braidplain Detritus in a Shelf Environment

Innundations Rework Braidplain Detritus Into a Complex of Moribund and Palimpsest Shelf Sediment

Transgressive Stillstands Promote Coastal Regime Established Braidplain Progradation as a Result of Foundering Passive Margin Tectonic Setting

Seaward

Figure**s 3 Schematic Representation\ of Episodic Transgression During Basal, and Possibly Middle and Upper, Lorrain Formation Time en o

GC GC O en LU Q o

CJ l—l h- LU LU M t-3 l— l—i CE O en

DC h- LU Q

LU GC ZD CD l—i LL

GC *t a. en a

NIVHdOI Photo 1.

The characteristic lithofacies sequence in the basal member of the Lorrain Formation in southwestern Auld Township. Finer-grained arenite lenses (fga) gradationally cap crudely tabular coarser-grained arenite bodies (cga) and are erosively succeeded by similar coarser-grained arenite units. A similar lithofacies sequence exists in the middle and upper members of the formation (see Photos 2 and 3). Large symmetrical waveforms (sw) occur along the upper contact of the finer-grained arenite lenses suggesting wave reworking of these surfaces. Nine centimeter scale.

114

Photo 2.

The characteristic lithofacies sequence of the middle member arenite in the Lorrain Formation as displayed in outcrop on Chiniguchi Lake, Mcdonnell Township. The darker colored, recessive weathering units (arrows) are finer-grained arenite lenses separating lighter weathering, coarser-grained arenite bodies. This lithofacies sequence is also found in the basal and upper members of the formation (see Photos l and 3). The top recessive horizon is ea. 45 cm thick

115

Photo 3.

The lithofacies sequence characteristic of the upper member of the Lorrain Formation as displayed in outcrop on southern Makobe Lake, McGiffin Township. Tabular, coarser-grained arenite bodies (cga) are separated by recessive horizons of finer-grained arenite (fga). This sequence also characterizes the basal and middle members of the formation (see Photos l and 2). Trees for scale.

116

Photo 4.

Clay drapes (arrows) accentuating trough-shaped foresets in the middle member arenite of the Lorrain Formation exposed on the western shore of central Lorrain Lake in South Lorrain Township. Nine centimeter scale with arrow pointing in the upstream direction.

117

Qm

Qm

Photo 5.

Photomicrograph of a sample (46/2) from the coarser-grained arenite association in the middle member of the Lorrain Formation in northwestern Willet Township showing a partially silicified plagioclase feldspar grain (Fp) surrounded by monocrystalline quartz grains (Qm) of approximately equal size. The near equivalence, with respect to size, of the feldspar and quartz grains suggests that the quartz is recycled, which in turn implies the presence of sedimentary bedrock in the source region, (crossed nicols, lOx objective, magnification through camera ^ 32, field of view through camera z 1.1 mm)

118 CONVERSION FACTORS FOR MEASUREMENTS IN ONTARIO GEOLOGICAL SURVEY PUBLICATIONS Conversion from SI to Imperial Conversion from Imperial to SI SI Unit Multiplied by Gives Imperial Unit Multiplied by Gives LENGTH 1 mm 0.039 37 inches 1 inch 25.4 mm 1 cm 0.393 70 inches 1 inch 2.54 cm 1m 3.280 84 feet 1 foot 0304 8 m 1m 0.049 709 7 chains 1 chain 20.116 8 m 1km 0.621 371 miles (statute) 1 mile (statute) 1.609 344 km AREA 1 cm2 0.155 0 square inches 1 square inch 6.451 6 cm2 1 m2 10.763 9 square feet 1 square foot 0.092 903 04 m2 1 km2 0.386 10 square miles 1 square mile 2.589 988 km2 1 ha 2.471 054 acres 1 acre 0.404 685 6 ha VOLUME 1 cm3 0.061 02 cubic inches 1 cubic inch 16.387 064 cm3 1 m3 35.314 7 cubic feet 1 cubic foot 0.02831685 m3 1 m3 1.308 0 cubic yards 1 cubic yard 0.764 555 m3 CAPACITY 1 L 1.759 755 pints 1 pint 0.568 261 L 1 L 0.879 877 quarts 1 quart 1.136 522 L 1 L 0.219 969 gallons 1 gallon 4.546 090 L MASS lg 0.035 273 96 ounces (avdp) 1 ounce (avdp) 28.349 523 g lg 0.032 150 75 ounces (troy) 1 ounce (troy) 31.103 476 8 g 1kg 2.204 62 pounds (avdp) 1 pound (avdp) 0.453 592 37 kg 1kg 0.001 102 3 tons (short) 1 ton (short) 907.184 74 kg 1 t 1.102311 tons (short) 1 ton (short) 0.907 184 74 t 1kg 0.000 984 21 tons (long) 1 ton (long) 1016.046 908 8 kg 1 l 0.984 206 5 tons (long) 1 ton (long) 1.016 046 908 8 t CONCENTRATION Ig/t 0.029 166 6 - ounce (troy)/ 1 ounce (troy)/ 34.285 714 2 g/i ton (short) ton (short) lg/1 0.583 333 33 pennyweights/ 1 pennyweight/ 1.714 285 7 g/i ton (short) ton (short) OTHER USEFUL CONVERSION FACTORS Multiplied by 1 ounce (troy) per ton (short) 20.0 pennyweights per ton (shorl) 1 pennyweight per ton (short) 0.05 ounces (troy) per ton (shot'O

Note: Conversion factors which are in bold type are exact. The conversion factors have been taken from or have been derived from factors given m the.Metric Practice Guide for the Canadian Mining and Metallurgical Indus tries, published by the Mining Association of Canada in co-operation with the Coal Association of Canada

V.

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O "O Q) CO TJ QL O 'F Q. -D C D r ir

n D

LEGEND Lalre Timiskaming planar tabular cross-strata trough cross-strata 1b basal member station 2m middle member station 3u upper member station 2u number of measurements

Note: planar tabular and trough cross-strata are not the only directional data recovered from the Lorrain Formation, but they are the dominant structures at most station locations

Scale;

o 30 km L -4*'

.-far

eg

-•raft-;

Qm