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MARGINAL NOTES t Ministry of Ministry of Mapping of the Paleozoic rocks on Manitoulin Island formed part Head of the Manitoulin Island Limestone-Dolostone Assessment Project. Natural Northern This project was funded by the Ontario Ministry of Northern Affairs DRUMMOND through the Northern Ontario Geological Survey (NOGS) program. Resources Affairs The principal objective of this project was to produce maps show N Ontario ing the distribution of the limestones and dolostones on the island O Hon. Michael Harris Hon. Leo Bernier according to their quality and usefulness fi T as construction material ISLAND Minister Minister and as metallurgical fluxes. However, in collecting data for this XIV H purpose new information on the Paleozoic stratigraphy of the Mary Mogford David Hobbs island became available, thus allowing production of new geologi Deputy Minister Deputy Minister cal maps. These new maps constitute revisions of earlier maps H A N N E L prepared by Dr. B.A. Liberty and published in 1972 based on field work during the period 1954 to 1957 (Liberty 1972a, 1972b, 1972c, Ontario Geological Survey 1972d. 1972e. and I972f). The Meldrum Bay map area displays moderately rolling topog MAP P.2667 raphy, broken by small plateaus. Relief within the map area amounts to about 60 m, mostly accounted for by bedrock knolls. GEOLOGICAL SERIES - PRELIMINARY MAP Glacial drift is thin in this map area, providing minor depression 11 infillings between glacially carved ridges, cuestas and areas of stripped bedrock. Shorelines form the most predominant physiog raphic features, with North Channel, Mississagi Strait, and Lake PALEOZOIC GEOLOGY Huron bounding the map area. North and west lacing shorelines ". l pi) HI t tend to occur as cliffs or escarpments. The south facing shores 11 mostly display bedrock pavements dipping gently below water fill V MELDRUM BAY AREA level, although minor swampy intervals and boulder beaches are present. This pattern results from the regional dip of the bedrock DISTRICT OF MANITOULIN strata on the island to the southwest at the rate of about 6 m per kilometre combined with Pleistocene glacial erosion. These fea Scale 1.50 000 tures have also resulted in exposure of the oldest strata in the north with successively younger beds exposed to the south. Bed Metre; 1000 O ______1 Kilometre rock is well exposed throughout the map area although most outcrops are of the bedding plane type. Mile l O l M, ~? STRATIGRAPHY NTS Reference: 41 G/14 \ C O C K ODM-GSC Aeromagnetic Map: 2225G SILURIAN OGS Geological Compilation Map: 2441 Cabot Head Formation The oidest unit present within the map area is the Cabot Head UNMAPPED Formation, The Cabot Head, Dyer Bay. Wingfield. and St. Edmund 1985 Government of Ontario rock units were previously designated as members of the Cabot Printed in Ontario, Canada Head Formation (Liberty and Bollon 1971. Liberty 1972). However, field work has shown all four units to be discrete and mappable Parts of this publication may be quoted if credit is and they should thus be accorded full formational status. This COCKIU©RN ISLAND given and the material is properly referenced. nomenclature was used by Bolton (1957) and earlier workers. This map is published with the permission of V.G. The Cabot Head Formation consists of 16.7 m (average thick 6 r. Milne, Director. Ontario Geological Survey. ness, this map area) of red and green shale This formation overlies the Manitoulin Formation, a brown thinly bedded shaly dolostone, not exposed in the map area. Subsurface studies have shown the contact between these units to be gradational. Cores recovered from Cabot Head strata by the Ontario Geological Sur vey (Johnson and Telford 1981a, 1981b) contain scattered bands Sg and laminae of evaporitic minerals. This unil is usually unlos- Litirc K siliferous on the island but may contain a number of fossiliferous Island. AND carbonate interbeds near the top of the formation. Due to the Munumriil recessive nature of these shales, exposures of this unit are poor in this map area. Limited exposure can be seen around Chamber lain Point (U.T.M. 340BOOE - 5091400N). The contact between the Cabot Head and overlying strata is not observed in the map area. although exposures elsewhere on the island (Ice Lake Road-Cut, U.T.M. 390500E - 5083400N. Kagawong map area, N.T.S. 410/16) A N ,D. suggest it to be sharp.
Dyer Bay Formation W ti g o s h The Dyer Bay Formation conformably overlies the shales of the Cabot Head Formation. The contact is usually placed at the last IV appearance of green shales of the underlying Cabot Head Forma tion. B ©t v The formation consists of about 6 m of blue-grey, thinly bedded, mediocrystalline dolostone. These rocks are quite fos siliferous, displaying an abundance of the pentamerid brachiopod Virgiana in the lower part (as at Whitiey Point, U.T.M. 338GOOE - III 5087700N) and a bryozoan-rich assemblage in the upper part (as seen along Meldrum Bay shoreline, U.T.M. 338000E - 5086500N). X This formation weathers buff-brown, with its fresh colour evident only in the most recent exposures, Shaly recessive partings are -OCATION MAP Scale : 1 : 1 548 000 or 1 inch to 25 miles found in most exposures in the map area.
Wingfield Formation The Wingfield Formation conformably overlies ihe Dyer Bay For mation. The contact between the two units is not exposed within the map area, although elsewhere on the island (Ice Lake, Kagawong map area, N.T.S. 41G/16) the contact is sharp. The Wingfield formation consists of about 10 m of thin and evenly bedded green shale, interbedded with brown, very fine LEGEND grained dolostone. The strata have a characteristic pale green weathering colour. The unit is poorly fossiliferous. with only a PHANEROZOIC sparse ostracod/lingulid brachiopod assemblage, Frequently, the PALEOZOIC strata display shallow water depositional features such as ripple marks and dessication cracks. A bedding plane exposure of this MIDDLE SILURIAN formation occurs near Macrae Cove (U.T.M. 336950E - 5086600N). Amabel Formation (Facies IV): Dolostone, granular, soft, white, massive St. Edmund Formation GREEN E ISLAND Field, mapping and subsurface studies (Johnson and Telford Amabel Formation (Facies III): Dolostone. 1981 a, 1981 b) carried out m this map area and elsewhere on medium lo finely crystalline, blue-grey, massive Manitoulin Island have shown that strata formerly separated into to thickly bedded ihe St. Edmund Member (Cabot Head Formation) and the Min- 16c* Facies III, abundant crinoid debris demoya Formation (Liberty 1972) constitute a single rock unit. The 16p Facies III. abundant pentamerid brachiopods name St. Edmund has priority (introduced by Williams 1919) and is therefore used here, with formational status, to define those strata Amabel Formation (Facies II): Dolostone, medium lying stratigraphically between the Wingfield and Fossil Hill Forma tions. to finely crystalline, blue-grey to buff, massive, minor, thinly bedded, lenticular bodies forming The St. Edmund Formation conformably overlies the Wingfield 16 p hummocky topography Formation. The contact is placed at the last appearance of green 15c* Facies II, abundant crinoidal debris shaies of the Wingfield Formation. The contact between these units is not exposed on the island, althougn drilling (Johnson and Telford 1981 a, 1981 b) suggests it may be gradational in some Amabel Formation (Facies l): Dolostone, finely places. Within the map area, the maximum recorded thickness of crystalline, brown, thinly bedded the St. Edmund Formation is 46.05 m (in O.G.S. D.D.H. No. 17) with A K E 14b* Facies l, richly fossiliferous a minimum of 22-2 m (in O.G.S. D.D.H. No. 19). There appears to be HURON l4ch*Facies l, abundant nodular chert a wesiward thickening of the unit across the map area. The formation consisls of thin and evenly bedded, pale grey, Fossil Hill Formation: Dolostone, fine to coarsely lithographic dolostone, alternating with thicker zones ol brown, crystalline, buff- brown, thinly bedded, chert-rich medium bedded, finely crystalline dolostone. These strata weather in upper part a lighter colour and have a strong tendency of developing closely spaced vertical joints, causing the rocks to break upon weathering St. Edmund Formation: Dolostone, lithographic, into a series of brick-sized blocks. Silty partings are common pale grey to finely crystalline, buff-brown, thin to within this formation. The unit is poorly fossiliferous, except for a medium bedding bed of "oncolites" (bulbous stromatoporoids) found 3 or 4 m below the top of the formation. This bed (about 1 m thick) is found Wingfield Formation: Interbedded dolostone and extending into the map-area from the east, and is present in the shale drill hole north of Loon Lake (D.D.H. No. 19). However, this bed is not present in the hole west of Meldrum Bay Village (D.D.H. Dyer Bay Formation: No. 17). The St. Edmund strata are predominantly pale grey Doloslonp, fine to medium lithog crystalline, buff lo raphic rocks in the upper part of the formation and brown, grey-brown, thinly bedded, finely fossiliferous crystalline beds in the lower part of the formation. In this map area, strata of the St. Edmund Formation are mostly exposed as LOWER SILURIAN sections along the northern shoreline. A good section is exposed on the west side of Vidal Bay (U.T.M. 344500E - 5088100N). Cabot Head Formation: Shales, red and green Fossil Hill Formation Manitoulin Formation: Dolostone, fine to medium Subsurface data (Johnson and Telford 1981 a, 1981 b) field work crystalline, thinly bedded, locally massive across the island has led, in the present study, to a more restric tive definition for the Fossil Hill Formation. DISCONFORMITY The Fossil Hill Formation disconformably overlies the St. Ed mund Formation. The contact is not clearly exposed in this map UPPER ORDOVICIAN area, although elsewhere on the island it is sharp but devoid of features indicative of extended periods of erosion (e.g. Cup and Georgian Bay Formation: Interbedded limestone, Saucer. U.T.M. 414200E - 5077950N, Kagawong map area, N.T.S. dolostone, decreasing carbonate to base, increasing 41G/16). The coniact is easily recognizable by the presence ol shale the distinctive Fossil Hill fauna and change in lithology. Between 2 Blue Mountain Formation: Shale, soft, blue-grey and 4 m above the base of the Fossil Hill Formation is an interbed (argillaceous) (1 to 3 m thick) of the same lithology as the uppermost strata of Western the St. Edmund Formation. This bed is informally called the "False MIDDLE-UPPER ORDOVICIAN Mindemoya" and can be used as a marker horizon across the island. Lindsay Formation: Limestone, finely crystalline Averaging close 4ft to 23 m in thickness across the island, the to sublithographic , partly argillaceous, minor Fossil Hill Formation S.T.©to consists of a buff to grey-brown, fine to dolostones, thinly bedded, overlain by black, coarsely crystalline dolostone. This unit is thin to medium irregu petroliferous shales larly bedded and displays frequent black, shaly partings. Char acteristic of this formation is its abundance of silicified fossils. Facies II (Unit 15,15C): A massive to thinly bedded, finely cry strata are mostly poorly fossiliferous These include coral, brachiopod and stromatoporoid material, fre {Unit 16), however, in the REFERENCES SYMBOLS MIDDLE-ORDOVICIAN stalline, blue lo buff dolostone, outcropping in a mound or southeastern part of the CREDITS quently disoriented and disarticulated within the strata. As map area, they become quile rich in these hummocky relief. Some of these mounds are of reefal remains are silicified and thus harder than the surrounding rock pentamerid brachiopods (Unit 16p) which are evident as interior Bolton, T.E, 1972d: Little Current Area Manitoulin District, Ontario Division of Bedrock outcrop origin, and some areas are rich in crinoid debris (15c), Geology by M.D. Johnson, Verulam Formation: Limestone and shale, they tend to weather out in "bas" relief on exposed surfaces. Also and exterior molds and casts. Facies l strata are present in the 1957: Silurian Stratigraphy and Paleontology of the Niagara Es Mines, Map 2247. scale 1:63 360. from which a sample P.G. Telford and assistants, 1979-1981. Facies III (Unit I6,16p,16c): A massive, alternation, limestone is coarsely crystalline to common in the upper part of the Fossil Hill Formation are abun finely crystalline,blue - grey, southeast and appear to be laterally equivalent to at least part of carpment in Ontario; Geological Survey of Canada, Memoir 1972e: Providence Bay Area, Manitoulin District; Ontario Division was taken and field cream-buff weathering dolostone, sublithographic, partly bioclastic and dant chert beds and nodules. outcropping as thick the Facies III strata. 289, 145p., 13 plates. of Mines, Map 2248, scale 1:63 360. data collected. Every possible effort has been made to ensure the accuracy of sheets. Parts of this facies argillaceous. Fossiliferous, shale and limestone Outcrops of this unit are rich in pentamerid brachio- Exposure of Amabel strata is extemely good, particularly along (N.B.AII outcrops the information presented on this map: however, the Ontario Min in the map area are frequent but of pods (16p) Johnson, M.D. and Telford, P.G. 1972f: Manitowaning Area, Manitoulin District. Ontario Division of is blue-grey restricted or crinoid remains {16c). the south shore which presents an almost unbroken line of out present on the island istry of Natural Resources does not assume any liability for errors vertical extent. The unit is quite well exposed on High 1981a: Preliminary Results of the 1978-1979 Drilling Programme. Mines, Map 2249, scale 1:63 360, way 540 at Meldrum Facies IV (Unit 17): A massive, granular to powdery, white, unfos- crop. are not shown on SOURCES OF INFORMATION that may occur. Users may wish to verify critical information; Bay (e.g. U.T.M. 338750E - 5084500N). Manitoulin Island Limestone-Dolostone Assessment Bobcaygeon Formation: Limestone, siliferous dolostone, previously mapped as Guelph Forma Project; Liberty, B.A. and Bolton, T.E. the map.) sources include both the references listed here and information Ontario Geological Survey, Open File Report 5360. on file at sublithographic and very finely crystalline, thinly tion (Liberty 1972). 1971: Paleozoic Geology of the Bruce Peninsula Area; Geological Topography from map 41 G/15 of the National Topographic the Resident or Regional Geologist©s office and the 19B1b: Preliminary Results of 1980 Drilling Programme, Series. Mining Recorder©s bedded, moderately fossiliferous Amabel Formation Disconformably overlying the Fossil Hill Formation, the ECONOMIC GEOLOGY Manitoulin Survey of Canada, Memoir 360, 163p. Quarry office nearest the map area. Island Limestone-Dolostone Assessment Project; Ontario Amabel Formation has a maximum thickness in the map area of Williams, M.Y. Additional geological information from The stratigraphy of the Amabel Formation on Manitoulin Island has Two dolostone quarries are present in the map area; an Geological Survey, Open File Report 5364. drill cores taken on Man Gull River Formation: Limestone, finely 21.35 m (O.G.S. D.D.H. No.l, Johnson and Telford 19813) at the aban itoulin Island between This project was funded by the Ontario Ministry of Northern Affairs proven to be more complex than previously reported. The forma doned quarry at Quarry Bay (U.T.M. 338750E 1919: The Silurian Geology and Faunas of Ontario Peninsula, and Geological Boundary 1978 and 1980 (Johnson and Telford crystalline to granular, dark grey, grading into extreme western end of the map area. At Quarry Bay (U.T.M. - 50B0800N}, Liberty. B.A. 19B1a, 1981b). through the Northern Ontario Geological Survey (NOGS) Program. tion is composed of various types of dolostone ranging from thinly originally used to provide armorstone blocks (Facies III) for con Manitoulin and Adjacent Islands, Geological Survey of lithographic, pale grey bedded, 336250E - 5081750N) on the south shore, only 5.67 m of Amabel 1968: Ordovician and Silurian Stratigraphy of Manitoulin Island, buff-brown chert-rich material to massive, blue-grey rocks struction of the lock system at Sault Ste. Marie, and a Canada, Memoir 111, 195 p. Geological has been recorded (O.G.S. D.D.H. No. 18). The contact between the new quarry Ontario. p.14-37rn Michigan Basin Geological Society, Issued 1985 of very high chemical purity. Nine recurring field-identifiable development on Mississagi Strait (U.T.M. Boundary, Amabel and the underlying Fossil Hill Formation is exposed at 327600E - 5086400N). Guidebook for 1968 Annual Field Conference. Basai Beds: Shales and sandstones, red and lithologies have been grouped into 4 facies associations, as fol The new quarry (Manitoulin Dolomite Limited) produces approximate several localities within the map area. The best locality is in the from an 18 Information from this publication green lows: m section of Amabel (Facies III) strata. 1972a: Meldrum Bay Area, Manitoulin District; Ontario Division of may be quoted if credit is given. dolostone quarry (U.T.M. 327600E - 5086400N) located on Missis- This operation produces It is recommended Facies l (Unit 14,14ch,14b): A thinly bedded, finely crystalline, several grades of crushed stone, processed Mines. Map 2244, scale 1:63 360. Geological that reference to this map be made in the sagi Strait. at the quarry and following form: DISCONFORMITY silty brown dolostone. This unit is mostly unfossiliferous but shipped by lake freighter from the dock facilities 1972b: Silver Water Area, Manitoulin District; Ontario Division of Boundary, Of the facies listed above, only 2 are present in the map area; built adjacent to can be locally biostromal (14b). It can be rich in chert the quarry. Mines, Map 2245, scale 1:63 360. interpreted PRECAMBRIAN Facies l and Facies III. Of these, Facies III predominates, covering (14ch). 1972c: Kagawong Area, Manitoulin District; Ontario Division almost half of the map area. These cream weathering, massive No petroleum exploration has been recorded in this map area. of PROTEROZOIC Mines. Map 2246, scale 1:63 360. O.G.S. Drillhole Johnson, M.D. and Telford, P.G. location 1985: Paleozoic Geology of the Meldrum Bay Area, District of Bar River and Lorrain Formations: (Huronian Manitoulin; Ontario Geological Survey, Geological Series- Supergroup. Cobalt Group) Quartzites and Preliminary Map P.2667, scale 1:50 000. Geology 1979 to Qrthoquarlzites 1981. * Not present in this map area