THESE TERMS GOVERN YOUR USE OF THIS DOCUMENT

Your use of this Geological Survey document (the “Content”) is governed by the terms set out on this page (“Terms of Use”). By downloading this Content, you (the “User”) have accepted, and have agreed to be bound by, the Terms of Use.

Content: This Content is offered by the Province of Ontario’s Ministry of Northern Development and Mines (MNDM) as a public service, on an “as-is” basis. Recommendations and statements of opinion expressed in the Content are those of the author or authors and are not to be construed as statement of government policy. You are solely responsible for your use of the Content. You should not rely on the Content for legal advice nor as authoritative in your particular circumstances. Users should verify the accuracy and applicability of any Content before acting on it. MNDM does not guarantee, or make any warranty express or implied, that the Content is current, accurate, complete or reliable. MNDM is not responsible for any damage however caused, which results, directly or indirectly, from your use of the Content. MNDM assumes no legal liability or responsibility for the Content whatsoever.

Links to Other Web Sites: This Content may contain links, to Web sites that are not operated by MNDM. Linked Web sites may not be available in French. MNDM neither endorses nor assumes any responsibility for the safety, accuracy or availability of linked Web sites or the information contained on them. The linked Web sites, their operation and content are the responsibility of the person or entity for which they were created or maintained (the “Owner”). Both your use of a linked Web site, and your right to use or reproduce information or materials from a linked Web site, are subject to the terms of use governing that particular Web site. Any comments or inquiries regarding a linked Web site must be directed to its Owner.

Copyright: Canadian and international intellectual property laws protect the Content. Unless otherwise indicated, copyright is held by the Queen’s Printer for Ontario.

It is recommended that reference to the Content be made in the following form: , . ; Ontario Geological Survey, , p.

Use and Reproduction of Content: The Content may be used and reproduced only in accordance with applicable intellectual property laws. Non-commercial use of unsubstantial excerpts of the Content is permitted provided that appropriate credit is given and Crown copyright is acknowledged. Any substantial reproduction of the Content or any commercial use of all or part of the Content is prohibited without the prior written permission of MNDM. Substantial reproduction includes the reproduction of any illustration or figure, such as, but not limited to graphs, charts and maps. Commercial use includes commercial distribution of the Content, the reproduction of multiple copies of the Content for any purpose whether or not commercial, use of the Content in commercial publications, and the creation of value-added products using the Content.

Contact:

FOR FURTHER PLEASE CONTACT: BY TELEPHONE: BY E-MAIL: INFORMATION ON The Reproduction of MNDM Publication Local: (705) 670-5691 Content Services Toll Free: 1-888-415-9845, ext. [email protected] 5691 (inside Canada, United States) The Purchase of MNDM Publication Local: (705) 670-5691 MNDM Publications Sales Toll Free: 1-888-415-9845, ext. [email protected] 5691 (inside Canada, United States) Crown Copyright Queen’s Printer Local: (416) 326-2678 [email protected] Toll Free: 1-800-668-9938 (inside Canada, United States)

LES CONDITIONS CI-DESSOUS RÉGISSENT L'UTILISATION DU PRÉSENT DOCUMENT.

Votre utilisation de ce document de la Commission géologique de l'Ontario (le « contenu ») est régie par les conditions décrites sur cette page (« conditions d'utilisation »). En téléchargeant ce contenu, vous (l'« utilisateur ») signifiez que vous avez accepté d'être lié par les présentes conditions d'utilisation.

Contenu : Ce contenu est offert en l'état comme service public par le ministère du Développement du Nord et des Mines (MDNM) de la province de l'Ontario. Les recommandations et les opinions exprimées dans le contenu sont celles de l'auteur ou des auteurs et ne doivent pas être interprétées comme des énoncés officiels de politique gouvernementale. Vous êtes entièrement responsable de l'utilisation que vous en faites. Le contenu ne constitue pas une source fiable de conseils juridiques et ne peut en aucun cas faire autorité dans votre situation particulière. Les utilisateurs sont tenus de vérifier l'exactitude et l'applicabilité de tout contenu avant de l'utiliser. Le MDNM n'offre aucune garantie expresse ou implicite relativement à la mise à jour, à l'exactitude, à l'intégralité ou à la fiabilité du contenu. Le MDNM ne peut être tenu responsable de tout dommage, quelle qu'en soit la cause, résultant directement ou indirectement de l'utilisation du contenu. Le MDNM n'assume aucune responsabilité légale de quelque nature que ce soit en ce qui a trait au contenu.

Liens vers d'autres sites Web : Ce contenu peut comporter des liens vers des sites Web qui ne sont pas exploités par le MDNM. Certains de ces sites pourraient ne pas être offerts en français. Le MDNM se dégage de toute responsabilité quant à la sûreté, à l'exactitude ou à la disponibilité des sites Web ainsi reliés ou à l'information qu'ils contiennent. La responsabilité des sites Web ainsi reliés, de leur exploitation et de leur contenu incombe à la personne ou à l'entité pour lesquelles ils ont été créés ou sont entretenus (le « propriétaire »). Votre utilisation de ces sites Web ainsi que votre droit d'utiliser ou de reproduire leur contenu sont assujettis aux conditions d'utilisation propres à chacun de ces sites. Tout commentaire ou toute question concernant l'un de ces sites doivent être adressés au propriétaire du site.

Droits d'auteur : Le contenu est protégé par les lois canadiennes et internationales sur la propriété intellectuelle. Sauf indication contraire, les droits d'auteurs appartiennent à l'Imprimeur de la Reine pour l'Ontario. Nous recommandons de faire paraître ainsi toute référence au contenu : nom de famille de l'auteur, initiales, année de publication, titre du document, Commission géologique de l'Ontario, série et numéro de publication, nombre de pages.

Utilisation et reproduction du contenu : Le contenu ne peut être utilisé et reproduit qu'en conformité avec les lois sur la propriété intellectuelle applicables. L'utilisation de courts extraits du contenu à des fins non commerciales est autorisé, à condition de faire une mention de source appropriée reconnaissant les droits d'auteurs de la Couronne. Toute reproduction importante du contenu ou toute utilisation, en tout ou en partie, du contenu à des fins commerciales est interdite sans l'autorisation écrite préalable du MDNM. Une reproduction jugée importante comprend la reproduction de toute illustration ou figure comme les graphiques, les diagrammes, les cartes, etc. L'utilisation commerciale comprend la distribution du contenu à des fins commerciales, la reproduction de copies multiples du contenu à des fins commerciales ou non, l'utilisation du contenu dans des publications commerciales et la création de produits à valeur ajoutée à l'aide du contenu.

Renseignements :

POUR PLUS DE VEUILLEZ VOUS PAR TÉLÉPHONE : PAR COURRIEL : RENSEIGNEMENTS SUR ADRESSER À : la reproduction du Services de Local : (705) 670-5691 contenu publication du MDNM Numéro sans frais : 1 888 415-9845, [email protected] poste 5691 (au Canada et aux États-Unis) l'achat des Vente de publications Local : (705) 670-5691 publications du MDNM du MDNM Numéro sans frais : 1 888 415-9845, [email protected] poste 5691 (au Canada et aux États-Unis) les droits d'auteurs de Imprimeur de la Local : 416 326-2678 [email protected] la Couronne Reine Numéro sans frais : 1 800 668-9938 (au Canada et aux États-Unis)

OBA, EXPLANATORY NOTES LEGEND* Ministry of o Northern Development . " PROTEROZOIC o INTRODUCTION Most supracrustal rocks in the Superior Prov PROTEROZOIC In the area, the Mesoproterozo The Paleozoic rocks of southern and northern a The letter "G" preceding a map unit number indicates and Mines * ^r* . ^ * ince of Ontario are of Neoarchean age. Such rocks ic Keweenawan Supergroup (unit 29) and asso Ontario (units 49 to 58) were deposited unconform MESOZOIC MESOPROTEROZOIC (0.9 to 1.6 Ga) lithologic information interpreted from geophysical data. The bedrock geology of the Province of Ontario Ontario g in the greenstone belts, along with rocks of uncer ciated intrusive rocks occupy the Midcontinent Rift, ably on the eroded Superior and Grenville prov CRETACEOUS AND JURASSIC UPPER KEWEENAWAN SUPERGROUP consists of rocks of the Canadian Superior Province Provinces b Phanerozoic stratigraphic nomenclature varies in the tain age, are assigned to units 4 to 8. Archean meta Southern and Superior and form sequences in excess of 25 km thick over inces. The Paleozoic rocks of southern Ontario oc LOWER CRETACEOUS AND MIDDLE { s 1086 Ma) Shield and Phanerozoic sedimentary rocks in ba level of detail to match the variable level of detail Province of Ontario includes sedimentary rocks within greenstone belts are as lying an attenuated Superior Province basement. cur within the and Appalachian basins JURASSIC Jacobsville Gp.; Oronto Gp.: sins that overlie the . Based oh dif The Archean Superior Paleoproterozoic and Mesoproterozoic rocks of the displayed on the map face. and Mesoarchean age. The signed to unit 7 with some exceptions: Mesoar in Ontario consist mostly of sed The lower part of the Keweenawan Supergroup and parts of the St. Lawrence Platform. In northern Kaolinitic clay, clay, sand, lignite: , shale, conglomerate ferences in age, metamorphism and tectonic set units of Neoarchean Southern Province c Unassigned. Superior Province is subdivided into subprovinces, chean quartz-rich metasedimentary rocks of unit 1; imentary and volcanic assemblages that overlie consists of 1107 to 1086 Ma basaltic and rhyolitic Ontario, Paleozoic strata are restricted to the Hud 60a Mattagami Fm.; Mistuskwia Beds ting, the Precambrian rocks are subdivided into the and metasedimentary-metavolcanic sequences of INTRUSIVE ROCKS commonly fault-bounded, that can be distinguished Archean rocks and are generally little deformed to volcanic rocks and minor volumes of sedimentary son Bay Basin, the Moose River Basin, and isolated 60b Evans Strait Fm. d Subdivisions of Precambrian geologic time and units Superior, Southern and Grenville provinces. The unit 9, which unconformably overlie older metavol rocks. Volcanic and sedimentary accumulations outliers. Lithostratigraphic and faunal similarities in Carbonatite-alkalic intrusive suite characterized by a range of ages are cited in terms of on the basis of contrasting rock type, structural moderately deformed. In addition, a wide variety of explanatory notes provide an overview of the geol canic rocks. Unit 7a is paragneiss within metasedi are thickest beneath Lake Superior, within agraben these widely separated regions suggest intermit JURASSIC (1.0 to 1.2 Ga): carbonatite, nepheline Ga. The subdivisions of geologic time correspond to geology, age and metamorphic grade. The subpro Proterozoic dikes and plutons have intruded the syenite, alkalic syenite, ijolite, fenite; ogy of Ontario and describe the map units of each of mentary subprovinces and unit 7b is conglomerate that developed at about the same time as the latest tent interconnection of these areas and a formerly Alkalic dikes and intrusions: kimberlite international standards as described in the marginal MAP 2545 and Ciesielski (1986) served as sub Province and the supracrustal associated mafic and ultramafic rocks the geologic regions in order of decreasing age. vinces of Card which occurs at the margins of metasedimentary rocks of the Superior phase of deformation in the Grenville Province. more extensive Paleozoic cover, an interpretation and lamprophyre notes. All ages of individual units cited in the legend are divisions for purposes of compilation of this map. subprovinces. Some units on earlier maps that are sequences of the Southern Province. Diabase dikes of the 1238 Ma Sudbury swarm (unit supported by the presence of numerous outliers Mafic and related intrusive rocks based on high precision U/Pb zircon ages, and are cited The legend is subdivided geochronologically Changes to the subprovince scheme of Card and likely of sedimentary origin, but previously identi 30b) are related to major Mesoproterozoic exten- (not shown) distributed across the Canadian PALEOZOIC (Keweenawan age)© in terms of Ma. in the Phanerozoic, but geochronometrically in the Diabase dikes of the 2454 Ma Matachewan Ciesielski (1986) resulting from this compilation are fied as grey , granite, gneiss and biotite and Hearst swarms (unit 17a) have intruded the sional events which are not otherwise represented Shield. Sedimentation was predominantly in a shal MISSISSIPPIAN TO DEVONIAN0 31 a Logan and Nipigon sills (1109 Ma): e grade units are shown by screened overprint. Proterozoic and Archean. The Archean rocks of the described in The Geology of Ontario (Ontario Geo gneiss, are included in unit 7. Supracrustal septa of in the Southern and Superior provinces of Ontario low marine environment with minor episodes of diabase sills Superior Province are subdivided into lithologic rocks of the Superior Province and are widely dis f The rocks of the Central Granulite Terrane in logical Survey 1991). medium metamorphic grade, found between gran tributed across northeastern Ontario. These dikes and are coincident with the main period of magmat continental deposition. The distribution and charac Shale: Port Lambton Gp. 31b Pigeon River and Pukaskwa BEDROCK GEOLOGY units. Supracrustal units of the Southern Province itoid and gneissic units or along strike from green ism in the Elzevir Terrane and Central Metasedi ter of the sediments was largely a function of spatial swarms: diabase dikes are coded in a lithologic sense only and represent units and the Phanerozoic Eon are subdivided lithostrati- In Ontario, granite-greenstone subprovinces are spatially associated with the 2480 to 2491 Ma of ea. 1050 to 1150 Ma in age. Equivalents of these rocks stone belts, are assigned to unit 8. Unit 9 comprises mentary Belt of the Grenville Province. In the Thun variation in water depth, determined by tectonic 31 c Ultramafic, gabbroic and granophyric The Grenville Province is subdivided include the Sachigo, Uchi, Wabigoon, Abitibi and to intrusive rocks in the vicinity are not known to be present in Ontario. graphically. coarse conglomerates with subordinate finer der Bay and Lake Nipigon areas, Keweenawan dia uplift, the balance between chemical and clastic intrusions tectonic blocks and within each block the Wawa subprovinces. The greenstone belts are of Elliot Lake (unit 17b), and the 2450 Ma basalt, UPPER DEVONIAN into major grained clastic metasedimentary rocks and alkalic base sills (unit 31 a), dikes of the Pigeon River and sedimentation, and the amount of terrigenous in 31 d Felsic to intermediate intrusive rocks 9 Rocks in these groups are subdivided lithologically. The legend is mainly lithologic, with only part of the su elongate areas of metavolcanic rocks and minor rhyolite and clastic/chemical sedimentary se Shale to subalkalic metavolcanic rocks. Unit 9 commonly quence of the Elliot Lake Group (unit 18b). The El Pukaskwa swarms (unit 31 b), ultramafic, gabbroic put. 31e Abitibi swarm (1141 Ma): diabase order does not imply age relationship within or among pracrustal rock record subdivided into lithostrati volumes of metasedimentary rocks that form linear 57a Kettle Point Fm. dikes groups. OF ONTARIO occurs in fault-bounded sequences unconformably to anastomosing patterns separated by elliptical liot Lake Group and the overlying clastic and car and granophyric plutons (unit 31 c), and felsic to in Mesozoic deposits (unit 60) occur in the 57b Long Rapids Fm. graphic units. supracrustal rocks of greenstone granitic complexes. The greenstone belts are char overlying older bonate sedimentary rocks of the Hough Lake, termediate plutons (unit 31 d) intruded Archean Moose River Basin of (Mattagami Mafic intrusive rocks© h This part of the legend describes Proterozoic units of the belts. Quirke Lake and Cobalt Groups (units 18b and 19) basement, Sibley Group and Animikie Group sedi MIDDLE DEVONIAN 30a Mackenzie swarm (1267 Ma): Southern Province, and those Proterozoic units within Terminology and Classification acterized by shear zone-bounded homoclinal and Formation and Mistuskwia Beds), and the Hudson complexly folded panels of supracrustal rocks. Mesoarchean to Neoarchean intrusive rocks constitute the Huronian Supergroup. These rocks mentary rocks, and Keweenawan volcanic rocks. Bay Basin where the Evans Strait Formation has , dolostone, shale diabase dikes the Superior Province. Most diabase dike and alkalic Time subdivisions are based on the International Greenstone belts are typically of low metamorphic of units 10 to 15 include most Archean granitoid form a sedimentary prism with a maximum thick Diabase dikes of the 1141 Ma Abitibi swarm (unit been recently discovered underlying a small area. 56a Hamilton Gp. 30b Sudbury swarm (1238 Ma): diabase intrusive rock map units listed for the Grenville Province EXPLANATORY NOTES AND LEGEND Union of Geological Sciences time scale for the grade in their centres and of medium metamorphic units and synvolcanic to posttectonic, mafic to ultra ness of approximately 12 km near . The 31 e), and possibly correlative dikes in the Atikokan The strata are mainly unconsolidated, continentally 56b Marcellus Fm. dikes cut Grenville and Southern provinces; therefore, they to an early stage of Keweena are listed in the Southern Province part of the legend. Phanerozoic (Cowie and Bassett 1989) and the grade near the margins of younger granitoid do mafic units. Granitoid units have been mapped in southward-increasing thickness is associated with area, may be related derived sediments. 56c Dundee Fm. MIDDLE AND LOWER KEWEENAWAN wan rifting. At approximately the same time as the proposed Precambrian time scale of the Subcom- mains. Pretectonic to syntectonic granitic units dis some detail in the Winnipeg River, English River, south-side-down normal faults. The Cobalt Group 56d Detroit River Gp.; Onondaga Fm. SUPERGROUP (1086 to 1107 Ma) 1 A generalized distribution of diabase dikes is shown. (unit 19) overlaps the lower groups and has the rifting, carbonatitic and alkalic plutons such as the Ultramafic lamprophyre and kimberlite dikes mission on Precambrian Stratigraphy (Plumb and play we 11-developed foliation and gneissosity, while and in the western parts of the Quetico and Wabi (unit 59), shown by the diamond 56e Williams Island Fm. Osler Gp.; Mamainse Point Fm., Some individual swarms occur in more than one most widespread distribution, being preserved in Coldwell Complex (unit 32) were emplaced along and small plutons province. 1986), with some of the modifications of late granitic intrusions have little or no tectonic fab goon subprovinces; less detail is available else 56f Murray Island Fm. Michipicoten Island Fm. geological James the Cobalt Embayment, extending north into the fault zones in the Superior Province north of Lake symbol, are commonly of Jurassic age. These Okulitch (1988; see Table 1). ric. where. Archean granitic rocks were classified pri rocks intrude the Paleozoic rocks of southern On 56g Moose River Fm. 29a Basalt and associated conglomerate i This unit has a geographic distribution from the west mineralogy and texture; aero Abitibi region. The lower part of the Huronian Su Superior. Clastic sedimentary rocks (unit 33) form This map published with the permission of V.G. Milne, Di The English River and Quetico metasedimen marily using modal tario, the Abitibi subprovince and the 56h Kwataboahegan Fm. and arkose shore of Lake Nipigon to the north shore of Lake Huron, Table 1. Subdivision of geologic time. magnetic interpretation aided the classification in pergroup, in the vicinity of Sudbury, is cut by the the upper part of the Keweenawan Supergroup and rector, Ontario Geological Survey. tary subprovinces are characterized by wacke- Lowland. Occurrences are known throughout the 29b Rhyolite, quartz feldspar porphyry; including the Cutler, Chief Lake, Croker Island, English poorly understood areas. Crosscutting relation 2388 to 2333 Ma Murray Granite and Creighton were deposited during regional subsidence, follow LOWER DEVONIAN conglomerate and arkose mudstone couplets, with migmatized equivalents in rest of the province, but have not been systemati associated Bay and Manitoulin granites. Eon Era Geochronometry (Ma) ships have established a general sequence of rock Granite plutons (unit 20); the entire Supergroup has ing cessation of magmatism. These rocks include Sandstone, dolostone, limestone Queen©s Printer for Ontario, 1991. the high grade parts of the subprovinces. Minor vol cally mapped. Sibley Gp.: conglomerate, sandstone, k This unit includes the Killarney and related granitoids units in order of relative age from early to late: been intruded by sills and dikes of 2219 Ma Nipis sandstone, shale and conglomerate of the Oronto 55a Bois Blanc Fm.; Oriskany Fm. umes of coarse clastic metasedimentary rocks oc shale equivalent metavolcanic units, as well as the Cenozoic gneissic tonalite suite (unit 11), foliated tonalite sing diabase and related rocks (unit 21 d). Even Group and unconformably overlying sandstone of and This map is one of a set published to mark the 1991 cen 65 - 250 cur at the subprovince margins. Metamorphic 55b Stooping River Fm. Killarney area granitoids. Phanerozoic Mesozoic suite (unit 12), diorite-monzonite-granodiorite suite though some folding of the Huronian Supergroup the Jacobsville Group. The alkalic intrusive suite of MESO- TO PALEOPROTEROZOIC tennial of the establishment of an Ontario Bureau of Paleozoic 250-570 grade is generally low at the margins of the metase FAULTS 55c Sextant Fm. (unit 14), muscovite-bearing granitic rocks (unit occurred during an unnamed event prior to 2219 unit 35 includes the Hecla-Kilmer intrusion, at the (0.9 to 2.5 Ga) 1 This unit includes the Chelmsford, Onwatin and Mines. It was produced specifically to accompany The Neoproterozic 570-900 dimentary subprovinces, but varies locally to me Ma, the major thrusting and folding of the Huronian north end of the Kapuskasing Structural Zone, and Two major classes of faults and shear zones are Onaping formations. Geology of Ontario, Ontario Geological Survey, Special 13), and massive granodiorite to granite (unit 15). intrusive rocks Proterozoic Me s oproterozoic 900 - 1600 dium grade; to granulite grade assem occurred at ea. 1.86 Ga during the Penokean Orog the stocks in Lake Nipissing. shown on the map: Felsic Volume 4. tonalite suite (unit 11) and the fo UPPER SILURIAN mThis unit includes the Gunflint and Rove formations. Paleoproterozoic 1600-2500 blages are found mainly in the interior. These as The gneissic eny. Other dike swarms which have not yet been 27a Granite, alkali granite, granodiorite, liated tonalite suite (unit 12) display the widest 1. Those faults traceable in surface exposures are Limestone, dolostone, shale, quartz feldspar porphyry; minor Neoarchean 2500-2900 semblages are cut by muscovite-bearing granitic precisely dated, but which are probably of similar n This unit includes the Gowganda, Lorrain, Gordon Lake range in age, from 3.17 to 2.71 Ga. These suites Grenville Province shown as long dashes. sandstone, gypsum, salt related volcanic rocks ©©(1.4 to 1.5 Ga) Archean Mesoarchean 2900 - 3400 rocks (unit 13) and granitic rocks of unit 15. age to the Nipissing sills, include the Preissac and Bar River formations. have been intruded by plutons of massive tonalite. 2. Those faults cutting Precambrian basement 54a Bass Islands Fm. 27b Killarney monzogranite and granitic Paleoarchean ^400 The Kapuskasing Structural Zone consists of swarm in northeastern Ontario (unit 21 a), the Mara Province is a Mesoproterozoic oro 0 This unit was formerly classified as Algoman and/or Muscovite-bearing granitic rocks (unit 13), which The Grenville rocks, and not known to affect overlying Phaner 54b Bertie Fm. rocks* (1.7 and 1.4 Ga) metavolcanic and metasedimentary rocks of high thon swarm east of Lake Nipigon (unit 21 b), and the genic belt extending from the Gulf of Mexico to Laurentian. Units 13,14 and 15 are mainly Neoarchean formed between 2.67 and 2.69 Ga, predominate in 54c Salina Fm. to felsic volcanic rocks* metamorphic grade, foliated tonalites and tonalitic Kenora-Fort Frances swarm in northwestern On ozoic platform units, and faults cutting lower Pa 27c Intermediate except in areas of the Sachigo Subprovince, where Terminology used in the Legend and Explana the metasedimentary subprovinces and postdate Scandinavia. The province is characterized in On 54d Kenogami River Fm. (Upper Silurian (1.8 to 1.9 Ga) , all cut by undeformed granitic units. The tario (unit 21 c). leozoic strata, but not extending to the surface, some examples of Mesoarchean age occur. tory Notes is based on the following standards: plu tonalites in those subprovinces. Two-mica granites tario by a period of widespread deformation and to Lower Devonian) Berens River and Winnipeg River plutonic subpro dashes. tonic rock nomenclature of Streckeisen (1976), no small plutons in the Winnipeg River, The Animikie Group (unit 22a), within the Ani metamorphism during the period 1.06 to 1.1 Ga. are shown as short PALEOPROTEROZOIC (1.6 to 2.5 Ga) P The intrusive rocks of Archean age range from vinces of Card and Ciesielski (1986) include minor also occur as MIDDLE AND LOWER SILURIAN menclature and geochemical classification of vol Uchi, Berens River, Wabigoon and Sachigo sub mikie Basin near Thunder Bay, includes iron forma Within Ontario, the Grenville Province consists of Geological and geophysical evidence has Sudbury Igneous Complex (1850 Ma): approximately 2.65 Ga to 3.2 Ga. canic rocks of Jensen (1976), and metamorphic volumes of high grade, metavolcanic and metase Sandstone, shale, dolostone, siltstone norite, gabbro, granophyre provinces, particularly along major shear zones. tion of the Gunflint Formation and wacke and argil two major lithotectonic subdivisions, the Central been used to identify faults and shear zones. Many 9 This unit was formerly classified as Haileyburian. grade terminology of Winkler (1976). dimentary remnants, older gneissic to foliated gra it forms a homoclinal se 53a Guelph Fm. Units 14 and 15 are widespread in granitoid lite of the Rove Formation; Gneiss Belt (units 36 to 40) and the Central Metase fault and shear zone systems are several hundred Whitewater Gp.©: fragmental rocks, nitic rocks, and a high proportion of posttectonic overlying the Superior 53b Lockport Fm. r This unit was formerly classified as Timiskaming. This Archean metavolcanic rocks are grouped into complexes of all subprovinces. Unit 15 is a volumi quence unconformably dimentary Belt (units 41 to 47). The boundary be metres in width and subsidiary faults produce an mudstone, wacke granitic batholiths. with the 53c Amabel Fm. unit comprises fluvial to marine metasedimentary rocks mafic to ultramafic, mafic to intermediate, and felsic unit ranging between 2.76 Province. The Animikie Group is correlated tween these two belts is a zone of ductile deforma anastomosing pattern. Space considerations dic Uranium-lead zircon age determinations de nous, widely distributed 53d Clinton Gp.; Cataract Gp. Carbonatite-alkalic intrusive suite with minor, commonly alkalic, metavolcanic rocks which to intermediate compositions, based on field map and 2.56 Ga in age. The youngest members of this upper part of the Marquette Range Supergroup, tion (unit 48), interpreted as a major deep crustal tate depiction of only the trace of the central part of (ea. 1.9 Ga): carbonatite, nepheline fine a limited spatial distribution of Mesoarchean to have 53e Thornloe Fm.; Earlton Fm. locally unconformably overlie units 1 to 6. They have ping supplemented by petrographic and geochemi granites (unit 13), as for south of Lake Superior, and is interpreted thrust zone. regional-scale fault systems. Faults and shear syenite, alkalic syenite, ijolite, fenite; rocks (units 1 to 3) in the Sachigo sub suite crosscut the two-mica 53f WabiGp. generally only undergone the late deformation common cal data. The field classification is based on esti supracrustal example in the English River subprovince. The old been deposited during the Penokean Orogeny. zones are not classified as active or inactive. No associated mafic and ultramafic rocks province and the central part of the Wabigoon sub of the Sutton Inlier (unit 22b), The Central Gneiss Belt can be subdivided into 53g Attawapiskat Fm. in greenstone belts. mates of colour index and on the nature of primary er parts of unit 15 include the 2.69 to 2.76 Ga, potas Sedimentary rocks assessment of seismic risk is implied in selection of province. Mesoarchean supracrustal sequences the Paleozoic Basin, a number of smaller tectonic domains, using struc 53h Ekwan River Fm. Mafic intrusive rocks© s These units are shown only in the English River and volcanic textures. Ultramafic sequences have a sium feldspar megacrysticgranite-granodiorite that exposed within faults for display on the map. In areas with abun to ultramafic metavolcanic rocks (unit tural trends, rock types, geochronologic data and 53i Severn River Fm. 23a Molson swarm (1884 Ma): diabase Quetico subprovinces. high colour index and consist largely of flows char include mafic forms large batholiths in the Winnipeg River, Ber overlie Archean basement and form part of the 1.9 dant major faults, the faults displayed are regionally 1) and intermediate to felsic metavolcanic rocks Orogen. Based on geo aeromagnetic patterns. These domains are sepa dikes; and Sutton Inlier: diabase sills acterized by the presence of spinifex texture and ens River and Sachigo subprovinces. These rocks to 1.8 Ga Trans-Hudson the most important features and commonly relate to © This unit was formerly classified as Keewatin. Most of (unit 2) similar to units within Neoarchean green units are inter rated by ductile deformation zones (unit 48). The 23b Wabigoon swarm: diabase dikes polysuturing. Flow sequences lacking the above by a distinctive pattern of high physical data, these sedimentary major crustal structures. these sequences range in age from 2.7 Ga to 2.8 Ga stone belts. Unit 3, commonly occurring within Me are characterized preted to be continuous with the Belcher Islands Central Gneiss Belt consists of a variety of migma- UPPER ORDOVICIAN 23c North Channel swarm: diabase dikes features are classified as mafic to intermediate in magnetic susceptibility caused by the anomalous Shear zones within the Superior Province oc based on U/Pb zircon ages. soarchean greenstone belts, is characterized by Bay and with the Fox River belt titic rocks and gneisses cf unknown protolith (unit Shale, limestone, dolostone, siltstone composition. Sequences with a low colour index concentration of magnetite. The Neoarchean dio fold belt in Hudson cur within subprovinces, form subprovince bound Sedimentary rocks distinctive, quartz-rich, mature metasedimentary in . In Manitoba, diabase of the 1884 Ma 38), of Archean, Paleoproterozoic and Mesoproter 52a Queenston Fm. u These units are large enough to show at the map scale that are predominantly fragmental are classified as rite to nepheline syenite suite (unit 16) rocks are aries and represent both brittle and ductile regimes. 22a Animikie Gp. m: wacke, shale, iron forming the Blake rocks and may also include carbonate metasedi Molson swarm (unit 23a) intruded the Fox River ozoic ages, which are cut by Mesoproterozoic to 52b Fm.; Blue Mountain only within the Abitibi Subprovince, felsic to intermediate in composition. generally the youngest Archean plutonic phases in The Murray Fault, in the Southern Province, sepa formation, limestone, minor volcanic Group and units south of Lake Abitibi. mentary rocks, iron formation, and mafic to ultra that intruded the Sutton Inlier are Neoproterozoic intrusive rocks of several ages Fm.; Billings Fm.; Collingwood Mb.; River the Superior Province. belt; thus, sills rates deformed, metamorphosed Huronian strata rocks mafic metavolcanic rocks. probably of similar age. The Wabigoon diabase (units 37, 39 and 40). Rocks of the Central Gneiss Eastview Mb. 22b Sutton Inlier: dolostone, chert v The units under this heading include those have all been metamorphosed to medium to in the south from less deformed Huronian strata in 52c Liskeard Gp. dikes (unit 23b), in , and the part , argillite, wacke, belts which are older than 2.9 Ga based on U/Pb zircon high grade; areas of granulite grade are indicated the Elliot Lake area. Major faults in the northern 52d Red Head Rapids Fm. chronology. All other Archean- greenstones have been North Channel swarm (unit23c), on the north shore of Lake Superior control the formation of the Lake conglomerate, iron formation of Lake Huron, are also probably of similar age. Co on the map. In many areas, several periods of 52e Churchill River Gp. placed in the Neo- to Mesoarchean subdivision of the Superior graben and the thickness of Keweenawan Mafic and related intrusive rocks© incident with the Penokean and Trans-Hudson oro metamorphism have occurred and these periods 52f Bad Cache Rapids Gp. legend. strata. The boundary between the Grenville and 21 a Preissac swarm: diabase dikes genic activity, ea. 1.9 Ga alkalic and carbonatite are not coincident across the entire Central Meta wThis unit comprises those greenstone sequences in Southern provinces is the crustal-scale, southeast MIDDLE ORDOVICIAN 21 b Marathon swarm: diabase dikes stocks (unit 24) intruded the vicinity of the Kapus sedimentary Belt. Archean and Paleoproterozoic which shallow-water supermature sediments (quartz ward-dipping Grenville Front Tectonic Zone. The dolostone, shale, arkose, kasing Structural Zone and several other localities rocks have only been reported in a zone between Limestone, 21 c Kenora-Fort Frances swarm: arenites, shallow-water carbonates) have been boundary between the Central Gneiss Belt and the sandstone diabase dikes in Ontario. the Grenville Front and the French River. Similar identified. This type of unit unconformably overlies older scale tectonic domains are also present in the ex Central Metasedimentary Belt as well as the 51a Ottawa Gp.; Simcoe Gp.; Shadow 21 d Nipissing sills (2219 Ma): diabase The 1850 Ma, noritic to granophyric, Sudbury boundaries between subsidiary tectonic units are granitoid rocks in the Steeprock Lake area, and older tension of the Central Gneiss Belt beneath the Lake Fm. sills, dikes and related granophyre greenstones in the North Caribou Lake area. Igneous Complex (unit 26) intruded brecciated Phanerozoic cover of southwestern Ontario. commonly defined by shear zones. In southern On 51 b Chazy Gp., Rockcliffe Fm. 21 e Mafic dikes and plutons of uncertain Index to Geology of Ontario Maps Archean and Proterozoic country rocks. The White tario, the faults shown cutting Phanerozoic strata age water Group (unit 25), which consists of fragmental The Central Metasedimentary Belt is a supra on the map have greater than 3 m of stratigraphic LOWER ORDOVICIAN Felsic intrusive rocks (Murray Granite rocks, wackes and mudstones, is entirely con crustal terrane, generally younger than 1.3 Ga, that offset. A number of faults controlling the location of can be subdivided into a number of smaller, fault- Dolostone, sandstone: Beekmantown Gp. 2388 Ma, Creighton Granite 2333 Ma): tained within and intruded by the Sudbury Igneous petroleum occurrences offset Lower Paleozoic granite Complex. The origin of this complex has been vari bounded terranes on the basis of structural trends, strata, and are not exposed at surface. ously attributed to events related to either a meteor rock types, geochronologic data, magmatic history, HURONIAN SUPERGROUP ite impact or an explosive volcanic event, or a com geophysics and relative timing of metamorphism. Conglomerate, sandstone, shale, {2.2 Ga to 2450 Ma) bination of both. These terranes are, from west to east, the Bancroft, COMPILATION AND PRODUCTION dolostone: Potsdam Gp.; Nepean Fm., Cobalt Gp. n: conglomerate, wacke, Elzevir, Sharbot Lake and Frontenac terranes. The Covey Hill Fm. arkose, quartz arenite, argillite Mesoproterozoic felsic intrusive rocks and mi Bancroft and Frontenac terranes consist mainly of This geological map of Ontario was compiled main nor volumes of related volcanic rocks form two ly from maps and reports of the Ontario Geological Quirke Lake Gp.; Hough Lake Gp.; shallow-water metasedimentary rocks (units 42 Elliot Lake Gp. zones: a 1.4 to 1.5 Ga magmatic zone along the and 43), with carbonate metasedimentary rocks Survey, the Geological Survey of Canada, and the PRECAMBRIAN* north shore of Lake Huron and the west shore of 18a Conglomerate, wacke, arkose, quartz (unit 43) predominant. Rocks of the Bancroft and geological surveys of Manitoba, Quebec, New GRENVILLE PROVINCE e arenite, argillite, limestone, dolostone Lake Nipigon (unit 27a), and the 1.4 to 1.75 Ga Kil York, and Michigan. In addition, the Frontenac terranes are metamorphosed to medium PROTEROZOIC 18b Volcanic rocks of the Elliot Lake Gp. larney magmatic zone south of Sudbury (units 27b grade and high grade. Most volcanic rocks (unit 41) compilation incorporated unpublished maps and and 27c). Unit 27a is part of an anorogenic magmat in the Central Metasedimentary Belt are in the Elze reports on file with the Ontario Geological Survey, NEO- TO MESOPROTEROZOIC INTRUSIVE ROCKS North America. Deformed ic suite extending across vir and Sharbot Lake terranes, with both calc-alkal university theses, papers in professional journals, (0.57 to 1.6 Ga) Mafic and ultramafic intrusive rocks equivalents of rocks of the Killarney magmatic zone ic and tholeiitic metavolcanic rocks present. The aeromagnetic maps, gamma ray spectrometry and 17a Matachewan and Hearst swarms occur within the adjacent Grenville Front tectonic Tectonite unit: tectonites, straight lowest metamorphic grade rocks in the Grenville gravity maps, aerial photographs and satellite gneisses, porphyroclastic gneisses, (2454 Ma)©: diabase dikes zone. The anorogenic granites cut rocks of the Province are present in these two terranes. Most unsubdivided gneisses in major Sibley Group (unit 28). The Sibley Group is a thin images. A complete reference list for the map and 17b Gabbro, anorthosite known mineral deposits in the Grenville Province explanatory notes is provided in The Geology of deformation zones, mylonites, (less than 1 km thick) sequence of predominantly occur in the Elzevir and Sharbot Lake terranes. protomylonites SUPERIOR PROVINCE clastic sedimentary rock, preserved within a fault- Ontario (Ontario Geological Survey 1991). Both carbonate and siliceous clastic metasedimen CENTRAL METASEDIMENTARY BELT ARCHEAN bounded basin between Lake Nipigon and Lake tary rocks were deposited contemporaneously dur The map was compiled by teams for each sub Superior. province of the Superior Province, the Southern Late felsic plutonic rocks©: NEOARCHEAN (2.5 to 2.9 Ga) ing volcanism. A variety of plutonic rocks of differ granodiorite, granite, syenite, pegmatite, ent ages intrude the supracrustal rocks. Plutonic Province and the Grenville Province, and for the alkalic granite, migmatitic gneisses INTRUSIVE ROCKS Phanerozoic rocks (Figure 1). The compilers for activity in the Elzevir terrane was concentrated be Diorite-nepheline syenite suite^0: Mafic to ultramafic plutonic rocks©: tween 1.25 to 1.22 Ga and 1.1 to 1.08 Ga, whereas each unit or area are as follows: pyroxenite, diorite, monzonite, syenite, diorite, gabbro, peridotite, pyroxenite, plutonism in the Frontenac terrane occurred mainly nepheline syenite (saturated to Province, subprovince, Compiler(s) anorthosite, derived metamorphic rocks between 1.18 and 1.16 Ga. unit or area undersaturated suite) at Alkalic plutonic rocks: nepheline Following the latest period of deformation Sachigo subprovince I.A. Osmani syenite, alkalic syenite, fenite; associated NEO- TO MESOARCHEAN ea. 1.07 Ga, the Grenville Province experienced Berens River subprovince LA. Osmani mafic, ultramafic and carbonatitic rocks (2.5 to 3.4 Ga) w minor intrusive activity in the form of pegmatite dike Uchi subprovince S. Neufeld, G.M. Stott swarms, and the injection of the Frontenac (ea. 0.9 English River subprovince F.W. Breaks, LA. Osmani Early felsic plutonic rocks©: INTRUSIVE ROCKS Ga) and Grenville (ea. 0.5 Ga) diabase dike Winnipeg River subprovince G.P. Beakhouse granodiorite, tonalite, monzogranite, Massive granodiorite to granite: swarms (unit 34). Wabigoon subprovince C.E. Blackburn, G.W. Johns, syenogranite; derived gneisses and massive to foliated granodiorite to granite P.M. Smith, G.P. Beakhouse, 15a Potassium feldspar megacryslic units Based on interpretation of subsurface geology R.H. Sutcliffe, P. Money GRENVILLE SUPERGROUP AND in southwestern Ontario, it appears that rocks of the Quetico subprovince H.R. Williams Diorite-monzonite-granodiorite suite: FLINTON GROUPS diorite, tonalite, monzonite, granodiorite, Midcontinent Rift are deformed in the Grenville Wawa-Shebandowan areas G.M. Stott, R.P. Sage, Front Tectonic Zone. Carbonate metasedimentary rocks: syenite and hypabyssal equivalents S. Neufeld, D. Stone, (saturated to oversaturated suite) P. Money, H.R. Williams marble, calc-silicate rocks, skarn, tectonic breccias Muscovite-bearing granitic rocks: PHANEROZOIC Abitibi subprovince A.J. Fyon, B. Hrabi, R.H. Sutcliffe, J. Ireland muscovite-biotite and cordierite-biotite SOURCES OF INFORMATION 200 Kilometres Clastic metasedimentary rocks©: Most of the units for the Phanerozoic are lithostrati Kapuskasing Structural Zone K.M. Chivers, H.R. Williams conglomerate, wacke, quartz arenite, granite, granodiorite-tonalite compiled from published and unpublished maps graphic and are assigned to geological periods. Grenville Province R.M. Easton arkose, limestone, siltstone, chert, minor Foliated tonalite suite: tonalite to Geology Miles and reports of the Ontario Geological Survey and the Geo Three Paleozoic units, the Port Lambton Group, the Southern Province G. Bennett, B.O. Dressler, iron formation, minor metavolcanic rocks granodiorite foliated to massive R.H. Sutcliffe logical Survey of Canada, and unpublished data on file Detroit River Group and the Kenogami River For Mafic to felsic metavolcanic rocks: Gneissic tonalite suite: tonalite tp with the Ontario Geological Survey. Data on the geology of Phanerozoic rocks M.D. Johnson, R.K. Bezys, flows, tuffs, breccias, minor iron formation, mation, however, contain geologic period bound D. Williams, A. Henry granodiorite foliated to gneissic with immediately adjoining areas of adjacent provinces and minor metasedimentary rocks; includes minor supracrustal inclusions aries. For simplicity, the legend shows the latter two Diabase dikes LA. Osmani, R.H. Sutcliffe reworked pyroclastic units, amphibolite states were provided by geologists of the government sur vey organizations of those jurisdictions (see Explanatory units within the period representing the dominant Manitoba W. Weber, M.T. Corkery, Mafic and ultramafic rocks©*: gabbro, part of the unit. The legend lists units instratigraphic R.K. Bezys MESOPROTEROZOIC (0.9 to 1.6 Ga) anorthosite, ultramafic rocks Notes). order with the oldest unit at the base of each period, Quebec M. Rive CENTRAL GNEISS BELT Base map assembled by the Ontario Geological Survey. D. Southwick, T.J. Boerboom such that unit 52e is older than unit 52d. This prac Minnesota rocks: tonalite, Geographic information, derived from maps 21-6, 22-6, Y. Isachsen Felsic igneous tice is followed so as to conform with the organiza New York granodiorite, monzonite, granite, syenite; 23-6, 24-6, 25-6, 26-6, 27-6 and 28, by the Surveys and Michigan R. Reed tion of the Precambrian part of the legend. Each derived gneisses Coarse clastic metasedimentary Mapping Branch, Ontario Ministry of Natural Resources, Grenville Front was compiled onto a Lambert Conformal Conic grid with chronostratigraphic subdivision lists northern On and alkalic igneous rocks: rocks©": mainly coarse clastic Tectonic Zone Anorthosite 490 N and 770 N, central meridian tario units followed by southern Ontario units. De The map was edited and produced as follows: anorthosite, anorthositic gabbro, gabbro metasedimentary rocks, with minor, mainly standard parallels 920 W and grid origin 920 W O0 N provided by Dataplotting tailed mapping has been conducted in southern scientific editing by P.C. Thurston; drafting and and related gneisses, nepheline syenite, alkalic, mafic to felsic metavolcanic flows, technical editing by K.M. Chivers, D.J. Hammar tuffs and breccias Services, Markham, Ontario. Ontario, and in the area of the Niagara alkalic syenite and eastern and S.E. Neufeld; technical and cartographic edit gneisses of to 3.4 Ga) For information as to the status and extent of all restricted Escarpment, whereas northern Ontario has been ing by T.C. Chin, T. Hoey, S.E. Neufeld, A. Perego, Migmatitic rocks and NEO- TO MESOARCHEAN (2.5 mapped at a reconnaissance scale, supplemented undetermined protolith: commonly lands in Ontario, users are referred to the provincial or fed B. Sifrer, R. Steenstra and A. Weatherston; carto layered biotite gneisses and migmatites; SUPRACRUSTAL ROCKS eral agency within whose jurisdiction the lands are admin by compilation of drilling records. graphic supervision by R. Balgalvis; design and locally includes quartzofeldspathic Migmatized supracrustal rocks^ istered. cartographic production by R. Balgalvis, gneisses, orthogneisses, paragneisses metavolcanic rocks, minor J.W. Boyd, A. Cheung, D.C. Ferguson, F.B. Paz, metasedimentary rocks, mafic gneisses of Geology not tied to surveyed lines. Mafic rocks: amphibolite, gabbro, diorite, uncertain protolith, granitic gneisses J.W. Reid and T.W. Watkins; computer graphics mafic gneisses systems management by B. Miller. Metasedimentary rocks^ wacke, Parts of the map have benefitted from reviews Gneisses of metasedimentary origin: arkose, argillite, slate, marble, chert, iron quartzofeldspathic gneisses, pelitic to formation, minor metavolcanic rocks by B.V. Sanford, formerly of the Geological Survey semi-pelitic gneisses, calc-silicate of Canada, and K. D. Card of the Geological Survey gneisses, minor , minor marble 7a Paragneisses and migmatites3 ACKNOWLEDGMENTS LEGEND* of Canada. and marble 7b Conglomerate and arenite Digital plots of colour separations produced by Environ PHANEROZOIC SUPERIOR AND SOUTHERN PROVINCES SOUTHERN" AND SUPERIOR Felsic to intermediate metavolcanic mental Information Systems Division, Environment Cana REFERENCES PROVINCES rocks^©: rhyolitic, rhyodacitic, dacitic and da. MESOZOIC NEO- TO MESOPROTEROZOIC andesitic flows, tuffs and breccias, chert, CRETACEOUS AND JURASSIC Card, K.D. and Ciesielski, A. 1986. DNAG 1: EARLY PALEOZOIC TO iron formation, minor metasedimentary and Felsic intrusive rocks subdivisions of the Superior Province of the NEOPROTEROZOIC (0.45 to 0.9 Ga) intrusive rocks; related migmatites 19 Sedimentary and alkalic intrusive rocks Canadian Shield; Geoscience Canada, v.13, Carbonatite-alkalic intrusive suite Mafic to intermediate metavolcanic p.5-13. PALEOZOIC Mafic intrusive rocks (450 to 600 Ma): carbonatite, nepheline rocksfl©: basaltic and andesitic flows, Cowie, J.W. and Bassett, M.G. 1989. 1989 global syenite, alkalic syenite, ijolite, fenite; tuffs and breccias, chert, iron formation, DEVONIAN mafic and ultramafic intrusions CREDITS Volcanic and sedimentary rocks stratigraphic chart; Episodes, v.12, no.2, associated minor metasedimentary and intrusive Sedimentary rocks supplement. 35a Intrusions of uncertain age rocks, related migmatites Compilation by staff of the Precambrian Geology and En MICHIGAN breccias Mafic intrusive rocks© 5a Andesitic flows, tuffs and gineering and Terrain Geology sections of the Ontario SILURIAN PALEOPROTEROZOIC Jensen, L.S. 1976. A new cation plot for classifying with minor rhyolites" Geological Survey {see Explanatory Notes). BASIN subalkalic volcanic rocks; Ontario Division of 34a Grenville swarm (-575 Ma): diabase Sedimentary rocks Mines, Miscellaneous Paper 66, 22p. dikes Mafic to ultramafic metavolcanic Cartographic production by staff of the Publication and 34b Frontenac swarm (850 to 900 Ma): rocksS": mafic metavolcanic rocks with Cartographic Services unit of the Ontario Geological Sur ORDOVICIAN Okulitch, A.V. 1988. Proposals for time Metasedimentary and metavolcanic rocks diabase dikes minor komatiite, minor metasedimentary vey (see Explanatory Notes). classification and correlation of Precambrian and pyroclastic rocks Sedimentary rocks 34c Gabbro, diorite, ultramafic rocks, rocks and events in Canada and adjacent granophyre Every possible effort has been made to ensure the accura SUPERIOR PROVINCE areas of the Canadian Shield, part 3: a MESOARCHEAN (2.9 to 3.4 Ga)" cy of the information presented on this map; however, the ARCHEAN Precambrian time chart for the Geological SUPRACRUSTAL ROCKS Ontario Ministry of Northern Development and Mines Atlas of Canada; Geological Survey of does not assume any liability forerrors that may occur. Us NEO- TO MESOARCHEAN Mafic metavolcanic and Canada, Paper 87-23, 20p. metasedimentary rocks©: mafic ers may wish to verify critical information. PRECAMBRIAN Massive to foliated granodiorite to granite Ontario Geological Survey 1991. The geology of metavolcanic rocks, minor iron formation Issued 1991. 82© Ontario; Ontario Geological Survey, Special Felsic to intermediate metavolcanic GRENVILLE PROVINCE Information from this publication may be quoted if credit is Foliated to gneissic tonalite to granodiorite Volume 4. rocks©: rhyolitic, rhyodacitic, dacitic and given. It is recommended that reference to this map be PROTEROZOIC Plumb, K.A. and James, H.L. 1986. Subdivision of andesitic flows, tuffs and breccias made in the following form: Metasedimentary rocks and derived SYMBOLS Precambrian time: recommendations and Metasedimentary rocks and mafic to NEO- TO MESOPROTEROZOIC gneisses Ontario Geological Survey 1991. Bedrock geology of Geological boundary ...... ^- --, suggestions by the subcommission on ultramafic metavolcanic rocks tw: Ontario, explanatory notes and legend; Ontario Migmatitic rocks and gneisses Precambrian stratigraphy; Precambrian coarse clastic metasedimentary rocks, Geological Survey, Map 2545. Metavolcanic and metasedimentary rocks Geological province boundary ...... Research, v.32, p.65-92. marble, quartz arenite, iron formation, komatiite, mafic metavolcanic rocks, and to ultramafic plutonic rocks Mafic Geological subprovince ^- Streckeisen, A.L. 1976. To each plutonic rock its minor felsic metavolcanic rocks MESOARCHEAN boundary (defined, approximate) ...... ___ proper name; Earth-Science Reviews, v.12, Felsic plutonic rocks, derived gneisses and distribution of major lithologic units, p.1-33. migmatites Metavolcanic and metasedimentary rocks Figure 1. Generalized Fault ...... ^ structures and subprovince boundaries. The subprovince Structural arch ...... __. Winkler, H.G.F. 1976. Petrogenesis of boundaries within the Superior Province are after Card and Cie metamorphic rocks; Springer Verlag New York Metavolcanic and metasedimentary rocks a Phanerozoic units are lithostratigraphic, whereas Pre sielski (1986) with minor revisions. Compilation by LA. The positions of all boundaries and surveyed lines are cambrian units are lithologic. Osmani. approximate. Inc., New York, 334p.