SUPPORTED IN PART BY THE MINNESOTA MINERALS DIVERSIFICATION PROGRAM MISCELLANEOUS MAP SERIES AS RECOMMENDED BY THE MINERALS COORDINATING COMMITTEE FOR THE MINNESOTA LEGISLATURE MAP M-119, SHEET 2 OF 2 MINNESOTA GEOLOGICAL SURVEY D.L. Southwick, Director CORRELATION OF MAP UNITS 91°00' SEDI- MENTARY ROCKS kfdl NORTH SHORE VOLCANIC GROUP MISCELLANEOUS 90°15' INTRUSIONS BEAVER BAY COMPLEX CANADA nsl 90°30' 90°45' 90°00' bsb 91°15' Gunflint Lake Knife Lake bbr 91°30' Tuscarora 89°45' 89°30' Lake Cucumber Poplar Lake Lake bsl bvh bms er 48°00' DULUTH COMPLEX iv R Pigeon Winchell Lake Pig TY e Point Layered Series bfg 91°45' on N Misquah bhc 48°00' Newton U Grand bcl bbl Hills 91°00' mdg mgp dlol dlbe dld bll bum Lake Portage bdf mdn Anortho- Fall CO Br nneu nnu nswu dlwl dlgl dlbl bfm E Midcontinent sitic ule Lake K COOK COUNTY 89°45' rift system dll3 Series bwl Mesoproterozoic Brule Lake dll1 dlsk dlwm LA CANADA 90°15' dlt dltu er Eagle* Pine* R 90°30' i nsu nhu Mountain Mountain v 90°45' dlpr dau bcc blp Riv e Gunflint Lake 90°00' r Hovland 91°15' PROTEROZOIC 92°00' Ely Farm Knife Lake Lake 91°30' 89°45' 89°30' bsp White wishiwi P Iron Ka 90°00' Poplar Lake Cucumber ige on er 48°00' Normal rk Tuscarora Lake iv Pigeon Lake o Lake Winchell Lake R F Point MAGNETIC POLARITY BOUNDARY Reverse 91°45' Early Gabbroic Felsic Series 48°00' Misquah Grand Marais Newton Grand Series South Lake Hills mbl 90°15' Portage 47°45' Fall B dep dec dfwl dfbl dfwf dfmw dfu ru mls Lake le nnel nru Brule Lake 89°45' dfcl dfmh 47°45' Toohey Lake Good Eagle Pine mdr R Harbor er * * Mountain nswl iv Mountain iv 90°30' R e Bay r Y Hovland Birch Lake 92°00' Ely Farm i Y kps Lake hiw Fourmile is White w ANIMIKIE GROUP Lake a TY Iron K 90°00' N . k TY r Cross Lake or Ptm Pvr Prv C U F N htali g th ug n Lutsen u U o So Grand Marais Penokean Orogen Pbi Pgi Paleoproterozoic H 90°15' Riv LAKE COUNT COOK COUNT 47°45' Ppk CO 90°45' r CO IS er e E Ninemile v U 47°45' Toohey Lake Good SUPRACRUSTAL N. Ri K Br a Lake Harbor ROCKS LO nch Tofte 90°30' LA . Osier Birch Lake Bay INTRUSIVE ROCKS idge Fourmile tr Lake r ST Y Lake Akn a ch Ma Schroeder T n Y P Seven a N . n T r C . Br C Superior Province Ag Late Archean ARCHEAN S i U Beaver t N htali g r Alv Apda Greenwood ou ug n o Lutsen Blesner O s U o (Neoarchean) H s Amv Am 92°15' Lake Lake 47°30' C Riv O R Anl Aeg Sonju Lake i C v 90°45' 47°30' Hoyt Lakes S I e r Lake er E Ninemile W U N. 91°00' K B e r O ra Lake st Br e A iv L nc Tofte L h R . Osier River e T s . Lake Cloquet Br Y g S M LAKE COUNT id nch Schroeder . Loui tr Seven ra a Lake Bapt East R r S. B n St a Beaver Greenwood it Finland P Blesner o DESCRIPTION OF MAP UNITS Lake Lake u 47°30' Anorthositic series PALEOPROTEROZOIC ROCKS i Little Marais 92°15' bum Upper Manitou gabbro sm O Lake R 47°30' Sonju iv I Hoyt Lakes W Lake e MESOPROTEROZOIC ROCKS r 91°00' dau Undifferentiated anorthositic rocks Animikie Group es t Ri s B bhc Houghtaling Creek troctolite R ui River r. r. North Shore Volcanic Group v Illgen Lo t B Ptm Thomson Formation Be Lax e t. as r City S Cloquet B E R a E a Normal magnetic polarity suites Felsic series v Lake Lake p Finland er t bdf Dam Five gabbronorite is Little Marais O Palisade Head m Pvr Virginia Formation Silver Bay P I nsl Schroeder–Lutsen basalts dfmw Mt. Weber granophyre R bwl Wilson Lake ferrogabbro iv R 0 10 20 mi U Illgen 91°15' B Lax e e r City Prv Rove Formation Riv a E nneu Upper northeast sequence dfwf Whitefish Lake granophyre v Lake 0 10 20 30 km S e er Beaver Bay r Palisade Head bfm Fourmile Lake ferrogabbro 47°15' P 47°15' Silver Bay Pbi Biwabik Iron Formation LOCATION DIAGRAM nswu Upper southwest sequence dfbl Beth Lake granophyre R U iv 91°15' e bcc Cabin Creek porphyritic diorite r Beaver Bay S Gooseber 47°15' dfwl Wine Lake monzodiorite Pgi Gunflint Iron Formation E 47°15' nnu Undifferentiated rocks Split Rock Point blp Leveaux porphyritic diorite ry K EXPLANATION Ppk Pokegama Formation Si Ri G dfmh Misquah Hills granophyre lv ve oos E e r eb Reverse magnetic polarity suites r A erry Split Rock Point K bsp Shoepack Lake inclusion-rich diabase Silver S R L ilv ive Creek e r A Bedrock is moderately well exposed—Density of outcrop is sufficient dfcl Cucumber Lake granophyre r nnel Lower northeast sequence ARCHEAN ROCKS Silver to map at 1:24,000 or smaller scale 91°30' Creek L Duluth Complex intrusions Intrusive rocks Cr dfu Undifferentiated rocks e 91°30' e nswl Lower southwest sequence C Layered series k re e Bedrock is poorly exposed—Mapping requires additional data from k Apda Porphyritic dacite to andesite drilling and geophysical maps dld Layered series at Duluth Early gabbroic series nru Undifferentiated rocks SCALE 1:500,000 Ag Granitoid bodies Scant to no exposure of bedrock—Geology inferred almost exclu- dec Crocodile Lake gabbro Two Harbors 0 10 20 mi Two Harbors Rocks of unknown magnetic polarity dlol Osier Lake intrusion 47°00' 47°00' 47°00' sively from geophysical maps and scattered drill holes 47°00' Am Mafic to ultramafic intrusions 0 10 20 30 km dep Poplar Lake intrusion nsu Undifferentiated rocks dlbe Bald Eagle intrusion L 91°45' Drill hole e L 91°45' s e te Supracrustal rocks st r e nhu Volcanic hornfels dlbl Boulder Lake intrusion Miscellaneous intrusions r R iv er Basal contact of the Duluth Complex Akn Knife Lake Group Riv mdg Diabase-to-gabbro intrusions Beaver Bay Complex intrusions dlgl Greenwood Lake intrusion er Alv Lake Vermilion Formation mgp Granophyre intrusion bsb Silver Bay intrusions dlwl Wilder Lake intrusion 92°00' Duluth Anl Newton Lake Formation bbr Beaver River diabase mdn Diabase dikes of normal polarity dlwm Western margin intrusion 92°00' Aeg Ely Greenstone . Diabase dikes of reverse polarity 46°45' 46°45' bsl Sonju Lake intrusion mdr dlsk South Kawishiwi intrusion N CO N r e Duluth v Amv Mafic volcanic rocks TO i mbl Brule Lake porphyry intrusions Elys R bvh Victor Head diabase dll1 Lake One intrusion . Peak 46°45' 46°45' ThomsonCARL is * u N CO r o mls Logan sills MAP SYMBOLS e Fond L bms Milepost 7 intrusion dll3 Lake Three intrusion v . TO du 92°15' t Ri Lac S Geologic contact Elys Peak bfg Finland granophyre dlpr Partridge River intrusion Sedimentary rocks CARL Thomson is Mafic sill * u GENERALIZED DENSITY OF BEDROCK OUTCROPS AND DRILL HOLES IN NORTHEASTERN MINNESOTA o kfdl Fond du Lac Formation L bcl Cloquet Lake layered series dlt Tuscarora intrusion Fond 92°15' t. Mafic dike of unknown polarity du S kps Puckwunge Sandstone Lac bll Lax Lake gabbro dltu Undifferentiated troctolitic rocks bbl Blesner Lake diorite MAP SHOWING TIME-STRATIGRAPHIC RELATIONSHIPS WITHIN THE DULUTH COMPLEX AND RELATED ROCKS, NORTHEASTERN MINNESOTA 91° 00' 13 Davidson, D.M., and Burnell, J.R., 1977, Reconnaissance geologic map of Brule Miller, J.D., Jr., Green, J.C., Severson, M.J., Chandler, V.W., Hauck, S.A., Peterson, 92°00' 91°30' 91°00' 90°30' 90°00' 89°30' Lake quadrangle, Cook County, Minnesota: Minnesota Geological Survey D.M., and Wahl, T.E., 2002, Geology and mineral potential of the Duluth Complex 90°15' 90° 90°30' Miscellaneous Map Series M-29, scale 1:24,000. and related rocks of northeastern Minnesota: Minnesota Geological Survey 91° 45' 90° Report of Investigations 58. Davis, D.W., and Green, J.C., 1997, Geochronology of the North American 15' 00' Midcontinent rift in western Lake Superior and implications for its geodynamic 52 Miller, J.D., Jr., and Jerde, E.A., 1990–1993 [unpublished field notes and maps C 91°30' A evolution: Canadian Journal of Earth Sciences, v. 34, p. 276–488. from Little Marais quadrangle]. 89°45' 89°30' N Davis, D.W., and Sutcliffe, R.H., 1985, U-Pb ages from the Nipigon plate and Miller, J.D., Jr., and Ripley, E.M., 1996, Layered intrusions of the Duluth Complex, U A . 48°00' S D northern Lake Superior: Geological Society of America Bulletin, v. 96, p. Minnesota, USA, in Cawthorn, R.G., ed., Layered intrusions: Developments in . A 1572–1579. Petrology 15; New York, Elsevier Science, p. 257–301. 91°45' 37 Foose, M.P., and Cooper, R.W., 1978, Preliminary geologic map of the Harris 36 Morey, G.B., and Cooper, R.W., 1977, Bedrock geology of the Hoyt Lakes–Kawishiwi 48°00' Lake area, northeastern Minnesota: U.S. Geological Survey Open-File Report area, St. Louis and Lake Counties, northeastern Minnesota: Minnesota Geological 78-385, 24 p., 1 pl., scale 1:12,000. Survey file maps, scale 1:48,000. Fralich, P.W., and Kissin, S.A., 1998, The age and provenance of the Gunflint 5 Morey, G.B., and Nathan, H.D., 1977, Geologic map of the South Lake quadrangle, CANADA lapilli tuff [extended abs.]: Institute on Lake Superior Geology, 44th Annual Cook County, Minnesota: Minnesota Geological Survey Miscellaneous Map 89° Meeting, Minneapolis, Minn., 1998, Proceedings, v.