l.'· .'· / ll. fof\1~ AEC-RD-10 UNITED STATES ATOMIC .ENERGY COMMISSION "l GHAND JUNCTION OFFICE HESOURCE DIVISION l GEOLOGIC BRANCH l J OPEN FILE J J MAY 2 5 1971 A GEOLOGIC ST1J1JY OF URANI\J!>! m:SOlifc~E:S IN PRECAMBRIAN ROCKS j OF THE WESTERN UNITED STATES J Distribution of Uranium and Thorium in Precambrian Rocks of the Western Great Lakes Region J by ] Roger C. Malan and David A. Sterling J J J ] ] J July 1969 J Grand .)'unction, Colore.do J ''~L'c: ;";~·ill ·,·:·.;; r:r';·:ro·J ~.;,;'I~ :l({'(':ilrl! r,l \'."'1111 spnmwrd hy 1~1C Un:lr< ~::.11;':; l;c;·n;;~i'ICnl. flr.i!I!Gr :;,:! :: .. ii.;,l ;;:::t.'.; ;;, r :; [;:Ji[:',J ;:L,;r_; ;\!,ln:ir. Cnu:.r C::;r;II1L$'1:(;n, nnr ~r.y r1J lil,·il rn:nL;Y8'~:i, r:nr :1ny nl :Ui c:Jn!rJ(:,!:~. f.t.l'':i:;.,;.-:.•... ,: .. r·r 11~,:;; ~~··;·l''>'~t'':l. rrrJii .. ~ ar.y w.\rr~r.ty, llx~u;,:·.; err irllphc:l, (lf J D~~n::1c:: '·"1 ),~.:::;1 li::iJ:Liy t'•r re:.pt1!1~.ii•i:l:y ICir ti.(! i':'ii•r;:~v. e,'mp'e[,~rw::s nr r:~··f::lr:,·:.~ ul .l:;y inlor· n,:1!illi1 ,'i'~,Jrttill.:., piotll!<:t or prot:n$:: dJ:>r:losec, or rcpe:>vi\l~ th:~t ~~~ us(: woullf ll'.lt iJ,Irirl!;~ prlv::tciy­ j U':dwd 11;::1tS." ; ' DISTRIBUTION OF UPJI.NiliM Al'ID THOlliUM IN PRECAMBRIAN ROCKS OF THE WESTERN GHEAT LAKES REGION ] ' ,-l TABLE OF CONTENTS i ] Page ,- ABSTRACT •. 1 1 J INTRODUCTION 2 i Previous Uranium Investigations 2 J Current Uranium Exploration Situation 2 ; PRECJI.MBRIAN GEOCHRONOLOGY OF THE WESTERN GREAT LAKES 4 J' SUJ.1NARY OF PHECAMBRIAN NETALLOGENESIS, GREAT LAKES REGION 9 DISTRIBUTION OF URANIUM AND THORIUM '3 ll Radioactive Granitic Rocks ll ~ Veins in Slate ll J Monazite Placers I 13 l Uranium in Iron Formations 13 Thoriferous Hyperalkalic Complexes 13 J Keweenawan Felsite Dikes 13 ] .uraniferous ~artz Pebble Conglomerate 13 Cambrian Franconia Formation 14 J Formational Background Level& 14 J UHAl'IIUM RESOURCE OUTLOOK 16 Animikie. Series 16 J Granitic Rocks 21 J Sioux ~artzite 21 CONCLUSIONS .•.•.•.•.•.•.•.•.• 22 J REFERENCES • • • 23 J i. J J u.·: • > ,J LIST OF ILLUSTRATIONS J J Figure l Index Map - Precambrian Study . • • • • 3 Figure 2 Generalized Geologic and Geochronologic Map of J the Precambri,m, Western Great Lakes Region •• 5 Figure 3 Generalized Lower and Middle Precambrian Paleo­ ] geologic and Metallogenetic Map, Southern Canadian Shield. • • . • • • . • . • • • • • 10 J J J LIST OF TABLES Table 1 Generalized Correlations of Precambrian Strati­ J graphic Units Referred to in Text .••••.• 6 ] Table 2 Uranium and Thorium Occurrences in the Western Great Lakes Region • • . • • . 12 Table 3 Distribution of Uranium and Thorium in Selected J Precambrian Lithic Units, \ole stern Great Lakes Region . .. a o • • • • b • • • • • 15 J Table 4 Comparison of Thorium and Urariium Contents of l Huronian and Animikie Strata • . • • • • • • 18 J J J J J J ii. J J J .. ] AEC-RD-10 A GEOlOGIC ST\IDY OJ' 1,iRAl'Hill~ RESOURCES IN PRECAMBRIAN ROCKS J OJ' THE WESTEr& illfiTED STATES . Distribution of Uranium and Thorium in Precambrian Rocks J of the 1Vestern Great Lakes Region J by J Roger C. Malan and David A. Sterling J J -----ABSTRACT Private prospecting and investigations by the U. S. Atomic Energy Com­ mission during the 1950's resulted in the discovery of several uranium J and thorium prospects in Precambrian rocks in the western Great Lakes region of the United States. In \visconsin and in upper Michigan, · ] Lo>rer, Middle, and Upper Precambrian silicic and hyperalkaliccpluton·ic rocks contain anomalous amounts of disseminated radioactive minerals. In upper Michigan, Middle Precambrian metasediments of the Animikie ] Series contain uranium veins in slate, monazite placers in conglomerate and irregular concentrations of ·uranium in iron formation adjacent to slate. l 1Vhile none of these prospects contain reserves that are economically mineable at present, some may contain important.~ong range, low grade resources of thorium and uranium. For example, 'limited sampling J indicates that masses of silicic igneous rocks in northeastern 1Vis­ consin may contain 50 to 100 parts per million U308. This is greater than the uranium content in any of about 250 bulk ·samples of Ijre­ J cambrian igneous rocks from the 1Vestern United States that have been analyzed in this pPoje~t. J A potentially great resource of thorium may exist in the monazite placers in conglomerates of the Goodrich Quartzite (Animikie Series) near Palmer in upper Michigan, but the uranium content is very low. J Anomalous amounts of uranium in sparse outcrops of other conglomeratic quartzites of the Animikie warrant additional study, but extensive J till cover precludes systematic sampling. · J J J - l - J l J' . •. ·~ -------INTRODUCTION :] Previous Uranium Investigations Initial investigations for uranium in the extensive Precambrian terrane in the ;restern Great Lak.os region (fig. 1) ;rere carried out by the Jones l and Laughlin Ore Company under contract with the U. S. Atomic Energy Conunission from April 30,. 1951 through June 30, 1953. L. P. Barrett ] was the senior investigator under this contract. Investigations were continued directly by the U. S. Atomic Energy Commission through the Ishpeming, Michigan Sub-Office of the Division of Raw Materials under 0 the direction of L. P. Barrett from 1953 to 1958. The investigations by the U. S. Atomic Energy Commission in the western ] Great Lruces during the 1950's included examinations of numerous radio­ active occurrences, a1.rborne and ground radiometric reconnaissance of favorable lithologic units, hydrogeochemical reconnaissance and elec­ J trical and seismic geophysical surveys (Illsley, 1958; Kinnaman, et al., w-ritten communication, 1958; Smith and Fickel, ~rritten communication, 1957). Superior Oil Company and the U. S. Geological Survey (Stead, J et al., 1950) did extensive airborne radiometric reconnaissance. Superior Oil and many individuals and small groups also did consi-derable ground radiometric prospecting. Shallow drilling and dozing were done J at a few selected prospects by pri-vate interests, but no economically exploitable uranium deposits were discovered.· J Current Uranium Exploration Situation One. two-week field trip was.made to the western Great Lakes region in J September 1967 for the following purposes: l. Assess the level of uranium prospecting and exploration J effort in that region. 2. Ex,amine the most significant prospects that were discovered J during the acti-vity of the 1950's. 3. Collect bulk samples of selected lithic units for establishing J background U and Th. 4. Compare geologic emrironments in the Precambrian of the J western Great Lrutes region with environments in the uranium districts in Canada. ] The western Great Lakes region of the United States has attracted very little attention during the current uranium exploration boom. Kerr­ McGee Corporation has made a few brief reconnaissance examinations J through its Toronto, Ontario office; in 1967, they ai:!quired a state lease on the quartz-calcite-pitchblende vein prospect in the Michiga~e Slate Formation of the Middle Precambrian P~imikie Series on Green's ] Creek ncar Palmer, Michigfu,, about 15 miles southwest of Marquette , '. )' . J - 2 - J ] L__ L__ L__j l_j Ll.J L__j L..Jj L_j L_j L_j L_j :.....:._] L_j L_j L..J :....:.:....J L_j L_____j L_____j . .__ 1 i.-- I ) . "'I .r· 'bD s t9 ~. f lnekx Mop· Precornbrion S1udy riillJ RD-9 ~ RD-10 Q RD-11 Figure I. Distribution of Precambrian Rocks in the Western United Slates 'J' .·. '-I In 1'l68 ~ · rt locr::.l g:::-·c.)UP, th~_~ Hard.1-rood Mining Company, Hardwood, Michigan, acquired a sLate leas~:; on the o1d Felch pl~ospect, alias Isham prospect, ] nbod lf5 miles soutlw·cst. of Marquette. R. C. Vickers (1953) collected sari"1plcs at this prospect from ;.j, .radiometrically anomalous biotite schist xen~lith in r.· -·"de granite tl1at contained O.Ol<f, to 0.02% eU and 0.006% ] to 0 .OO'i'h U. In 1968, sr.mplcs of mineraliZ8d qum·tz--dioritic orthogneiss from a new ·l prospect in northern Minnesota contained O.lOOh eU303, 0.10% U308 and 322 ppm Mo. Uranini t-~, pyr·ite a;~d molybdenite -;;·ere identified in the samplces. Prior to this disc.ove:r-y_, the only reported uranium occurrences ] in Minnesota were a few unimportant radioactive pegmatites. j PRECA!\1BRI/\N GEOCHRONOIO:.:;y OF THE ViESTERL"T GREAT LAKES Figure 2 is a generalized geologic and geochronologic map of the Pre- J . camorian of the western Great L-akes region that was constructed from compilations by Goldich, et al. (1961) and Bayley a.-od Muehlberger (1968). The geology of this region he.s been studied by scores of investigators J during the past J.OO yea.rs particularly in the areas of the Middle Pre­ cambrian sedimentc-.r.-y· iron for.uat.ions of Michigan, Minnesota, and Wisconsin and in the UPP''r Precambri<m stratiform copper deposits of Michigan. l Concepts of the geologic history of the Prec<?Jllbrian in the we stern Great Lakes region that evolved from the classic work of Van Hise and Leith . (1911), Leith (1934), LeJ.th, Lund11.nd Leith (1935), Grout, et 'al.,(l951), J and Marsden (1955) have been better defined in recent years through isotopic age dating (James, 1958; Goldich, et al., 1961; Hurley, et al., l 1962;.• Catanzaro, 1963; Peterman, 1966). The U. S. Geological Survey subdivides the Precambrian of the western Great Lakes into Lower (.>2.5 b.y.), Middle (2.5 to l.Tb.y.) and Upper J (1. 7 to .6 b .y.), (James, 1958). The Minnesota Geological Survey (Goldich, et al., 1961) applies Early, Middle, and Late t~ the same intervals.