Program, Abstracts, and Guidebooks - University of Minnesota Duluth

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-23- and this complicates exploration for base metal deposits. It Vs essential to recognize markedly metamorphosed exhalative centres. These centres, originally defined by accumulations of felsic flows, pyroclastics and cherts may be represented by quartz—sericite schists or gneisses, quartzites, quartzitic "conglomerates" or "breccias". Their bulk composition is important, for it survives metamorphisw, but primary textures may be much altered or obliterated. Minor— element geochemical studies of oxide, sulphide and carbonate—facies iron formations may be useful in guiding exploration from remote lateral lithofacies toward exhalatLve centres.
-25-- ROOT SEVERANCE AND TECTONIC TRANSPORT OF OREBODIES IN METAVOLCANIC HOST ROCKS WILLIAM F. JENKS University of Cincinnati ABSTRACT Association of lenticular, concordant, semi—concordant, and cross—cutting massive sulfide bodies with mafic and felsic volcanic sequences is well known. Some are clearly of submarine exhalative or replacement origin. Others may well be related to subaerial volcanism, but near sea level in a zone of negative crustal movement, since preservation of near surface phenomena in a eugeosynclinal environment requires relatively rapid covering and burial. Meta— volcanic sequences originating in active and subsiding tectonic belts have been subjected to all postvolcanic events affecting the enclosing metasedimentary rocks; they may have undergone deformation by overthrust faulting, nappe folding, and refolding. Separation of the volcanic pile (and associated ores) from its roots during such deformation would be expected. These structures, in meta— volcanic terranes, can go unrecognized because of originally complex volcanic—stratigraphic relations, transposition by sliding, md deep folding and metamorphism. Tectonic severance appears to be the reason for the absence of obvious plutonic source rocks in many metavolcanic sequences and their ores. Separation of ores from roots may be more than 50 1cm if we take Alpine deformation as a model. Certain types of volcanic masses such as rhyolite domes would yield to tectonic transport in a manner controlled by local contrasts in ductility, shape, and size., The deformational style is quite unlike that produced in regularly layered rocks. Orebodies, with their normal envelopes of hydrothermal alteration, may 'be transported in an environment especially susceptible to structural irregularity because they are in ductile shells adjacent to irregular volcanic masses. Resultant structural details would be expected to be still more complicated by selective flowage of some sulfide minerals and by migration in response to new chemical gradients.
Page 1 and 2: -ç — — I: .t. F Geology Superi
Page 3 and 4: TABLE OF CONTENTS INSTITUTE DIRECTO
Page 5 and 6: -2- "P R 0 G R A M" Tate day, Ma9 5
Page 7 and 8: -4- SESSTOM 2 1.00 Business Meeting
Page 9 and 10: -6- F'viday, May Slit, 1970 Page No
Page 11 and 12: -8- SYNTHESIS OF EARLY PRECAMBRIAN
Page 13 and 14: -10- THE SOUTHERN ASSOCIATED PART O
Page 15 and 16: -12- THE STRUCTURE OF THE NORTHERN
Page 17 and 18: -14- MT. ST. JOSEPH - AN ARC}IAEAN
Page 19 and 20: -16- A MODEL FOR TECTONIC VARIATION
Page 21 and 22: -18- EARLY PRECAMBRIAN GEOLOGY OF T
Page 23 and 24: DEFORMATION OF THE SEINE CONGLOMERA
Page 25: -22- MINERAL POTENTIAL IN CREENSTON
Page 29 and 30: -27- STRUCTURE OF ThE DULUTH GABBRO
Page 31 and 32: -29- 1. Department of Geology and G
Page 33 and 34: -31-. KEWEENANWAN COPPER DEPOSITS I
Page 35 and 36: —33- The youngest rocks in the ar
Page 37 and 38: -35- STRUCTURAL AN!) METAMORPHIC HI
Page 39 and 40: -37.- ARCHAEAN VOLCANIC STRATIGRAPH
Page 41 and 42: ______ __________ _____ IDEALIZED S
Page 43 and 44: —41- (3) The upper liimit of 30 p
Page 45 and 46: -43- Fjgire 2 The revised classific
Page 47 and 48: —45— EVIDENCE FOR A TROPICAL CL
Page 49 and 50: —47-- WIDESPREAD OCCURRENCE OF AL
Page 51 and 52: —49— PROTEROZOIC ROCKS IN THE T
Page 53 and 54: —51— Guide to the Proterozoic R
Page 55 and 56: WEST EAST f * . . .. . . S S S S 5S
Page 57 and 58: ________ — ;—=- — —-- —
Page 59 and 60: —53— The uppermost submember of
Page 61 and 62: —55— Morey notes that sediment
Page 63 and 64: —57— (c) layered mafic bodies,
Page 65 and 66: —59— DESCRIPTION OF STOPS Milea
Page 67 and 68: —6 P- Note downwarping of beds on
Page 69 and 70: —63— Note the lenticular chert
Page 71 and 72: —65— 0.0 From the intersection
Page 73 and 74: —67— STOP 16 In the roadcut to
Page 75 and 76: —69— ThE BEARDMORE-GERALDTON BE
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—72— the Quetico belt by Stockw
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—72 B— ABITIBI BELT —ø.jsour
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—74— Most of the metavolcanic
Page 83 and 84:
—76— SELECTED REFERENCES Anonym
Page 85 and 86:
—78— Stockwell, C. II., 1964; F
Page 87 and 88:
—80— ae DESCRIPTION OF STOPS 0.
Page 89 and 90:
—82— STOP 8 (Paint Lake Fault).
Page 91 and 92:
-84— Outcrops near the road are o
Page 93 and 94:
—87— Guide to the Port Coldwell
Page 95 and 96:
AGE RELATIONSHIPS The volcanosedime
Page 97 and 98:
.• ____________________ . — .._
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-I- + -4.- -I- - - - - — - 4- ; E
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—93— (3) 'flow—layering' exhi
Page 103 and 104:
GOSSAN ZONE IN SULPHIDE BEARING GAB
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—95— (3) feldspars variably fol
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—97— Fig. 6c Fig. 6b ;' TRAIL T
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Pig. 7 West contact of CROSS SECTIO
Page 111:
PRINCE AR THUR HOTEL ® 0 ® SHOREL
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Program, Abstracts, and Guidebooks - University of Minnesota Duluth

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