A Study of the York River Formation in the Rimouski-Matapedia Area, Quebec Qe 193 A986 1962 Qfo

TH 1460 A STUDY OF THE YORK RIVER FORMATION IN THE RIMOUSKI-MATAPEDIA AREA, QUEBEC QE 193 A986 1962 QFO r 1 • A study of the York River formation in the Rimouski-Matapedia area, Québec ~ 2~ORT1-I';.EGTE:?2t UNSVEr SIT. Y A â;t1Dy OF TIM Y Cn MN= Fû1 iIATZCN IN 11I140U3Y.I-;ATArEDIA nE A, QU.â?EC A TILL, Is Stm;;rsnED TQ TNr;. G:iADUn.TE SCHOOL FAA T IAL; ; ILL~ ~~ ~T CF TI-Iï REQ.UIRE: T S : or the deLlree EASTER CF scams Field of GeQlozv ~Lr WILLIAM GREY A Twat; ~.J \ T Gt Evar.$i:oi`IR Illino3a .-. ~ ; ,,a, i~~ / E t"CJ `- June, 1962 ; -, : , ,_; ; -~1 C5. ..,.._.... r 4~~~~~.i f TABLE OF CONTENTS PAGE CHAPTER I . INTRODUCTION I 1. GENERAL STATEnEN:' 1 2, FIELD WORK 1 3. GENERAL GEOLOGY OF GASPE 3 4. PREVIOUS WORK 7 CHAPTER II . GEOLOGY OP THE SOUTHWESTERN l?IYOUSKI- M10'I'APEDIA AREA 11 1. STRATIr3RAPFiY 11 St , Leon To. eicn 13 Capes Don AMi Fort-talon 16 Grande Greve Formation 31 Fortin Group 26 York River £omation 32 2. INi'P.USIVE S 51 3, STRUCTURAL GEOLOGY 54 4. PALEONTOLOGYQLCGY G, CHAPTER III ... I N :' E IF P :i E T A T I 0 N 73 CHAPTER IV ... CONCLUSIONS 90 REFERENCES CITED 92 . APPENDIX PILOT S TmY I ILLU3TRATIO273 PAGE PAP 1 Location of the Rimou3ki-iiatape1ia Area MAP Regional Distribution of the Gaspe Sandstone Group 3 MAP 3 General CeoloTy of the Heppe' Syncline 14 MAP 4 Structural Oeorretr7 of the Southwestern Rimouski-Matapedia Area 59 MAP 5 Approxirate F:ealr:a of the Amphigcriia and alobithyrie Faunas 69 MAP 6 Tectonic framework During York River Tirrs 714 MAP 7 restored Isopach Map of the York River Formation 77 MAP R Location of Sandstone Samples Plotted in Appendix Fiure 5 VIII MAP 9 Geology of the Southwestern Rimouski- In back Matapedia Area Pocket * • I • • • • • * 4 • • Irld. I Generalized Diamrammatio Section Showing Stratigraphie and Structurai Relationships in Gaspe. FIG. 2 Thin-section of Volcanic Sandstone within the St. Leon Formation 17 FIG. 3 Thin-section of Grande Greve Forraticn 25 FIG. 4 Stratiçraphic Relationships Across the Heppol Syncline PIG. 5 Tri$n7u1er Dia-j:ram Shdwtn• 'he M1no alo7ica1 Cor.pcait_ton of Twelve Sandstones from the York Rover Forrar icon PAGE~.._...,..,. Fia. 6 Thin-section of odiu:-grained Sandstone from tho York River Formation 47 FIG. 3 Thin-section of Diorite Dike 51 FIG. 9 Stereographio Projections of Structural Data 56 FIG. 10 Possible Relationships at Northwest Corner of Area Napped 62 FIG. 11 Structural Cross-sections 63 FIG. 12 F.xrrples of Foliation 66 FIG. 13 Graphs orQuartz, Felds^ r and ? atrlx versus X Appendix VII . TABLE 1 Review of the Gaspe Devonian Nomenclature 10 TABLE 2 Summary of the Stratigraphy of the Rimouaki- Iatapedia Area 12 TABLE 3 Fauna of the York River Formation 72 TABLE 4 Comparison of Flyach Deposits 81 TABLE 5 Nodes Determined at 'Intervals from 23 to 600 Appendix IV TABLE 6 Pilot study Data Sheet Appendix VT TABLE 7 A ineral Composition of Samples Appendix IX TABLE 8 Structural Data Appendix X PLATE I a) York River Formation Sandstone 40 b) York River Formation Siltatore - ACKNOWLEDGEMENTS The field work for this study was done while the writer was employed by the Quebeo Department et' wines. Special acknowledgement is due to Dr. Jacques Beland of the Quobea Depart:ent of Mines, who supervised this study in the field, and who provided the writer with the benefit of his considerable field experience in Gaape, Dr. E.H.T. Whitten of Northwestern University guided and advised the writer during the preparation of this thesis. Professors L.L. Sloss and E.C. Dapples of North- western University, and Dr. E.X. Walton, visiting professor from the University of Edinburgh read the manuscript and offered zany helpful suggestions.. Professor A.J. Dou et. of the Massachusetts Institute of Technology identified the fossil eolleoticns. John Pressley, technician at Northwestern University cut thin-sections. To all of the above, the writer wishes to express his appreciation. Particular acknowledgement is due to my wife, with- out whose assistance and encourage cnt this thcsie would have been long delayed. CHAPTER I INTRODUCTION 1. GENERAL yTAT~ ~::2.î This study is primarily concerned with the petrology, stratigraphy and structure of the York River Formation, the lowest unit of the Gaspe Sandstone Group (Devenian). The area chosen for study is in the southwestern part of the Rimouski• catapedia area of southeastern Quebec (reap 1). The distribution of lithology, the tectonic framework of sedimentation and the environment of deposition are also examined. Fossils were collected but no attempt is rade to make a detailed paleontological study. 2. FIELD WORK A combination of thick glacial till, denSe forests, and the location of the area alone a rain drainage divide, results in a lack of continuous exposure and difficult mapping. The writer became familiar with soma of the regional 1 70° \15. \60• AREA MAPPED O f GE ~ P Es ~ ~ S w I \ QUEBEC ` .t t .1 r U. S . A . ,;S MONTREAL. ~~ ...; ,...I...2...5( --------- 70° \ 65. MAP I. LOCATION OF RIMOUSKI — MAT APEDIA AREA. e 3 41* and otratigraphie problems while tapping similarracks east cf the present area in 1952, Four weeks were spent mapping the York River Formation in the Rimouski- :atapedia area in 1959. Access to this area is fairly good, by gravel roada. Advance topographic raps, 2" to 1 rile, prepared by the Department of Mines and Technical Surveys, Ottawa, were used together with aerial photographs taken by the Royal Canadian Air Force. The photographs were not particularly useful because of the dense forest cover. Many of the roads have been constructed recently and are not shown on the photographs. The best exposures occur in cuts along the roads; the strews cut through the thick glacial till and for the most part are still clogged with this raterial. Yany streams were traversed using pace and compass methods, but in general did not provide such rock exposure. Jean Claude Dube and Denis Gagne were field assistants. G 0~.7RAL GEOLOGY OF QA3PE The Gaspe Feniraule and the Riclouski. atapedia area are part of the northeastern end of the Appalachian mountain eystem on the continental mainland. The rooks comprise folded and faulted Paleozoic eedi:entary strata intruded by granites, diorites, dolerite dikes and cerpentinites. The regional structural trend is approximately parallel to the arcuate outline of the peninsula. The rocks of the sedimentary column can be divided into four sequences, separated by three striking angular unconfcrmities (Fig. 1). The tern "sequence", used in the sense defined by Wheeler (1958, p.10511, "is a preserved stratal aseemblage which is unconfor .ably separated from underlying and overlying rocks . The oldest sequence consists of the Maquersau Group, the Shickshock Croup and the Murphy Creek Formation, all of which are pre-fiddle Ordovician. The Vaquereau Group, which crops out only in southeast Gaspe, comprises metamorphosed untossiliferous graywaekes and greenstanes, whereas the Shickehack Group, which crops out in northwest Gaspe, comprises mainly horn- blende-chlorite eohistel McCerrigle (1954) has interpreted the latter as metamorphosed basis to intermediate volcanics. The fossiliferous limestones and shales of the Murphy Creek Formation (Upper Cambrian) crop out in eastern Gape. The stratigraphie relationships between these three isolate=d units le as yet unknown. Examples of lithologic units (not necessarily in stratigrophic order ) CARBONIFEROUS BONAVENTURE CONGLOMERATE GASPE SANDSTONE GROUP LAKE !RANCH FORMATION D EVONIAN YORK RIVER FORMATION GASPE LIMESTONE GROUP AN D GRANDE GRIVE FORMATION CAPE SON AMI FORMATION FORTIN GROUP S ILURIAN CHALEURS BAY GROUP ETC. MATAPEDIA GROUP UPPER AND MIDDLE NORMANSKILL FORMATION DEEPKILL FORMATION ORDOVICIAN MICTAM GROUP ETC. PRE- MIDDLE ORDOVICIAN MAQUEREAU GROUP SHICKSHOCK "SERIES' MURPHY CREEK FORMATION FIG. I. GENERALIZED . DIAGRAMMATIC SECTION SHOWING STRATIGRAPHIC AND STRUCTURAL RELATIONSHIPS IN GASPE. The second aequen:e includes the niddle and Upper Ordovician strata. This series of closely folded conglom- erates, sandstones, shales, slates and limestones is unoon- for cable on the first sequence. This unconfori able relation- ship is best seen outside the thesis area in southeastern Gaspe, where ccn,lomerates of the Middle Ordovician Mictaw Group overlie the Taquereau Group (Âyrtan, 1960). Overlying the second sequence, with angular uncon- fortuity, are folded Silurian and Devonian strata, generally referred to as the Gaspe Limestone and Gaspe Sandstone Groups. Volcanics are present in this sequence. Crickray . (1932) believed that the urccnforrity separating the second and third sequences is evidence of the Taconic Orogeny, which caused defamation of the Northern Appalachians during the Late Ordovician. The third sequence is unconforrably overlain by subhorizontal Carboniferous red non-rarir.e conglomerate* and sandstones of the fourth sequence, (Alcock, 1935 p. P9). This third regional unconfor ity is attributed to the Acadian Crogeny, the last major orogenie episode to affect the Northern Appalachians (Peaerrigle, 1950, p.105). Volcanics are associated rairly with the first and third sequences. Intrusive igneous rock are found, but are not widespread. A large granitic body intruded Ordovician strata in north-central Gaspe, and two bands or $erpentinites can be outlined rouhly. Dikes and sills of rhyolite, diorite and dolerite are common throughout the peninsula. PF~EVICV3 WoP.n No previous work has been done within the area napped by the writer. Since the Gaspe Sandstone Group and the York River Formation in particular, crop out along the length of the Caape Peninsula, a considerable amount of work has been done oleewhere on these unit (Map 2). Much or the early work has been concerned with establishing lithologic units, outlining their areal distribution and determining their geologic age.

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