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Recommended citation: Knight, I., Boyce, W.D., Skovsted, C.B. and Balthasar, U. 2017: The Lower Cambrian Forteau Formation, southern Labrador and Great Northern Peninsula, western Newfoundland: Lithostratigraphy, trilobites, and depositional setting. Government of Newfoundland and Labrador, Department of Natural Resources, Geological Survey, St. John’s, Occasional Paper 2017-01, 72 pages. Authors Addresses I. Knight W.D. Boyce Department of Natural Resources Department of Natural Resources P.O. Box 8700 P.O. Box 8700 St. John’s, NL St. John’s, NL A1B 4J6 A1B 4J6 (Email: [email protected]) (Email: [email protected]) C.B. Skovsted U. Balthasar Swedish Museum of Natural History School of Geography Department of Palaeobiology Earth and Environmental Sciences SE-104 05 Stockholm, Sweden Plymouth University, Drake Circus (Email: [email protected]) Plymouth PL4 8AA UK (Email: [email protected]) THE LOWER CAMBRIAN FORTEAU FORMATION, SOUTHERN LABRADOR AND GREAT NORTHERN PENINSULA, WESTERN NEWFOUNDLAND: LITHOSTRATIGRAPHY, TRILOBITES, AND DEPOSITIONAL SETTING I. Knight, W.D. Boyce, C.B. Skovsted and U. Balthasar Occasional Paper 2017-01 St. John’s, Newfoundland 2017 CONTENTS Page ABSTRACT . vii INTRODUCTION . 1 REGIONAL GEOLOGY AND SETTING . 5 STRATIGRAPHY OF THE FORTEAU FORMATION: INBOARD SHELF SEQUENCE . 6 DEVILS COVE MEMBER . 7 Lithology. 10 Labrador. 10 Western Newfoundland . 10 MIDDLE SHALE . 10 Lithology. 12 Labrador. 12 Lower Archeocyathid Biohermal Buildups and Bedded Open-shelf Facies Interval . 12 Upper Interval. 13 Great Northern Peninsula . 16 UPPER LIMESTONE . 20 Lithostratigraphy. 21 Lower Archeocyathid‒Grainstone Interval . 22 Archeocyathid Complex, Southern Labrador. 22 Oolitic Grainstone Association, Southern Labrador . 23 Upper Limestone, Great Northern Peninsula . 24 Archeocyathid Bioherms . 25 Grainstone-dominated Interval. 26 Upper Heterolithic Interval. 26 Siltstone‒Sandstone. 26 Carbonate. 29 Dolostone. 29 Shale to Sandstone . 29 Upper Limestone, Route 432 and Big East River Road . 30 Heterolithic Association with Quartz Arenite . 33 Blue Mountain and Long Range Outliers . 34 BIOSTRATIGRAPHY . 34 STRATIGRAPHIC DISTRIBUTION OF THE TRILOBITES. 35 BIOFACIES CONSIDERATIONS . 41 CORRELATION WITH THE STANDARD EARLY CAMBRIAN ZONATIONS OF LAURENTIA. 41 OTHER CORRELATIONS . 44 INTERPRETATION OF THE FORTEAU FORMATION IN SOUTHERN LABRADOR AND NORTHWEST GREAT NORTHERN PENINSULA . 44 THE TRANSGRESSIVE SYSTEM TRACT (TST). 45 MAXIMUM FLOODING SURFACE (MFS) AND HIGH-STAND TRACT (HST). 47 HIGHSTAND CARBONATE SHELF . 47 The Upper Archeocyathid Biostrome in Labrador . 47 The Inner Ramp, GNP . 49 The Carbonate Shoal Complex. 49 i Page The Heterolithic Interval, Uppermost Forteau Formation:Evidence of Sea-level Rise and Later Advance of the Clastic Sediment at the Northwestern Landward Margin of the Ramp . 50 IMPLICATIONS OF THE FORTEAU TRILOBITE FAUNAS . 51 REFERENCES . 53 APPENDIX 1: Fauna Previously Identified from the Forteau Formation. 61 APPENDIX 2: Study Area Since 1976 . 62 FIGURES Figure 1. Geology map of western Newfoundland showing its main geological terranes and the loca- tion of study areas (arrows) hosting rocks of the Lower Paleozoic shelf succession. S. Lab – southern Labrador, MSM – Mount St. Margaret, R432 – Route 432, BER – Big East River resource road, and DH – Drillhole DH-NF-1B (Savage Cove). TRF – Torrent River Fault. HPF – Hatters Pond Fault. LR – Long Range Cambrian Outliers. BM – Blue Mountain. GM – Gros Morne National Park. The heavy dashed line marks the approximate divide between the inboard and outboard zones of the Forteau shelf . 2 Figure 2. A graphic log of the Forteau Formation in DH NF-1B drilled near Savage Cove (Figure 1). Section measured in 2010. The upper contact with the Hawke Bay Formation shows two potential choices: lower one at top of a dolostone unit, and the upper one at base of the first, white quartz arenite of Hawke Bay Formation above the last Forteau carbonate. The latter is used in this discussion . 3 Figure 3. Geology map of the south coast of Labrador showing localities in the Forteau Formation, Labrador Group that were studied (map based on Bostock et al., 1983 and Gower, 2010). LLQ – L’Anse au Loup quarry, DCQ – Diablo Cove quarry, K07, K08 studies in 2007, 2008. GK-7 and the others – studied in 1993 with C.F. Gower . 4 Figure 4. Geology map of Ten Mile Lake to Canada Bay area of the Great Northern Peninsula showing localities studied in the Forteau Formation at Mount St. Margaret quarry, East Castor Pond road (ECP), and Route 432 (e.g., R432-1). CPF – Castor Pond fault, PPF – Plum Point fault . 5 Figure 5. Geology map of Hawke Bay‒Highlands of St. John area of the Great Northern Peninsula showing localities studied in the Forteau Formation along the Big East River (BER) resource road. SL–Torrent River salmon ladder . 6 Figure 6. A and B) Sections measured in the Forteau Formation of south Labrador coast. Open shelf and biohermal patch reef facies lie adjacent to each other on the foreshore at and east of Fox Cove. Section FC2 comprises a lower.