Seabed Processes and Resources

A tlantic Geology 153 GEOLOGICAL ASSOCIATION OF CANADA NEWFOUNDLAND SECTION ANNUAL MEETING SEABED PROCESSES AND RESOURCES MARCH 17-18, 1994 MEMORIAL UNIVERSITY OF NEWFOUNDLAND The annual meeting of the Newfoundland Section of the Geological Association of Canada was devoted to research in seabed processes and seabed resources. It focused on coastal and continental shelf areas o f Newfoundland and eastern Canada. Diverse topics related to the various aspects of seabed geology were presented, including sedimentary basin analysis, modern sedimentary processes, Quaternary marine sedimentation, and reality of marine mining. The eclectic combination of lectures also covered geological significance of iceberg scouring of the seafloor, as well as environmentally sensitive issues of harvesting of shellfish and tracing provenance of seawater pollution in St. John’s Harbour. The following pages include abstracts, in alphabetical sequence, of the papers presented at the conference. The conference was jointly organised by the Newfoundland Section of the Geological Association of Canada and the Department of Earth Sciences, Memorial University of Newfoundland. Organising Committee, Geological Association of Canada - Newfoundland Section Tomasz Dec and Donald James Kelly Steinhauer and Derek Wilton Geological Survey Branch Department of Earth Sciences Department of Mines and Energy Memorial University of Newfoundland Atlantic Geology 30, 153-160 (1994) 0843-5 561/94/02015 3-8S2.20/0 154 Abstracts Exploring the wreck of the Titanic: seabed processes at 3800 metres in the North Atlantic S.M. Blasco Atlantic Geoscience Centre, Geological Survey o f Canada, Bedford Institute o f Oceanography, Dartmouth, Nova Scotia B2Y 4A2, Canada The wreck of the passenger liner Titanic lies in 3800 erentially deposited in the leeward areas of the decks. Sea m of water on the continental rise adjacent to the southeast bed sediments consist of surficial recent soft muds and sands, ern tip of the Grand Banks of Newfoundland. Sunk on her 10 to 15 cm thick, unconformably overlying dense friable maiden voyage 82 years ago, the Titanic represents a unique clays of infinite radiocarbon age. At the unconformity, ap time gauge by which to assess environmental processes ac proximately 20 m of the dense clays have been eroded since tive in the deep waters of the North Atlantic. Two Russian deposition. More resistant beds subcrop on the canyon floor Academy of Sciences ‘3 person’ MIR submersibles and the as 3 m high ridges or scarps covered with the recent soft research vessel Akademik Keldysh were contracted by IMAX muds. ‘Icicles’ of rust or rusticles hanging from the wreck Corporation in June 1991 to film a large format documen are frequently bent or curved by prevailing currents. Corro tary and to conduct a scientific investigation of the wreck sion appears to be controlled more by biological rather than site. Seventeen submersible dives averaging 14 hours in duration chemical processes. Fauna inhabiting the wreck site are more were completed. State-of-the-art broadcast quality video, 3-D abundant, with twice the diversity anticipated by biologists. video, IMAX 70 mm film, and wide angle still photographic Twenty-four species of invertebrates (crabs, shrimps, anemones, imagery of the wreck site were acquired. Bottom sediment sponges, starfish, corals, etc.) and four species of fish, in core samples and metal fragments were recovered by remote cluding large Grenadier or rat-tail fish, were observed. Met manipulators on the MIR 2 submersible. The wreck lies in allurgical analysis of a recovered hull plate fragment indi 2 pieces on the floor of Titanic Canyon. The intact bow and cates that the ship’s plating was brittle, suggesting that the badly damaged stern sections are separated by 600 m. Ini iceberg damage was more extensive than previously thought. tial findings suggest the seabed at 3800 m depth is more The scientific program was a joint project with the Russian environmentally active and dynamic than anticipated. Bot Academy of Sciences, CANMET, Petro-Canada, the National tom currents up to 1 knot were observed. Patches of active, Geographic Society, and the Geological Survey of Canada, wave generated symmetric sand ripples are located in close and was funded by IMAX Corporation and the Federal Pro proximity to the wreck and debris field. In response to cur gram on Energy Research and Development (PERD). rent action, a thin veneer of recent sediment is being pref Environmental impact of shallow water small-scale marine placer mining I.B. C larkl, L. Davis^ and W.J. Scott2 1 Department of Earth Sciences, Memorial University of Newfoundland, St. John’s, Newfoundland A IB 3X5, Canada 2Centre for Cold Ocean Resources Engineering (C-CORE), Memorial University o f Newfoundland, St. John’s, Newfoundland A IB 3X5, Canada A shallow water, small-scale marine placer gold min a conventional clamshell dredge. A multi-year monitoring ing test study is to take place this summer at Pine Cove, program will determine the physical, chemical and biologi Baie Verte, Newfoundland. Three mining methods will be cal environmental impacts associated with the mining op applied including a SCUBA diver assisted hydraulic dredge, erations. a remotely controlled crawler-mounted hydraulic dredge, and The mysterious disappearance of the Great Auk and Northern Cod: is the northwest Atlantic ecosystem in crisis? R.G. Coombs Department o f Fisheries, Government o f Newfoundland and Labrador, P.O. Box 8700, St. John's, Newfoundland A IB 4J6, Canada Contemporary scientific debate and investigation on the problem. A review of macroscopic indicators from a bio catastrophic decline of the Northern Cod stock is focusing logical and historical analysis of the fishery provides a simple on the purported instantaneous disappearance of approxi explanation of the events which is unpalatable to existing mately 500,000 metric tonnes of biomass on or about Feb fisheries epistemology. Historical catches of northern cod, ruary of 1992. This science is directed primarily at the in spawning stock biomass and retrospective Fo. l ’s can be used vestigation of environmental anomalies coincident with the to exhibit a decline of the Northern Cod Stock since 1960— decline. This presentation offers a cursory examination of a decline from which the stock has never been permitted to some of the suggested contributors to the current resource recover. crisis and proposes an alternate, more salient culprit to the Atlantic Geology 155 An overview of the surficial and shallow bedrock geology of the Grand Banks of Newfoundland G.B J. Fader and R.O. Miller Geological Survey of Canada, Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, Nova Scotia B2Y 4A2, Canada The Geological Survey of Canada has been involved in An area in Halibut Channel containing multiple tills the mapping and study of the Quaternary and shallow bed has been sampled with a series of boreholes. Geotechnical, rock geology of the Grand Banks of Newfoundland for the biostratigraphic, chronostratigraphic and seismostratigraphic past 20 years. This has resulted in the production of a suite analyses suggest that both early and late Wisconsinan ice of published maps and reports and a regional understand was extensive across the shelf south of Newfoundland. Ice ing of the geological history. domes may have formed during late Wisconsinan ice re Quaternary sediments are very thin on most of the off treat on the outer banks and were isolated from Newfound shore bank areas, overlying a monotonous sequence of shallow, land centered ice. seaward dipping, Tertiary strata. The present seabed sedi Recent studies on northern Grand Bank and the south ments were derived through reworking of previously depos ern part of the Northeast Newfoundland Shelf have revealed ited glacial materials during a post glacial sea level fall and a complex Quaternary stratigraphy with varying styles of subsequent Holocene marine transgression. Sediment transport glacial deposition: ( 1) a large ice stream with a floating front is widespread in depths shallower than 100 m, and the pre in Trinity Trough, and (2) a retreating ice sheet margin that dominant bedforms consist of sand ridges, sand ribbons, sand changed from a floating front to a tidewater front in shal waves, megaripples and ripples in gravel. Bedform orienta lower water. Till deltas, together with terraced and ribbed tions suggest sediment transport to the southwest. Sand ridges moraines, indicate a change in ice marginal conditions. Buried are the largest bedforms and are oriented more or less and open meltwater channels are interpreted as subglacial north-south. Their origin is not clearly understood. Some tunnel valleys. Some occur in a radiating pattern with the may in part be relict with cores of late Wisconsinan mo deposition of distal, 90 m thick, coarse morainal banks at rainal coarse sediment, while others may be modern fea the seaward end of the valleys, interpreted to have been de tures formed in response to infragravity waves. posited in a tidewater frontal environment. The timing and extent of glacial ice across the Grand A wide variety of other seabed and subsurface features Banks has been difficult to determine, as most of the glacial occur across the Grand Banks of Newfoundland and include sediments are buried beneath thick sand and gravel depos iceberg furrows and pits, megaflutes, pockmarks, gas-charged its, resulting in problems in sampling. Much of the glacial sediments,

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