1 GlacialGlacial Processes,Processes, Ice-FlowIce-Flow IndicatorsIndicators andand RemoteRemote PredictivePredictive MappingMapping ApplicationsApplications toto DriftDrift ProspectingProspecting RogerRoger C.C. PaulenPaulen GeologicalGeological SurveySurvey ofof CanadaCanada WhyWhy StudyStudy GlacialGlacial Processes?Processes? • Basic principles of glaciers • Glacial erosion • Glacial transport • Glacial deposition Photo: R. Paulen Extent of glaciers during the last glacial event. LGM: 18k – 20k 14C years BP (Late Wisconsin) Older and more extensive glaciations dating to the Quaternary period (last 2.6 Ma) ContinentalContinental IceIce SheetSheet Glaciated vs. unglaciated regions GLACIATED UNGLACIATED Soils developed to a Soils can developed depth of about 1 m to depth in excess of several meters (regolith) (Shilts, in Menzies, 1995) Glaciated vs. unglaciated regions GLACIATED UNGLACIATED Enrichment in Enrichment of bedrock: dispersed element or mineral by glacial processes generally confined to the bedrock source, unless remobilized by fluvial, eolian, or chemical processes. Glaciated vs. unglaciated regions GLACIATED UNGLACIATED • Dispersal patterns • Dispersal confined not confined to a to a drainage basin drainage basin except in mountainous regions with valley glaciers Glaciated vs. unglaciated regions GLACIATED UNGLACIATED • Minerals of different • More likely to have origins can be minerals of a single intermixed in glacial source sediments (e.g. ultramafic and granitic) Accumulation zone Ablation zone IceIce DynamicsDynamics GlacialGlacial FlowFlow ModelModel Glacier flow dependant on mass balance gradient: mass balance transferred from accumulation wedge to flow wedge BasicBasic VariablesVariables Topography Basal substrate Ice and basal water (Sugden and John 1976, p. 41) Equilibrium line Photo: R. Paulen Accumulation zone Equilibrium line Ablation zone Photo: R. Paulen IceIce flowflow Basal sliding Internal deformation Glacial bed deformation IceIce DynamicsDynamics Shield Three Mechanisms Basal Sliding Ice Centre Internal Deformation Subglacial Bed Deformation and Decoupling Plains (Bennett(Bennett andand GlasserGlasser 1996,1996, p.p. 43)43) WarmWarm--basedbased iceice (erosional) Photo: I. McMartin ColdCold--basedbased iceice (protective) Photo: I. McMartin EROSION MechanismsMechanisms AbrasionAbrasion PluckingPlucking MeltwaterMeltwater Photo: I. McMartin TRANSPORT (Boulton 1996) basal & englacial sediment transport Photo: B. Shilts DEPOSITION Till: implies genesis, sediment type directly deposited by ice; non-sorted. Diamicton: textural term, poorly to non-sorted sediment, just like till, but not necessarily deposited by ice. Deposition by: lodgement, meltout, deformation, sublimation, and more…. (Boulton 1996) DepositionDeposition LodgementLodgement ProcessProcess (Benn and Evans 1998, p. 198) DepositionDeposition isis rarelyrarely straightforward,straightforward, severalseveral variationsvariations cancan existsexists atat aa singlesingle location.location. Friction at the base of glacier >>>> force of traction Photo: R. Paulen basal till Photo: B. Shilts basal till Photo: A. Plouffe DeformingDeforming BedBed (Bennett(Bennett andand GlasserGlasser 1996, 1996, p.p. 42)42) VariablesVariables Basal Contact Pressure Ice Velocity Substrate Lithology Basal Debris: “Tools of Erosion” (Kjær et al., 2006) Ablation till (meltout) Till deposited because of the melting of ice (Eyles,(Eyles, 1979)1979) ablation till Photo: R. Paulen ablation till basal till Photo: R. Paulen WaterlainWaterlain Photo: R. Paulen Till but also: • Glaciofluvial sediments • Glacial lake sediments • Glaciomarine sediments Glacier 34 Till Debris Flow Silt and Clay Gravel Plane Bedding Channel with Cross Bedding Massive Sand Cross Lamination with Ball and Pillow Structure (From Shaw, 1985) (modified from Sugden and John, 1976) Ice-FlowIce-Flow IndicatorsIndicators ObjectiveObjective:: tracetrace anan indicatorindicator toto itsits sourcesource •• RecognizeRecognize iceice--flowflow indicatorsindicators •• ReconstructReconstruct iceice--flowflow historyhistory •• IdentifyIdentify dispersaldispersal trainstrains (Paulen et al., 2006) TypesTypes ofof iceice--flowflow indicatorsindicators Depositional • drumlin ridges Erosional • fluted till plain • roches moutonnées • till clast fabric • whalebacks • dispersal train • rock drumlins Combined • flutings • crag-and-tail • glacial grooves • ice-thrust ridges • striations • hill-hole pair • bullet-shaped boulders • boulder pavements LandformsLandforms • Oriented landforms visible on topographic and geological maps and air photographs • Morphology strongly influenced by bedrock topography • Typically occur in groups, showing a characteristic pattern on maps and air photographs • Accentuated by vegetation and drainage • Provides a general regional impression of flow directions DrumlinizedDrumlinized plateau,plateau, PrincePrince GeorgeGeorge area,area, BCBC ice flow From Clague, 1989. (Paulen, in prep) OverprintingOverprinting ofof landformslandforms ice flow older younger OverprintingOverprinting ofof landformslandforms ice flow bedrock structure Photo: R. Paulen CragCrag andand tailtail ice flow Photo: R. Paulen Double crag-and-tail landform, Princess Mary Lake, Nunavut younger older Photo: I. McMarten Rogen moraines, Schultz Lake, Nunavut (McMarten & Paulen, 2009) ice flow 1 km (Paulen, in prep) Flutings and ice-thrust ridges, Pearless Highlands, Alberta ice flow McMartin and Paulen, 2009 Roche moutonnée, Fisher Bay, northern Québec ice flow Photo: I. McMarten SmallSmall--scalescale erosionalerosional formsforms • striations • rat tails and mini crag-and-tails • crescentic fractures and gouges • nailhead striae • stoss-and-lee topography ice flow (McMarten & Paulen, 2009) Ashley et al. (1985) Striations: • erosional marks on bedrock surface made by sole of glacier • most convenient and reliable means of determining ice-flow trends ice flow Photo: I. McMarten RatRat tailstails ((erosionalerosional shadows)shadows) tail ice flow ice flow crag Photos: I. McMarten GroovesGrooves ice flow Photo: R. Paulen ice flow Photo: R. Paulen ice flow Photo: R. Paulen ice flow Photo: R. Paulen ice flow Photo: R. Paulen CrescenticCrescentic fracturesfractures younger older ice flow CrescenticCrescentic gougesgouges ice flow Photo: R. Paulen CrescenticCrescenticNailheadNailhead striaegougesstriaegouges ice flow Photo: I. McMarten NailheadNailhead striaestriae ice flow Photo: R. Paulen MultiMulti--directionaldirectional indicatorsindicators older older younger younger Photo: I. McMarten MultiMulti--directionaldirectional indicatorsindicators 61 older younger Photo: R. Paulen MultiMulti--directionaldirectional indicators??indicators?? ice flow glaciomarine iceberg grounding Photo: R. Paulen MultiMulti--directionaldirectional indicators??indicators?? 63 lake ice grounding ice flow Photo: R. Paulen NoNo bedrock?bedrock? Striations on boulder pavements • One clast thick • Clasts separated by • Enclosing sediment (diamicton) • Tops of boulders are flat and striated • Striations on upper surfaces Photos: R. Paulen Photos: R. Paulen TillTill FabricFabric Strike and dip Horizontal surface… McMartin and Paulen, 2009 •• Measure Measure clastclast orientationsorientations inin lodgmelodgmentnt till,till, inin C-horizonC-horizon soilsoil (>1(>1 mm depth)depth) •• Elongated Elongated (prolate)(prolate) clasts,clasts, minimumminimum ofof 5050 measurementsmeasurements •• Can Can bebe conductedconducted atat thethe exactexact sitesite ofof indicatorindicator mineralmineral samplesample •• Not Not recommendedrecommended inin permafrostpermafrost terrainterrain (Paulen et al., 2005) younger ice flow older ice flow McMartin et al., 2006 NoNo bedrock?bedrock? Bullet-shaped boulders ice flow ice flow Photos: R. Paulen McMartin and Paulen, 2009 McMartin and Paulen, 2009 •• Asymmetric Asymmetric stoss-and-leestoss-and-lee formform withwith smoothedsmoothed upglacierupglacier (stoss) (stoss) sideside andand fracturedfractured down-glacierdown-glacier (lee)(lee) side;side; gentlegentle up-glacierup-glacier imbricationimbrication •• Measure Measure orientationsorientations ofof boulderboulder andand striationsstriations onon upperupper surfacesurface (McClenaghan and Kjarsgaard, 2007) IceIce--flowflow reconstructionreconstruction Veillette and McClenaghan, 1996 (McMartin and Henderson, 2004) IceIce--flowflow reconstructionreconstruction Veillette and McClenaghan, 1996 (Tremblay et al., 2007) IceIce--flowflow reconstructionreconstruction Veillette and McClenaghan, 1996 BC Southern Interior (Paulen, 2001) IceIce--flowflow reconstructionreconstruction Veillette and McClenaghan, 1996 (Paulen, 2009) IceIce--flowflow reconstructionreconstruction BC Rocky Mountains (Paulen & Bobrowsky, 2003) Veillette and McClenaghan, 1996 (Paulen, 2009) IceIce StreamsStreams 74 KIM Palimpsest Dispersal Train, Nunavut (Stea et al., 2009) NewNew ppublicationublication forfor additionaladditional InformationInformation (late(late 2009)2009) SummarySummary ofof IceIce--FlowFlow IndicatorsIndicators inin newnew PublicationPublication (McMartin & Paulen) REFERENCESREFERENCES Benn, D.I and Evans, D.J.A. 1998. Glaciers and Glaciation. Arnold, London, 734 p. Bennett, M. R. and Glasser, N.F. 1996. Glacial Geology: Ice Sheets and Landforms. John Wiley & Sons Ltd., 364 p. Boulton, G.S. 1996. Theory of glacial erosion, transport and deposition as a consequence of subglacial sediment deformation. Journal of Glaciology 42: 43-62. Clague, J.J. 1989. Quaternary Geology