INTERPRETING SEDIMENTS WORKSHOP: GLACIAL SEDIMENTS

Grahame J. Larson Traverse City, July 28 – August 1 , 2014

1 Extent of the last ice sheet

2 The 20,000 14C year old Gardena bryophyte bed, Sangamon Geosol (beneath shovel) at the Felts Section, north-central Illinois. [Image: L. Follmer] northern Illinois. [Image: B. Curry]

Sample of the 11,800 14C year old Cheboygan The 10,000 14C year old Lake Gribben buried forest, bryophyte bed, southern Michigan. [Image: G. Larson] northern Michigan. [Image: K. Pregitzer] 3 Extent of drift sheets in the mid-continent of North America. [Compiled from Ehlers and Gibbard 2004] 4 Comparison of time-distance diagrams for Illinois and the Lake Michigan basin (modified from Johnson et al. 1997) and the eastern and northern Great Lakes (Karrow et al. 2000).

5 Glacial Sedimentation in the Great Lakes Region

• Sediments deposited directly from ice

• Sediments deposited by meltwater

• Sediments deposited in glacial lakes

6 Sediments deposited directly from ice Till (definition from Bennett and Glasser, 2009)  sediment deposited by ice  has not been disaggregate  may have been subjected to some deformation, either subglacially or supraglacially  normally consists of pebbles, cobbles or boulders within a fine-grained matrix

Duck Lake Till, Peterson Park, Lower Michigan. [Image: K. Kincare] 7 Diamictons and tills Diamicton – is non-sorted or poorly sorted unconsolidated sediment of no assumed genisis and that contains a wide range of particle sizes Examples: Debris-flow deposits – deposited by mass movement on land Turbidites – deposited by turbidity currents in water Tills - deposited by glacier ice All tills are diamictons but not all dimictons are tills

Death Valley debris-flow deposit. [Image: Tim Cope] Northern Maine till. [Image: G. Larson] 8 TilliteS - assumed to be the lithified equivalents of glacial till

Michigan puddingstone. Precambrian in age. Gowgonda tillite. Precambrian in age. Origin is Origin is Lorrain located 30-40 miles southern Ontario. [Image: J. Dexter] southeast of Sault Sainte Marie, Ontario.

9 Till depositional domains Subglacial tills Deposited by direct lodgement Deposited by subglacial melting Deposited by cavity deposition Formed from subglacial deformation Supraglacial tills Deposited by supraglacial melting

Schematic showing till depositional domains of a glacier

10 Subglacial till - deposition by direct lodgement  Melting by geothermal heat and heat from sliding brings englacial debris particles in contact with the glacier substrate.  Friction results in reduced particle velocity and ice flow around particles.  Particles will lodge into the substrate when their forward velocity is reduced to zero.  Deposition may be assisted by plowing into a soft substrate, jamming against lodged particles, and lodgement of a debris-rich ice mass.

Path taken by a particle when melting is Schematic showing a clast flowing (ploughing) occurring at the bed of a flowing glacier. [Image: into a soft substrate. [Image: G. Larson] modified from Sudgen and John (1976)] 11 Deposition by direct lodgement  Melting by geothermal heat and heat from sliding brings englacial debris particles in contact with the glacier substrate.  Friction results in reduced particle velocity and ice flow around particles.  Particles will lodge into the substrate when their forward velocity is reduced to zero.  Deposition may be assisted by plowing into a soft substrate, jamming against lodged particles, and lodgement of a debris-rich ice mass.

Example of jamming against lodge particles. Example of lodgement of a debris-rich ice mass. [Image: G. Larson] [Image: modified from Boulton (1982)]. 12 Characteristics of till deposited by lodgment  Particle packing – dense, well consolidated  Particle lithology – dominated by local rock types  Particle size – either bimodal or multimodal  Particle shape – rounded edges, Lodgement till, Sólheimajökull forefield, Iceland. striated and faceted, some bullet [Image: Ó. Ingólfsson] shaped  Particle fabric – elongated particles have strong fabric aligned to ice flow  Structure – massive and generally matrix supported; structureless; well developed shear planes, boulder Schematic showing shear structures in clusters or pavement; may include lodgement till. [Image: modified from Boulton some channel deposits (1970)]

13 Subglacial till - deposition by subglacial melting  Ice containing debris moves slowly or becomes stagnant.  Melting at glacier bed by geothermal heat brings debris particles in contact with the glacier substrate.  Particles are released by melting and accumulate on the glacier substrate.

Schematic showing path taken by a particle when melting is occurring at the bed of stagnant ice. [image: G. Larson]

14 Characteristics of till deposited by subglacial meltout  Particle packing – dense, consolidated, but less so than by the lodgement process because of no basal shear stress and generally thinner ice  Particle lithology – dominated by local rock types but may show inverse superposition  Particle size – either bimodal or multimodal, some fines may be removed by winnowing Basal meltout till (?) from Minnesota. [Image:  Particle shape – rounded edges, striated and M. Johnson] faceted  Particle fabric – elongated particles have strong fabric aligned to ice flow, but generally with a greater range of orientation and less inclination than that typical of lodgement process  Structure – usually massive and matrix supported; crude-to-well developed relic stratification may be present; no evidence of primary shearing , boulder clusters or Schematic showing subglacial deposition by pavements may be present; may include meltout. some channel deposits; subsequent modification due to flowage 15 Subglacial till - deposition in a subglacial cavity (rare in lower Michigan)  Cavities can form where glacier ice flows over bedrock obstructions, especially where the ice is thin and fast moving .  Debris at the glacier bed can enter into a cavity as debris-rich ice “curles”, fine slurry from the ice-rock interface, melting from the glacier sole and clast expulsion.

Cavity till deposition, Casement Glacier, Alaska. [Image: G. McKenzie] 16 Characteristics of till in a subglacial cavity Particle packing – dense to loosely packed Particle lithology – dominated by local rock types Particle size – either bimodal or multimodal Particle shape – rounded edges, striated and faceted Particle fabric - elongated particles have poor to strong fabric Structure – usually massive and matrix supported

Till “curles”, Casement Glacier, Alaska. [Image: G. McKenzie]

17 Subglacial till - “deposition” from subglacial deformation  High water pressure develops in pores of unfrozen sediments beneath the glacier sole reducing the resistance between individual grains.  The sediment develops characteristics of a slurry-like mass that flows in response to shear stress imposed by the overriding glacier.

Schematic showing deformation of till beneath ice Sediment deformation beneath Breidamerkurjokull, stream B, West Antarctica. [Image modified from Iceland. [Image: modified from Boulton and Alley et al. (1986)] Hindmarsh (1987)]

18 Subglacial till - “Deposition” from subglacial deformation  Deformation can occur by pervasive (ductile deformation) or discrete shear (brittle deformation).  Rate of deformation will vary spatially and temporally (sticky Glaciotectonized Kara Diamicton. Yamal, spots). Russia1997 (reversed);  Accumulation of sediment will http://www3.hi.is/~oi/siberia_photos.htm occur if more sediment is advected into an area than out (compressive flow).  Downcutting and assimilation of new sediment will occur if more sediment is advected out

of an area than in (extentional Deforming bed, Bering Glacier, Alaska. flow). [Image: G. Larson] 19 Different levels of subglacial deformation. [Modified from Hart and Boulton (1991)]

20 Charcteristics of a deforming bed  Particle packing – dense, consolidated  Particle lithology – diverse range of lithologies reflecting that of original sediments  Particle size – diverse range of sizes reflecting that found in original sediment; may contain rafts of original sediment A deformation till (?), Netherlands. [Image: G.  Particle shape – dominated by Larson] original sediment that is being deformed  Particle fabric – Poor elongated clast fabric if pervasively sheared, strong if discretely sheared  Structure – usually massive and

matrix supported; structureless if Schematic showing formation of a deformation pervasively sheared, folded, thrusted till. [Image: G. Larson] if discretely sheared 21 A reassessment of subglacial till types  It is now generally recognized that subglacial tills owe their origin to a combination of sedimentary processes, of which deformation dominates.  Many of the micro and macromorphological characteristics of subglacial tills are similar to those of a fault gauge.  It is therefore best to interpret the Fault gauge in the Gharif formation of Northern Oman. [Image: Wouter van origin of subglacial tills in a tectonic der Zee] framework.

22 Till Domains Subglacial tills Deposited by direct lodgement Deposited by subglacial melting Deposited by cavity deposition Formed from subglacial deformation Supraglacial tills Deposited by supraglacial melting

Till depositional domains of a glacier 23 Supraglacial till – Deposited by supraglacial melting  Melting at the glacier surface releases debris within the ice, either at a high level or near the bed of a glacier.  Left undisturbed the debris Schematic showing formation of supraglacial accumulates at the glacier meltout debris surface forming a debris mantle.

Supraglacial meltout debris, Casement Glacier, Alaska. [Image: G. McKenzie]

24 Characteristics of till deposited by supraglacial melting  Particle packing – poorly consolidated  Particle lithology – variable, may include far-travelled rock types  Particle size – either bimodal or multimodal, some fines may be removed by winnowing Supraglacial meltout till, Matanuska Glacier,  Particle shape – angular, unstriated Alaska. [Image: G. Larson] when debris derived from a high level; rounded edges, striated and faceted when debris derived from near ice base  Particle fabric - elongated particles have poor to strong fabric  Structure – crude to well developed

bedding Schematic showing formation of supraglacial meltout till. [Image: G. Larson] 25 Supraglacial debris-flow deposits  Rarely is supraglacial till preserved in the geologic record.  Variations in thickness of accumulating debris causes variations in insulation of the ice and leads to an uneven ice-surface topography.  Debris over ice topographic highs slumps or flows and is redistributed to topographic lows.  Resedimentation by slump and debris flow occurs multiple times as the ice surface melts eventually

leaving an irregular chaotic Progressive development of supraglacial debris-flow deposits with down-wasting of landscape. buried ice. [Modified from Eyles (1979)]

26 Landscape dominated by debris-flow deposits, Matanuska Glacier, Alaska. [Image: G. Larson]

27 BREAK TIME

NNW/SSE-trending 5 miles south of Charlevoix, MI. [Image: L. Maher]

28 Characteristics of drumlins  Smooth, oval-shaped or elliptical hills of glacial origin  Between 5 and 50 m high and 10-3000 m long  Length to width ratio of <50  Proximal slope usually steeper than distal slope  Tend to occur in multiples or “swarms”  Composed of till, bedrock, deformed mixtures of till, and gravel and undeformed beds of sand and gravel

Large fields in the Great Lakes region. [Image: R. Schaetzl} 29 Theories for the Origin of Drumlins  Subglacial deformation (Boulton, 1987) – Two zones of enhanced sediment flow either side of a slowly deforming obstacle and a zone of slower flow in its lee produces a sheath of “soft” sediment around the obstacle.  Subglacial meltwater (Shaw, 1994) – Inverted erosional marks at the ice bed formed during a subglacial outburst flood are infilled with deposits of sand and gravel that are subsequently capped by a deforming bed.

Drumlin field. Manitoba, Canada. [Image: nsidc.org] 30 Sediments deposited from meltwater Subglacial deposits Esker (channel fill) deposits Ice-marginal Kame terrace deposits Outwash deposits (fluvial)

Development of an outwash deposit. [Image: modified from L. Benítez] Development of kame, kame terrace and esker deposits. [Image: (1971)) 31 Characteristics of kame deposits  Formed within an ice-walled channel or depression in stagnant ice  Composed of poorly to well sorted stratified sand and gravel; may include lacustrine sediments, debris-flow deposits and boulders  Rapid lateral variations in grain size  Margins cut by normal Typical sedimentary structures found in . [Image: modified from Boulton (extensional) faults; bedding often (1972)] deformed by subsidence of buried ice  Can vary in shape from “mound- like” to “flat-topped”  Can occur singularly or in groups Kame in lower Michigan. [Image: G. Larson] 32 Characteristics of esker deposits  Formed subglacially or englacially within an ice-walled tunnel or supraglacially within an ice channel  Can be <1 to hundreds of kilometers long  Composed of well rounded cross- Englacial esker melting out of ice, Burroughs bedded sand and gravel; may Glacier, Alaska. [Image: G. Larson] include lacustrine sediments, ‘till balls’ and boulders  Flanks cut by normal (extensional) faults; bedding sometimes deformed by subsidence of buried ice  Can be single-ridged, braided, or beaded Blue Ridge esker, Michigan. [Image: G. Larson] 33 Characteristics of kame terrace deposits  Formed between the ice margin and a topographic restraint  Composed of poorly to well sorted stratified sand and gravel; may include lacustrine sediments, debris-flow deposits and boulders  Proximal margins cut by normal Formation and diversity of kame terraces (extensional) faults; bedding often deformed by subsidence of buried ice  Can include holes, particularly near proximal margin  Can form multilevel surfaces Kame terraces, Breidarmerkuljökull, Iceland. [Image: G. Larson]

34 Development of an outwash plain  Outwash fans build up in front of relatively stationary ice margins with the apex of each fan located near where meltwater emerges from the ice.  Coarse material is deposited close to the meltwater source and finer material is deposited further downstream.  Outwash fans along an ice margin may Schematic showing the formation and merge away from the glacier to form a development of a simple outwash fan. large outwash plain drained by a braided [Image: modified from Bennett and Glasser river system. (2009)]  Discharge in the braided river system will greatly vary both daily and seasonally and result in erosional and depositional cycles.  The final surface morphology of an outwash plain will depend on the amount

of buried ice and supply of sediment. Outwash plain (sandur), Skeidararjökull, Iceland. [Inage: G. Larson] 35 Characteristics of an outwash deposit  Proximal – mainly multistorey, massive or crudely bedded gravel with imbrication; associated with longitudinal bars and lag deposits in gravel-dominated steams  Medial – mainly horizontally bedded massive gravel to pebbly sand; associated with linguoid or lobate bars in gravel-sand dominated streams  Distal – mainly horizontally bedded sand to silt; associated with poorly differentiated channels and bars in sand-silt dominated streams

Facies of an outwash deposit. [Image: Zielinski and van Loon (2003)] 36 Facies of an Outwash Depsit

Proximal Medial Distal

Medial outwash, Warham, Distal outwash, Warham, . [Image: G. Larson] Massachusetts. [Image: G. Larson]

Proximal outwash, Kalamazoo, Michigan. [Image: G. Larson]

37 Sediments deposited in glacial lakes  Grounded glacier – deposition by a combination of meltout, lodgement and deformation  Floating ice margin – deposited within a water body

Ice-marginal lake, southeast Alaska. [Image: G. Larson]

38 Sedimentary processes associated with a grounded glacier  Direct deposition by meltwater currents  Settling from suspension  Resedimentation from gravity flows  ‘Rain-out ‘ by icebergs  Current reworking

Middle to distal subaqueous grounding-line fan deposit, Champlain Valley, NY. [Image: L. Gillett]

Schematic representation of a grounding line fan. [Image: R. Powell (1990)]

39 Development of a kame delta  Forests- formed from sediment avalanches down the delta front  Bottomsets – formed by fine-grained sediment flows in the prodelta environment  Topsets – formed from fluvial deposition on delta

surface Kame delta, Mohawk Valley, New York [Image: G. Larson]

Schematic representation of kame delta. [Image: Gilbert style delta Bennett and Glasser (2009)]

40 Sedimentary processes in a water body  ‘Rain out’ from icebergs  Settling from suspension  Subaqueous resedimentation by gravity flows  Current reworking  Sediments can be very varied

Glaciolacustrine sediments, Glacier Bay, Alaska. [Image: G. Larson]

Model of glaciolacustrinesedimentary processes. Image: modified from Eyles (1984)] 41 Stop4

Stop 3

Stop 2 Stop 1 Traverse City

Glacial geomorphic map of Grand Traverse Bay region. [Image: modified from Lundstrom et al. (2003)] 42 Glacial geomorphic map of Grand Traverse Bay region. [Image: Lundstrom et al. (2003)] 43

Hotel

Field trip stops for interpreting sediments workshop, August 16, 2010

44 Selected References:

Alley, R.B., Blankenship, D.D.,Bently, C.R. & Ronney, S.T. (1986). Deformation of till beneath ice stream B, West Antactica. Nature, 322, 57-9. Boulton, G.S. (1970). On the deposition of subglacial and melt-out tills at the margin of certain Svalbard . Journal of , 9, 231-245. Boulton, G.S. (1972). Modern Arctic glaciers as depositional models for former ice sheets. Journal of the Geological Society of London, 128, 361-393. Boulton, G.S. (1982). Subglacial processes and the development of glacial bedforms. In Davidson- Arnott, R., Nicking, W. & Fahey, B.D. (eds), Research in Glacio-fluvial and Glaciolacustrine Systems, Geo Books, Norwich, 1-31. Boulton, G.S. (1987). A theory of drumlin formation by subglacial sediment deformation. In Menzies, J. & Rose, J. (eds), Drumlin Symposium, Balkema, Rotterdam, 25-80. Boulton, G.S. & Hindmarsh, R.C.A. (1987). Sediment deformation beneath glaciers: rheology and geological consequences. Journal of Geophysical Research, 92, 9059-82. Bennett, M.R. & Glasser, N.F. (2009). Glacial Geology: Ice Sheets and . Wiley-Blackwell, 385 p. Eyles, N. (1979). Facies of supraglacial sedimentation on Icelandic and Alpine temperate glaciers. Canadian Journal of Earth Sciences, 16, 1341-1361. Ehlers, J. & Gibbard, P.L. (2004). Quaternary Glaciations – Extent and Chronology, Part II. Elsevier, 488 p. Flint, J.F. (1971). Glacial and Quaternary Geology. John Wiley & Sons, 892 p. Hart, J.K. & Boulton, G.S. (1991). The inter-relation of glaciotectonic and glaciodepositional processes within the glacial environment. Quaternary Science Reviews, 10, 335-350. Lundstrom, S., Kincare K.A., Grannemann, N.G., Yancho, S., Passino-Reader, D.R., Van Sistine, D.P., & Havens, J.C. (2003). Quaternary geologic framework of the Grand Traverse Bay region, Michigan: relationships to water, land, and ecological resources. Geological Society of America Abstracts with Programs, 35, 67 Shaw, J., (1994). A qualitative view of sub-ice-sheet landscape evolution. Progress in Physical Geography, 18, 159-84. 45 Sudgen, D.E. & John, B.S. (1976). Glaciers and Landscape. John Wiley and Sons, New York, 376 p.