PINGOSPINGOS

Jennifer VinckJennifer Vinck

Geology 495Geology 495

University of Regina, 2006University of Regina, 2006

To be discussed:To be discussed:• What is a pingo?What is a pingo?

• DistributionDistribution

• Pingo FeaturesPingo Features

• Pingo Growth and DevelopmentPingo Growth and Development

- Hydrostatic (closed) System- Hydrostatic (closed) System

- Hydraulic (open) system- Hydraulic (open) system

• Case Study: Ibyuk Pingo,Tuktoyaktuk Case Study: Ibyuk Pingo,Tuktoyaktuk

• Current Research Current Research

PingosPingos

• Inuit term Inuit term pinguryuaqpinguryuaq meaning “hill”meaning “hill”

• Ice cored, conical Ice cored, conical mounds and hillsmounds and hills

• Periglacial environments: Periglacial environments: permafrost ground stays permafrost ground stays below 0below 0°C for at least 2 °C for at least 2 yearsyears

• Size varies: 10-70m high, Size varies: 10-70m high, 20-400m diameter20-400m diameter

• Result from preferential Result from preferential migration of watermigration of water

• 25 - >1000 years old25 - >1000 years old

Pingo in the Canadian Arcticsource: http://www.mbari.org/news/news_releases/2003/paull_images/pingo1_350.jpg

Global distributionGlobal distribution• ~5000 worldwide~5000 worldwide• 25% of these are 25% of these are

found in Mackenzie found in Mackenzie Delta – Tuktoyaktuk Delta – Tuktoyaktuk PeninsulaPeninsula

• Other locations: Other locations: Yukon, Alaska, Yukon, Alaska, Siberia, Spitsbergen Siberia, Spitsbergen (Norway), Greenland(Norway), Greenland

• Occur in drained lake Occur in drained lake basins, or former basins, or former fluvial channelsfluvial channels

• ~200 undersea ~200 undersea pingos mapped in pingos mapped in submarine submarine permafrost of permafrost of Beaufort SeaBeaufort Sea Source: Mackay, 1962

Pingo FeaturesPingo Features

Source: Source: http://www.thecanadianencyclopedia.com/index.cfm?http://www.thecanadianencyclopedia.com/index.cfm?PgNm=TCE&Params=A1SEC826257PgNm=TCE&Params=A1SEC826257

•Pingos grow upward from the base as the ice core expands

•Cover/Overburden of vegetation and soil similar to surrounding area

•Dilation and Radial cracks induced by growth of the summit and base

•Cracks may form trenches, gullies, craters, and fractures

Hydrostatic (Closed) System Hydrostatic (Closed) System PingosPingos

• Lake underlain by talik: Lake underlain by talik: unfrozen ground/sediments unfrozen ground/sediments in permafrostin permafrost

• Lake is drained, bottom is Lake is drained, bottom is exposed to cold air temps.exposed to cold air temps.

• Permafrost Permafrost aggrades/advancesaggrades/advances

• Unfrozen ground water Unfrozen ground water within the talik experiences within the talik experiences hydrostatic pressurehydrostatic pressure

• Pressures force water to Pressures force water to move upward and laterally move upward and laterally to where it is forced toward to where it is forced toward the ground surface. the ground surface.

• As the water approaches As the water approaches the surface, it freezes and the surface, it freezes and forms a conical, ice-cored forms a conical, ice-cored hill; a pingo. hill; a pingo.

Source: British Geomorphological Research Group, www.bgrg.org/

Hydrostatic (Closed) System Hydrostatic (Closed) System PingosPingos

• Larger, isolated pingosLarger, isolated pingos

• Mackenzie DeltaMackenzie Delta

• Derive water pressure Derive water pressure from pore water from pore water expulsion within talik expulsion within talik (maintains form of the (maintains form of the pingo)pingo)

• Confined to zones of Confined to zones of continuous permafrostcontinuous permafrost

Source: British Geomorphological Research Group, www.bgrg.org/

Source: Mackay, 1998

•Cross Sectional View of a Hydrostatic Pingo

Hydraulic (Open) System Hydraulic (Open) System PingosPingos

• Common in Alaska, the Common in Alaska, the Yukon, Greenland, and Yukon, Greenland, and Spitsbergen, areas of Spitsbergen, areas of discontinuous permafrostdiscontinuous permafrost

• Requires flowing water Requires flowing water beneath permafrostbeneath permafrost

• May form on sloping May form on sloping terrain, which sets up terrain, which sets up hydrostatic gradienthydrostatic gradient

• Water beneath or within Water beneath or within permafrost is under high permafrost is under high pressurepressure

• Water under pressure Water under pressure forces its way towards forces its way towards the surface the surface

• As it freezes, doming As it freezes, doming occurs, pingo formsoccurs, pingo forms

Source: British Geomorphological Research Group, www.bgrg.org/

Pingo Age DataPingo Age Data•Radiometric data shows N.A. pingos are approx. 4000-7000 years old

•Timing of climatic conditions can be obtained from pingo ice

•Seasonal growth bands within the ice core record climate changes

•Radiocarbon dating of organic material in overburden

•Changes in vegetation cover may record recent climate change

Source: Source: http://www.hi.is/~oi/quaternary_geology.htm http://gsc.nrcan.gc.ca/beaufort/pingos_e.php http://gsc.nrcan.gc.ca/beaufort/pingos_e.php

Pingo CollapsePingo Collapse

• Ground stretches to Ground stretches to accommodate pingo accommodate pingo growthgrowth

• Dilation cracks form in Dilation cracks form in Tundra near the summit, Tundra near the summit, can create a cratercan create a crater

• Water collected in the Water collected in the crater may melt the ice crater may melt the ice corecore

• Or, the steep slopes Or, the steep slopes erode, exposing the core erode, exposing the core to sunlight, which leads to to sunlight, which leads to melting of the ice core melting of the ice core and pingo collapseand pingo collapse

Source: Parks Canada, 1988

www.pc.gc.ca/docs/v-g/ pingo/sec3/natcul1_e.asp

Collapsed Pingo

Pingo Collapse – 3 FactorsPingo Collapse – 3 Factors

• Mass WastingMass Wasting

- - slumping of overburdenslumping of overburden

• Wave ErosionWave Erosion

- - storm surges/tides storm surges/tides erode slopeserode slopes

• Thermokarst effectsThermokarst effects- Exposure of ice core to - Exposure of ice core to

warmer temps = warmer temps = greater risk for greater risk for collapsecollapse

Case Study – Ibyuk Pingo, Case Study – Ibyuk Pingo, TuktoyaktukTuktoyaktuk

Source: http://www.pwnhc.ca/inuvialuit/placenames/ibyukwhat.html

Case Study - IbyukCase Study - Ibyuk

• The presence of The presence of numerous lakes in numerous lakes in the Tuktoyaktuk the Tuktoyaktuk Peninsula may Peninsula may explain the explain the abundance of abundance of pingospingos

• Pingo Canadian Pingo Canadian Landmark protects Landmark protects 8 pingos in the area 8 pingos in the area around Tuktoyaktukaround Tuktoyaktuk

Source: Mackay (1998)

Ibyuk Pingo – Hydrostatic Ibyuk Pingo – Hydrostatic (Closed) (Closed)

Cross Sectional View of Ibyuk PingoSource: Mackay, 1998

Profile View of Ibyuk Pingo

Current ResearchCurrent Research

• Marine Geophysical Research• Gas-hydrates are a potential source of clean

burning natural gas• Paull and Ussler, 2003

- Studied submarine pingos for methane gas-hydrate content- found gas in cores of sediments from pingos

• Clough, 2004- Studied pingos along fault zones in Alaska for methane “gas seeps”

• Mechanisms for entrapment/extraction of gas-hydrates in pingo-like features still poorly understood

The The EndEnd