GEOL 4010 QUATERNARY GEOLOGY Instructor: Dr' Hester Jiskoot

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GEOL 4010QUATERNARY GEOLOGYInstructor Dr.
Hester Jiskoot
LECTURE 4
QUATERNARY ICE AGES
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CAUSES OF CENOZOIC ICE AGES (LAST 65 MILLION YRS)

• Himalayan uplift started 40 million y BP
• ? Reduction of atmospheric CO2
• ? Onset monsoons
• 1st Antarctic ice cap at 33 million y BP
• ? permanent at 16 million y BP
• Arctic ice cap appears 2.5 million y BP, due
  to
• closure of Isthmus of Panama
• changed oceanic circulation
• ? Once ice caps formed, controlled by
  Milankovitch cycles

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MILANKOVITCH CYCLES GLACIATION
Cyclic variations in the Earth's eccentricity
axial tilt precession
Milankovitch Cycles variations in seasonality,
location and amount of solar energy on Earth
? contrasts between the seasons
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eccentricity
aphelion
perihelion
0 to 5 ellipticity ?(aphelion-perihelion)
At present 3 Variations in distance
Sun-Earth Variations in amount of solar
radiation
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axial tilt
At present 23.5 tilt The more tilt the more
seasonal variations Ice Ages would occur when
there is little tilt TSummer low PWinter
high
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Precession of the equinoxes
at present
in 5250 yrs
in 10500 yrs
Effective when combined with eccentricity 15
variation in radiation at high latitudes
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MILANKOVITCH CYCLES
www.museum.state.il.us/exhibits/ice_ages/
100000 yrs
22000 yrs
41000 yrs
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ICE AGE CYCLES
www.museum.state.il.us/exhibits/ice_ages/
Wisc.
Illinoian.
? Pre-Illinoian ?
G glaciations in midwest USA
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ICE AGE PERIODICITY
Glacial Period 100000 years Interglacial
period 10000 years
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DOWN TO EARTH AGAIN.
So. Several Cold Periods in the last 2.5
My How can we reconstruct these from geologic
evidence?
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STRATIGRAPHY
Stratigraphy Study of layered rocks/deposits
within a chronostratigraphic framework Strata
Layers stratification bedding stratum
sedimentary unit of relatively uniform
composition, ? separated by discontinuities in
lithological composition, structure or texture.
Stratigraphic discontinuities visible from
gradual or abrupt changes in colour, hardness,
structure, erosion lag, dielectric properties,
etc.
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ASSUMPTIONS IN STRATIGRAPHY

• Original Horizontality (sedimentary layering)
• Superposition (young over old)
• Cross-Cutting Relationships (intrusions, faults)
• Unconformities (buried erosion surfaces)
• Correlation (lateral continuity, facies setting)

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(Lithostrati-) GRAPHIC LOGGING
15 m
structures
scale

• stratigraphy
• sedimentary structures
• deformation structures
• bed contacts
• colour
• fossil content
• erratics
• lateral variations

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5
lithology
fossils
0
m
f
c
clay/silt
sand
pebbles
mean grain size
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SEDIMENTOLOGY VS TECTONICS

• Sedimentary processes (wind, water)
• lamination
• bedform morphology
• texture
• structure
• transitions relate to energy/input
  (abrupt/gradual) FU, CU

Tectonic processes (ice, orogenesis, gravity)
syn-, or post- sedimentary deformation or pre-,sy
n-,post-tectonic sedimentation
Glaciotectonic dislocations disrupt
stratigraphic units ? tills of one glaciation
can be discontinuous
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KINETO-STRATIGRAPHY(Berthelsen, 1973, 1978
Boulton, 1996)
Focus on the structural instead of the
sedimentary record
Kineto-stratigraphic zones of deposition and
erosion
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2
3
4
Ice divide slight erosion
Overdeepening Strong erosion
Inner margin advance/retreat tills with erosion
surfaces
Outer margin continuous till deposition
Extension
Compression
Ice flow
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RELATIVE AND ABSOLUTE DATING METHODS
1. Sidereal (calender/annual) varves,
Palaeomagnetism 2. Isotopic ?18O K/Ar or
Ar/Ar-method Th/U Fission track (U/U
isotopes) 3. Radiogenic C14 Thermolumines
cence (TL), optical stimulated luminescence
(OSL) electro spin resonance (ESR) 4.
Chemical/biological pollen, amino-acid,
lichenometry 5. Geomorphic 6. Correlations
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Quaternary stratigraphy 2.5 My
(Zagwijn, 1957)
PLEISTOCENE STAGES
Weichselian g Eemian i Saalian g Holsteinian
i Elsterian g Cromerian i
gGLACIAL - regression i INTERGLACIAL -
transgression
About 750000 yr BP
Bavelian/Menapian gi Waalian ig Eburonian
gi Tiglian ig Praetiglian gi
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PRAETIGLIAN
1st Pleistocene cold stage pollen spectra
resemble Weichselian treesBetula, Pinus,
Alnus herbs dominate graminae, cyperae, ericacae
UK Red Crag formation?
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TIGLIAN Tegelen clay
Main Quaternary transgression Stratigraphic
information needed
trees Fagus (beech) herbs water fern fauna
warm molluscs
Also ice wedges (cold)
UK Ludhamian and Beestonian Cromer forest
beds Baventian (IRD?)
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EBURONIAN
7 units counted Glacial periods know
from sediments fluvial clasts from Baltic River
System fauna lemming
UK missing
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WAALIAN
3 unitsWaalian A, B, C (WCmildw)
pollen Tertiary relicts
UK missing.
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MENAPIAN
CWC (cold/warm/cold) ice wedges and
cryoturbation Scandinavian erratics
BAVELIAN
WCWC vegetation succession
UK both missing
N-Am PRE-ILLINOIAN (formerly Nebraskan)
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CROMERIANOriginally named after Cromerian Forest
Beds (UK), which are actually of Tiglian Age
CROMERIAN I, A, II, B, III, C, IV Letters
glacials Numbers interglacials
UK fluvial aggradations of quartz-rich
gravel Glaciation Welsh Mountains no
chronological control
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ELSTERIAN COLD STAGE

• Ice extent unknown most till eroded by Saalian
  ice
• Flint-line best preserved in Saxony (river
  Elster)
• Change in regional drainage (e.g. Elbe,
  Ice-dammed lakes)
• Incised subglacial tunnel channels troughs
• Origin fluvioglacial/glacial/liquefaction ???
• Late-glacial glaciolacustrine clays (up to 150
  m FU sequence)
• (e.g. Lauenburger Ton/Potklei)

UK Anglian Glaciation Thames valley southern
margin Norfolk interaction Scandinavian and
British ice 5 tills but no interglacial
N-Am PRE-ILLINOIAN (formerly Kansan)
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HOLSTEINIAN INTERGLACIAL
Typesite Sleswick-Holstein Major transgression
onset by isostatic depression Sites with
Holsteinian deposits widespread fossil soils,
lacustrine and organic strata (diatoms), pollen
UK Hoxnian Interglacial typesite Hoxne
(Suffolk) Vegetational succession similar to the
continental
N-Am YARMOUTH ? Typesite SE Indiana ? organic
deposits climate warmer and drier than Holocene
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SAALIAN COLD STAGE
Start nonglacial prolonged cold 2 ice advances
(Drenthe and Warthe) Older, Middle and Younger
Saalian Till
UK Wolstonian glaciation typesite Wolston on
Avon (Warwickshire) Limited ice extent compared
to continent (why?) No contact between British
and Scandinavian Ice sheets?

• N-Am ILLINOIAN ? Typesite Illinois 8 tills/4
  fossil soils
• 2 major glaciations
• Toronto York Till
• Hudson Bay 4 tills

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OLDER SAALIAN ADVANCE PUSH MORAINES OF THE
REHBURG PHASE
From Van der Wateren, 1995 and 1987
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EEMIAN INTERGLACIAL
Typesite Eem river in central
Netherlands Slightly warmer than Holocene marine
deposits, vegetational history and soils
UK Ipswichian Interglacial Bobbitshole (Ipswich)
and Trafalgar Square (London) botanical record
associated with large mammals

• N-Am SANGAMONIAN (130000-75000 BP)
• Paleosols found outside Wisconsin limit
• drier and warmer than Holocene (Newfoundland)
• Sea level-25 to 9m (San Francisco Bay and
  Mexico)
• Canada sea level 4-6 m above present

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WEICHSELIAN COLD STAGE
Maximum ice advance in late Weichselian Last
Glacial Maximum (LGM) (22000 -18000 BP) Younger
Dryas (10800-10000 BP) Fennoscandian ice sheet
completely melted by 8500 BP
UK Devensian Glaciation LGM Dimlington
Stadial Loch Lomond Younger Dryas Irish Sea hot
debate
N-Am WISCONSIN Laurentide 3 glaciation centres
(Labrador/Keewatin/Fox Basin) Cordilleran western
Canada
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LAURENTIDE ICE SHEET DURING LGM
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RECONSTRUCTION FORMER ICE SHEETS
Dynamics Processes Location
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LAURENTIDE ICE SHEET TIME SERIES

• Shifting centres
• Shifting ice divides
• Number of domes

Changing morphology ice dynamics cross-cutti
ng relationships in streamlined forms
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Past and future temperature trends.
lt 10,000 y BP based on deep-sea cores
terrestrial glacial evidence. gt 10,000 yrs,
constructed from mountain glacier variations
other climate-proxy data, Projections based
on Milankovitch (Earth-orbital) variations. Red
curve various greenhouse warming scenarios
http//faculty.washington.edu/scporter/Rainierglac
iers.html