Introduction to Quaternary Geology (MA-Modul 3223) Prof. C ... · 1 Introduction to Quaternary...
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Introduction to Quaternary Geology (MA-Modul 3223)
Prof. C. Breitkreuz, SS2012, TU Freiberg
1. Introduction:- Relevance, and relations to other fields of geoscience- Lower stratigraphic boundary and subdivision of the Quaternary
2. The paleoclimatic evolution: - paleoclimatic proxies and controlling parameters
3. Stratigraphic methods and age dating of Quaternary processes
4. Glacials: glacial and periglacial processes on land, deposits and structures
5. Glacio-marine processes
6. Interglacials, including the Holocene, the Pleistocene-Holocene transition
14.07.12: one-day Field trip to Quaternary outcrops (put your name into list at Frau Klocke’s office)
11.07.12: written test / Klausur
Large glaciations (Vereisungen)
Zachos et al. 2001
East Greenland:IRD* in N Atlantic(Eldrett et al. 2007, Nature)
*ice rafted debris
Glacial (Eiszeit) - InterglacialWithin a Glacial:- Stadial and Interstadial
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Bradley 1999
Paleoclimate archives
isotopes
700 ka30 ka
Bradley 1999
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18O - Master-Proxy in:• Water, Ice cores • Biogene carbonates (forams)
Recent forams
Ice
Ocean
PDB
Cool climate (e.g.):1. Temperature proxy:
a) ocean: forams* w. high 18Ob) polar air: low 18O, low D
2. Ice volume proxy:High volume: high marine 18O
* 18O in a foram is controlled by water temperature and salinity, and by volume of land ice shields
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Oxigen isotope stages: - the first studies
Odd number = warmEven number = cold
Marine sediment cores offshore
Greenland
First Ocean-land correlations: e.g., marine 18O vs. Dead Sea pollen
Hor
owit
z 19
89, P
PP,
fig
ure
inco
mpl
ete
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Channell et al. 2009, EPSL
Stacked marine oxygen isotope record (“PISO-1500”) of 13 sites
30 years later…
Thin section of ice core under polarized light
Working on an ice core…
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www.awi-bremerhaven.deamrc.ssec.wisc.edu
18O Master-Proxy:- In ice cores
Delmas 1992
Recent data from snow (1b > 2)
Ice
PDB
Greenland
Compare scales!
Ice cores
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The central Greenland GISP2 δ18O record for the past 80 kyr, interpreted as a proxy for air temperature (Grootes and Struiver, 1997). The abrupt warming events (called Dansgaard-Oeschger Interstadials) have been numbered. Also shown are the amplitudes of several events estimated from measurements of N2(+Ar) isotopes in trapped air (Severinghaus et al. 1998; Severinghaus and Brook, 1999; Lang et al., 1999).
Univ. Texas
Delmas 1992
GISP
Dansgaard-Oeschger-Cycles (DO),Starting with quick warming
Age-depth models!
GRIP
Heinrich-Layers*
Bradley 1999
Marine isotopes & temperature-sensitive forams vs. Greenland ice core
*IRD
-rich horizons in marine sedim
ents in the northern Atlantic
DO
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Ice core drill sites
Ice thickness (Univ. Washington) >>
Ice coring in the Antarctic ice shield
NERC
Vostokice core
Petit et al. 1999
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After Petit et al. 1999
Typical evolution of a glacial (< 500 ka):c. 100 ka, slow start, quick finish
Vostokice core
EPICA Dome Cice core: < 700 ka!
EPICA community members, Nature, 2004
Differences in orbital forcing between northern and southern hemisphere! (Milankovich cycles, see below)
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MIS: Marine Isotope StageLGM: Last Glacial MaximumEDC: Epica Dome CEDML: Epica Droning Maud LandNGRIP: N Greenland Ice coreDO: Dansgaard-Oeschger-Cycle
Epica Community Members 2006, Nature 444
North-south-polar paleoclimate correlation
More examples of paleoclimate proxies in the next chapter!
AIM: Antarctic Isotope MaximumA1, A2: Antarctic warming eventsByrd: Bird Ice Core
Methan Synchronisation
Epica Community Members 2006, Nature 444
Atlantic climate swing:Atlantic
MeridionalOverturning Circulation
(MOC):DO seems to
follow Antarctic
warming event
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What controls climate change? • Variation in solar and cosmic radiation• Climate-sensitive processes on Earth (volcanism, plate tectonics, human
polution etc.)• Complex system of positive and negative feed backs in the hydro-
atmosphere system (e.g., albedo of ice cover, marine gas hydrates)
Bradley 1999
Lozan et al. 1998
Model data from Vostok ice core (Petit et al. 1999)
July, 65°N ≤ 100 W/m2!
Climate forcing (Anfachung) by Milancovich-Orbital-Cycles:
• Excentricity 100 ka• Obliquity 41 ka• Precession 19, 23 ka
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Stack of 57 marine benthic 18O records
(Lisiecki & Raymo 2005, Paleoceanogr.)
(Wikipedia, after Lisiecki & Raymo 2005)
* *
*dominance of…
The radiation budget of the Earth’s atmosphere (units in W/m2)
Kiehl et al. 1997, Bull-Amer-Meteor-Soc
Short wave Long wave
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Absorption of long wave radiation from the Earth surface by greenhouse gases
Variation in ppm CO2: greenhouse effect is not linear!
Mitchell 1989, Rev. Geophys.
GasContribution(%)
Water vapor
36 – 72 %
Carbon dioxide
9 – 26 %
Methane 4 – 9 %
Ozone 3 – 7 %
Short wave Long wave
Hydrocarbon emission at sea floor
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Kvenvolden 1993
Burning gas hydrates Sampled from the sea floor
Kvenvolden 1993
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Hobro et al., JGR 2005
3D seismic tomography of gas hydrates
BSR = Bottom simulating reflector
(Ehlers 1996) Kvenvolden 1993
Recent permafrost regions on the northern hemisphere
Positive feedback
Marine gas hydrates:negative feedback