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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