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3/8/15 Objective
Uplift of Tibetan Plateau
as Active Driver for
Cenozoic Climate Change
v  Use Paleoarchives from the Tibetan Plateau to support
the uplift weathering hypothesis for global cooling
over the last 50 million years
v  Hypothesis: The uplift of the Tibetan Plateau is an
active driver for global cooling of the Cenozoic period
By Roslyn Gober
11 February 2015
onebigphoto.com/stunning-dolomites-mountains-italy/
Cenozoic
Period
Global
Cooling
Cenozoic: CO2 & Climate Change
Atmospheric
CO2 Levels
v  Atmospheric CO2 and
global temperature
decline
Uplift
Weathering
Hypothesis
v  Clear relationship
between climate and
atmospheric CO2
Tibetan
Plateau
v  Need to identify driver of
atmospheric CO2 removal
Extensive
High Terrain
Physical
Weathering
Chemical
Weathering
(Beerling, 2011)
1 3/8/15 Cenozoic: Icehouse Climate
Uplift Weathering Hypothesis
Uplift is the cause of large-scale climate changes,
through both direct physical impacts and indirect
biochemical effects
v  Benthic foraminifera
δ18O measurements
over last 70 Myr
v  Trend toward more
positive values of δ18O
v  Progressive cooling
of deep ocean
v  Continental ice sheet
growth
v  Proposed by Maureen Raymo in the late 1980’s
v  Physical impact
v 
Changes in circulation of atmosphere and ocean
v  Chemical impact
v  Drawdown of atmospheric CO2 is a result of chemical
weathering of silicate rocks
(Raymo, 1992)
Uplift Weathering Hypothesis
(Ruddiman, 1997)
Uplift Weathering Hypothesis
Positive Feedback
(Ruddiman, 2014)
Negative Feedback
(Ruddiman, 2014)
2 3/8/15 Criteria for Uplift Weathering
1) Extensive High Terrain
Extensive High Terrain: Tibetan Plateau
v  Collision between India
v  Must be proven to be uniquely high compared to past
geologic eras
and Asia created most
extensive plateau on Earth
v  55 Myr ago
2) Unusual Physical Weathering
v  2.5 million km2
v  High terrain must be causing large amounts of rock
v  Avg. elevation > 5 km
fragmentation
v  Marine limestones show
3) Unusual Chemical Weathering
v  Exposure of fresh debris must be causing high rates of
plateau was below sea level
70 Myr ago
chemical weathering
www.standeyo.com/NEWS/06_Earth_Changes/061117.Himalaya.megaEQ.html
(Ruddiman, 2014)
Extensive High Terrain: Is it uniquely high?
v  Cannot prove modern elevations are unusually high or
extensive based on age
v  India-Asia first major continental collision in 150 Myr
v  Sufficient evidence that amount of high terrain is more
extensive than in earlier geologic eras
(Ruddiman, 2014)
Criteria for Uplift Weathering
1) Extensive High Terrain
✔
v  Must be proven to be uniquely high compared to past
geologic eras
2) Unusual Physical Weathering
v  High terrain must be causing large amounts of rock
fragmentation
3) Unusual Chemical Weathering
v  Exposure of fresh debris must be causing high rates of
chemical weathering
http://www.shantitravel.com/en/tibet-travel/
(Ruddiman, 2014)
(Ruddiman, 2014)
3 3/8/15 Unusual Physical Weathering
Unusual Physical Weathering: Himalayan Sediments
v  Ocean basin sediment influx
is best record of physical
weathering
v  Increase in sediment influx
in last 40 Myr
v  Result of two factors:
v  Steep Terrain
v  Monsoons
v  Uplift of Tibetan Plateau led
to increased physical
weathering
Himalayan Sediments in Indian Ocean
(Ruddiman, 2014)
Unusual Physical Weathering: Monsoons
(Ruddiman, 2014)
Criteria for Uplift Weathering
1) Extensive High Terrain
✔
v  Must be proven to be uniquely high compared to past
geologic eras
2) Unusual Physical Weathering
✔
v  High terrain must be causing large amounts of rock
fragmentation
v  Differential heating of Tibetan Plateau and Indian
Ocean creates powerful monsoons
3) Unusual Chemical Weathering
v  Exposure of fresh debris must be causing high rates of
v  Causes greater physical weathering
chemical weathering
(Ruddiman, 2014)
(Ruddiman, 2014)
4 3/8/15 Chemical Weathering of Continental Rocks
v  Removes CO2 from
atmosphere through
hydrolysis
Unusual Chemical Weathering:
Isotope Record in Marine Limestones
87Sr/86Sr
v  Proxy of mantle processes and continental weathering
v  Preserved in marine carbonates
v  Isotopic composition inputs
v  Measure ions
v  Low 87Sr/86Sr Ratio: Mantle
dissolved in rivers
v  High 87Sr/86Sr Ratio: Continental Weathering
v  Difficult to
determine chemical
weathering rates
v  Synthetic Stratigraphic Column of marine limestones
v  Continuous over past 500 million years
(Ruddiman, 2014)
Unusual Chemical Weathering:
Isotope Record in Marine Limestones
87Sr/86Sr
(Edmond, 1992)
Unusual Chemical Weathering:
Isotope Record in Marine Limestones
87Sr/86Sr
v  Increase in oceanic 87Sr/86Sr
due to chemical weathering
v  Marine isotopic oscillations
signal dampened
v  Seafloor spreading too slow
to impact record
v  Weathering of Himalayas
Late Cenozoic increase in 87Sr/86Sr
(Edmond, 1992)
caused dramatic increase in
marine isotope ratio over last
40 Myr
(Edmond, 1992)
(Raymo, 1992)
5 3/8/15 Unusual Chemical Weathering:
Isotope Record in Marine Limestones
87Sr/86Sr
Unusual Chemical Weathering:
and Atmospheric CO2
87Sr/86Sr
(Ruddiman, 2014)
Criteria for Uplift Weathering
1) Extensive High Terrain
✔
(Garzione, 2008)
Conclusion
v  Global cooling and declining atm. CO2 levels in last 50 Myr
v  Must be proven to be uniquely high compared to past
geologic eras
v  Evidence for Uplift Weathering Hypothesis in Cenozoic:
v  Creation of Tibetan Plateau 55 Myr ago
2) Unusual Physical Weathering
✔
v  Increased rate of sediment influx to Indian Ocean
v  High terrain must be causing large amounts of rock
v  Increased 87Sr/86Sr Isotope Ratio in Marine Limestones
fragmentation
3) Unusual Chemical Weathering
v  Hypothesis Supported
✔
v  The uplift of the Tibetan Plateau is an active driver for global
v  Exposure of fresh debris must be causing high rates of
cooling during the Cenozoic period
chemical weathering
(Ruddiman, 2014)
6 3/8/15 References
v 
Beerling, D.J. and Royer, D.L., 2011, Convergent Cenozoic CO2 History: Nature
Geoscience V. 4, p. 418-420.
v 
Edmond, J.M., 1992, Himalayan tectonics, weathering processes, and the strontium isotope
record in marine limestones: Science, V. 258, p. 594–1,597.
v 
Garzione, C. N., 2008, Surface uplift of Tibet and Cenozoic global cooling: Geology, V. 36,
p. 1003–1004.
v 
Raymo, M.E. and Ruddiman, W.F., 1992, Tectonic Forcing of Late Cenozoic Climate:
Nature, V. 359, p. 117-122.
v 
Ruddiman, W.F., 2014, Earth’s Climate Past and Future: New York, W.H. Freeman and
Company, 445 p.
v 
Ruddiman, W. F., 1997, Tectonic uplift and climate change. New York: Plenum Press.
Questions?
http://www.cits.net/china-guide/places/meili-snow-mountain.html
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