Paleoclimate Records Flashcards
What are the four major hypotheses for the controls on long-term (geologic-scale) climate
change?
- BLAG Hypothesis
- Uplift Weathering Hypothesis
- Organic Carbon Hypothesis
- Ocean Heat Transport Hypothesis
Describe the BLAG Hypothesis
- Involves Sea Floor Spreading
- In areas with higher rates of spreading and higher rates of subduction (more volcanism and so more CO2 in the atmosphere), you get warmer temperatures. When spreading and subduction slows (less volcanism and less CO2), you get cooler temperatures.
Who came up with the BLAG hypothesis?
Berner, Lasaga, & Garrels in 1983
Describe the Uplift Weathering Hypothesis
- Suck CO2 out of the atmosphere from the weathering of silicate rock
Who came up with the idea of Uplift Weathering Hypothesis?
Maureen Raymo & Ruddiman in 1982
What happen in the Cenozoic Time Frame that causes uplift of rock to high elevation?
Uplift happens during the Cenozoic is caused by collision (ocean/continent & continent/continent) India to Eurasia creating the Himalayas
Provide an analogy for Uplift Weathering Hypothesis
Think about this as the ice cube process – start with a block of ice and want it to melt. Stick it out in FL in August. How to melt this ice faster but at the same temperature? You would break it into smaller pieces.
Draw a diagram explaining Uplift Weathering Hypothesis
- Large mountain glaciers to the high elevations this creates mass wasting.
- Gravity creates slope precipitation also known as a monsoon.
- You don’t have this smooth plateau – jagged rough topography that has a lot of surface area and many interspatial sections that allow water and atmosphere gases to chemically weather that rock.
- Exposure of large volume of crust increases chemical weathering and lowers atmospheric CO2.
Uplift Weathering Hypothesis using the Himalayas as an example
- India collides into Eurasia
- Uplift of the Himalayas start to really show at about 35 myr
- Tibetan Plateau is what is being uplifted – large amount of rock available for erosion.
- On top of that, this creates the Indian monsoon. This is where you have winds blowing across the India plateau. This moist humid air moves up and rises as it moves up the Himalayas and then cools, condenses, and rains.
- This creates a lot more chemical weathering during the monsoon.
What happens during continent-continent collision
- Slow down spreading and reduces the amount of vulcanism
- Creating rugged mass of rock that can be eroded, weathered, and then suck out CO2
The Ganges delta is not only the biggest sediment sink but also…
largest sink for organic carbon
Who developed the Organic Carbon Burial Hypothesis?
- France-Lanord & Derry – Galy
The Ganges and Bengal Fan is responsible for what percent of burial of terrestrial organic carbon?
20%
The Ocean Heat Transport Hypothesis
- Changes in ocean circulation due to changes in continental positions-> opening & closing oceanic gateways
- That ocean circulation controls the transfer of heat from the tropics to the polls
- Key things have happened during the Cenozoic timeframe (65 Myr) that have something to do with the Ocean Heat Transport Hypothesis
- Southern Ocean – Australia was connected to Antarctica
- Antarctica and South America were connected to each other.
- 33,26 Myr ago – opening of Tasmanian-Antarctica gateway
- 25-20 Myr – opening of Drake passage (South America & Antarctica) -> This allows for the Southern Ocean we know today and allows for Southern Ocean circulation.
- Clockwise rotation around antarctica – this stops the transfer of heat.
What is Eccentricity and draw a diagram?
- How circular versus elliptical is the Earth’s orbit around the sun
- Periodicity: 96,000 yrs
What is Precession and draw a diagram?
Circular precession of axis of rotation
- Periodicity: 23,000 years
What is Obliquity and draw a diagram
Amount of tilt of the earths axis: affects seasonality
Periodicity:41,000 yrs
