1. How does the benthic foraminifera δ18O vary with the changing temperature of ocean water? 2. Characteristics of Tectonic-scale processes. 3. When is Earth closest to the Sun in its present orbit? 4. Definition of eccentricity of earth orbit to sun. 5. The process of monsoon. 6. How climate determines Mg/Ca ratios in foraminifera shells: 7. Which regions of the North American continent were flooded by high seas 100 Myr ago? 8. Geologic evidence indicates the Mediterranean Sea acquired a freshwater lid periodically in the last 100,000+ years. What caused this? 9. Relationship between mean annual temperature and leaf shape? 10. How do sediment archives accumulate? 11. Which of the following climate records has the highest resolution (i.e., can be used to analyze changes through time with the greatest detail)? 12. What is the Drake's Passage gateway hypothesis about? 13. What is the precession of the equinoxes? 14. How does the resolution from sedimentary archives vary with depositional environment? 15. What type of feedback does chemical weathering have on climate? Brief describe it. 16. What are climate proxies, how they are used to reconstruct past climate. 17. What is faint young sun paradox? What are possible solutions for it? 18. Which latitudes are mostly affected by changes in earth’s axial tilt? And why? 19. What is orbital monsoon hypothesis? What are assumptions behind it? 20. What are two major types of chemical weathering that occur on continents? How do they impact the climate? 21. What are the four long-term changes in Earth’s orbit? What is Precessional index? 22. List actual climate records for evidence of orbital monsoon hypothesis in North Africa and explain how are they linked to summer monsoon intensity?
1. We know oxygen has 3 isotopes one is 16O ,17 O and 18O . 17O isotope has abundance is very less in earth . 18O is heavier isotope and 16 O is lightest isotope of oxygen and it's abundance is very high.
- during fractionation process lighter isotope goes in vapour state relatively more than heavier isotope .
Del18O ={ [(18 O/16 O)sample ÷ (18 O / 16 O) standard] - 1} × 1000
- so during fractionation process 16O isotope goes into vapour in more number than 18O isotope and 18O isotope present in liquid or some small amount goes to vapour state.
- in case of benthic foraminifera all climate record present in its shell.
- At the glacial time all 16O isotope goes towards polar region from ocean by evaporation process and it precipitation occurs in polar regions and it locked with ice in ploar region but in ocean allmost all 16O absent and present only 18O isotope due to it heavy nature and it doesn't go into vapour state.
-so in foraminifera shell del18O increase or shows positve value because ratio of (18O /16O) of sample increase.
- During inter glacial period or high temperature time all glacier melts whatever 16O isotope was present inside ice that comes into ocean and increase of 16O isotope concentration in ocean .so ratio of (18O /16O) sample value decrease. So del18O vale is come in negative.
- so foraminifera shell shows del18O negative value.
2. Characteristics of tectonic scale process.
Earthquake - Suddenly vibrates the ground . It is a very short term time sensitivity tectonic process.depend upon its magnitude it affect the area.large magnitudes it will affect more area. It comes under small to large scale tectonic process.
Volcanism - it is very small scale to very large scale process. Depend upon mobility of magma it affect the area. Basaltic lava it's affect large area and cause less explosive. Acidic lava cover small area and causes more violent .
Orogeny - this is the mountain building activities phase. Due to plate collision mountain formed. It is a long term tectonic process. It cover large area in earth surface .it mainly formed due to horizontal plates motion and collision of plates.
Seafloor spreading - it is formed at position of two plates move away from each other. Here volcanic and igneous intrusion occurred. In mid oceanic ridge new oceanic plate originated and seafloor spreading happens.
3. In January 4 earth comes closes to sun through its orbit .it is called perihelion . It happens after 2 week of December solstice.when winter season in northern hemisphere of earth.
4. Eccentricity - Change of Earth orbit around sun ,elliptical shape to circular shape or reverse . it takes total 100,000 year to changes the circular orbit to elliptical orbit or reverse.
Due to the changes of eccentricity or earth orbit it's affecting the distance between earth and sun.
1. How does the benthic foraminifera δ18O vary with the changing temperature of ocean water? 2....