Term
What are the main differences in the configuration of the continents and ocean between the Createous and today? |
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Definition
| Two continents: Laurasia in North and Gondwana in South. Continents started rifting |
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Term
What evidence or proxy data shows that the world was warmer than 100 Myr ago than today? |
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Definition
Arctic palm trees
Smooth leafs at high lats
Antarctic forests
Oxygen isotopes in benthic foram |
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Term
How can we the use the stable oxygen isotope composition (18O) of foraminifera to study temperature in the past? In other words, how do oxygen isotopes work as a temperature proxy? |
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Definition
Isotopic Fractionation:
Clouds contain light isotope
Ocean contains heavier isotope
O16 is preferentially evaporated |
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Term
Planktoic Foram have what similar to surface water? |
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Definition
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Term
Benthic Foram have what similar to bottom waters |
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Definition
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Term
During Glacial times what is removed from ocean and stored on land? |
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Definition
| more 16O is stored on land |
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Term
| How do we know the causes for a warm climate? |
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Definition
We can model the cretaceous climate under differant boundary conditions
The fossil and geochmical proxy record |
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Term
| How well do model simulations capture the distribution of temperatures 100 Myr ago and what are the possible causes of mismatch with the proxy record? |
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Definition
| There is an offset between data and models which indicate: a poor understand of climate sensitivity. Or issus with models, proxy data or both. It is difficult to contrain parameters for tempurature. |
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Term
| What is Climate Sensitivity? |
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Definition
| The tempurte change with a doubling of atmospheric co2 |
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Term
| Why was the cretaceous so warm? |
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Definition
The concentration of atmospheric co2 was higher than today.
LIPS
Enhanced ocean stratification
More Chemical Westhering
More organic Carbon |
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Term
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Definition
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Term
| What were the sources of CO2 during the Cretaceous greenhouse Perio |
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Definition
| LIPS and volcanic eruption |
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Term
| What were the effects of enhanced atmospheric CO2 and elevated temperature in the chemistry of the oceans? |
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Definition
(Oceanic Anoxic Events, OAEs) Black shale
Volcanism relesed co2 -> elevates global temps -> Enhanced ocean stratifacation and reduced oxygen soulbility -> oxygen reduction -> enhanced chemical weathering and hydrology -> higer nutrient inpout |
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Term
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Definition
| Dark finely grained sed rock with elevaated organic content. Low energy environments with high organic input. Used in most fossil fuel production today |
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Term
| Which regions of the continents were flooded by high seas 100 Myr ago and what caused high sea level during the Cretaceous? |
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Definition
Many regions were flooded at any given time. Large inland seas split the continent of north america into two landmasses.
Water in ocean basins being diplaced by enlargement of midoceanic ridges |
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Term
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Definition
| A mass extinction is any substantial increase in the amount of extinction (i.e. lineage termination) suffered by more than one geographically widespread higher taxon during a relatively short interval of geologic time, resulting in an at least temporary decline in their standing diversity |
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Term
| What causes mass extinction events? |
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Definition
Bolide impaces
Massive colcanism
Climate change
Low oxygen Levels
Global climate
Sea level change
Nutrient collapse |
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Term
| How did higher sea level affect global climate? |
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Definition
The high Cretaceous sea level is thought to have been primarily the result of water in the ocean basins being displaced by the enlargement of midoceanic ridges.
As a result marine waters inundated the continents.
Continents shrank
Land convered only 18$ of world
No changes of temp throughout the world
Water circulation was not as greate because of constriction
Temps between poles and equator were minimal
anoxic climates |
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Term
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Definition
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Term
| Mass extinction creatceaous-Paleogene boundary? |
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Definition
Massive colcanism
75% of species extiction
Nevitive carbon isotop excursion
Decrease
Dust and aersol cover that leads to low temp -> less photosythesis -> long recovery -> extiction of tropical zones -> wild fires, acid ran, ozone destruction. |
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Term
| How can we use the stable carbon isotope composition (13C) of bulk carbonate or calcareous fossils to study changes in carbon cycling across the K/Pg boundary? |
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Definition
Carbon has two stable isotopes c12 and c13.
Carbon has one radioactive isotope c14.
Changes in marine productivity can change the dela(13C) of sea water.
Carbon isotope records suggest reduced productivity and a perturbed C cycle for 105-106 years |
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Term
| What caused the Paleocene-Eocene Thermal Maximum (PETM) and what were the consequences for our climate system and ocean chemistry? You should be familiar with the effects of a large carbon release to the atmosphere on global temperature and ocean pH. |
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Definition
A very war period in earth history.
Warm because of emisions of isotopically light carbon compouns CH4 and CO2
Ocean Acidification (low ph) and deoygenation (O2 reduction)
Intensified hyrological cycle
Extinction of benthic foraminifera
Mammalian Dispersal |
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Term
| What happened at the Paleocene-Eocene Boundary? |
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Definition
Rapid Warming event
large release of isotopically light carbon to the atmosphere and ocean |
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Term
| What’s the evidence for changes in climate and ocean chemistry across the PETM? What proxies indicate changes in temperature and pH? |
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Definition
| Coupled carbon oxygen isotop data from benthic forams across the PETM indicates rapid warming with a perturbation of carbon cycle. (Negative carbon isotope excursion) |
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Term
| Negative carbon isotope excursion |
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Definition
| a large decrease in 13C/12C ratio of marine and terrestrial carbonates and organic carbon. |
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Term
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Definition
| file:///home/evan/Pictures/blackshale3.jpeg |
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Term
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Definition
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Term
| Isotopic Fractionation ( ralleigh) |
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Definition
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Term
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Definition
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Term
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Definition
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Term
| Isotopic fractionation extended |
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Definition
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Term
| Isotopic fractionation extended |
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Definition
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Term
| Isotopic Frationation Extended |
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Definition
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Term
| Simplified marine carbon cycle |
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Definition
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Term
| Simplified marine carbon cycle |
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Definition
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Term
Chapter 7
How can we the use the stable oxygen isotope composition (18O) and chemistry (Ma/Ca) of foraminifera shells to study temperature in the past? |
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Definition
Planktonic and benthic foraminifera have δ18O similar to surface and boHom waters, respecLvely.
δ18O is mostly affected by ice accumulaLon on conLnents (Raleigh disLllaLon), temperature and salinity
Laboratory cultures have found an empirical relaLonship between oxygen isotopes in planktonic forams and temperature
The incorporaLon of Mg in shells of calcifying organisms during the precipitaLon of carbonate skeletons correlates with temperature. Thus, the Mg/Ca raLo of planktonic and benthic foraminifera (as well as other calcareous fossilscan be used to reconstruct past temperatures. |
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Term
| How can we use the size and shape of plant leaves to study temperature changesin the past? |
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Definition
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Term
| When did the glaciation of the southern hemisphere occur, and what’s the proxy evidence for this transition? |
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Definition
On the Eocene-Oligocene boudary in which a cold event that glaciated the southern hemisphere.
Plant leaf margins
O18 increased
Ice rafted Debris |
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Term
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Definition
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Term
| How do changes in CO2 explain the long-term cooling of the Cenozoic and the glaciation of the northern hemisphere? |
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Definition
Changes in spreading rates
Uplift of moutain ranges
Enhanced physical and chemical weathering
Enhanced organic carbon burial in seds |
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Term
| How do other theories (e.g., opening and closing of seaways, uplift weathering) explain changes in atmospheric CO2 and the long-term cooling of the Cenozoic? |
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Definition
Opening seaways: during the early eocene both the drake passage and tasmanian seaways were closed so no ciculation exsited around antartica.
On the boundary they both opened and ACC was established.
Uplifted weathing: the uplift of mountain rages and high plateaus during the cenozoic much have enhanced physical and chemical weathering. Physical and chemical weathering increases the sed supply in lower areas and sed burial in coastal regiions. |
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Term
| How can scientists measure atmospheric CO2 in the past (examples other than ice cores)? |
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Definition
Plant stomas
Plant margins
Fossils |
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Term
CH 8
What are Milankovitch cycles and what causes them? |
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Definition
Variations in the orbit of Earth around the Sun.
Eccentricity: Orbit is elipical 100,000 years
Oblquity: Axial tilt between 22.1 and 24.5. 41,000yrs. Strenghth of seasons
Precession: Wobbing of the earth. Lean. 25,700years. Causes earth rotation axis to point in differant directions |
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Term
| What configurations in orbital changes provide minima and maxima in solar insolation at low and high latitudes? |
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Definition
Preccession has stronger effect on low latitudes.
Obliquity(tilt) dominates the changes in insolation at high lats. |
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Term
| How are orbital cycles expressed/preserved in climate archives? |
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Definition
Variations in temp and oxygen isotopes
Variations in marine seds
Variations in plant assemblages
Varaiations in atmospheric gases |
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Term
CH 9
How do monsoons functions |
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Definition
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Term
CH 9
What makes a summer monsoon? |
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Definition
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Term
| What is present in a northern hemisphere monsoon? |
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Definition
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Term
| What happens in a northern hemisphere monsoon? |
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Definition
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Term
| How do monsoons function? |
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Definition
| a persistent surface windflow pattern caused by differential heating that shifts direction from one season to another |
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Term
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Definition
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Term
| How do tropical monsoons respond to changes in insolation? |
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Definition
| Monsoonal circulation results from seasonal changes in solar radiation. Orbiatal scale changes insolation. More insolation can intisify Wet summer monsoons. |
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Term
| How does the proxy record reflect changes in the African monsoon system |
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Definition
| Insolation maxima with a precession signal dominates the occurrence and disappeaance of lakes in northern Africa due to changes in precipitation. Lakes dried out and the fine seds containing freswater diatoms were blown by the wind and trasported to the ocean.Dry adapted african fauna. |
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Term
| How does the proxy record reflect changes in the African monsoon system (e.g., precipitation, vegetation) |
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Definition
Diatoms must have grown in N. African Lakes
Diatoms blown off shore as aeolian sediments during winter monsoons
insolation maxima with a precession signal dominates the occurence and disappearance of lakes. |
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Term
| How did the African monsoon system evolve during the Pliocene and Pleistocene? |
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Definition
| African climate became progressively more arid after step-like shifts that coincide with the onset of high latitude glacial cycles. Dry adapted aftrican fauna were to show for this. |
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Term
| What are Mediterranean sapropels and how did they form? |
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Definition
| Sapropels are putrefacted mud. Cyclic dark sediments in marine seds from the mediterranean during pliocne. They show organic rich intervals deposited under oxygen depleted conditions and without evidece of perturbation by benthic fauna. |
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Term
| How did oxygen levels in the Mediterranean Sea change during the deposition of sapropels? |
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Definition
| Stagnant basins such as the Black sea have poor circulation and ventilation which leads to the depletion o2 in bottom waters. These conditions promote organic carbon in seds and the formation of organic rich seds. |
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Term
CH 10
How do ice sheets form and disappear in response to changes in solar insolation? |
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Definition
Ice sheets don't grow or are reduced to a minimum during times of max solar insolation because the equilibrium line over the continent is placed in an locations that favors ablation.
Ice sheets begin to develop when solar insolation drops and the equalibrum line over the continet is placed in a location that favors accumulation |
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Term
| When do ice sheets form. (Pic) |
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Definition
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Term
| What explains the lag between solar insolation and the time response of ice sheets? |
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Definition
| There is a lag in the response of ice sheets to solar insolation which causes the signals to differ in 10kyr for obliquity changes and 6kyr for prcssion changes. |
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Term
| What are the main environmental factors affecting 18O records since the southern and northern hemispheres became glaciated? |
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Definition
| Salinity and Ice volume effect. |
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Term
| What are the key characteristics of the climate system during the Plestocence Epoch? |
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Definition
350-400ppm co2 but temp was 2-3 degress more. Lower than today. Maybe coldest period in recent history.
Most human evolution |
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Term
| What makes the Pliocene a potential analogue for future climate change? |
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Definition
| It has similar continental locations as today. Higher global temp. sea level higher. |
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Term
| What caused the global cooling from the Pliocene to the Pleistocene and the glaciation of the northern hemisphere? |
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Definition
Milankovich cycles.
Last glacial max 21,000 years |
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Term
| What are the main features in the geologic record that support a glaciation of the northern hemisphere during the Pleistocene? |
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Definition
Oxygen isotopes in benthic forams indicate ice value and deep water temps.
Ice rafted debris
There are glacial deposits on n america europ and asia |
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Term
CH 11
What explains the 100 kyr periodicity of glacial cycles during the last 900 kyr? |
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Definition
| Insolation minima were strong enought to displace the equilibrium line across the glaciation threshold. |
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Term
| What are marine isotope stages and what do they indicate? |
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Definition
| Oxygen isotopes in benthic forams that indicate changes in ice volume and deep water temps related to ice ages |
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Term
| How do ice cores inform about past changes in ice sheets, climate and atmospheric chemistry? |
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Definition
| They trap air, water, volcanic ashes, radioiostopes and others. |
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Term
| What is the pattern of greenhouse gases in ice cores during the last 800,000 years and what does it indicate? |
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Definition
| Ice cores indicated synchronous changes in greenhouse gases during glacial interglcial times. Today co2 and ch4 values are much higher than the last 800ky |
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Term
| What caused changes in atmospheric CO2 and CH4 across glacial-interglacial periods? |
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Definition
| Exchagne of co2 from land to ocean |
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Term
| What are the main pathways of carbon transfer across glacial-interglacial periods? |
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Definition
| The lost carbon from the terrestrial biosphere and the atmosphere during intergralcail periods was transferred to the deep ocean and sediments |
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Term
| How can we study carbon cycling across glacial-interglacial periods using the 13C of benthic foraminifera? |
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Definition
| Changes in marine productivity can change the 13C of sea water |
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Term
| What’s the effect of iron fertilization on marine productivity, carbon cycling and atmospheric CO2 across glacial-interglacial periods? |
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Definition
| Iron fertilization fertilizes the ocean by iron input. Iron is a limiting micronutrient for ocean productivty. A dry and cold climte during glacial periods may have stimulated iron fluxes to the ocean. Dust transport contributed to input of FE into ocean. Iron fertilization promoted primary productivity, organic mater export, and burial of seds. |
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Term
| How did ocean circulation affect the transfer of carbon between the ocean and the atmosphere across glacial-interglacial periods? |
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Definition
| Changes in ocean cirulation during glacial times may have made nutrients more avalible for prductivity in surface water. Also, the presence of more corrosive deep water during glacial times may have promoted carbonate dissolution at the sea floor and the reduction of co2 levels in surface waters. |
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Term
| How to you calculate periodicicy? |
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Definition
Years are given in most cases. If years are not given, you should be able to calculate them from the sedimentation rate of the record. For example, is sediment record has a sedimentation rate of 25 m/1,000,000 years, then a 10 meters-long record was deposited in 400,000 years.
An example of periodicity is: 800,000 years/8 cycles = 100,000 years/cycle. |
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Term
| What is the periodicity of obliquity |
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Definition
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Term
| What is the periodicity of Eccentricity |
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Definition
| 100,000 cycles per year. Fast |
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Term
| What is the periodcity of precessions. |
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Definition
|
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Term
| High stomata density means |
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Definition
| That low atmospheric co2 which indicates low global temperature. |
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Term
| Low stomata density means |
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Definition
High atmospheric co2
Which means high global tempurature |
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