Geology Week 12
Geology Week 12 GEOL1005
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This 3 page Class Notes was uploaded by Kate Notetaker on Thursday April 7, 2016. The Class Notes belongs to GEOL1005 at George Washington University taught by Catherine A. Forster in Winter 2016. Since its upload, it has received 29 views. For similar materials see Historical Geology in Geology at George Washington University.
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Date Created: 04/07/16
April 5, 2015 Biogeography study of the spatial distribution of organisms o Where are they? o Why do we find animals and plants where they are? Paleobiogeography spatial distribution of organisms through time Cosmopolitan organism has a widespread distribution o Found in a lot of places Endemic something has a localized distribution o Only find them in one place How do organisms get where they are? o Evolve in place Your ancestors were there, so now you are there o Disperses there / migration Moves there from somewhere else Range extension if an organism has a small or endemic range and extends that range Environmental tracking a lot of organisms have evolved to live in certain conditions When conditions change, they are going to move with that condition Sweepstakes dispersal rare Dispersal across a major geographic boundary o Vicariance Separation or division of a group of organisms by the erection of a geographic boundary Can be very large scale, can be very small scale How did isolation of the continents effect life? o Endemism Late Triassic through Middle Jurassic Disparate dinosaur faunas still show great similarity in taxa and faunal composition Ocean circulation pattern o Major driver of climate o Water stores heat extremely well Top few meters of sea water store as much heat energy as the entire atmosphere o The ocean surface stabilizes the atmospheric flow patterns depend on heat supply o General circulation of the atmosphere is closely related to the circulation of the ocean April 7, 2016 Cenozoic o Still quite warm o Low pole-to-pole gradients o No ice at the poles Early part of the Cenozoic Right at the Paleocene-Eocene boundary o Warming trend PE Thermal Maximum (PETM) First recognized in 1990 o 56 million years ago o Lasted for 200,000 years o Temperatures increased from about 6 to 9 degrees Centigrade globally o Average global temperature is around 73 degrees Fahrenheit/ 23 degrees C o We know this from ocean cores forams Forams live in the ocean, build a shell out of calcium carbonate We can look at the shells and test the oxygen composition over time 16 18 O to O o Deep water was around 60 degrees Fahrenheit Natural Carbon cycle on Earth o Lots of CO2 is produced and then absorbed in carbon sinks 13 12 o Huge amounts of carbon C depleted / more C o Entering the atmosphere and entering the carbon cycle This is what is causing the warming of the Earth Volcanism o Centered around Greenland/Baffin Island o Opening of the North Atlantic Rifting and volcanism going on in this part of the world o Looks at the igneous basalts You can estimate what kinds of gases are coming out of this material Estimated that there is 1C depleted CO2 and CH4 gases produced by volcanism o Basalts were placed out onto the sea floor Sea floor is full of carbon rich sediment Start warming up the atmosphere by all the greenhouse gases coming up o A lot of the CO2 in the atmosphere gets absorbed into the ocean Trying to balance out the carbon o Result of this is that the ocean warms o If you warm the ocean up enough, you start melting methane hydrate/clathrate o Methane hydrate Methane molecule that is enclosed in ice Trapped on the sea floor o When the methane hydrate melts, you increase the amount of greenhouse gases Add enough CO2 and methane into the atmosphere, the ocean absorbs more of the CO2 o Acidifies the ocean o 50% extinction of benthic forams during this PETM Benthic the ones that live on the bottom CCD carbonate compensation depth o Below this, the pressure is so high that calcium carbonate will dissolve o If you have sediment below 4 km, you don’t get any fossils because all of the shelves dissolved o During PETM, the CCD rose to about 2 kilometers A lot more of the ocean floor with no fossils in it Because of the acidification of the ocean, more calcium carbonate shells dissolved o In a lot of places, you find red clay in the PETM area if you took a core of the sea floor o If there is a lot of CO2 in the ocean, its harder to deposit any limestone Boundaries are named because of the big events that happened When you look at the PE boundary, you see a huge diversification of mammals o We see the first real flourishing of primates during the PETM o Some sort of correlation between the PETM and the evolution of mammals Multituberculates existed for 100 million years Monotremes alive today: platypuses and echidnas o Live only in Australia and New Guinea today Marsupials o Southern hemisphere success story Placentals 4000 known species alive today o Dominate everywhere except Australia
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