geol guide

geol guide - Hadean and Archean Eons Hadean Eons 4.56-3.8...

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Sheet1 Page 1 Hadean and Archean Eons Hadean Eons 4.56-3.8 Ga Archean Eon 3.8 -2.5 Ga Craton Canadian Shield How does the radiometric age of meteorites have to do with the age of Earth? What evidence supports the Big-Bang theory? How did EarthO s internal layers differentiate? How did EarthO s Moon form? How did EarthO s early ocean form and what was itL s composition? How did EarthO s early atmosphere form and what was its composition? Over what period did early meteorite impacts occur on Earth? How did continental crust form in the Archean? Zircons provide age of oldest continental crust? Why were Archean cratons small? How do Greenstone Belts form? Miller and Ulrey experiment The oldest stromatolite found occur in 3.5 Ga old rock. Isotopically-light gases trapped in 3.5 Ga old igneous rock suggests organic activity in oceans at this time. Prokaryotic filaments are found in 3.2 Ga old pillow basalts. Why is it likely that life originated at MORs? What evidence indicates that the atmosphere was poorly oxygenated in the Archean Eon? C12 Proterozoic Eon Proterozoic Eon age 2.5 Ga- 0.5 Ga Wopmay Orogeny is the earliest example of modern-like plate tectonics. Foreland basin = a downwarp of the craton approaching a subduction zone. Flysch = early-phase deep-water sediment deposited in a deep foreland basin. Molasse = late-phase shallow-water and non-marine sediment filling a foreland basin. Animal-like protists (eukaryotes) evolved when an amoeba-like prokaryote engulfed a bacteria that formed a mitochondrion in s Plant-like protists (eukaryotes) evolved when an animalp-like protist engulfed a cyanobacteria that formed a chloroplast instea d The oldest eukaryote fossil, Grypania, is dated to be 2.1 Ga. Prokaryotes were more abundant than Eukaryotes in the Proterozoic. Eukaryotic acritarchs, single-celled algae, were abundant after 2 Ga. The first appearance of animals occurred in the Neoproterozoic. The oldest animal-like unicellular organisms resemble modern amoeba and appeared at 750 Ma. The oldest multi-cellular animal appeared at 580 Ma. Edicarian Fauna lack skeletons and are known to have existed by 570-560 Ma (including ancestral echinoderms, arthropods, c The first skeletal fossils (Cloudina) are found in Neoproterozoic strata. The earliest evolution of animals occurred shortly after Snowball Earth ended. Oxygen buildup in the Proterozoic was due to photosynthesis by cyanobacteria. Eukaryotes became dominant over prokaryotes in Proterozoic as oxygenation of the atmosphere produces Nitrates, a necess a Cratons grew larger by continental accretion and orogenic stabilization. ±aurentia assemblaged in 4 stages during the Proterozoic.
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This note was uploaded on 04/08/2011 for the course GEOL 1003 taught by Professor Hanor during the Spring '08 term at LSU.

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geol guide - Hadean and Archean Eons Hadean Eons 4.56-3.8...

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