Earth history ppt

earth's early history powerpoint and geologic time and earth history ppt and history of earth formation ppt
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Prof.EvanBaros,United Kingdom,Teacher
Published Date:26-07-2017
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Earth History & Geobiology 1Chronology of the early Earth 4567 Ma: Formation of Solar system (Pb-Pb) 0 4530±10: Core segregation (Hf-W-U-Pb) 30-50 4480±20: Moon forming event (Rb-Sr) 70-110 4450±50: Accretion of Earth nearly complete 120±50 4450±50: formation of the Atmosphere (I-Xe) 120±50 4420±80: Formation of the oldest Crust (Sm-Nd) 140±80 4417 Ma: oldest minerals on Moon (Zircon) 150 4404 Ma: oldest minerals on Earth (Zircons from Aus) 163 4000 Ma: oldest preserved continental crust 570 2 Photograph courtesy of NASA. Image in the public domain.Why does the Earth have so much water ? Photograph courtesy of NASA. Image in the public domain. 3Hydrogen loss Image by Boris Starosta © John Wiley & Sons. All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/help/faq-fair-use/. • accretion of the early earth due to impact of numerous planetesimals o • Thereby native iron was added to the 1000 C hot surface. gas mass 0 • On the surface iron reacts with H O: Fe + H O = FeO + H 2 2 2 H 2 2 • Even today on Earth (final size) H and He can escape, He 4 • Only the two lightest elements can reach the escape velocity CH 16 4 • of 40,300 km/h (11 km/s) • The early earth had no magnetic field so solar wind reached CO 44 2 • earth surface enhancing the loss of the atmosphere N 28 2 O 32 2 4 Ar 40 © W. H. Freeman and Company. All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/help/faq-fair-use/. 5Why does the Earth have so much water ? Evidence for surface water © source unknown. All rights reserved. This content is excluded from our Creative Commons license. For more information, see /. http://ocw.mit.edu/help/faq-fair-use Photograph courtesy of NASA. Image in the public domain. 6 Likely added by a later event… 1 Hydrogen H Likely most of the volatiles elements originate from meteorites 2 Deuterium H The D/H of comets © source unknown. All rights reserved. This content is excluded from our Creative is distinctive different Commons license. For more information, see http://ocw.mit.edu/help/faq-fair-use/. 7 from Earth Comets are “dirty snowballs”, composed of dust and ice Photograph courtesy of NASA. Image in the public domain. Halley’s Comet 8Artist's recreation of late heavy bombardment event removed due to copyright restrictions. We think the water was added by the late heavy 9 bombardment event. Impact rate on the Earth Earth is to small during the main accretion event to retain hydrogen H O react with Fe to FeO and H 2 2 → depletion of H, noble gases etc. Giant impact add additionally energy – Evidenz für Ozeane Volatile elements get “lost in space” Later addition of volatiles by a “late heavy bombardment” Evidence for it are observed on the moon (ages spectra of impact melts), indirect evidences on Earth. “late heavy bombardment” might not happen in all planetary systems © source unknown. All rights reserved. This content is excluded From our Creative Commons license. For more information, see 10 http://ocw.mit.edu/help/faq-fair-use/.Analyses of oxygen isotopes in Zircons possible indicate presence of water at 4 Ga U-Pb + Trace elements oxygen U-Pb © source unknown. All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/help/faq-fair-use/. 11We formed a early earth but what were the condition on It? Courtesy of Brian Smallwood. Used with permission. 12© sources unknown. All rights reserved. This content is excluded from our Creative 13 Commons license. For more information, see http://ocw.mit.edu/help/faq-fair-use/.© sources unknown. All rights reserved. This content is excluded from our Creative 14 Commons license. For more information, see http://ocw.mit.edu/help/faq-fair-use/.BIF: Banded Iron Formations Chert (=SiO ) coated with Fe-Oxide 2 II III Magnetite-layers(Fe Fe O ) 2 4 © sources unknown. All rights reserved. This content is excluded from our Creative 15 Commons license. For more information, see http://ocw.mit.edu/help/faq-fair-use/.Presence of free water is puzzling given the low luminosity of the young sun. © sources unknown. All rights reserved. This content is excluded from our Creative 16 Commons license. For more information, see http://ocw.mit.edu/help/faq-fair-use/.17 © sources unknown. All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/help/faq-fair-use/.Feedback between silicate weathering and CO sequestering. 2 © sources unknown. All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/help/faq-fair-use/. 18Timeline of earth history removed due to copyright restrictions. 19Courtesy of NASA. Image in the public domain. Some people, like Fred Hoyle, proposed that life came from another planets with the help of meteorites.. 20

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