Origins, Oxygen & Eukaryotes Flashcards
How did planet earth form? (dust)
Condensation of dust scattered in the solar system
Physical collision creates planetesimals which have gravity pulling matter creating protoplanet
What happened to planet earth 4.5 Bya?
An impact with another planetary body
What did the impact from 4.5 bya do to earth?
did a radical resetting of composition, structure and position
Formation of moon
How far back can rock crystallisation be used to date?
4.4 Ga (zircon - ZrSiO4)
from western Australia
What are the benefits of using Zircon as a dating method?
Robust and resistant to degradation
Incremental growth as material becomes abundant
What are some relics of the first rocks formed as an origin of earth?
Acaste gneiss complex
Northwest territories, Canada
4 billion years ago
What has the Acaste gneiss complex undergone?
Substantial metamorphism
What is a heavily contested period/ pause within the origin of earth that occured around 3.9-3.8 Bya?
The late heavy bombardment
What is the late heavy bombardment?
‘Rocks fell from the sky’
Extremely intense meteoritic bombardment
What would have potentially be worst affected by the late heavy bombardment?
surface organisms if life had developed on land before it would have been wiped due to a surface reset
What can be identified in the Isua greenstone belt in Greenland that shows there was water on land 3.8 Ga?
Non-vesicular pillow lava
How is pillow lava evidence of water on land 3.8 Ga?
This structure only forms due to the rapid cooling of lava due to water
How can the ocean edge be seen as an area for the origin of life?
Presence of Oparin-Haldine ‘prebiotic soup’ in reducing ocean (lack of oxygen) which when energy was received from lightning allows synthesis of organic compounds
What experiment has shown that life might have formed at ocean edges?
Miller-Urey
How have frozen seas been presented as a potential zone for the origin of life?
Trinks et al 2005 suggested sea ice could be the template for producing nucleotide chains
How has shallow tidal pools been suggested as an area for the origins of life?
Use clay as scaffolding to trap nucleotide chains between clay crystals
How can earth be a considered a clay factory?
as weathering of earths surface essentially produces clay
What was discovered in the 1980’s which completely rewrote the books on the origins of life?
Hydrothermal vents
What is the advantage to life of spawning around hydrothermal vents?
they spew complex chemical cocktail and a lot of energy which are needed for replication
What is potential evidence of life developing at hydrothermal vents seen in thin section and what is the contradiction?
Haematite filaments from Nuvvuagittuq supracrustal belt
Lokken jaspers
Contradiction hard to tell if cell or fracture in rock
What is more an indication of life forming around hydrothermal vents than filaments?
haematite tubes in the Nuvvuagittuq supracrustal belt and Løkken jaspers more likely due to similar modern day structures forming in these environments