Earth History

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The Mantle does not contain any

40K or 129I

 All 129 Xe in mantle came from 129I

Slide 10

Age of differentiation

From the ratio of 129 Xe in the Mantle to that of 129 Xe in the Atmosphere it possible to gain some idea of the age of differentiation as the Xe due to Nucleosynthesis would have been OUTGASSED into the atmosphere.

Slide 11

Ratios of Isotopes

The Argon trapped in Mantle evolved from the radioactive decay of 40K 40K

The Xenon trapped in Mantle evolved from the radioactive decay of 129I

The ratio of the amount in the mantle to the atmosphere can give information about the process of differentiation

Slide 12

Conclusions from Isotope Analysis

 If outgassing occurred at the beginning

the atmosphere would not contain 40Ar 4r

But would contain 129Xe

Results and Calculations indicate

80% to 85% of the Earth’s Atmosphere was outgassed in the first million years

Slide 13

Collecting the evidence

The other 15% has arisen due to slow release over 4.4 billion years

Difficult Analytical Problem requiring

Concentration of the samples

Specific Choice of Sampling Sites

Slide 14

Early Atmosphere

Majors: CO2, N2, H2O (Water Vapour)

Traces: CH4, NH3, SO2, HCl

Water Vapour Oceans

FeO/Fe2O3 (Grand Canyon) indicates

O2 emerged in the atmosphere about 2 billion years ago`

Slide 15

Origin of Life

Stanley Miller (1950) “ Early Earth ”

Experimental Setup

CH4, NH3, H2, H2O(g) ( Atmosphere)

H2O(l) ( Oceans)

Electrode discharge (Simulate Lightning)

Analysis of Fractions

Slide 16

Formation of Simple Amino Acids

Glycine was found

How Glycine (NH2CH2COOH) Formed

HCOH + NH3 + HCN  NH2CH2CN + H2O

Formaldehyde Cyanide Hydrogen

Aminonitrile

NH2CH2CN + 2 H2O  NH2CH2COOH + NH3

Slide 17

Murchison Meteor

A number of the compounds discovered in the discharge fractions are precursors to life.

Years later a meteor struck at Murchison

(Victoria) was also analyzed and its contents found to be similar to those of the discharge experiment of Stanley Miller

Slide 18

Early Energy System