Geobiology

Carbon-the basis of life

Microbes

Life in extreme environments

Origin of life on earth

Origin of the atmosphere

Astrobiology...

Where do we find Carbon?

• Present in all living things• Diamonds and graphite• Calcium carbonate (limestone)• Oil • Coal• Atmosphere (CO2)• Meteorites• Volcanic eruptions

Carbon

Carbon

Sea creatures get C from the ocean water to make CaCO3

(carbonate)

Ooze fun facts

Sediment with >30% organic matter

Carbonate ooze: 48% of the ocean floor

Accumulates: 5 cm/1000 years

50 meters per million years

Dissolves at depths > 4.5 km

Foraminifera-carbonate shell

(this guy is < 1 mm wide)

Ocean Thermometers!

Carbon

Shells and coral and carbonate ooze forms limestone

Siliceous ooze

Plankton with silica shells

Covers 15% of the ocean floor

Makes chert

Carbon

Diatoms are algae with a silica shell...

45% of the total production of biomass from CO2 in the ocean water

Carbon

Radiolaria are another algae with a silica shell...

Chewy carbon center with a silica coating

Chert

Made from radiolaria

Ooze Summary

• Ooze is plankton with shells of:

-Carbonate: Foraminifera

-Silica: Diatoms and Radiolaria

• Ooze pulls carbon out of the water.

• When buried and heated, it can form PETROLEUM

Microbes

• Used to make bread and beer• Yogurt and cheese• Antibiotics• Minerals such as pyrite or magnetite

Microbes are everywhere

Single-celled organisms:

Bacteria, fungi, algae, protozoa

Microbe cell wall

Enzyme

Bacteria

Intracellular production of iron minerals is an example of direct precipitation.

Microbe cell wall

Bacteria

Extracellular precipitation of calcium carbonate is an example of indirect precipitation.

Ancient stromatolitesform columns.

Modern stromatolitesgrow in the intertidal zone.

Ancient stromatolitesform columns.

Modern stromatolitesgrow in the intertidal zone.

A cross section reveals layering similar to that seenin ancient stromatolites.

Ancient stromatolitesform columns.

Modern stromatolitesgrow in the intertidal zone.

A cross section reveals layering similar to that seenin ancient stromatolites.

Microbes live on thesurface of the stromatolite.

Sediment is depositedon the microbes,...

...which grow upward through the sediment, forming a new layer.

Life in Extreme Environments

• High Temperature• High Acidity (low pH)• High Salinity• Low Temperature

Thermophiles like it hot

Acidophiles like acidicwater

• pH can be as low as 1• They turn mine drainage

into sulfuric acid

Halophiles like it salty

Iceworms like it chillyThese live in frozen

methane

Origin of Life

• The Life in a Flask experiment

• The Murchison Meteorite

• Early earth had minimal oxygen-mostly CO2

Origin of Life

• Oldest microbes are 3.5 Ga

• Only microbes for 1 billion years!

Earth’s Atmosphere #1

• Earth’s first atmosphere was H and He• Heat from sun and magma drove it away

Earth’s Atmosphere #2

• 4.4 Ga• Volcano erupts gases• Gases = CO2, some N, some H2O• After cooling, CO2 went into oceans• Carbonate deposition

Atmosphere #3

• Cyanobacteria (3.3 Ga to 2.7 Ga) • Photosynthesis produces Oxygen (O)• Early O reacts with Fe in oceans to form

Iron oxide minerals• When Fe is gone, excess O goes into

atmosphere

Cambrian Explosion

• At 540 Ma there was an explosion of life

• Related to rise in oxygen in atmosphere?

Early animals: Hallucigenia

Div

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ity o

f org

an

ism

s

Age (Ma)

0200400600

800

0

200

400

600

Cambrianradiation

429 MaMass

extinction

364 MaMass

extinction

End-Permianmass extinction

208 MaMass extinction

End-Cretaceousmass extinction

Geologic Time Scale

• Boundaries of Geologic Time are related to extinction events

4560 MaEarth and planets form

4510 MaMoonforms

4000 MaOldestcontinentalrocks

3500 MaRecord of magnetic field Fossils of primitive bacteria

Mass extinctions

359 Ma 251 Ma 200 Ma 65 Ma Present

1500

1000

2000

3000

4000

500

Geologic Time Scale

• Precambrian (4.6 Ga to 540 Ma)• Paleozoic (540-250 Ma)• Mesozoic (250-65 Ma)

– Triassic– Jurassic– Cretaceous

• Cenozoic (65 Ma to the present)

To have life, we need water

Drainages on Mars:

Extraterrestrial Life?

Mars Earth

Martian Meteorite

Martian bacteria?

ET life?The Drake equation states that:

N = R* X fp X ne X fℓ X fi X fc X L

where:

N is the number of civilizations in our galaxy with which we might hope to be able to communicate;

and

R* is the average rate of star formation in our galaxy fp is the fraction of those stars that have planets ne is the average number of planets that can potentially support life per star that has planets fℓ is the fraction of the above that actually go on to develop life at some point fi is the fraction of the above that actually go on to develop intelligent life fc is the fraction of civilizations that develop a technology that releases detectable signs of their existence into space L is the length of time such civilizations release detectable signals into space.